SX-829 help

[dudefromla]

So as I said last night on another thread, after a yr of sitting idle I hooked up my SX-828 and she fired right up and sounds great but...I noticed that after it's been on for a while I get static in the right channel in all modes. Turn it off for 30 sec and it's gone, until it happens again.
Since it happens in all modes I'm assuming it's internal and not just a de-oxit fix or ???.
Any suggestions will be appreciated

 

[dudefromla]

Sorry for the double post guy's don't know how to delete.

 

[john stumpf]

more likely caps and tired transistors i'm in the middle of one right now.it had a all the problems you describe and more. i deoxited the gang switches and lever switches 3 times recapped the the af, head amp,and rebuilt the power supply. also replaced the transistors to modern fairchild items.it was getting progressively better but still had a sound like the ocean in one channel. waiting for parts for the main amp board now.its fair to note while i havent checked all the e caps ive changed, at least a half dozen were bulging and one was leaking black goo.its 40 yrs old and its got some 725's in it. if its never been touched let your conscience be your guide.

 

[dudefromla]

more likely caps and tired transistors i'm in the middle of one right now.it had a all the problems you describe and more. i deoxited the gang switches and lever switches 3 times recapped the the af, head amp,and rebuilt the power supply. also replaced the transistors to modern fairchild items.it was getting progressively better but still had a sound like the ocean in one channel. waiting for parts for the main amp board now.its fair to note while i havent checked all the e caps ive changed, at least a half dozen were bulging and one was leaking black goo.its 40 yrs old and its got some 725's in it. if its never been touched let your conscience be your guide.

As far as I know nothing has been done to it. Unfortunately I'm not knowledgeable enough to undertake a refurb like you are doing. I guess I'll have to put it in the shop to find out for sure.

 

[larryderouin]

If you can change a spark plug, and a coil on a car, you can change out caps, and even transistors. We have the tools, and the technology to make it better.

Seriously, we've(meaning the forum and not me personally) taken guys who'd make MONGO look like a Phd in Quantum physics, and have shown them how to rebuild their units to better than new operating condition. Thing is, you have to be dedicated to tackle it, listen to and follow exactly all instructions, and don't go off on a tangent or get ahead of us or yourself by doing un-planned operations. This can hurt or kill the unit, AND OR YOU! Granted the 828 isn't one of the units I wouldn't personally start out on. It's more of an intermediate to advanced skill level unit. I'd find a SX-434 or 535 to work on 1st. Get it rebuilt with instructions from here, and notice how well it plays. Then if you feel confident enough, go ahead and rebuild the 828 under instruction.

Rehab lists here almost always filter down eventually to MARK THE FIXER, who (as far as I'm concerned,) slightly edges out Echowars for TOP GURU status on the PIONEER Forum. He's been working with Solid State PIONEER GEAR from the 70's since about when they came out. He has databases that are continually upgraded to reflect new parts as they come out. Another of the TOP Tech's are MATTSD, and Zebulon1. Any of these guys can maneuver you thru the Rocks and shoals of PIONEER Solid State Electronics thru the 70's.

 

[markthefixer]

not your model, but it will give you the general idea.

http://www.audiokarma.org/forums/in...-sx-636-rushing-sound-on-left-channel.517531/

in the meantime, you can do a bit of troubleshooting, on the back panel there are jacks labeled "pre-out" and "main-in" between the preamp and the power amp
when the static sound is happening, IF the jumper bars in the jacks are removed, and the static continues, it's the power amp that needs attention first

also you can cris-cross the left to right and right to left "pre-out" and "main-in" with cables instead of the bars, and if the static sound moves to the other channel we then know the preamp is in jeopardy and needs attention first. this would be my bet.
btw the static sound cannot be affected by the volume control, correct?


also, sorry there's no listed thread for the 828, the 828's I did were so far back, they were done with paper records, I hadn't started using (easily shared) spreadsheets for the parts lists yet. I did get a partial one together, but it only focused on semiconductors.

 

[john stumpf]

there is a cap list in the data base with some of the transistor replacements. on the main amp board listing there are 6 caps that should be ukl's not upw's. now for something that will put you off but i MUST tell you this. as has been pointed out there are easier set's to learn on.mine was late 73 production and it has a anp-060-c af board in it. it appears to be almost identical to the earlier awk 012 and has about the same parts on it. there are a lot of parts to replace on this board. i cant comment on the earlier board but the anp-60-c is double sided (solder runs on both sides) with plated through holes.if you have never worked on this style board before and have limited soldering experience i dont recommend you attempt to work on this board.its very difficult to desolder and remove parts from this type of board with out specialized soldering gear and knowing how to use it.ive NO experience with the earlier board.but it may well be the same.maybe others know.

 

[john stumpf]

i just found out by looking at an af board on ebay that they are in fact all the same as as far as double sided and plated through holes. mine wasnt marked on the component side ergo i thought that anp-60-c was the board number as there wasnt any other number on it.but that doesnt change anything!

 

[dudefromla]

Thanks for all the info. Appreciate it.