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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
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Rickenbacker RM112P monitor amp intermittnet popping and crackling.
This Rickenbacker RM112P monitor amp came to me with the complaint that it
randomly crackles and pops. I plugged it in this afternoon and of course it didn't make any pops or crackles. I disassembled it and cleaned the controls. They were only slightly noisy. I was unable to locate a schematic for it. If it does decide to break down and make the noises, I would like to be able trace the signal. Does anyone have a link for a schematic? It's very clean inside. There are a few potential problem places that I see. One is that there is double sided sticky tape holding the filter capacitors in place. The p.c. trace is not insulated and I was wondering if that could be causing a problem. Secondly, there seems to be some type of chemical reaction happening leaving a flakey orange substance where some of the components are connected to the circuit board. http://webpages.charter.net/mrfixite...-terminals.jpg http://webpages.charter.net/mrfixite...ilter-caps.jpg Thanks for your reply. -- David Farber Los Osos, CA |
#2
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Rickenbacker RM112P monitor amp intermittnet popping and crackling.
On 06/11/2017 06:00, David Farber wrote:
This Rickenbacker RM112P monitor amp came to me with the complaint that it randomly crackles and pops. I plugged it in this afternoon and of course it didn't make any pops or crackles. I disassembled it and cleaned the controls. They were only slightly noisy. I was unable to locate a schematic for it. If it does decide to break down and make the noises, I would like to be able trace the signal. Does anyone have a link for a schematic? It's very clean inside. There are a few potential problem places that I see. One is that there is double sided sticky tape holding the filter capacitors in place. The p.c. trace is not insulated and I was wondering if that could be causing a problem. Secondly, there seems to be some type of chemical reaction happening leaving a flakey orange substance where some of the components are connected to the circuit board. http://webpages.charter.net/mrfixite...-terminals.jpg http://webpages.charter.net/mrfixite...ilter-caps.jpg Thanks for your reply. What date? Assuming 2006 then first diagnostic procedure is to waft a bird feather around the components while powered up, if you've not been manually touching things inside. |
#3
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Rickenbacker RM112P monitor amp intermittnet popping and crackling.
I would suggest you re-solder those two resistors - making sure that the leads have not corroded to any degree. Ideally, replace them and clean the solder traces. I use an electric eraser for this purpose.
https://www.artsuppliesonline.com/prodimg/6150.jpg With a very soft insert. Wonderful devices that do not 'pull' traces or leave conductive scarf. I expect your problem is thermal - and due to vibrations when hot. So, get the thing going, and using a wooden stick - something like a drumstick, tap the various components and see where you get a reaction. Clean that up, and you will be fine. Peter Wieck Melrose Park, PA |
#4
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Rickenbacker RM112P monitor amp intermittnet popping and crackling.
On Monday, 6 November 2017 06:02:48 UTC, David Farber wrote:
This Rickenbacker RM112P monitor amp came to me with the complaint that it randomly crackles and pops. I plugged it in this afternoon and of course it didn't make any pops or crackles. I disassembled it and cleaned the controls. They were only slightly noisy. I was unable to locate a schematic for it. If it does decide to break down and make the noises, I would like to be able trace the signal. Does anyone have a link for a schematic? It's very clean inside. There are a few potential problem places that I see. One is that there is double sided sticky tape holding the filter capacitors in place. The p.c. trace is not insulated and I was wondering if that could be causing a problem. Secondly, there seems to be some type of chemical reaction happening leaving a flakey orange substance where some of the components are connected to the circuit board. http://webpages.charter.net/mrfixite...-terminals.jpg http://webpages.charter.net/mrfixite...ilter-caps.jpg Thanks for your reply. Poor connection. Tap around gently with an insulating stick to locate it. NT |
#5
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Rickenbacker RM112P monitor amp intermittnet popping andcrackling.
On Sun, 05 Nov 2017 22:00:52 -0800, David Farber wrote:
This Rickenbacker RM112P monitor amp came to me with the complaint that it randomly crackles and pops. I plugged it in this afternoon and of course it didn't make any pops or crackles. I disassembled it and cleaned the controls. They were only slightly noisy. I was unable to locate a schematic for it. If it does decide to break down and make the noises, I would like to be able trace the signal. Does anyone have a link for a schematic? It's very clean inside. There are a few potential problem places that I see. One is that there is double sided sticky tape holding the filter capacitors in place. The p.c. trace is not insulated and I was wondering if that could be causing a problem. Secondly, there seems to be some type of chemical reaction happening leaving a flakey orange substance where some of the components are connected to the circuit board. http://webpages.charter.net/mrfixite...-terminals.jpg http://webpages.charter.net/mrfixite...ilter-caps.jpg Thanks for your reply. Looks like the filter cap lead in the middle of the pic may not be soldered properly! |
#6
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Rickenbacker RM112P monitor amp intermittnet popping and crackling.
N_Cook wrote:
On 06/11/2017 06:00, David Farber wrote: This Rickenbacker RM112P monitor amp came to me with the complaint that it randomly crackles and pops. I plugged it in this afternoon and of course it didn't make any pops or crackles. I disassembled it and cleaned the controls. They were only slightly noisy. I was unable to locate a schematic for it. If it does decide to break down and make the noises, I would like to be able trace the signal. Does anyone have a link for a schematic? It's very clean inside. There are a few potential problem places that I see. One is that there is double sided sticky tape holding the filter capacitors in place. The p.c. trace is not insulated and I was wondering if that could be causing a problem. Secondly, there seems to be some type of chemical reaction happening leaving a flakey orange substance where some of the components are connected to the circuit board. http://webpages.charter.net/mrfixite...-terminals.jpg http://webpages.charter.net/mrfixite...ilter-caps.jpg Thanks for your reply. What date? Assuming 2006 then first diagnostic procedure is to waft a bird feather around the components while powered up, if you've not been manually touching things inside. There is no date that I could find on the unit. I called the Rickenbacker company in Santa Ana, CA, and was told they don't have schematics for the older amplifiers. They couldn't even tell me the manufacturing date of the amplifer when providing them the model number. My educated guess is that it's from the1990's or older. Thanks for your reply. -- David Farber Los Osos, CA |
#7
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Rickenbacker RM112P monitor amp intermittnet popping and crackling.
David Farber wrote:
------------------------ This Rickenbacker RM112P monitor amp came to me with the complaint that it randomly crackles and pops. I plugged it in this afternoon and of course it didn't make any pops or crackles. I disassembled it and cleaned the controls. They were only slightly noisy. I was unable to locate a schematic for it. If it does decide to break down and make the noises, I would like to be able trace the signal. Does anyone have a link for a schematic? It's very clean inside. There are a few potential problem places that I see. One is that there is double sided sticky tape holding the filter capacitors in place. The p.c. trace is not insulated and I was wondering if that could be causing a problem. Secondly, there seems to be some type of chemical reaction happening leaving a flakey orange substance where some of the components are connected to the circuit board. http://webpages.charter.net/mrfixite...-terminals.jpg http://webpages.charter.net/mrfixite...ilter-caps.jpg Thanks for your reply. ** Good servicing practice requires that you FIRST observe a fault before delving inside to find the cause. Consider that the unit may have no fault at all, the reported noises being fed in from an external device and / or are due to AC supply transients. ..... Phil |
#8
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Rickenbacker RM112P monitor amp intermittnet popping and crackling.
Phil Allison wrote:
David Farber wrote: ------------------------ This Rickenbacker RM112P monitor amp came to me with the complaint that it randomly crackles and pops. I plugged it in this afternoon and of course it didn't make any pops or crackles. I disassembled it and cleaned the controls. They were only slightly noisy. I was unable to locate a schematic for it. If it does decide to break down and make the noises, I would like to be able trace the signal. Does anyone have a link for a schematic? It's very clean inside. There are a few potential problem places that I see. One is that there is double sided sticky tape holding the filter capacitors in place. The p.c. trace is not insulated and I was wondering if that could be causing a problem. Secondly, there seems to be some type of chemical reaction happening leaving a flakey orange substance where some of the components are connected to the circuit board. http://webpages.charter.net/mrfixite...-terminals.jpg http://webpages.charter.net/mrfixite...ilter-caps.jpg Thanks for your reply. ** Good servicing practice requires that you FIRST observe a fault before delving inside to find the cause. Consider that the unit may have no fault at all, the reported noises being fed in from an external device and / or are due to AC supply transients. .... Phil Hi Phil, I would agree with you up until the point where after several days of waiting, and no faults are exhibited, then a peek inside the unit might give you a clue. Maybe something spilled inside, or perhaps another tech might have done some creative repairs. I haven't mentioned until now but I did find this (photo links below) sitting in the wide open space below the speaker inside of the amp box. I don't think it belongs inside the amp. But even if it's loose inside, I still don't think it would cause popping and crackling noises. Can you identify what it is? It looks to me like it is from a wall attachment for a telephone. View 1 http://webpages.charter.net/mrfixite...y-object-a.jpg View 2 http://webpages.charter.net/mrfixite...y-object-b.jpg Thanks for your reply. -- David Farber Los Osos, CA |
#9
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Rickenbacker RM112P monitor amp intermittnet popping and crackling.
David Farber wrote:
------------------- ** Good servicing practice requires that you FIRST observe a fault before delving inside to find the cause. Consider that the unit may have no fault at all, the reported noises being fed in from an external device and / or are due to AC supply transients. .... Phil I would agree with you up until the point where after several days of waiting, and no faults are exhibited, then a peek inside the unit might give you a clue. Maybe something spilled inside, or perhaps another tech might have done some creative repairs. ** The flaw with that idea is that you will very often find something odd looking and wrongly assume it must be the cause of the reported fault - when it is not. False alarm reports are VERY common with guitar amps and accessories plus also with disco equipment and PA gear. If after a reasonable time running and testing a unit, it shows no sign of the reported fault then it becomes the owner's problem to DEMONSTRATE the fault to the repairer. ..... Phil |
#10
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Rickenbacker RM112P monitor amp intermittnet popping and crackling.
On Wednesday, November 8, 2017 at 7:45:11 PM UTC-5, Phil Allison wrote:
David Farber wrote: ------------------- ** Good servicing practice requires that you FIRST observe a fault before delving inside to find the cause. Consider that the unit may have no fault at all, the reported noises being fed in from an external device and / or are due to AC supply transients. .... Phil I would agree with you up until the point where after several days of waiting, and no faults are exhibited, then a peek inside the unit might give you a clue. Maybe something spilled inside, or perhaps another tech might have done some creative repairs. ** The flaw with that idea is that you will very often find something odd looking and wrongly assume it must be the cause of the reported fault - when it is not. False alarm reports are VERY common with guitar amps and accessories plus also with disco equipment and PA gear. If after a reasonable time running and testing a unit, it shows no sign of the reported fault then it becomes the owner's problem to DEMONSTRATE the fault to the repairer. .... Phil The difference is: An amp in service is loaded, unloaded, lifted, carried, vibrated, kicked, and otherwise physically abused. An amp in the shop sits quietly on a bench or on a shelf with nothing to disturb it. A customer who puts equipment into the hands of a tech - and is thereby spending money has no reason to create a false (and possibly costly) alarm. An Honest Tech is obligated to take the customer at their word. Hence the advice to check for visible defects, to tap the parts with a diddle-stick or similar - in other words, go looking for trouble. Further, and Honest Tech who has been around a while will kinda-sorta have a good idea where to start based on historical experience. And an Honest Tech, when confronted with obvious 'not right' things will correct them - within the minimum charge limit at the very least. Peter Wieck Melrose Park, PA |
#12
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Rickenbacker RM112P monitor amp intermittnet popping and crackling.
On Thursday, November 9, 2017 at 3:19:06 PM UTC-5, David Farber wrote:
wrote: On Wednesday, November 8, 2017 at 7:45:11 PM UTC-5, Phil Allison wrote: David Farber wrote: ------------------- ** Good servicing practice requires that you FIRST observe a fault before delving inside to find the cause. Consider that the unit may have no fault at all, the reported noises being fed in from an external device and / or are due to AC supply transients. .... Phil I would agree with you up until the point where after several days of waiting, and no faults are exhibited, then a peek inside the unit might give you a clue. Maybe something spilled inside, or perhaps another tech might have done some creative repairs. ** The flaw with that idea is that you will very often find something odd looking and wrongly assume it must be the cause of the reported fault - when it is not. False alarm reports are VERY common with guitar amps and accessories plus also with disco equipment and PA gear. If after a reasonable time running and testing a unit, it shows no sign of the reported fault then it becomes the owner's problem to DEMONSTRATE the fault to the repairer. .... Phil The difference is: An amp in service is loaded, unloaded, lifted, carried, vibrated, kicked, and otherwise physically abused. An amp in the shop sits quietly on a bench or on a shelf with nothing to disturb it. A customer who puts equipment into the hands of a tech - and is thereby spending money has no reason to create a false (and possibly costly) alarm. An Honest Tech is obligated to take the customer at their word. Hence the advice to check for visible defects, to tap the parts with a diddle-stick or similar - in other words, go looking for trouble. Further, and Honest Tech who has been around a while will kinda-sorta have a good idea where to start based on historical experience. And an Honest Tech, when confronted with obvious 'not right' things will correct them - within the minimum charge limit at the very least. Peter Wieck Melrose Park, PA Hi Peter, I am doing this as charity work for a local Jazz group. I occasionally play with the group at their Vets' Hall in Pismo Beach, CA. http://pismojazz.com/ I know the people there very well and the person that gave me the amp to fix told me how it failed during a concert last month. As was previously stated, the problem could be external to the amp. When I continue testing it today, I'll include lots of tapping and prodding to see if anything unusual occurs. By the way, are you able to identify this "extra" part that I found inside the box? View 1 http://webpages.charter.net/mrfixite...y-object-a.jpg View 2 http://webpages.charter.net/mrfixite...y-object-b.jpg Thanks for your reply. -- David Farber Los Osos, CA Make sure that you clean the 1/4 inch jacks as well. I have seen poor connections here cause noise. Dan |
#13
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Rickenbacker RM112P monitor amp intermittnet popping and crackling.
On Thursday, November 9, 2017 at 3:19:06 PM UTC-5, David Farber wrote:
I am doing this as charity work for a local Jazz group. I occasionally play with the group at their Vets' Hall in Pismo Beach, CA. http://pismojazz.com/ I know the people there very well and the person that gave me the amp to fix told me how it failed during a concert last month. As was previously stated, the problem could be external to the amp. When I continue testing it today, I'll include lots of tapping and prodding to see if anything unusual occurs. By the way, are you able to identify this "extra" part that I found inside the box? View 1 http://webpages.charter.net/mrfixite...y-object-a.jpg View 2 http://webpages.charter.net/mrfixite...y-object-b.jpg Thanks for your reply. -- David Farber Los Osos, CA Short answer, no I have no clue. Much longer answer: I just installed half-a-dozen sharps containers in one of our practices, and if that device were 14" across and about 8" deep, it would bear an uncanny resemblance to the baseplate. That mounts to a wall or counter, and the container snaps into it and may be locked in place with a key. A tool is used to depress the cam (black sprung device) to remove the container. Every so often, they let me out of the office and into the field to troubleshoot everything from tattoo-removal lasers to electronic door locks. Those things requiring certifications (lasers and surgical or treatment devices, cryostats and such) I will diagnose so that the certified repair technician has a starting point, usually with that tech on the phone. Those that do not, I will repair and test. So, rather than calling an outside carpenter, I installed the sharps containers as I was in the area. New Jersey, Texas, Oregon, Virginia, North Carolina, Georgia - it does get me around. But the resemblance is very close. |
#14
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Rickenbacker RM112P monitor amp intermittnet popping and crackling.
peter ****wit puked:
-------------------- ** Good servicing practice requires that you FIRST observe a fault before delving inside to find the cause. Consider that the unit may have no fault at all, the reported noises being fed in from an external device and / or are due to AC supply transients. .... Phil I would agree with you up until the point where after several days of waiting, and no faults are exhibited, then a peek inside the unit might give you a clue. Maybe something spilled inside, or perhaps another tech might have done some creative repairs. ** The flaw with that idea is that you will very often find something odd looking and wrongly assume it must be the cause of the reported fault - when it is not. False alarm reports are VERY common with guitar amps and accessories plus also with disco equipment and PA gear. If after a reasonable time running and testing a unit, it shows no sign of the reported fault then it becomes the owner's problem to DEMONSTRATE the fault to the repairer. .... Phil The difference is: An amp in service is loaded, unloaded, lifted, carried, vibrated, kicked, and otherwise physically abused. An amp in the shop sits quietly on a bench or on a shelf with nothing to disturb it. ** Not in my shop it don't !!! A customer who puts equipment into the hands of a tech - and is thereby spending money has no reason to create a false (and possibly costly) alarm. ** Irrelevant garbage. An Honest Tech is obligated to take the customer at their word. ** Only a stupid tech believes that garbage. Hence the advice to check for visible defects, to tap the parts with a diddle-stick or similar - in other words, go looking for trouble. ** In my shop, "testing" involves a full range of operation and performance checks - including some rough treatment plus tapping on PCBs and tubes while running at full power and idle. The OP here has a simple SS monitor amp with a vague complaint of pops and crackles that will not show. My advice was 100% solid and professionl. As bloody usual yours is the opposite. ..... Phil |
#15
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Rickenbacker RM112P monitor amp intermittnet popping and crackling.
On Thursday, November 9, 2017 at 9:04:06 PM UTC-5, Phil Allison wrote:
My advice was 100% solid and professionl. As bloody usual yours is the opposite. Sure, you walk on water. Get your meds adjusted. Peter Wieck Melrose Park, PA |
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