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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
Posted to sci.electronics.repair
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newbie solder question
I've been following the electronics newsgroups for some time, and decided to
try a small repair job. I have a 20Wx2 small single-board amplifier which has only worked on one channel since it was given to me. Due to its' small size, I'd like to repair it. Anyway, I used a DMM to test each of the 20 or so electrolytic capacitors on the board. I know, I know, you can't really test them in the circuit and expect a 100% accurate result. But as it's a two-channel amp, I figured that at least the equivilant capacitors in Channel A and Channel B should exhibit identical behavior. I located two 470uF caps which differed in that one of them had zero resistance which did not rise, even on the highest resistance scape of my DMM, 20M ohm, as did all of the other caps. So, I figured I'd swap the two identical caps (channel A and channel B). I tried using desoldering braid (which I've used many times with great results) and found that the solder on this board just wouldn't melt with my 30W iron. Well, says I , I'll just use a bigger stick. I grabbed the 45W iron and still couldn't seem to melt the solder through the braid, although the 45W iron WOULD melt the solder directly. I heated each lead and wiggled and jiggled it loose. When I had both caps removed I put the desoldering braid directly over the hole in the PCB and with a pointed tip leaned on the board until the braid cleared up the solder. This took maybe a minute or more of continuous heat. When I removed the brad, AAAAGGGHH, it seems to have removed all of the metal around the hole, not just the solder. Now the trace itself to which the cap is connected is on the other side of the board and I could put in a cap with slightly longer leads and solder it on the top. But if there's a way to fix what I've done that'd be even better. When I put in the original cap the solder just won't seem to go into the hole any more, it just sticks to the iron. Any advice greatly appreciated, I suppose this is how folks learn. BTW, when I got both caps out they tested identically out of the circuit so I'm pretty sure my problem is elsewhere. The circuit consists of a simple power supply, unregulated, a whack of tiny (mainly 10uF 50V) electrolytic caps, some mylar caps, resistors, a bass/treble IC, two 20W TO-220 amplifier chips. I can very very faintly hear sound in the bad channel. When I turn the volume up and down on the bad channel it makes a sort of "thumping" sound from the bad speaker but doesn't amplify the sound. I've replaced the amplfier chip on the bad channel as it was cheap and simple but this did not help. Anybody have any suggestions what to check next? I do not own an oscilloscope. I have checked and cleaned all of the knobs (bass, treble, balance, volume), they all work as they're supposed to. Thanks Dave |
#2
Posted to sci.electronics.repair
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newbie solder question
You often have to isolate components or parts of the circuit to
diagnose things anyway. Personally, I prefer a very hot temperature controlled soldering iron and vacuum type solder sucker. Work fast and don't let the heat travel beyond where you want it. I know others prefer your method. If you do lift a pad or trace, cut it with an exacto knife to keep it from lifting any more and replace it with hookup wire wrapped around the component leads and soldered to the edge of the broken trace. If the traces are covered with a solder mask, you'll have to scrape some of that away before you can solder. Dave wrote: I've been following the electronics newsgroups for some time, and decided to try a small repair job. I have a 20Wx2 small single-board amplifier which has only worked on one channel since it was given to me. Due to its' small size, I'd like to repair it. Anyway, I used a DMM to test each of the 20 or so electrolytic capacitors on the board. I know, I know, you can't really test them in the circuit and expect a 100% accurate result. But as it's a two-channel amp, I figured that at least the equivilant capacitors in Channel A and Channel B should exhibit identical behavior. I located two 470uF caps which differed in that one of them had zero resistance which did not rise, even on the highest resistance scape of my DMM, 20M ohm, as did all of the other caps. So, I figured I'd swap the two identical caps (channel A and channel B). I tried using desoldering braid (which I've used many times with great results) and found that the solder on this board just wouldn't melt with my 30W iron. Well, says I , I'll just use a bigger stick. I grabbed the 45W iron and still couldn't seem to melt the solder through the braid, although the 45W iron WOULD melt the solder directly. I heated each lead and wiggled and jiggled it loose. When I had both caps removed I put the desoldering braid directly over the hole in the PCB and with a pointed tip leaned on the board until the braid cleared up the solder. This took maybe a minute or more of continuous heat. When I removed the brad, AAAAGGGHH, it seems to have removed all of the metal around the hole, not just the solder. Now the trace itself to which the cap is connected is on the other side of the board and I could put in a cap with slightly longer leads and solder it on the top. But if there's a way to fix what I've done that'd be even better. When I put in the original cap the solder just won't seem to go into the hole any more, it just sticks to the iron. Any advice greatly appreciated, I suppose this is how folks learn. BTW, when I got both caps out they tested identically out of the circuit so I'm pretty sure my problem is elsewhere. The circuit consists of a simple power supply, unregulated, a whack of tiny (mainly 10uF 50V) electrolytic caps, some mylar caps, resistors, a bass/treble IC, two 20W TO-220 amplifier chips. I can very very faintly hear sound in the bad channel. When I turn the volume up and down on the bad channel it makes a sort of "thumping" sound from the bad speaker but doesn't amplify the sound. I've replaced the amplfier chip on the bad channel as it was cheap and simple but this did not help. Anybody have any suggestions what to check next? I do not own an oscilloscope. I have checked and cleaned all of the knobs (bass, treble, balance, volume), they all work as they're supposed to. Thanks Dave |
#3
Posted to sci.electronics.repair
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newbie solder question
In article 2jOzf.93171$AP5.22906@edtnps84, "Dave" wrote:
I've been following the electronics newsgroups for some time, and decided to try a small repair job. I have a 20Wx2 small single-board amplifier which has only worked on one channel since it was given to me. Due to its' small size, I'd like to repair it. Anyway, I used a DMM to test each of the 20 or so electrolytic capacitors on the board. I know, I know, you can't really test them in the circuit and expect a 100% accurate result. But as it's a two-channel amp, I figured that at least the equivilant capacitors in Channel A and Channel B should exhibit identical behavior. I located two 470uF caps which differed in that one of them had zero resistance which did not rise, even on the highest resistance scape of my DMM, 20M ohm, as did all of the other caps. So, I figured I'd swap the two identical caps (channel A and channel B). I tried using desoldering braid (which I've used many times with great results) and found that the solder on this board just wouldn't melt with my 30W iron. Well, says I , I'll just use a bigger stick. I grabbed the 45W iron and still couldn't seem to melt the solder through the braid, although the 45W iron WOULD melt the solder directly. I heated each lead and wiggled and jiggled it loose. When I had both caps removed I put the desoldering braid directly over the hole in the PCB and with a pointed tip leaned on the board until the braid cleared up the solder. This took maybe a minute or more of continuous heat. When I removed the brad, AAAAGGGHH, it seems to have removed all of the metal around the hole, not just the solder. Now the trace itself to which the cap is connected is on the other side of the board and I could put in a cap with slightly longer leads and solder it on the top. But if there's a way to fix what I've done that'd be even better. When I put in the original cap the solder just won't seem to go into the hole any more, it just sticks to the iron. Any advice greatly appreciated, I suppose this is how folks learn. BTW, when I got both caps out they tested identically out of the circuit so I'm pretty sure my problem is elsewhere. The circuit consists of a simple power supply, unregulated, a whack of tiny (mainly 10uF 50V) electrolytic caps, some mylar caps, resistors, a bass/treble IC, two 20W TO-220 amplifier chips. I can very very faintly hear sound in the bad channel. When I turn the volume up and down on the bad channel it makes a sort of "thumping" sound from the bad speaker but doesn't amplify the sound. I've replaced the amplfier chip on the bad channel as it was cheap and simple but this did not help. Anybody have any suggestions what to check next? I do not own an oscilloscope. I have checked and cleaned all of the knobs (bass, treble, balance, volume), they all work as they're supposed to. Thanks Dave You didn't mention measuring at the same points with caps removed. I usually recompose circuit traces with solid conductor wire. Probably at least a 50% chance the chip is bad. Sometimes I have to double up on irons. I've also lit the Bic next to the iron for more heat. My Radio Shack 250 watt gun for big jobs! greg |
#4
Posted to sci.electronics.repair
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newbie solder question
Give up using the braid...that stuff sucks (or, rather, it doesn't).
Get yourself a solder sucker if you're going to do stuff like this. BTW, if I had an audio power amp that didn't work, I think the caps would be near the end of my list of things to check. Start with the power (aka output) transistors and work your way backwards. Unless this is a really esoteric unit, both channels probably share the power supply, so if one channel is working, you can probably assume that's OK. |
#5
Posted to sci.electronics.repair
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newbie solder question
"Mr. Land" wrote in message oups.com... Give up using the braid...that stuff sucks (or, rather, it doesn't). Get yourself a solder sucker if you're going to do stuff like this. As I noted before I've used the braid quite a bit in the past and found it to work well... but will pick up a sucker anyways as obviously I need it. BTW, if I had an audio power amp that didn't work, I think the caps would be near the end of my list of things to check. Start with the power (aka output) transistors and work your way backwards. Unless this is a really esoteric unit, both channels probably share the power supply, so if one channel is working, you can probably assume that's OK. I did start at the output transisters and replaced them all on the bad channel (they're all on an integrated 20W amp chip, NS LM1875). I swapped the caps in an effort to avoid trying to source a 10-year-old base/treble IC which is likely the problem. Other than the output IC's, mixer IC, and rectifier, there ain't a whole lot on the board except caps and resistors. Resistors all checked out OK, move on to electrolytics... No? |
#6
Posted to sci.electronics.repair
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newbie solder question
"Dave" wrote in message news:AtQzf.93177$AP5.80078@edtnps84... "Mr. Land" wrote in message oups.com... Give up using the braid...that stuff sucks (or, rather, it doesn't). Get yourself a solder sucker if you're going to do stuff like this. As I noted before I've used the braid quite a bit in the past and found it to work well... but will pick up a sucker anyways as obviously I need it. My general rule is a solder sucker for standard work and braid for smaller or awkward tasks, especially certain surface mount work. A solder sucker is far more appropriate for removing components like electrolytic caps from an amp IMO. BTW, if I had an audio power amp that didn't work, I think the caps would be near the end of my list of things to check. Start with the power (aka output) transistors and work your way backwards. Unless this is a really esoteric unit, both channels probably share the power supply, so if one channel is working, you can probably assume that's OK. I did start at the output transisters and replaced them all on the bad channel (they're all on an integrated 20W amp chip, NS LM1875). I swapped the caps in an effort to avoid trying to source a 10-year-old base/treble IC which is likely the problem. Other than the output IC's, mixer IC, and rectifier, there ain't a whole lot on the board except caps and resistors. Resistors all checked out OK, move on to electrolytics... No? Do you still have a short? If so that makes things very easy- a short is probably the easiest fault there is to diagnose. Simply trace the two PCB tracks which are shorted and find all other components across these tracks. One of them must be shorted out. Is the capacitor in question on the supply rail? Check that the new IC you fitted doesn't have any solder bridges, and if it has a mica heatsink insulator, make sure it's not damaged. I doubt it's a shorted cap, but it is possible nonetheless. It's possible the 470uF capacitor is part of the decoupled supply to the preamp section, if so it may have a zener diode in parallel to give a regulated supply. Therefore, check for shorted zeners. The output ICs no doubt are coupled to the speakers via large electrolytic capacitors, what is the voltage level on the IC side of this cap with respect to ground? It should be close to half supply potential. Compare it with the good side, but take care not to short anything out. Are both output ICs getting a supply? Are they both getting a ground? Have you measured voltage levels on each pin and compared them with the good side? Have you downloaded a datasheet for the ICs, found the input pin and injected a signal there to listen for output? Even touching a finger to the input pin may give a buzz from the speaker, or a screwdriver may give a click. There's ways and means, even without test equipment! Dave |
#7
Posted to sci.electronics.repair
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newbie solder question
On Thu, 19 Jan 2006 15:33:18 GMT, "Dave"
wrote: I've been following the electronics newsgroups for some time, and decided to try a small repair job. I have a 20Wx2 small single-board amplifier which has only worked on one channel since it was given to me. Due to its' small size, I'd like to repair it. Anyway, I used a DMM to test each of the 20 or so electrolytic capacitors on the board. I know, I know, you can't really test them in the circuit and expect a 100% accurate result. But as it's a two-channel amp, I figured that at least the equivilant capacitors in Channel A and Channel B should exhibit identical behavior. I located two 470uF caps which differed in that one of them had zero resistance which did not rise, even on the highest resistance scape of my DMM, 20M ohm, as did all of the other caps. So, I figured I'd swap the two identical caps (channel A and channel B). I tried using desoldering braid (which I've used many times with great results) and found that the solder on this board just wouldn't melt with my 30W iron. Well, says I , I'll just use a bigger stick. I grabbed the 45W iron and still couldn't seem to melt the solder through the braid, although the 45W iron WOULD melt the solder directly. I heated each lead and wiggled and jiggled it loose. When I had both caps removed I put the desoldering braid directly over the hole in the PCB and with a pointed tip leaned on the board until the braid cleared up the solder. This took maybe a minute or more of continuous heat. When I removed the brad, AAAAGGGHH, it seems to have removed all of the metal around the hole, not just the solder. Now the trace itself to which the cap is connected is on the other side of the board and I could put in a cap with slightly longer leads and solder it on the top. But if there's a way to fix what I've done that'd be even better. When I put in the original cap the solder just won't seem to go into the hole any more, it just sticks to the iron. Any advice greatly appreciated, I suppose this is how folks learn. BTW, when I got both caps out they tested identically out of the circuit so I'm pretty sure my problem is elsewhere. The circuit consists of a simple power supply, unregulated, a whack of tiny (mainly 10uF 50V) electrolytic caps, some mylar caps, resistors, a bass/treble IC, two 20W TO-220 amplifier chips. I can very very faintly hear sound in the bad channel. When I turn the volume up and down on the bad channel it makes a sort of "thumping" sound from the bad speaker but doesn't amplify the sound. I've replaced the amplfier chip on the bad channel as it was cheap and simple but this did not help. Anybody have any suggestions what to check next? I do not own an oscilloscope. I have checked and cleaned all of the knobs (bass, treble, balance, volume), they all work as they're supposed to. Thanks Dave Well back in the "old days" we used "eyelets" - didn't have plated through holes for circuit boards. The eyelets were just miniature one part hollow rivets - or similar to grommets used in sails or tarpaulins. That would be an ideal fix if you burnt the plating off. Solder Wick for single sided boards - solder sucker for double sided boards. Regarding the amp. Have you checked the DC voltages between the channels? Is this a single supply or plus and minus supplies? TO220 - five lead power op amp? built in thermal, short circuit, and safe operating area protection? I assume you only have one chip per channel (or "bridged" with two chips per channel?) If you can identify the chip and its input(S), you might try using a capacitor to bridge signal from the working channel's input into the input of the dead channel. (observing polarity if using an electrolytic). Unplug the input to the dead channel while testing if possible. The cap size will be 10 uf or less for a high impedance audio stage input. That should localize the problem between the input or output of the power amp chip. If it is like the TO220's I'm using, there's a differential input (inverting and non-inverting) inputs - make sure you drive the correct one). One assumes you switched speakers at some point. -- ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#8
Posted to sci.electronics.repair
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newbie solder question
default wrote in message ... On Thu, 19 Jan 2006 15:33:18 GMT, "Dave" wrote: Well back in the "old days" we used "eyelets" - didn't have plated through holes for circuit boards. The eyelets were just miniature one part hollow rivets - or similar to grommets used in sails or tarpaulins. That would be an ideal fix if you burnt the plating off. I think I'll solder to the trace on the other side of the board, just means that the cap won't sit flush anymore but that's okay, lots of room in the enclosure. Solder Wick for single sided boards - solder sucker for double sided boards. Yes, must buy solder sucker. It's on my list now. Regarding the amp. Have you checked the DC voltages between the channels? No. Do you mean between the channel A and channel B signal outputs with no signal applied to the inputs? If there WAS a DC voltage differential what might this tell me? Failed coupling cap? There are no output caps, the amp output pin (see below) goes straight to the center pin of the RCA jack on the back. Is this a single supply or plus and minus supplies? Both the amp and bass/treble/volume/balance IC's run off +Vcc. TO220 - five lead power op amp? built in thermal, short circuit, and safe operating area protection? I assume you only have one chip per channel (or "bridged" with two chips per channel?) One chip per channel. They're LM1875T's, yes they have built-in thermal, short circuit, etc. As I noted I have already replaced the one on the bad channel (they are a TO-220 package). If you can identify the chip and its input(S), you might try using a capacitor to bridge signal from the working channel's input into the input of the dead channel. (observing polarity if using an electrolytic). Unplug the input to the dead channel while testing if possible. The cap size will be 10 uf or less for a high impedance audio stage input. That should localize the problem between the input or output of the power amp chip. Does it matter if I use an electrolytic or not? See pinout below, but I'd connect pin 1 of channel A (working) to pin 1 of channel B (dead). If I do use electrolytics, which end is positive, A or B? Why do I need to use a capacitor to bridge as opposed to a wire? If it is like the TO220's I'm using, there's a differential input (inverting and non-inverting) inputs - make sure you drive the correct one). Here's the pinout: 1 +IN 2 -IN 3 -V(EE) 4 OUTPUT 5 V(CC) From what I can see, pin 1 is signal in, pin 2 is used as the negative feedback loop, being connected to pin 4 via a 20K resistor. There are no coupling caps on the outputs. One assumes you switched speakers at some point. -- Yes, first thing I tried. |
#9
Posted to sci.electronics.repair
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newbie solder question
"Dave D" wrote in message news Do you still have a short? If so that makes things very easy- a short is probably the easiest fault there is to diagnose. Simply trace the two PCB tracks which are shorted and find all other components across these tracks. One of them must be shorted out. Is the capacitor in question on the supply rail? Check that the new IC you fitted doesn't have any solder bridges, and if it has a mica heatsink insulator, make sure it's not damaged. I doubt it's a shorted cap, but it is possible nonetheless. I checked for solder bridges on the new IC VERY carefully when I put it in, as I did also inspect the mica insulator. It's possible the 470uF capacitor is part of the decoupled supply to the preamp section, if so it may have a zener diode in parallel to give a regulated supply. Therefore, check for shorted zeners. The balance/tone/volume IC (which is basically my entiere 'pre-amp section') has a zener internally, BUT I see that it also uses an external decoupling cap on the internally regulated voltage supply... must check which cap performs this function. The output ICs no doubt are coupled to the speakers via large electrolytic capacitors, what is the voltage level on the IC side of this cap with respect to ground? It should be close to half supply potential. Compare it with the good side, but take care not to short anything out. No, no output caps at all. Output pin of amp IC goes directly to RCA plug via large trace. Are both output ICs getting a supply? Are they both getting a ground? Have you measured voltage levels on each pin and compared them with the good side? Have you downloaded a datasheet for the ICs, found the input pin and injected a signal there to listen for output? Even touching a finger to the input pin may give a buzz from the speaker, or a screwdriver may give a click. There's ways and means, even without test equipment! Dave |
#10
Posted to sci.electronics.repair
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newbie solder question
"Dave" wrote in message news:t1Uzf.110817$km.52961@edtnps89... default wrote in message ... On Thu, 19 Jan 2006 15:33:18 GMT, "Dave" wrote: Well back in the "old days" we used "eyelets" - didn't have plated through holes for circuit boards. The eyelets were just miniature one part hollow rivets - or similar to grommets used in sails or tarpaulins. That would be an ideal fix if you burnt the plating off. I think I'll solder to the trace on the other side of the board, just means that the cap won't sit flush anymore but that's okay, lots of room in the enclosure. Solder Wick for single sided boards - solder sucker for double sided boards. Yes, must buy solder sucker. It's on my list now. Regarding the amp. Have you checked the DC voltages between the channels? No. Do you mean between the channel A and channel B signal outputs with no signal applied to the inputs? If there WAS a DC voltage differential what might this tell me? Failed coupling cap? There are no output caps, the amp output pin (see below) goes straight to the center pin of the RCA jack on the back. Is this a single supply or plus and minus supplies? Both the amp and bass/treble/volume/balance IC's run off +Vcc. TO220 - five lead power op amp? built in thermal, short circuit, and safe operating area protection? I assume you only have one chip per channel (or "bridged" with two chips per channel?) One chip per channel. They're LM1875T's, yes they have built-in thermal, short circuit, etc. As I noted I have already replaced the one on the bad channel (they are a TO-220 package). If you can identify the chip and its input(S), you might try using a capacitor to bridge signal from the working channel's input into the input of the dead channel. (observing polarity if using an electrolytic). Unplug the input to the dead channel while testing if possible. The cap size will be 10 uf or less for a high impedance audio stage input. That should localize the problem between the input or output of the power amp chip. Does it matter if I use an electrolytic or not? See pinout below, but I'd connect pin 1 of channel A (working) to pin 1 of channel B (dead). If I do use electrolytics, which end is positive, A or B? Why do I need to use a capacitor to bridge as opposed to a wire? If it is like the TO220's I'm using, there's a differential input (inverting and non-inverting) inputs - make sure you drive the correct one). Here's the pinout: 1 +IN 2 -IN 3 -V(EE) 4 OUTPUT 5 V(CC) From what I can see, pin 1 is signal in, pin 2 is used as the negative feedback loop, being connected to pin 4 via a 20K resistor. There are no coupling caps on the outputs. One assumes you switched speakers at some point. -- Yes, first thing I tried. All of the advice given so far regarding the fault, is good stuff. As far as solder wick / solder sucker / desoldering stations go, it's horses for courses. Contrary to what one of the posters said about solder wick " sucking " ( or not ... ), in my experience, this is only the case when you either buy cheap, or use the wrong size for the job. Buying cheap at radio rallies, will just get you old stock, where the flux has gone off, and then, it doesn't suck. Using a solder wick with too big a size, with an iron that's too small tip wise, or power wise, results in insufficient heat transfer to the joint, and then it doesn't suck. A solder sucker is very good for medium sized joints, but there is a real technique to using one well, and if you use it on a ' poor ' quality board, it will readily suck the print off as well as the solder. There is a real balance between getting enough heat into the joint to melt the solder to a point where it will stay molten enough to be sucked cleanly off the board, and not destroying the bonding between the copper and the substrate. If you do get yourself a solder sucker, get a good one for which all parts are available - nozzle, neoprene suction washer, circlip ( you'll lose it ! ) etc. Practice a lot on a scrap board to get the heat / time thing right. Clean it out regularly, and don't buy cheap !! Arfa |
#11
Posted to sci.electronics.repair
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newbie solder question
"Arfa Daily" wrote in message ... All of the advice given so far regarding the fault, is good stuff. As far as solder wick / solder sucker / desoldering stations go, it's horses for courses. Contrary to what one of the posters said about solder wick " sucking " ( or not ... ), in my experience, this is only the case when you either buy cheap, or use the wrong size for the job. Buying cheap at radio rallies, will just get you old stock, where the flux has gone off, and then, it doesn't suck. Using a solder wick with too big a size, with an iron that's too small tip wise, or power wise, results in insufficient heat transfer to the joint, and then it doesn't suck. Well, my desolder braid is cheap and old, and PERHAPS a bit too thick for the job, but it's worked well recently on similar-sized joints using the same iron. A solder sucker is very good for medium sized joints, but there is a real technique to using one well, and if you use it on a ' poor ' quality board, it will readily suck the print off as well as the solder. There is a real balance between getting enough heat into the joint to melt the solder to a point where it will stay molten enough to be sucked cleanly off the board, and not destroying the bonding between the copper and the substrate. If you do get yourself a solder sucker, get a good one for which all parts are available - nozzle, neoprene suction washer, circlip ( you'll lose it ! ) etc. Practice a lot on a scrap board to get the heat / time thing right. Clean it out regularly, and don't buy cheap !! Thanks for the advice, have not used one before. Unfortunately where I live there are very few stores which sell electronic parts and buying one off of the internet generally costs twice as much when you get done with shipping and taxes and the like. |
#12
Posted to sci.electronics.repair
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newbie solder question
"Dave" wrote in message newspVzf.80723$m05.78222@clgrps12... "Arfa Daily" wrote in message ... All of the advice given so far regarding the fault, is good stuff. As far as solder wick / solder sucker / desoldering stations go, it's horses for courses. Contrary to what one of the posters said about solder wick " sucking " ( or not ... ), in my experience, this is only the case when you either buy cheap, or use the wrong size for the job. Buying cheap at radio rallies, will just get you old stock, where the flux has gone off, and then, it doesn't suck. Using a solder wick with too big a size, with an iron that's too small tip wise, or power wise, results in insufficient heat transfer to the joint, and then it doesn't suck. Well, my desolder braid is cheap and old, and PERHAPS a bit too thick for the job, but it's worked well recently on similar-sized joints using the same iron. A solder sucker is very good for medium sized joints, but there is a real technique to using one well, and if you use it on a ' poor ' quality board, it will readily suck the print off as well as the solder. There is a real balance between getting enough heat into the joint to melt the solder to a point where it will stay molten enough to be sucked cleanly off the board, and not destroying the bonding between the copper and the substrate. If you do get yourself a solder sucker, get a good one for which all parts are available - nozzle, neoprene suction washer, circlip ( you'll lose it ! ) etc. Practice a lot on a scrap board to get the heat / time thing right. Clean it out regularly, and don't buy cheap !! Thanks for the advice, have not used one before. Unfortunately where I live there are very few stores which sell electronic parts and buying one off of the internet generally costs twice as much when you get done with shipping and taxes and the like. This is true. I used to use solder wick years ago, and it wasn't very good, so I stuck to a solder sucker. Then, a few years ago, huge amounts started appearing at rallies for like 1 UKP per reel, so I bought loads, as did friends. It was crap. I then read an article in my national ham radio journal about this, and it said that the reason that the stuff didn't work was because even though it was housed in a basically airtight container, over several years of storage, the oxygen in the atmosphere reacted with the powder flux that it's impregnated with, and destroyed its fluxing characteristics. Hence the reason that it had been dumped cheap on the amateur market, as it was of no commercial value at all. Soon after this disappointing experience, I had occasion to be in a fellow professional's workshop, and saw him using some solder wick made by " Multicore ", and was amazed at its efficacy, so I immediately ordered a reel, and now always have some at the ready. It's not cheap at 30 UKP for a 30m reel ( about $48 ) but it lasts a long time. I also use a Weller vacuum desoldering station, but that's too expensive for amateur use, unless one can be picked up cheap on e-Bay. Arfa |
#13
Posted to sci.electronics.repair
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newbie solder question
In article 2jOzf.93171$AP5.22906@edtnps84,
"Dave" wrote: I located two 470uF caps which differed in that one of them had zero resistance which did not rise, even on the highest resistance scape of my DMM, 20M ohm, as did all of the other caps. So, I figured I'd swap the two identical caps (channel A and channel B). I tried using desoldering braid (which I've used many times with great results) and found that the solder on this board just wouldn't melt with my 30W iron. Well, says I , I'll just use a bigger stick. I grabbed the 45W iron and still couldn't seem to melt the solder through the braid, although the 45W iron WOULD melt the solder directly. I heated each lead and wiggled and jiggled it loose. When I had both caps removed I put the desoldering braid directly over the hole in the PCB and with a pointed tip leaned on the board until the braid cleared up the solder. This took maybe a minute or more of continuous heat. Thanks Dave Liquid flux. If you solder, you need it. Liquid flux. If you desolder, you need it. Liquid flux. Good solder braid is better than any sucker I've ever used, with the exception of the heated, power suckers, which are a tad pricy for the casual hobbyist. Liquid flux. Did I mention liquid flux? A minute of continuous heat? I'd recommend a better quality soldering iron. You shouldn't be taking any longer than a second or two to solder, and two or three to desolder, small components like that. Also, get some liquid flux. |
#14
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newbie solder question
Dave wrote:
Well, my desolder braid is cheap and old, and PERHAPS a bit too thick for the job, but it's worked well recently on similar-sized joints using the same iron. My experience with solder sucking bulbs and plungers has been a lot worse than with braid, except when the joint had a huge amount of solder, and even then I sometimes had to remove the final traces of solder by using braid I once used braid that was over 1/8" wide, and it was terrible because it absorbed too much heat. 0.06" - 0.08" works best for me. I also avoid braid that's tarnished (won't stick to solder) or coarse (not enough surface area, probably low quality as well), and I keep the soldering iron tip really clean and cut off used braid right away because dangling braid just draws heat away from the joint. I cut it even if it isn't full of solder because its flux has been ruined by the heat, keeping it from stick to solder. When solder won't melt into the braid, I add more solder to the joint because it seems that factory solder has a higher melting point or some kind of film over it. I don't understand why 45W isn't enough heat, but some irons seem to deliver more heat to their tips than others of the same watt rating do, or they get weak with age. 35W has been enough for me with single-layer boards, except on large copper areas, and 45W should be able to do 2-layer boards or even the smaller components on multilayer boards, even when the lead connects to the internal ground or voltage plane (I normally use 50W). |
#15
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newbie solder question
"Dave" wrote in message news:2jOzf.93171$AP5.22906@edtnps84... ... I tried using desoldering braid (which I've used many times with great results) and found that the solder on this board just wouldn't melt with my 30W iron. Well, says I , I'll just use a bigger stick. I grabbed the 45W iron and still couldn't seem to melt the solder through the braid, although the 45W iron WOULD melt the solder directly. I heated each lead and wiggled and jiggled it loose. When I had both caps removed I put the desoldering braid directly over the hole in the PCB and with a pointed tip leaned on the board until the braid cleared up the solder. This took maybe a minute or more of continuous heat. That's far too long to hold an iron to a joint. Aside from using functional (i.e. quality) wicks, something you need to keep in mind is tip cleaning and tinning. http://www.inlandcraft.com/Uguides/tipcare.htm As for wicks, I've tried lots of different brands and from my experience Tech-Spray's Pro Wicks and Easy Braid's Quick Braids give the best bang for the buck. I've never had a spool of Pro Wick fail me, even after many years in storage. Quick Braid is a little less expensive, though both are priced very reasonably. Pro Wick performs better, with a little quicker heating and a faster solder draw. Avoid Pro's Tool wicks like the plague. A good compromise between an expensive professional desoldering station and a cheap solder sucker is one of the powered solder suckers. These have a heated barrel like the desoldering station guns and a simple vacuum chamber like the inexpensive solder suckers. The wattage of these irons is typically 30-45W. They can be had for around $20-$30US. |
#16
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newbie solder question
In article , Smitty Two wrote:
In article 2jOzf.93171$AP5.22906@edtnps84, "Dave" wrote: I located two 470uF caps which differed in that one of them had zero resistance which did not rise, even on the highest resistance scape of my DMM, 20M ohm, as did all of the other caps. So, I figured I'd swap the two identical caps (channel A and channel B). I tried using desoldering braid (which I've used many times with great results) and found that the solder on this board just wouldn't melt with my 30W iron. Well, says I , I'll just use a bigger stick. I grabbed the 45W iron and still couldn't seem to melt the solder through the braid, although the 45W iron WOULD melt the solder directly. I heated each lead and wiggled and jiggled it loose. When I had both caps removed I put the desoldering braid directly over the hole in the PCB and with a pointed tip leaned on the board until the braid cleared up the solder. This took maybe a minute or more of continuous heat. Thanks Dave Liquid flux. If you solder, you need it. Liquid flux. If you desolder, you need it. Liquid flux. Good solder braid is better than any sucker I've ever used, with the exception of the heated, power suckers, which are a tad pricy for the casual hobbyist. Liquid flux. Did I mention liquid flux? A minute of continuous heat? I'd recommend a better quality soldering iron. You shouldn't be taking any longer than a second or two to solder, and two or three to desolder, small components like that. Also, get some liquid flux. I would not be without my flux pen. I never tried to make some. Just alcohol and regular flux. greg |
#17
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newbie solder question
GregS wrote:
In article , Smitty Two wrote: In article 2jOzf.93171$AP5.22906@edtnps84, "Dave" wrote: I located two 470uF caps which differed in that one of them had zero resistance which did not rise, even on the highest resistance scape of my DMM, 20M ohm, as did all of the other caps. So, I figured I'd swap the two identical caps (channel A and channel B). I tried using desoldering braid (which I've used many times with great results) and found that the solder on this board just wouldn't melt with my 30W iron. Well, says I , I'll just use a bigger stick. I grabbed the 45W iron and still couldn't seem to melt the solder through the braid, although the 45W iron WOULD melt the solder directly. I heated each lead and wiggled and jiggled it loose. When I had both caps removed I put the desoldering braid directly over the hole in the PCB and with a pointed tip leaned on the board until the braid cleared up the solder. This took maybe a minute or more of continuous heat. Thanks Dave Liquid flux. If you solder, you need it. Liquid flux. If you desolder, you need it. Liquid flux. Good solder braid is better than any sucker I've ever used, with the exception of the heated, power suckers, which are a tad pricy for the casual hobbyist. Liquid flux. Did I mention liquid flux? A minute of continuous heat? I'd recommend a better quality soldering iron. You shouldn't be taking any longer than a second or two to solder, and two or three to desolder, small components like that. Also, get some liquid flux. I would not be without my flux pen. I never tried to make some. Just alcohol and regular flux. greg BTW, one use for the flux--I use the paste stuff, must try the liquid--is to 'activate' old desoldering braid. When doing a lot of work on old boards, I keep the tin of flux open, heat the braid and dip the end into the flux between uses. It activates the braid and makes for much easier desoldering. Is that also the way to use the liquid stuff? It would probably be a less messy than my procedure..... jak |
#18
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newbie solder question
In article , jakdedert wrote:
GregS wrote: In article , Smitty Two wrote: In article 2jOzf.93171$AP5.22906@edtnps84, "Dave" wrote: I located two 470uF caps which differed in that one of them had zero resistance which did not rise, even on the highest resistance scape of my DMM, 20M ohm, as did all of the other caps. So, I figured I'd swap the two identical caps (channel A and channel B). I tried using desoldering braid (which I've used many times with great results) and found that the solder on this board just wouldn't melt with my 30W iron. Well, says I , I'll just use a bigger stick. I grabbed the 45W iron and still couldn't seem to melt the solder through the braid, although the 45W iron WOULD melt the solder directly. I heated each lead and wiggled and jiggled it loose. When I had both caps removed I put the desoldering braid directly over the hole in the PCB and with a pointed tip leaned on the board until the braid cleared up the solder. This took maybe a minute or more of continuous heat. Thanks Dave Liquid flux. If you solder, you need it. Liquid flux. If you desolder, you need it. Liquid flux. Good solder braid is better than any sucker I've ever used, with the exception of the heated, power suckers, which are a tad pricy for the casual hobbyist. Liquid flux. Did I mention liquid flux? A minute of continuous heat? I'd recommend a better quality soldering iron. You shouldn't be taking any longer than a second or two to solder, and two or three to desolder, small components like that. Also, get some liquid flux. I would not be without my flux pen. I never tried to make some. Just alcohol and regular flux. greg BTW, one use for the flux--I use the paste stuff, must try the liquid--is to 'activate' old desoldering braid. When doing a lot of work on old boards, I keep the tin of flux open, heat the braid and dip the end into the flux between uses. It activates the braid and makes for much easier desoldering. Is that also the way to use the liquid stuff? It would probably be a less messy than my procedure..... jak right! |
#19
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newbie solder question
So, Dave...
This topic seems to have drifted off of the subject of helping you troubleshoot your amp and onto desoldering techniques and tools...(not that that isn't great content). So have you fixed it? If not, what's this 10-year-old mixer IC you mention? Do you have a pinout of it? How do the DC voltages on all the pins of the output IC compare? If you have a meter-based meter (was that redundant?), can you see any DC fluctuation on the input or output pins of the output IC's when you spin the volume control? Check both channels and compare them. I've seen speaker "thumping" occur when DC was getting to an input it shouldn't be. |
#20
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newbie solder question
"Mr. Land" wrote in message oups.com... So have you fixed it? Um, not yet. As you noted below, I also thought about DC getting to the speakers being the cause of the thumping. That's what started me on my capacitor-testing adventure in the first place. Which led to my frying the PCB traces trying to remove the caps and associated solder with solder braid. So I've got to procure a new pair of 470uF caps (with nice long leads) that I can solder onto the other side of the board. After (hmm, maybe at the same time) I procure a solder sucker and some new decent-quality solder braid and some liquid flux (from other posters) to clean up the mess I've made. I see that there is quite a bit of technique involved with this de-soldering stuff... I'll get there. The IC in question is an LM1036N, combo volume/tone/balance control. It's available from Digikey for $5, maybe I'll just order one for the price of a Big Mac and fries, get my caps and assorted tools too. When I get the caps back in I'll bridge one amp IC's input to the other one (via a 10uF cap according to another poster perhaps to limit any DC voltage from getting from the "bad" channel to the "good" and wreaking havoc there). This should at least tell me if the output stage is working correctly. I guess I should check input voltages at both op-amp IC's to make sure the bad channel is being powered first. As I noted I've already replaced the bad channel's output stage (LM1875T 20W amp TO-220). I've already tested all of the diodes and resistors and (to the extent that they can be tested in-circuit) caps with a DMM (not the best test but will show if a cap is open circuit or shorted). If not, what's this 10-year-old mixer IC you mention? Do you have a pinout of it? How do the DC voltages on all the pins of the output IC compare? If you have a meter-based meter (was that redundant?), can you see any DC fluctuation on the input or output pins of the output IC's when you spin the volume control? Check both channels and compare them. I didn't think of using an analog meter, that's a good way to roughly compare outputs... I'll make up a CD with continuous tones to feed a signal via the unit's RCA inputs and test the signal at various points moving backwards from the output stage. I have a feeling it's the combo volume/tone/balance IC but then I had a feeling it was the amp too and it ain't.... I think I suffer from "jump to unsubstantiated conclusion" syndrome and I just have to slow down and think things through before running off to the store to replace another part. I'll keep folks updated (a retain-my-pride way of saying "I'll likely have more questions") via this thread. Thanks for your help so far... Dave I've seen speaker "thumping" occur when DC was getting to an input it shouldn't be. |
#21
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newbie solder question
In article ,
jakdedert wrote: BTW, one use for the flux--I use the paste stuff, must try the liquid--is to 'activate' old desoldering braid. When doing a lot of work on old boards, I keep the tin of flux open, heat the braid and dip the end into the flux between uses. It activates the braid and makes for much easier desoldering. Is that also the way to use the liquid stuff? It would probably be a less messy than my procedure..... jak I manage a small electronic assembly company, so I've been intimately involved with soldering on a daily basis for more than 20 years. I don't know a hell of a lot about troubleshooting, but I know how to solder. We use liquid flux in little 2 oz. plastic squeeze bottles with 0.010" inside diameter needles. A drop or two of flux goes a long, long, way towards making beautiful solder joints, painlessly, and very fast. For single sided boards, a drop is fine. For double sided, a drop will flow through the hole and take the solder with it. For desoldering double sided, put a drop on top and one on the bottom. If you haven't used it, you haven't experienced soldering. |
#22
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newbie solder question
"Smitty Two" wrote in message news In article , jakdedert wrote: BTW, one use for the flux--I use the paste stuff, must try the liquid--is to 'activate' old desoldering braid. When doing a lot of work on old boards, I keep the tin of flux open, heat the braid and dip the end into the flux between uses. It activates the braid and makes for much easier desoldering. Is that also the way to use the liquid stuff? It would probably be a less messy than my procedure..... jak I manage a small electronic assembly company, so I've been intimately involved with soldering on a daily basis for more than 20 years. I don't know a hell of a lot about troubleshooting, but I know how to solder. We use liquid flux in little 2 oz. plastic squeeze bottles with 0.010" inside diameter needles. A drop or two of flux goes a long, long, way towards making beautiful solder joints, painlessly, and very fast. For single sided boards, a drop is fine. For double sided, a drop will flow through the hole and take the solder with it. For desoldering double sided, put a drop on top and one on the bottom. If you haven't used it, you haven't experienced soldering. Have you had to have a go with this hateful lead-free stuff yet ? If you're a soldering professional, used to lovely shiny joints that'll see you out to the grave, this stuff is gonna make you weep ... If you only assemble for the US market, I guess that you're not going to have to get to grips with it ( at least not yet ) as the US has sensibly declined to get involved for the moment, but if any of your products are destined for Europe, or one or two other places that have signed up to this particular piece of eco-nonsense, then you're soon gonna be finding out alllllllll about it .... :~{ Arfa |
#23
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newbie solder question
In article ,
"Arfa Daily" wrote: Have you had to have a go with this hateful lead-free stuff yet ? If you're a soldering professional, used to lovely shiny joints that'll see you out to the grave, this stuff is gonna make you weep ... If you only assemble for the US market, I guess that you're not going to have to get to grips with it ( at least not yet ) as the US has sensibly declined to get involved for the moment, but if any of your products are destined for Europe, or one or two other places that have signed up to this particular piece of eco-nonsense, then you're soon gonna be finding out alllllllll about it .... :~{ Arfa That research project is rapidly moving to the top of my list of priorities. Some of my customers distribute worldwide, and are starting to make lead-free noises. I haven't seen the stuff personally just yet, but I've heard reports similar to yours. I'm generally very eco-minded, and don't mind making sacrifices to retard the speed with which mankind is destroying what's left of the planet, but I'll agree that the logic on which *this* regulation is founded seems a bit shaky. Since you brought it up, maybe I should start now. Do you have any specific suggestions as to choices of solder and flux, methods, equipment, cleaning considerations, primers I should read, etc? Or is lead-free simply an inferior "drop-in" replacement that doesn't mean I have to change everything else? |
#24
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newbie solder question
"Smitty Two" wrote in message news In article , "Arfa Daily" wrote: Have you had to have a go with this hateful lead-free stuff yet ? If you're a soldering professional, used to lovely shiny joints that'll see you out to the grave, this stuff is gonna make you weep ... If you only assemble for the US market, I guess that you're not going to have to get to grips with it ( at least not yet ) as the US has sensibly declined to get involved for the moment, but if any of your products are destined for Europe, or one or two other places that have signed up to this particular piece of eco-nonsense, then you're soon gonna be finding out alllllllll about it .... :~{ Arfa That research project is rapidly moving to the top of my list of priorities. Some of my customers distribute worldwide, and are starting to make lead-free noises. I haven't seen the stuff personally just yet, but I've heard reports similar to yours. I'm generally very eco-minded, and don't mind making sacrifices to retard the speed with which mankind is destroying what's left of the planet, but I'll agree that the logic on which *this* regulation is founded seems a bit shaky. Since you brought it up, maybe I should start now. Do you have any specific suggestions as to choices of solder and flux, methods, equipment, cleaning considerations, primers I should read, etc? Or is lead-free simply an inferior "drop-in" replacement that doesn't mean I have to change everything else? Smitty Mail me direct and I'll sort you out some links and articles. Arfa |
#25
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newbie solder question
On Thu, 19 Jan 2006 22:04:09 GMT, "Dave"
wrote: default wrote in message .. . On Thu, 19 Jan 2006 15:33:18 GMT, "Dave" wrote: Well back in the "old days" we used "eyelets" - didn't have plated through holes for circuit boards. The eyelets were just miniature one part hollow rivets - or similar to grommets used in sails or tarpaulins. That would be an ideal fix if you burnt the plating off. I think I'll solder to the trace on the other side of the board, just means that the cap won't sit flush anymore but that's okay, lots of room in the enclosure. Solder Wick for single sided boards - solder sucker for double sided boards. Yes, must buy solder sucker. It's on my list now. Regarding the amp. Have you checked the DC voltages between the channels? No. Do you mean between the channel A and channel B signal outputs with no signal applied to the inputs? If there WAS a DC voltage differential what might this tell me? Failed coupling cap? There are no output caps, the amp output pin (see below) goes straight to the center pin of the RCA jack on the back. Sometimes the DC levels can tell you a lot. No signal - since without a scope it wouldn't do much good. Check input output ground and Vcc - don't assume it is connected check it at the solder joint or component leads. Assume nothing. Believe the voltmeter not your eyes when it comes to connections. I don't know if I buy the no output caps and single supply . . . With class AB (which is your amp) the output of the amp running on a single supply HAS to be one half the supply voltage with no signal present. That means the speaker would be driven close to its travel in one direction at all times if the circuit doesn't have a transformer or cap to take the DC from the speaker. The choice is a coupling cap (high value like 400 to 4,000 ufd) in series with the speaker - or two amps per channel with the speaker between the outputs. Both amps sitting at 1/2 half the total supply so the speaker has no voltage differential across it - the amps when driven are working out of phase to one another - one side becomes more positive the other more negative. (a technique used in car radios) The other choice is a plus and minus supply with one side of the speaker to ground. http://www.national.com/ds/LM/LM1875.pdf See the application datasheet for the details of dual/single supply operation - note the cap in the single supply version . . . Is this a single supply or plus and minus supplies? Both the amp and bass/treble/volume/balance IC's run off +Vcc. TO220 - five lead power op amp? built in thermal, short circuit, and safe operating area protection? I assume you only have one chip per channel (or "bridged" with two chips per channel?) One chip per channel. They're LM1875T's, yes they have built-in thermal, short circuit, etc. As I noted I have already replaced the one on the bad channel (they are a TO-220 package). If you can identify the chip and its input(S), you might try using a capacitor to bridge signal from the working channel's input into the input of the dead channel. (observing polarity if using an electrolytic). Unplug the input to the dead channel while testing if possible. The cap size will be 10 uf or less for a high impedance audio stage input. That should localize the problem between the input or output of the power amp chip. Does it matter if I use an electrolytic or not? See pinout below, but I'd connect pin 1 of channel A (working) to pin 1 of channel B (dead). If I do use electrolytics, which end is positive, A or B? Why do I need to use a capacitor to bridge as opposed to a wire? It does matter, to the capacitor in particular. Electrolytics don't tolerate over-voltage or reversed polarity very well. There are non-polar electrolytic caps, but they aren't common. The data sheet suggests you use a one or two microfarad cap for input coupling. A .1 may also work but give some tinny sound quality. You can "make" a non-polar cap from two polar caps. Take two caps with the same specs - preferably from the same maker and batch. Tie either both plus terminals together, or both minus terminals together - use as you would a normal un polarized cap. The voltage rating will be the rating of one cap and the capacity will be 1/2 the value of each cap. (2 X 4 ufd / 25 volts = 1 X 2 ufd / 25 volts) An electrolytic is usually specified at something like a tolerance of +100% / -30% of capacity - a loose spec to be sure. The designer takes this into account and what AC current the cap will have to transfer at what frequency then allows for tolerance. A point one microfarad may just sound like there's less bass present. Likewise if you have a 2,000 ufd speaker coupling cap (as shown in the data sheet) a working 100 ufd may sound a lot better than a non working 2,000 . . . If it is like the TO220's I'm using, there's a differential input (inverting and non-inverting) inputs - make sure you drive the correct one). Here's the pinout: 1 +IN 2 -IN 3 -V(EE) 4 OUTPUT 5 V(CC) Bridge pin one on one amp to pin one on the other with a non-polar cap (to be safe). You could just touch the terminals with the cap but that may cause some output noise and it would be safer to clip the cap in then apply power. From what I can see, pin 1 is signal in, pin 2 is used as the negative feedback loop, being connected to pin 4 via a 20K resistor. There are no coupling caps on the outputs. One assumes you switched speakers at some point. -- Yes, first thing I tried. -- ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#26
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newbie solder question
On Thu, 19 Jan 2006 22:04:09 GMT, "Dave"
wrote: PS turn on thump is almost always a sign of a DC offset in the output. It may suggest a DC offset in the input to the amp and carrying that logic further - the built in protection is saving the speakers from frying. Some amps do thump when nothing is wrong - the design just comes up in an unbalance condition and straightens out after a millisecond or two as caps charge in the input stages. Check the voltages . . . -- ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#27
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newbie solder question
I haven't kept up with this thread, but I have been using lead free solder
for over 5 years now. I had to jack up the tip tmeperatures to 700 degrees in order to get good flow. A touch of standard external flux helps a lot. I use smaller guage solder also, flows better. I do keep standard solder on the bench. I once, early on, did an amplifier repair and the customer who picked it up returned it sayng that the side I had repaired sounded so much better he wanted me to fix the other side. I had used the lead free solder on the repair. I replaced the lead free with standard solder and both sider were equal and he was happy. I do admit, I hated the lead free in the beginning, but I've become used to it and can work around it's mlimitations. I do cheap a bit and sometimes tin old joints with leaded solder before applying lead fee. Stu |
#28
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newbie solder question
Not all lead free solder is the same, though even the best that I have used
is not as good in terms of flow as leaded. The best formulation that I have found is Sn 96.5, Ag 3.0, Cu 0.5 that I got from Mitsubishi. It only requires a slightly higher temp than normal, about 30 degrees. Leonard "audiodir" wrote in message news:FrMIf.22597$0H1.18375@trnddc04... I haven't kept up with this thread, but I have been using lead free solder for over 5 years now. I had to jack up the tip tmeperatures to 700 degrees in order to get good flow. A touch of standard external flux helps a lot. I use smaller guage solder also, flows better. I do keep standard solder on the bench. I once, early on, did an amplifier repair and the customer who picked it up returned it sayng that the side I had repaired sounded so much better he wanted me to fix the other side. I had used the lead free solder on the repair. I replaced the lead free with standard solder and both sider were equal and he was happy. I do admit, I hated the lead free in the beginning, but I've become used to it and can work around it's mlimitations. I do cheap a bit and sometimes tin old joints with leaded solder before applying lead fee. Stu |
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