Vintage Pioneer SA-6200 sound problem coming from power amplifier assy! - diyAudio
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Old 3rd May 2010, 12:16 PM   #1
SeMu is offline SeMu  Italy
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Location: Pisa, Italy
Default Vintage Pioneer SA-6200 sound problem coming from power amplifier assy!

Hi to every one.
I have a problem with this old vintage amp I found in my parents garage.

The problem is that when I power it on, there is a loud crackling coming out the speakers, regardless the volume wheel, like if it is not depending from the source in but from the out amp assy.

I made some tests and I found that unplugging the rear pre out/power in jacks, the crackling is still there at power up, so It might come from the power amp assembly.

Other thing, the sound is coming expecially from the RIGHT channel, regardless the A or B line channel (this amp model has 2x R and 2x L channels for 4 speakers total).

I went to a service shop where they use to fix vintage amps like this, and they just called me back after a week telling me that the problem is indeed on that assembly part, but that the fixing is getting too expensive because they had to verify each single components and because it seams like that the components on it must almost be all replaced.
Theyalso called me because they actually stopped working on it because they can't read some transistors part number because the numbers are not readable, and without the electornic schemes its hard to indentify them.

I found the service manual on the internet after a fast search, but I am thinking to go to the shop and take the amp away and try to fix it by my self now that I have the power schemes.

My question is: does some one here know what could generate this crackling noise??
If yes, can he please let me know what components should be involved and why?? Should I even think about changing them with different kind???

Ps: I don't have any problem in replacing electronic components with power schemes because is something I already done with cell phones.

Thank you.
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Old 3rd May 2010, 06:46 PM   #2
SeMu is offline SeMu  Italy
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UPDATE!

I got my amp back from the service shop and they told me that first of al they tried to replace all the capacitors, and that with this the noise got reduced.
After this they tried to replace the transistors, but they couldn't replace them all due to the problem about reading the part number of a few of them.
By replacing the few they could replace, the noise got reduced just a more bit.
They told me that probably with al the transistors replaced the noise could get reduced for the 80%, and maybe there could be some other component that would have need to be replaced, but without the schemes that was impossible.

Now...I have the service manual with the full electric schemes, and I am thinking to replace all the capacitors and transistors my self and see if that could solve the problem.

Any help about what could be damaged on the power amp board?
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Old 3rd May 2010, 07:10 PM   #3
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These really arent a terribly complicated amp, I suggest you take it to someone who knows what they're doing!
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Old 3rd May 2010, 07:46 PM   #4
SeMu is offline SeMu  Italy
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Quote:
Originally Posted by kevvywevvywoo View Post
These really arent a terribly complicated amp, I suggest you take it to someone who knows what they're doing!
Here the prices for fixing things like this are very high, about 35-45 euros per hour, and everyone tells me that is a 2/3 h work, plus material, and in some cases plus extra 30-40 euros for opening the amp and retrive informations before fix.

The serive center I found was some kind of freelands just a little cheaper, but the fix was around about 100 euros at least.

For that price I can get one used here in Italy already fixed, but the fact is that I don't want 2 of these amps, and one of them with noise.

I woul like mine fixed without wasting money!

Do you think that starting from replacing the capacitors and all the transistors could be the right thing to do as first to start?
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Old 4th May 2010, 09:40 AM   #5
Orit is offline Orit  Italy
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If you happen to come to Milan, I can take care of your Pioneer.
Noises usually come either from base bias resistors, or from faulty transistors, or from both. It's easy to pinpoint the defective part, no need to change everything !

Marco
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Old 4th May 2010, 01:44 PM   #6
SeMu is offline SeMu  Italy
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Quote:
Originally Posted by Orit View Post
If you happen to come to Milan, I can take care of your Pioneer.
Noises usually come either from base bias resistors, or from faulty transistors, or from both. It's easy to pinpoint the defective part, no need to change everything !

Marco
The electronic service shop told me that almost all capacitorsand transistors were working not in range, and he tried to change several of them noticing that the crackling was reducing loudness, but as I wrote up here, he could change all of them due to the fault nerial numberreading on them.
I think I have found a guy that can help me indentify the location of the problem and retrive the fault components.
I'll let you know tomorrow!

Ps: thank you for the help! If this things goes bad, I'll contact you.
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Old 4th May 2010, 02:55 PM   #7
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vintage and other amplifier repairs cannot be ghost chase for a device like that a prize of 100 euros is more or less normal ( for recaping and cleaning ).... but if the technician cannot locate any other faults through this procedure this will end up a ghost chase for him and too expensive for you


for example if your approach is replacing parts to trace the fault this is way too expnsive to do and actually impossible since many of these parts can no longer be sourced in the original quality

if you have a 2SB 669 transitor you may find plenty that look and write the same but down under you have a chance in a million to have an original part

so 100 euros will not be enough with this kind of approach ....
any good technician that his able to find the damage within 5 minutes and then replace the electrolytics within one hour and spent another 55 minutes to make all available tests then yes !!! 100 euros will be enough ....this is the style we work in my company and everybody is more than happy !!!!

regards sakis
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Old 4th May 2010, 03:19 PM   #8
SeMu is offline SeMu  Italy
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Quote:
Originally Posted by sakis View Post
vintage and other amplifier repairs cannot be ghost chase for a device like that a prize of 100 euros is more or less normal ( for recaping and cleaning ).... but if the technician cannot locate any other faults through this procedure this will end up a ghost chase for him and too expensive for you


for example if your approach is replacing parts to trace the fault this is way too expnsive to do and actually impossible since many of these parts can no longer be sourced in the original quality

if you have a 2SB 669 transitor you may find plenty that look and write the same but down under you have a chance in a million to have an original part

so 100 euros will not be enough with this kind of approach ....
any good technician that his able to find the damage within 5 minutes and then replace the electrolytics within one hour and spent another 55 minutes to make all available tests then yes !!! 100 euros will be enough ....this is the style we work in my company and everybody is more than happy !!!!

regards sakis
If I'll pass by near you guys, I'll remember to bring my amp with me

I understand you, and reparing it as you say would be the best thing for me, but I have spoken to several people, an all of them told me that your kind of repair is a hell of a goo repair, so something that is going to cost me alot!
There is one repair shop at about 100Km from here that can do that kind of repair afterhaving analized the board and identified the correct components that fault and that must be replaced: 100 euro min price for taking the amp in care, and you'll never know how much will it raise!
This kind o working will push people to repair things them self without any method, and ending with old amps with new stuff inside and not that good sound as in the past.

I'll let you know how this will end.
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Old 4th September 2011, 09:01 AM   #9
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Default Pioneer 6200

Hi SeMu

I have the same Amp with the same problems and i like to love that
I see that you have the electric schemes and i would friendly ask if you can mail me these so i can fix the problems

Thank you
Greetings
Lee (from Holland)

Quote:
Originally Posted by SeMu View Post
UPDATE!

I got my amp back from the service shop and they told me that first of al they tried to replace all the capacitors, and that with this the noise got reduced.
After this they tried to replace the transistors, but they couldn't replace them all due to the problem about reading the part number of a few of them.
By replacing the few they could replace, the noise got reduced just a more bit.
They told me that probably with al the transistors replaced the noise could get reduced for the 80%, and maybe there could be some other component that would have need to be replaced, but without the schemes that was impossible.

Now...I have the service manual with the full electric schemes, and I am thinking to replace all the capacitors and transistors my self and see if that could solve the problem.

Any help about what could be damaged on the power amp board?
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Old 26th August 2015, 04:31 PM   #10
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I have stumbled across this thread with the same issue and hoping my findings will be of some use to someone i too have the same problem. From searching it seems to be a common fault with this range of vintage Pioneer amplifiers, i narrowed down the fault to the Tone / control board. First of all i took out the bridging bars on the rear of the amp to confirm the issue was not with the main output pcb. I noticed by moving the tone defeat switch to 'on' it made the issue a lot worse, to combat the issue i have temporarily bypassed this board by soldering the input signal to the output where there join the board while also removing them from the board. There appears to be 6 x transistors on this board and 17 small capacitors, some of the joints on the transistors are showing signs of oxidization, this is very hard to spot but it looks like a small darkened circle around where the pin is meant to be soldered. I soaked the switches and pots in solvent cleaner but had no improvement so then i decided to replace the transistors and capacitors with poly equivalents - problem solved! I cannot confirm if it was the transistors or the caps but if you are going to take it apart to this level you may as well change the lot. I am no amp expert but i managed to solve the issue relatively easily and i hope this was of some help to anyone who has the same issue.
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