SA-6500 II: Normal to hear static turning on/off?

[slayer44]

Hey guys...I picked up this 6500 for nearly nothing on ebay. It works great but has fade in static noise when first turned on and noise when turned off. I am not familiar with this amp, so I was wondering if this is normal.

 

[QSilver]

I don't think that model has a protection/speaker relay so past that I can't comment. But I've never owned a Pioneer amp that had any static when powered on or off... There might be a timing circuit issue somewhere to do with supplying the inital amplifcation stage with power...

 

[Kevin D]

The 6500 ii was my first amp in 1977 still have it for a second system. Their is a 4 second delay before sound but no static noise.

 

[markthefixer]

There is no protect relay, but there should not be noise. Q21, Q22 and Q26 keep the power amps disabled for a set time delay.

Probably a dried out capacitor has lost value, and timeout is too fast.

 

[slayer44]

Thanks guys...I figured the caps would be a problem so I ordered them all at the same time as I bought it (and transistors). I started replacing them last night and will continue to do so. I will jot this down and start with Q21, Q22 and Q26 tonight after the rest of the caps. I might have described the noise wrong. It's not really static, it's music chunking in and out, but you guys already knew what I was talking about. Thanks.

 

[Essay]

The SA-6500 ii is an easy recap. Good luck and show us some pictures when you're done.

 

[slayer44]

sure thing Essay...I got this for 35 bucks on ebay and with 20 spent from Mouser, I think it will be a nice finished product.

 

[slayer44]

Update on this 6500...Hi guys. just finished my recap on this little guy. All went well. After each cap replacement I powered up and tested outputs. Each time got better and better, however, after completion, it still chunks music on and off. I then proceeded to replace transistors like Mark suggested. The cap list I found on an old post here wanted mouse part 512-KSA1013YBU to replace the 2sa777's. After changing my first transistor (Q21) I got an immediate hum and no tunes, so I stopped there and wanted to verify the trans I bought are correct. Please advise and if I need to buy obsolete parts to match I will...Thanks

 

[zebulon1]

KSA1013's are ECB

MTF's 2012 SA-6500 list:
2sa777 / 2sc1438 bias / vas 150v 0.05a 0.5w 150hfe 130mhz to-92
512-KSA1013YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.34 (R=60-120, O=100/200, Y=160/320)
512-KSC2383YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17

 

[slayer44]

Nice to hear from you again Zeb. Okay, I got these parts right. I will re-trace my steps, must of zigged when I should have zagged.

 

[markthefixer]

The replacement transistors can be COUNTED ON to NOT have the SAME pinout as the originals. If they do, it's a lucky accident.

6 ways to install a transistor, and 5 of them are wrong... when I list a part as ECB, it means on a fairchild transistor that with the lettering facing you, and the leads pointing down, the leftmost lead is the emitter
the center lead is the collector
and the rightmost lead is the base.

small on-semi transistors tend to be an exception to this, which is why I stressed "FAIRCHILD".

 

[slayer44]

Hi Mark...thanks for the info. I looked at the data sheet for these and sketched out what mouser had. lead one being emitter. After looking over what I did, I erred and messed up this one:
2sa850 / 2sc1735 drivers 100v 0.5a 0.8w 300hfe 130mhz to-92
512-KSA1220AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.39 (R=60-120, O=100/200, Y=160/320)
512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40

I purchased the top line (512-KSA1220AYS) and followed the pin out from the data sheet and I believe I got it in correctly. I know how to read the board symbol. That's when I got the constant hum. I'm not sure if I should keep going or not. I'm leaving the old one back in and systematically replacing the others, leaving these for the end. Also, to avoid confusion, the 512-KSA1220AYS (PNP) is for the 2sa850 and the 512-KSC2690AYS is for the 2sc1735, correct?

Also, it doesn't help that I need glasses and refuse to admit it. Thanks.

 

[slayer44]

Thanks all for your help...another successful rebuild of a Pioneer piece. A nice sounding little amp. I am really finding vintage restoration to be therapeutic! Now I need another project!

 

[The Fuxtor]

Hi Mark...thanks for the info. I looked at the data sheet for these and sketched out what mouser had. lead one being emitter. After looking over what I did, I erred and messed up this one:
2sa850 / 2sc1735 drivers 100v 0.5a 0.8w 300hfe 130mhz to-92
512-KSA1220AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.39 (R=60-120, O=100/200, Y=160/320)
512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40

I purchased the top line (512-KSA1220AYS) and followed the pin out from the data sheet and I believe I got it in correctly. I know how to read the board symbol. That's when I got the constant hum. I'm not sure if I should keep going or not. I'm leaving the old one back in and systematically replacing the others, leaving these for the end. Also, to avoid confusion, the 512-KSA1220AYS (PNP) is for the 2sa850 and the 512-KSC2690AYS is for the 2sc1735, correct?

Also, it doesn't help that I need glasses and refuse to admit it. Thanks.

Did these replacements work or were they the cause of the hum??

 

[slayer44]

Fuxtor...wow. this was from quite a while ago. its been so long I forgot. this piece is still in my collection so I need to open it up again to see what I used. will get back to you when I can.