Sometimes a little acetone works to soften up the glue. Not too much since it will eat away the plastic.
Project: Sansui AU-717 (BKs)
- Thread starter Super Noob
- Start date
MIJ_Pioneer
Super Member
Woah. Yup, I sure did use the incorrect transistors. Excellent catch - lesson learned for me to read and understand these BOMs before executing. Swapping them out shortly with new ones. Thank you for taking the time to review this.
Haven't gotten that far yet! But I will be sure to take extra precaution when I get there
Only have done the tone and now power board. I dunno why but this thing is taking long time to work on. That powerboard took me about 8 hours!
Hi all!
(Sorry about my language, English isn't first one for me)
I am folloing this AU-717 rebuild for my amp; it is great, thank you!
My amp is fixed over years by some repair company in Germany, badly done; glue was never removed and miss match parts used, parts changed from here and there, so I need to replace much more then was done in this build.
Issue is I am "electronicly - challenge" in other words; First time with solder.
So I question is; Is first page list of what parts to use for replace what correct, specially from these quited parts (I don't know if this forum let's you change posts);
"TR09-10 – 2SC1708"
"TR11-12 – 2SA847"
It looks like the very first post with the links to the Word doc and PDF is still incorrect. If you see someone recommending a KSA as a replacement for a 2SC, you know there's an error.
You might want to practice on a less ambitious project before attempting a full restoration of an AU-717.
Thank you; thing is I have no knolage, what KSA's are, but as long as I can follow first page written part, that is really nice done, I think even with my limited knolage, I can folow this.
Well.. let's say we are too late for that, but if you are going to start from somewhere , it might be 717 as it needs service.
Scott Muni
Well-Known Member
I recently picked up a non working au 717. Both channels no sound, protector light flashes and then stays on steady. There is a ton of glue and damage on the PS. Left channel is missing the -31 output. My plan is to rebuild all boards.
Is this BOM correct, I read there were some errors, but have they been corrected? Also @MIJ Pioneer, you made a mistake on the PS, but I'm confused with what it was or how you fixed it, could you explain?
Many thanks to everyone that has helped with listing their parts lists and mods. Leestereo super noob
Is this BOM correct, I read there were some errors, but have they been corrected? Also @MIJ Pioneer, you made a mistake on the PS, but I'm confused with what it was or how you fixed it, could you explain?
Many thanks to everyone that has helped with listing their parts lists and mods. Leestereo super noob
Last edited:
F-2721 / F-2722 Driver Circuit Board Right/Left
TR06 & TR09 – Original 2SC945 / Now KSC945CY
I had issue with one side every now and then, maybe once in hour I had serrie of small "pop" sound from deep low base and found that replacing TR06 under heatsink fixed this issue. I got KSC945CY's bit late and swap them when they arrived. I would think there is a reason why that transistor is under there.
TR06 & TR09 – Original 2SC945 / Now KSC945CY
I had issue with one side every now and then, maybe once in hour I had serrie of small "pop" sound from deep low base and found that replacing TR06 under heatsink fixed this issue. I got KSC945CY's bit late and swap them when they arrived. I would think there is a reason why that transistor is under there.
Last edited:
Top notch work! But it's not done until you put the roaches back in.Getting Ready to Go Back to BK:
Decided to Go Back In and Clean Coupling Switch:
One note, F-2720, the transistor BOM portion looks incorrect?
"TR01-TR06 – Original 2SA726 (PNP) ECB / Now 512-KSA992FBU (HFE Match) TR1/TR5 & TR2/TR6
TR09-TR12 – Original 2SC1400 ECB / Now 512-KSC1845FTA
TR07-TR8, TR13-TR14 – Original 2SA750 (PNP) ECB / Now KSA992FB"
Should be like this I think:
No wait a minute, this list in the SM must be wrong:
"TR01-TR06 – Original 2SA726 (PNP) ECB / Now 512-KSA992FBU (HFE Match) TR1/TR5 & TR2/TR6
TR09-TR12 – Original 2SC1400 ECB / Now 512-KSC1845FTA
TR07-TR8, TR13-TR14 – Original 2SA750 (PNP) ECB / Now KSA992FB"
Should be like this I think:
No wait a minute, this list in the SM must be wrong:
Last edited:
That's why you shouldn't use the Service Manual as a primary source of information, the Golden Source of information is what's in the unit NOW, backed up by the schematic which is usually more accurate for what these parts should be, and if that fails to clarify, consult the information and experts on here.
Sui-Yogi
Super Member
That's why you shouldn't use the Service Manual as a primary source of information, the Golden Source of information is what's in the unit NOW, backed up by the schematic which is usually more accurate for what these parts should be, and if that fails to clarify, consult the information and experts on here.
That's why you shouldn't use the Service Manual as a primary source of information, the Golden Source of information is what's in the unit NOW, backed up by the schematic which is usually more accurate for what these parts should be, and if that fails to clarify, consult the information and experts on here.
Yes! Sometimes that doesn't work though. Someone had "repaired" one of the Driver boards in this unit and Franken replaced transistors with whatever transistor he had, as if they're all equal.
That was the reason for this amp having a bad right channel. Also used some low quality solder so it took a while to clean up.
Agree, that can make it more difficult.
tnsilver
Stereo Puppy
Welcome to AK. It's common to take baby steps, complete a single board, and then verify the fix with a sanity power up test using a current limiter such as a DBT. Errors associated with a recap, such as putting in the wrong value capacitor or installing it with the wrong polarity, can lead to a cascading failure up/down stream, so a DBT is a must!. With that said, a power up alone is just the most basic test and is not usually very indicative. The DBT bulb behavior supplements the power up test with important and more indicative information, on top of supplying crucial protection. Verifying power supply voltages, bias current and DC offset after power up, would validate the fix way better.
Can you please exemplify some light bulbs specs (wattage, input voltage) you're using for power up tests of amp individual boards?
Many thanks!
Personally I have three bulbs.
I use a 100W bulb normally unless I want to be extra cautious, then I use a 60W bulb.
Running via DBT lowers the voltages and some amps don't work using a 60W bulb, most work with a 100W bulb.
For the rare occasion I also have a 130W bulb.