Servicing a Pioneer SA-9500II amplifier with finicky right channel

sent in by a viewer.
right channel is temperamental. let's see what's up.

[@lox_5017]

Thanks buddy for working on my amp..great job. Can't wait to get it home and plug her in.

[@iroll]

Holy cow... are you in Phoenix? I had a Pioneer exactly like that with a balky right channel, that I sold maybe 3 or 4 years ago! I think I had a voodoo "fix" where if you switched it to FM mode (which seemed to work fine!), and then back to the aux input, the right channel would often mysteriously reappear. I hadn't recapped it; pretty sure it was virgin when I sold it. I got it in the mid 2000s from a friend who got it as a hand-me-down from his dad.

[@lox_5017]

@@iroll So why did you sell it?

[@iroll]

​@@lox_5017 A long story... but, I've still got plenty of janky old electronics hoarded. Sometimes you have toss one back into the pond.

[@Poppinwheeeeellllllieeeeez]

Nice to see a vid today. Love to see some more vintage audio repairs. The knowledge that is acquired by watching the trouble shooting process is much appreciated. Oxidized legs that creep into the body of the transistors cause issues apparently. This is because it can not be cleaned.

[@dirtydon8661]

Couldn’t click on this video quick enough! I restored a SA-9500. Swapped all the prone to get noisy transistors before they got bad. Love my unit.

[@RenegadeSound]

Is this the unit that has a 'cut out switch' or limiter that stops you blowing the fuses ?

[@fredfabris7187]

Great video, thanks for taking the time and putting forth the effort to show us your diagnostic process. That quality is not easy to find in a KZbin video.

[@steveoszman8746]

This was very educational and you really show a passion for older gear. Thank You.

[@craigm.9070]

This was an excellent head scratcher/troubleshooting adventure. I enjoyed your process thinking; and it was good luck to get outputs close enough to put this amplifier back in the game. Your customer will be happy I'm sure, these amps are really something when they are properly tuned.

[@billdang3953]

Agree with you, it is uncommon to find someone that takes the time and trouble to go through the troubleshooting process. So many times, people blame "bad capacitors" and shoot the parts cannon at something like this (they even go so far as to replace every single capacitor, even film and ceramic disc capacitors, every single resistor even of it measures within tolerance and every single semiconductor even ones which are not known to be troublesome).

[@josephsirois2353]

It pays to be thorough, good thing You took the time to find those leaky transistors. Nice work bro

[@andymouse]

Thoroughly enjoyed that tutorial and what a great looking amp, they don't make 'em like that anymore...cheers.

[@justsumguy2u]

I always love the audio stuff, and this was very interesting. Great job of diagnostics. I'll bet 90% of the shops out there would've sent that back to the customer, stating that the right channel still works, and that they couldn't find any issues

[@CliveTrezona]

Thanks JP. Love watching audio repair vids. Keep them coming.

[@doctorcircuit5338]

Wow first time I've heard anyone mention the curve tracer I've been using one forever makes troubleshooting so much easier

[@marka1986]

Have been using a component tracer for years. Won't give you gain but shows up leaky junctions right away. In a power amp would unsolder 2 of the 3 leads of all the transistors and find all the bad and questionable transistors in 1 shot. Not 100 percent foolproof but sure is helpful. I don't see it covered much on KZbin.

[@doctorcircuit5338]

@@marka1986 once you learn the signatures of the components you can run through most circuits and find the defective parts

[@johnbleau4564]

Thanks for the video. I'm having similar problems with mine. This gives me a place to start checking.

[@wendellporter4875]

i worked on a pioneer sa-8500II that was doing some pretty crazy stuff, the protection circuit was flipping out, noise on the outputs (crackling), i replaced those dreaded dual pnp 2sa798 transistors, replaced a couple of those dual diodes in the power that cause issues and now the amp runs well no problems

[@Omegaman1969]

I had exactly the same issue on my 9500 , swapped out those flaky transistors and it’s been working fine ever since,

[@colleton60]

Nice video, thank you. I got a lot out of it, esp. the problems that poorly matched betas can cause.

[@craignehring]

Fun ride, thanks for the output transistor lesson

[@StevenSmith6942_]

awesome rig... just got one in for repair as well... complaint was volume control glitich but will see have not set it up yet... thanks awesome video i nee to finish watching...

[@robertplayer846]

Thanks for audio vid. I always eagerly await them. Such a nice amp but found it surprising they used those batwings, I would have expected some nice TO3s in one of their higher end units.

[@JordanPier]

The original 9500 had TO3. I think they cut a few corners with the MK2

[@chinmeysway]

@@JordanPierdoes this affect the sound much between the two different types ?

[@JordanPier]

@@chinmeysway no

[@zx8401ztv]

Excellent repair 😀 I've had a few amplifiers with blown outputs, i check every part in the bias circuit and the drivers. I would rather check too much than miss something and pop goes the outputs. When you said it was your writing, i though two jordans eeek :-D joke. Not solder or sodder but Smolder 😀

[@zx8401ztv]

XraytonyB is another expert like yourself, he seems a really nice bloke.

[@JordanPier]

I'm a sub. He's a good watch for sure.

[@Synthematix]

Nice one mate, great little amps these were

[@paulm749]

Little? They're heavy as a box of bricks! That big dual power supply would make all the lights in my house dim momentarily when I first powered it up after it had been sitting for a while.

[@Synthematix]

@@paulm749 Yup inrush current

[@Nirky]

Automatic thumbs up!

[@chriscimino7854]

Yesterday I saw an ad that advertised radio for sale one dollar volume stuck on high. Thought I can't turn that down

[@JordanPier]

Lol.

[@RenegadeSound]

What a find this channel is !

[@marka1986]

I have that model of all in one tester too. I am going to do the external clip on leads as well. The internal socket is horrible

[@randallfawc7501]

Jordan; I have a Sony SQD-2020 4 channel Quad decoder. (mid 70s) The left front output channel has an issue. Sometimes it fails completely, other times it will work for a few minutes and other times will work properly for hours on end. A Sony STR 7035 tuner is the main (front) input to the decoder and the rear channels is a Sony TC 1055 integreated amp. Is this something you would like or be able to troubleshoot and maybe even find the problem for me? Please let me know. I bought this system new in 1975!

[@JordanPier]

When it fails is there anything you can do to bring it back? wack on the side, messing with switches and controls, etc? Does the sound in that channel go away completely, or does it become weak, or does it become distorted? The pros of this machine are that its a very well designed set with all discrete decoding (I know, I have the service manual) but they are jam packed and are very tedious to troubleshoot. Trying to follow the signal path through the layers of boards and cables is no fun. Unless you're willing to drop $300+ on time to troubleshoot and repair this with the risk this could be a layered failure with multiple problems - I would look for another. Old quad stuff is cool, but I got out of it for this reason. Just so time consuming to repair.

[@randallfawc7501]

@@JordanPier Hey Jordan; Thanks for replying! Sometimes rocking the rotary selector on the tuner makes it come back on. But trying to use the process of elimination, when that fails I switch the decoder itself to its 2 channel tape input and the output remains dead. I have questioned the tuner in the past but I don't think it is the source of the problem. juggling that tuner selector back and forth from radio to aux or phono must be jumping something in the decoder. But as I said, that only works sometimes. If my understanding or the decoder is correct, it is quite a complex piece of electronics

[@johnrsherwood]

I've got one of these that I would like to have restored, it does have a couple of issues.

[@samanthakumara1065]

wonderful

[@johnbellas490]

You have good content here but there is a LOT of jittering of the image. Does your camera have any form of image stabilization??

[@JordanPier]

I do but I find when I use it I'll get image drift and movement when looking at circuit boards and CRT screens

[@rogertyler3237]

Do You Use Burnzomatic Solder?

[@JordanPier]

Kester

[@brandonbaldwin4535]

Hi I've got a question about my VM record changer. I've tried for awhile to find someone to help me but had no luck. I came up on a video of yours doing a complete service on one. My problem is my changer does really great except for the last record when it drops it doesn't play it instead it shuts off as if it's already played the last record when it hasn't. Do you have a video anywhere that would help me adjust the problem or could you tell me how to do it? I would really be greatful for it. I'm going to subscribe to your channel I believe I could learn a lot from your videos .. thanks!

[@JordanPier]

m.facebook.com/groups/498063417008273/permalink/2210125582468706/ There's someone with an identical problem. Follow this. I'm guiding him through troubleshooting

[@lorenzofernando94]

Hey Jordan, do you sell any vintage electronics?

[@JordanPier]

On occasion. My eBay handle is jpdylon

[@larryshaver3568]

I HATE windows too,always updates at the worst possible time!

[@billmcdonald2436]

I hate pioneer’s wire wraps.

[@rogertyler3237]

I Dont Use All Those Scopes & Stuff Like That. Even Radio TV Phono Nut Dont Use All That Stuff. & Neither Do I.

[@JordanPier]

We all have our methods. I was taught by techs who preferred a scope to troubleshoot problems that were not easily heard. I'm trying to get back into signal tracers which I haven't had to use for more than a decade. Whatever works best for you is what matters!

[@nomusicrc]

Last

[@flyweed]

Hey Jordan. Great video.I have this same integrated amp. My power lamp burnt out and I need to replace it (lamp just above the power switch). Can you tell me how to replace get to and replace that lamp?

[@JordanPier]

You will need to solder. 8v 50ma was the original value. 4.12mm in diameter. Joseph Mirabella can hook you up. I think his ebay handle is projectblk86

[@jdmccorful]

Nice sleuthing. Thanks for the look!