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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, sci.electronics.equipment,rec.audio.tubes, rec.audio.pro
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Repair broken Tek 485 or buy good used 2465/A/B?
Greetings,
I have a ('77 ?) Tektronix 485 scope (serial starts with a 'B' or an '8', number is 167020) that I received 4 years ago. At the time it worked, although I was (still am somewhat) pretty "green" regarding electronics as I am more of a hobbyist than a professional as I love to learn and "tinker". In the past, I have serviced tube amplifiers for friends. Right now I have a 3M (Mincom) M56 professional multitrack tape recorder I am currently in the process of aligning. I guess you could say I am an "analog dinosaur" of sorts... LOL. When I initially got the 485, the unit powered up and I could do some basic sweeps, but I have not really used it since I initially got it (mainly due to getting married, having kids and buying a new house - funny how those things take up gobs of your life ;-). When I went to turn it on about a year ago, I noticed a clicking or chirping with no beam. Apparently as I understand it based on some quick research on the 'net, this is not an uncommon symptom on these 'scopes having a power supply trying to start but failing due to current overload of some sort (capacitors?). So, I did a search on Tektronix repair and came up with a person that thinks they will be able to fix it. However, for the price of the repair (and maybe a little more), I am wondering if I wouldn't be better served with something like a 2465/A/ B? Here's some reasons why maybe I think I should go with the 2465: 1) Compared to the 485, it's a newer 'scope with perhaps less hours than my 485 (don't know how much use my 485 has had; it appears to be in average or slightly better condition) 2) Less "mechanical" parts in the 2465 (e.g., pots, etc. from my understanding) to fail 3) Lots think this is the epitome of the analog oscilloscope Reasons why I should maybe stay with my 485: 1) Better proprietary IC availability (?, don't beat me up; I thought this was what I read...) 2) Easier to service/repair than the 2465 3) More robust for the beginner Obviously if I am thinking like this, I have no idea what I should ultimately do. What does everyone think? ducking |
#2
Posted to sci.electronics.repair,sci.electronics.equipment,rec.audio.tubes,rec.audio.pro
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Repair broken Tek 485 or buy good used 2465/A/B?
wrote in message ... Greetings, I have a ('77 ?) Tektronix 485 scope (serial starts with a 'B' or an '8', number is 167020) that I received 4 years ago. At the time it worked, although I was (still am somewhat) pretty "green" regarding electronics as I am more of a hobbyist than a professional as I love to learn and "tinker". In the past, I have serviced tube amplifiers for friends. Right now I have a 3M (Mincom) M56 professional multitrack tape recorder I am currently in the process of aligning. I guess you could say I am an "analog dinosaur" of sorts... LOL. When I initially got the 485, the unit powered up and I could do some basic sweeps, but I have not really used it since I initially got it (mainly due to getting married, having kids and buying a new house - funny how those things take up gobs of your life ;-). When I went to turn it on about a year ago, I noticed a clicking or chirping with no beam. Apparently as I understand it based on some quick research on the 'net, this is not an uncommon symptom on these 'scopes having a power supply trying to start but failing due to current overload of some sort (capacitors?). So, I did a search on Tektronix repair and came up with a person that thinks they will be able to fix it. However, for the price of the repair (and maybe a little more), I am wondering if I wouldn't be better served with something like a 2465/A/ B? Here's some reasons why maybe I think I should go with the 2465: 1) Compared to the 485, it's a newer 'scope with perhaps less hours than my 485 (don't know how much use my 485 has had; it appears to be in average or slightly better condition) 2) Less "mechanical" parts in the 2465 (e.g., pots, etc. from my understanding) to fail 3) Lots think this is the epitome of the analog oscilloscope Reasons why I should maybe stay with my 485: 1) Better proprietary IC availability (?, don't beat me up; I thought this was what I read...) 2) Easier to service/repair than the 2465 3) More robust for the beginner Obviously if I am thinking like this, I have no idea what I should ultimately do. What does everyone think? ducking The 485 is a really excellent scope, and the problem you describe should be fairly easy to repair. There's no sense in upgrading, as a beginner you probably won't use a large portion of the features the 485 provides even. |
#3
Posted to sci.electronics.repair,sci.electronics.equipment,rec.audio.tubes,rec.audio.pro
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Repair broken Tek 485 or buy good used 2465/A/B?
"James Sweet" writes:
wrote in message ... Greetings, I have a ('77 ?) Tektronix 485 scope (serial starts with a 'B' or an '8', number is 167020) that I received 4 years ago. At the time it worked, although I was (still am somewhat) pretty "green" regarding electronics as I am more of a hobbyist than a professional as I love to learn and "tinker". In the past, I have serviced tube amplifiers for friends. Right now I have a 3M (Mincom) M56 professional multitrack tape recorder I am currently in the process of aligning. I guess you could say I am an "analog dinosaur" of sorts... LOL. When I initially got the 485, the unit powered up and I could do some basic sweeps, but I have not really used it since I initially got it (mainly due to getting married, having kids and buying a new house - funny how those things take up gobs of your life ;-). When I went to turn it on about a year ago, I noticed a clicking or chirping with no beam. Apparently as I understand it based on some quick research on the 'net, this is not an uncommon symptom on these 'scopes having a power supply trying to start but failing due to current overload of some sort (capacitors?). So, I did a search on Tektronix repair and came up with a person that thinks they will be able to fix it. However, for the price of the repair (and maybe a little more), I am wondering if I wouldn't be better served with something like a 2465/A/ B? Here's some reasons why maybe I think I should go with the 2465: 1) Compared to the 485, it's a newer 'scope with perhaps less hours than my 485 (don't know how much use my 485 has had; it appears to be in average or slightly better condition) 2) Less "mechanical" parts in the 2465 (e.g., pots, etc. from my understanding) to fail 3) Lots think this is the epitome of the analog oscilloscope Reasons why I should maybe stay with my 485: 1) Better proprietary IC availability (?, don't beat me up; I thought this was what I read...) 2) Easier to service/repair than the 2465 3) More robust for the beginner Obviously if I am thinking like this, I have no idea what I should ultimately do. What does everyone think? ducking The 485 is a really excellent scope, and the problem you describe should be fairly easy to repair. There's no sense in upgrading, as a beginner you probably won't use a large portion of the features the 485 provides even. I agree 100 percent. My first guess would be one or more of those imfamous tantalum gumdrop caps have decided to turn into short circuits. These are on the power supply PCB on the bottom. Save yoursefl some grief and replace them all (maybe 2 dozen). I have just been putting in aluminum electrolytics. Not sure how much difference it makes. --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. |
#4
Posted to sci.electronics.repair, sci.electronics.equipment,rec.audio.tubes, rec.audio.pro
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Repair broken Tek 485 or buy good used 2465/A/B?
On Nov 27, 1:59 pm, Sam Goldwasser wrote:
I agree 100 percent. My first guess would be one or more of those imfamous tantalum gumdrop caps have decided to turn into short circuits. These are on the power supply PCB on the bottom. Save yoursefl some grief and replace them all (maybe 2 dozen). I have just been putting in aluminum electrolytics. Not sure how much difference it makes. Or can I just stick with tantalum replacements? Mouser shows some, though I have no idea values. http://www.mouser.com/search/Refine....user_Wildcards I assume radial termination style? You say you've been putting in AL 'lytics. Do tants come polarized? Say I go with Nichicon AL 'lytic radials. Is there a preferred series? They have all kinds... http://www.nichicon.co.jp/english/pr...ini/daia_f.htm |
#5
Posted to sci.electronics.repair,sci.electronics.equipment,rec.audio.tubes,rec.audio.pro
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Repair broken Tek 485 or buy good used 2465/A/B?
Sam Goldwasser wrote:
Reasons why I should maybe stay with my 485: 1) Better proprietary IC availability (?, don't beat me up; I thought this was what I read...) 2) Easier to service/repair than the 2465 3) More robust for the beginner Obviously if I am thinking like this, I have no idea what I should ultimately do. What does everyone think? ducking I'm an expert on these things. The 485 is the best portable analog scope ever made. It is arguably the best analog scope ever made, though the 7904 series competes well on the bench. Do anything you can to keep one working. There is no substitute for a 485/7904, and I've used them all, including $50,000 digital ones. For repairing analog electronic oddities, digital frequently simply doesn't work. A 485 is 350 MHz scope. The 2465 is a very poor substitute, though a good scope. Doug McDonald |
#6
Posted to sci.electronics.repair, sci.electronics.equipment,rec.audio.tubes, rec.audio.pro
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Repair broken Tek 485 or buy good used 2465/A/B?
On Nov 28, 1:31 pm, Doug McDonald
wrote: I'm an expert on these things. The 485 is the best portable analog scope ever made. It is arguably the best analog scope ever made, though the 7904 series competes well on the bench. Do anything you can to keep one working. There is no substitute for a 485/7904, and I've used them all, including $50,000 digital ones. For repairing analog electronic oddities, digital frequently simply doesn't work. A 485 is 350 MHz scope. The 2465 is a very poor substitute, though a good scope. Hi Doug, Thanks for your thoughts. Do you do repairs on these scopes? Or does anyone in the group know some noteworthy techs I can send my scope to for repair? It seems most here think I should just stick with the 485. I have no problem with that. However, it's good that I brought this thread up as now I've learned that there may be issues with the 485 to be concerned about, namely the attenuator problem Mr. Yanik has brought up (that is somewhat disconcerting). BTW, how long do the CRTs last on these scopes? |
#7
Posted to sci.electronics.repair
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Repair broken Tek 485 or buy good used 2465/A/B?
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#8
Posted to sci.electronics.repair, sci.electronics.equipment,rec.audio.tubes, rec.audio.pro
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Repair broken Tek 485 or buy good used 2465/A/B?
I no longer recommend owning or using Tektronix analog scopes,
period. Yes, they were very well built, but none of them are 100% supported and they all lose the same parts. The hybrid issue is a big one, but CRTs, attenuators, and high voltage parts on all solid state Teks are getting unavailable even through the back channels. If some company decided to FULLY SUPPORT certain Tek models, guaranteeing availability of every part from new production-or at least every part that is getting scarce-I'd say yes. Ironically you can still get every possible part for many tube Teks, but the size, weight, power draw and heat make them nonstarters. That is why the parts are available. Buy a new scope. |
#9
Posted to sci.electronics.repair,sci.electronics.equipment
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Repair broken Tek 485 or buy good used 2465/A/B?
Doug McDonald wrote in
: Sam Goldwasser wrote: Reasons why I should maybe stay with my 485: 1) Better proprietary IC availability (?, don't beat me up; I thought this was what I read...) 2) Easier to service/repair than the 2465 3) More robust for the beginner Obviously if I am thinking like this, I have no idea what I should ultimately do. What does everyone think? ducking I'm an expert on these things. Oh? The 485 is the best portable analog scope ever made. It is arguably the best analog scope ever made, though the 7904 series competes well on the bench. Do anything you can to keep one working. There is no substitute for a 485/7904, and I've used them all, including $50,000 digital ones. For repairing analog electronic oddities, digital frequently simply doesn't work. A 485 is 350 MHz scope. The 2465 is a very poor substitute, though a good scope. Doug McDonald IMO,the 485 is much worse than a 2465,having lots of flaky attenuator problems,a bitch of a power supply repair-wise,and less accuracy than the 2465 series.And you get a better CRT display with the 2465. The 2465 was the best portable scope TEK ever made.What killed it was TEK selling off the ICO/Hybrid plant to Maxim,and Maxim cutting TEK's throat by forcing a last-time buy on TEK-made ICs. The 485s are getting really old,the HF switch contacts are degrading and unavailable. The 2465 is more serviceable -if you can get the parts. the 485 has the same problem. I worked for TEK for 21.5 years in their Field Service centers repairing and calibrating these scopes.I'd much rather work on a 2465 than a 485. 485s were a PITA even when TEK was still issuing the mod summaries on fiche.There were SO many ECO changes,you couldn't keep up with them all. I agree about the 7904 lab scopes being great.Had one on my bench. -- Jim Yanik jyanik at kua.net |
#10
Posted to sci.electronics.repair
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Repair broken Tek 485 or buy good used 2465/A/B?
Jim Yanik a écrit :
Doug McDonald wrote in : Sam Goldwasser wrote: Reasons why I should maybe stay with my 485: 1) Better proprietary IC availability (?, don't beat me up; I thought this was what I read...) 2) Easier to service/repair than the 2465 3) More robust for the beginner Obviously if I am thinking like this, I have no idea what I should ultimately do. What does everyone think? ducking I'm an expert on these things. Oh? The 485 is the best portable analog scope ever made. It is arguably the best analog scope ever made, though the 7904 series competes well on the bench. Do anything you can to keep one working. There is no substitute for a 485/7904, and I've used them all, including $50,000 digital ones. For repairing analog electronic oddities, digital frequently simply doesn't work. A 485 is 350 MHz scope. The 2465 is a very poor substitute, though a good scope. Doug McDonald IMO,the 485 is much worse than a 2465,having lots of flaky attenuator problems,a bitch of a power supply repair-wise,and less accuracy than the 2465 series.And you get a better CRT display with the 2465. The 2465 was the best portable scope TEK ever made.What killed it was TEK selling off the ICO/Hybrid plant to Maxim,and Maxim cutting TEK's throat by forcing a last-time buy on TEK-made ICs. The 485s are getting really old,the HF switch contacts are degrading and unavailable. The 2465 is more serviceable -if you can get the parts. the 485 has the same problem. I worked for TEK for 21.5 years in their Field Service centers repairing and calibrating these scopes.I'd much rather work on a 2465 than a 485. 485s were a PITA even when TEK was still issuing the mod summaries on fiche.There were SO many ECO changes,you couldn't keep up with them all. I agree about the 7904 lab scopes being great.Had one on my bench. Totally agree on the 2465. As for the DSOs, the OP clearly don't know what good ones can do. See the DSA/11k plugins series. That's simply the best scope I've seen. Period. I currently have a setup with a DSA and one 11A34 and one 11A33 diff plug-in from which I *measure* signals at the 10uV level with excellent accuracy (has been checked against some calibration tooling). But the truely amazing parts are the plug-ins (11A33 & 11A34 checked) recovery from deep saturation. Right now after a 200mV step down to 0V (on a 1mV/div scale), both plug-ins show not more than 40uV thermal tail and recovers from saturation in under 50ns. All this being very well behaved and hence can be well compensated for, pushing the performances one step further. We're trying to find a 'modern' DSO doing that: nada, nothing. The last we've tested (DPO7054 @ euro 15K) showed near 2mV thermal tailing after a 200mV step. What I wonder is what did make Tek losing the art of those exceptional input stages... Now, try to do this with a 485 or a 2465. And no, a 7K series with a 7A22 PI can't do that either (too much drift and not enough BW). -- Thanks, Fred. |
#11
Posted to sci.electronics.repair
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Repair broken Tek 485 or buy good used 2465/A/B?
IMO,the 485 is much worse than a 2465,having lots of flaky attenuator problems,a bitch of a power supply repair-wise,and less accuracy than the 2465 series.And you get a better CRT display with the 2465. The 2465 was the best portable scope TEK ever made.What killed it was TEK selling off the ICO/Hybrid plant to Maxim,and Maxim cutting TEK's throat by forcing a last-time buy on TEK-made ICs. The 485s are getting really old,the HF switch contacts are degrading and unavailable. The 2465 is more serviceable -if you can get the parts. the 485 has the same problem. What about the 2245, 2247? |
#12
Posted to sci.electronics.repair,sci.electronics.equipment,rec.audio.tubes,rec.audio.pro
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Repair broken Tek 485 or buy good used 2465/A/B?
James Sweet wrote:
The 485 is a really excellent scope, and the problem you describe should be fairly easy to repair. There's no sense in upgrading, as a beginner you probably won't use a large portion of the features the 485 provides even. Agreed, and I bet a nickel the issue is that there is too much dust and dirt providing leakage paths in the high voltage section. Have the tech give it a good cleaning and you will probably be fine. I'm still using a Tek tube scope at work and it's always been flawless although the calibration guys hate me. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#13
Posted to sci.electronics.repair,sci.electronics.equipment,rec.audio.tubes,rec.audio.pro
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Repair broken Tek 485 or buy good used 2465/A/B?
"James Sweet" wrote in message news:no13j.19418$XT.16175@trnddc01... wrote in message ... Greetings, I have a ('77 ?) Tektronix 485 scope (serial starts with a 'B' or an '8', number is 167020) that I received 4 years ago. At the time it worked, although I was (still am somewhat) pretty "green" regarding electronics as I am more of a hobbyist than a professional as I love to learn and "tinker". In the past, I have serviced tube amplifiers for friends. Right now I have a 3M (Mincom) M56 professional multitrack tape recorder I am currently in the process of aligning. I guess you could say I am an "analog dinosaur" of sorts... LOL. When I initially got the 485, the unit powered up and I could do some basic sweeps, but I have not really used it since I initially got it (mainly due to getting married, having kids and buying a new house - funny how those things take up gobs of your life ;-). When I went to turn it on about a year ago, I noticed a clicking or chirping with no beam. Apparently as I understand it based on some quick research on the 'net, this is not an uncommon symptom on these 'scopes having a power supply trying to start but failing due to current overload of some sort (capacitors?). So, I did a search on Tektronix repair and came up with a person that thinks they will be able to fix it. However, for the price of the repair (and maybe a little more), I am wondering if I wouldn't be better served with something like a 2465/A/ B? Here's some reasons why maybe I think I should go with the 2465: 1) Compared to the 485, it's a newer 'scope with perhaps less hours than my 485 (don't know how much use my 485 has had; it appears to be in average or slightly better condition) 2) Less "mechanical" parts in the 2465 (e.g., pots, etc. from my understanding) to fail 3) Lots think this is the epitome of the analog oscilloscope Reasons why I should maybe stay with my 485: 1) Better proprietary IC availability (?, don't beat me up; I thought this was what I read...) 2) Easier to service/repair than the 2465 3) More robust for the beginner Obviously if I am thinking like this, I have no idea what I should ultimately do. What does everyone think? ducking The 485 is a really excellent scope, and the problem you describe should be fairly easy to repair. There's no sense in upgrading, as a beginner you probably won't use a large portion of the features the 485 provides even. Hi James. I had a 485 many years ago to use for field work ( not that easy schlepping it around the country). I think it had a 250 MHz bandwidth. It's really packed so be careful when attempting repairs. Starting with checking the low voltage power supplies is a good idea. Also be careful if sending it out prepaid for service. Check the service place thoroughly for references and for viable guarantees. The 485 is a professional scope that way exceeds the hobbyists requirements. So if you can repair it reasonably, you will own a classic gem. Cordially, west |
#14
Posted to sci.electronics.repair,sci.electronics.equipment
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Repair broken Tek 485 or buy good used 2465/A/B?
"West" wrote in news:OQ53j.37950$Xg.23109@trnddc06:
"James Sweet" wrote in message news:no13j.19418$XT.16175@trnddc01... wrote in message ... Greetings, I have a ('77 ?) Tektronix 485 scope (serial starts with a 'B' or an '8', number is 167020) that I received 4 years ago. At the time it worked, although I was (still am somewhat) pretty "green" regarding electronics as I am more of a hobbyist than a professional as I love to learn and "tinker". In the past, I have serviced tube amplifiers for friends. Right now I have a 3M (Mincom) M56 professional multitrack tape recorder I am currently in the process of aligning. I guess you could say I am an "analog dinosaur" of sorts... LOL. When I initially got the 485, the unit powered up and I could do some basic sweeps, but I have not really used it since I initially got it (mainly due to getting married, having kids and buying a new house - funny how those things take up gobs of your life ;-). When I went to turn it on about a year ago, I noticed a clicking or chirping with no beam. Apparently as I understand it based on some quick research on the 'net, this is not an uncommon symptom on these 'scopes having a power supply trying to start but failing due to current overload of some sort (capacitors?). So, I did a search on Tektronix repair and came up with a person that thinks they will be able to fix it. However, for the price of the repair (and maybe a little more), I am wondering if I wouldn't be better served with something like a 2465/A/ B? Here's some reasons why maybe I think I should go with the 2465: 1) Compared to the 485, it's a newer 'scope with perhaps less hours than my 485 (don't know how much use my 485 has had; it appears to be in average or slightly better condition) 2) Less "mechanical" parts in the 2465 (e.g., pots, etc. from my understanding) to fail 3) Lots think this is the epitome of the analog oscilloscope Reasons why I should maybe stay with my 485: 1) Better proprietary IC availability (?, don't beat me up; I thought this was what I read...) 2) Easier to service/repair than the 2465 3) More robust for the beginner Obviously if I am thinking like this, I have no idea what I should ultimately do. What does everyone think? ducking The 485 is a really excellent scope, and the problem you describe should be fairly easy to repair. There's no sense in upgrading, as a beginner you probably won't use a large portion of the features the 485 provides even. Hi James. I had a 485 many years ago to use for field work ( not that easy schlepping it around the country). I think it had a 250 MHz bandwidth. It's really packed so be careful when attempting repairs. Starting with checking the low voltage power supplies is a good idea. Also be careful if sending it out prepaid for service. Check the service place thoroughly for references and for viable guarantees. The 485 is a professional scope that way exceeds the hobbyists requirements. So if you can repair it reasonably, you will own a classic gem. Cordially, west if you ship it anywhere,**pack it very well**,with at least 3-4 inches of padding on EVERY side,top,and bottom. Using loose peanuts is a great way to have your scope smashed up. Better to pack the peanuts in plastic bags,making "pillows" and place those around the scope. I've seen plenty of poorly packed instruments,and UPS/FedEx/DHL/USPS is not liable for poorly packed items. -- Jim Yanik jyanik at kua.net |
#15
Posted to sci.electronics.repair,sci.electronics.equipment,rec.audio.tubes,rec.audio.pro
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Repair broken Tek 485 or buy good used 2465/A/B?
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