| PacificStereo |
Howdy!
First, let me say how refreshing it is to have the Man himself among us... we're not worthy! Totally cool.
I've got an SA/4 that I obtained broken (paid almost nothing, too!). It's in perfect cosmetic shape, and I'd like to try using this amp for awhile.
Initially, it was blowing fuses on one side upon power-up. I discovered a single bad output device on the channel, and changed it. I also checked every other device and resistor on the side. Changing that device solved the problem at idle.
Unfortunately, there is still trouble. At about 1 watt of output on the defective channel, current draw from the mains moves massively up and distortion goes way up, as well. I have been all over the driver board for that channel and measured every passive and every semi (de-soldered), and can't find anything out of sorts. And I'm out of ideas, particularly because I don't have a schematic.
Can anyone help with one? Does anyone have an idea of what this might be?
Appreciate the help, and very glad to be here!
-Pacific |
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| Netlist |
I'm totally unfamiliar with that amp but suppose the zobel network (if any) would be shorted to ground?
Oh...and Jacco is a fairly nice guy. :)
/Hugo |
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| jacco vermeulen |
Hugo,
i bet you're very good at charming les merveilleuse femmes as well.
Pacific friend, send me an email for the SA/4e schematic, courtesy of the one and only who ocassionally does a sleazeball like me a big favor.
Paid almost nothing ? Oh dear, i'm fainting again.
His Holiness himself may be arriving shortly on this stage, has a lot more hair than Tenzin Gyatso, let me just cough 1-2-3-testing in the mic. |
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| Netlist |
| Me?…To..ta..lly innocent. Although I wouldn’t mind the drawing. :D |
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| PacificStereo |
Hi, guys:
Sorry to not check in earlier- shortly after that first post, my main box (sigh- this is the one I do all my audio remastering and video projects on) crashed harder than Humpty Dumpty on crack. Totally hosed Windows, cross-links on data files (on ANOTHER, different partition!), the works.
I am only now coming back to life... Still can't get the install of 2K to work right (may have to give up). Since my practice is always to stay one generation of OSes behind, I guess this is my calling to get on with the business of living with and trying to like XP.
Happily, almost all the data lost was either backed up, or very recent. About the only thing I haven't been able to recover is some recent cover art that I should be able to recreate without too much trouble.
Lesson: Regular back ups. I had gotten lazy and that's a fatal error when things go bad.
Anyway, thanks for the reply! Jacco and Hugo, nice to meet you both. Jacco, look for a private from me for a mailng addy, your generous offer is very much appreciated.
Please let me make one in return:
Along with many hats before then, I was the undertaker for Pacific Stereo when it died in 1986. I eventually ended up with 18,000 paper service manuals, mountains of microfiche, and boxes and boxes of original parts, including semis, lots of them. I've even got new optics for a CDP-101. :) Need factory heads for the original Advent cassette deck? Got 'em... You get the idea.
The S/M collection is supplemented by stuff from The Federated Group and other service organizations, and goes to about 1996 for many, many brands.
If anyone here needs a part, a schematic, or anything else along those lines, please PM me and I'll get you fixed up.
Jacco, watch your message box!
-Pacific |
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| PacificStereo |
Ugh. It would appear that I am still under moderation, so I can't use the email feature of the forum. As soon as I am out of Forum Purgatory <grin>, I'll contact you, Jacco.
-Pacific |
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| jacco vermeulen |
| Let's do better, i'll fill your mailbox instead if you put a time window on your email button to let me in briefly. |
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| Nelson Pass |
You might want to take a look at the thread "Repair question re:
threshold 400a" which follows the progress of a major repair
effort.
:cool: |
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| Nelson Pass |
I don't have SA4e schematics, but I do have the SA12e
which is very similar. I have uploaded the 15 pages of the service
manual to www.passlabs.com/np
:cool: |
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| PacificStereo |
Nelson, nice to meet you, and thank you! I will grab that manual, and check out the 400a repair thread as well.
-Pacific |
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| barchetta |
| quote: | Originally posted by PacificStereo
Nelson, nice to meet you, and thank you! I will grab that manual, and check out the 400a repair thread as well.
-Pacific |
How old is the SA/4? If its anywhere near 20 yrs Id replace all the electrolytics.. Unless you have a method for testing... I am the person to blame for the 400a repair thread but its nothing like the symptom you have... I think the SA/4 is a predecessor to the 400a and very similar.. if it took out a output transistor did you replace all the emitters? mine were all cooked and had 3-4 bad output devices.. you might have a few bad emitters... better check em.
Send pics, I wanna see the guts! |
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| PacificStereo |
Hi, Barchetta:
Yes, I tested every output device on that channel, and measured every emitter resistor- everything is good.
I don't know the age of the amp (it's not with me, here).
And I agree, replacing electrolytics is a good idea, if for no other reason that good Panasonic FG or FM series parts have ultralow ESR, very long life and sound great! I haven't done that on the bad channel (or the good one, for that matter) but might try that as a next step, since it's so easy and cheap to do.
I've lived the life of bad electrolytics- I was right in the middle of the "bad Nichicon/Panasonic SMD capacitors" phenomenon in the 90's. Ever replaced every single SMD cap in a camcorder? I have, hundreds of times. There are 103 in a Sony CCDF55. Plus, boards often had to be repaired because of the damage done by leaking electrolyte. Man, does that stuff stink when it gets heated.
And don't get me started on that nasty yellow glue that turns to carbon and traps moisture underneath... Great stuff. It conducts all by itself AND corrodes boards and parts at the same time. It was so notorious in my shop that we even made a song up about it. Gah!
Anyway, I may not make it to the lab until next week. (I live a dual life- LA area weekdays, central CA weekends, and the GF wants me here this weekend.) If I don't, I'll snap pictures next week.
This is an odd symptom, indeed. I was really hoping someone here had run across it before. However, a schematic will really help. Sometimes, you just gotta have one!
I'll keep ya'll posted. :)
-Pacific |
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| spind |
| quote: | Originally posted by PacificStereo
Hi, guys:
Along with many hats before then, I was the undertaker for Pacific Stereo when it died in 1986. I eventually ended up with 18,000 paper service manuals, mountains of microfiche, and boxes and boxes of original parts, including semis, lots of them. I've even got new optics for a CDP-101. :) Need factory heads for the original Advent cassette deck? Got 'em... You get the idea.
-Pacific |
Very interesting PacificStereo! You may want to check in at the Vintage Forum of the AudioKarma site (Audiokarma.org). There are quite a few fans of the Concept line of receivers on that site and I'm sure they would be very happy to hear from you. Any service manuals or even parts would be cool. There are many there that feel that the Concept 16.5 was one of the best receivers ever.
hope you check in,
Steve. |
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| Netlist |
| quote: | Originally posted by PacificStereo
Hi, Barchetta:
Yes, I tested every output device on that channel, and measured every emitter resistor- everything is good.
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And, did you check the zobel?
/Hugo |
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| MashBill |
| quote: | Originally posted by barchetta
How old is the SA/4? If its anywhere near 20 yrs Id replace all the electrolytics.. Unless you have a method for testing... I am the person to blame for the 400a repair thread but its nothing like the symptom you have... I think the SA/4 is a predecessor to the 400a and very similar.. if it took out a output transistor did you replace all the emitters? mine were all cooked and had 3-4 bad output devices.. you might have a few bad emitters... better check em.
Send pics, I wanna see the guts! |
The SA/4 was made between 1989 and 1995 which makes it a successor of the 400a (1976-1979) by at least a decade. |
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| PacificStereo |
Hi, guys:
Spind:
That Concept line of products really shone. I've got two 12.0Ds sitting around that I just love the sound on.
There never were what I would call "real" service manuals for the Concept line, at least as far as I know. It's odd- we made all these products, but the documentation was terrible. What literature there is is almost all microfiche, with a few paper service bulletins. For example, the only thing I have for the 12.0D is a microfiche of the schematic, and a typed-up, Xeroxed alignment procedure for the FM section.
But I will definitely head over there and check the place out. I've got a lot of Concept, Calibre, Quadraflex and Transaudio parts and info- thanks for the suggestion!
Hugo:
I did not check the zobel. Is this something that tends to fail? This is where a schematic starts to help... heh. Since the amplifier seems to work well on the affected channel up to about 1 watt of output, a static check of the zobel components might not reveal much, but I'll take a look this weekend and report in.
Talk with ya'll soon.
-Pacific |
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