Sansui AU-888 Restoration

[Skip Lunch]

This is my first post on here so bare with me. I came across this beat up Sansui AU-888 and even though it's pretty beat up I figured it's worth a shot at restoring. It's filthy and oxidized, the case is broken, the fuses have been removed, I found a mismatched output transistor(not working), a pot is bent, and a knob is mismatched. It's safe to say this is going to be a real dog to work on. There's not too many write ups on these so it'll be bad karma for me not to document and I can possibly get some advice along the way.

 

[kevzep]

Welcome to the Forum, yes you have your work cut out for you there, but I think it will come up okay....

There was a member that restored one of these recently, you might want to do a search and have a look at how his one went.

 

[Skip Lunch]

Thank you Kevzep! I'll check it out! I've been looking at AU-999 builds for reference since they are both similar. I'll post up pictures of my progress tomorrow.

 

[gslikker]

Welcome. My recent one, https://audiokarma.org/forums/index.php?threads/au888-restore-discussion.848630/

You will find that because of the possibility just taking out the boards it turns out to be no big deal, this amp actually is in the league of the few "most easy to work on" amps!


Although I replaced all electrolytics during restoration, I did quick tests on the replaced ones and I did not find any of them defective or obviously measuring bad.


I used 10 Watts resistors soldered on blown fuses to protect additional output transistors see the picture. They come in handy for at least some old Sansui and Pioneer amps.

390 ohms is high enough for some protection and low enough to set bias having sufficient remaining voltage on the output stage.

ONE PRECAUTION: before tinkering, have bleeder resistors mounted on the big capacitors or discharge them! Voltage stays on the big capacitors for a long time, or "forever"when no cards in.

BEFOREHAND, it is also good to check speaker fuses, since if blown, there may be a real shorted out triac or thyristor depending on what protection board is mounted (it was the case in one of my other Sansuis, I believe the au666)

good luck!

 

[Skip Lunch]

Scrubbed, cleaned, and polished a few things. Nobody wants to work with dirty parts. I used lots of elbow grease and waddling polish on the chassis. Now it's time to make a parts list.

 

[slimecity]

fantastic job.

Losing those flying saucers, trimmers and doing a recap would work wonders.

These amps sound very nice.

Have you tried firing it up under a DBT to see if its working in its current state?

 

[Skip Lunch]

fantastic job.

Losing those flying saucers, trimmers and doing a recap would work wonders.

These amps sound very nice.

Have you tried firing it up under a DBT to see if its working in its current state?

I haven't since yet since I know one output transistor is blown and it doesn't have any fuses yet. I'll try and get a parts list together tonight. I was thinking MJ15001G's to replace 2SC111 outputs.

 

[kevzep]

Excellent cleaning job on the chassis!!

 

[Skip Lunch]

Here's my first draft list of parts compete with Mouser ID. Capacitors are Nichicon PW for power supply, ES for bipolar, and Elna Silmic II for the rest. Please take a look and see if anything is missing or if there might be any suggestions. My list was compiled from similar builds I've seen around the net for the AU-999 with a few tweaks I've made to fit the AU-888. Full disclosure I'm a hobbyist at best that moves furniture for a living. I really want to get this down right. Thanks again!

Head Amp Block (F-1228)
C603 10uf 25v 10uF 35v 555-RFS35V100ME3#5
C604 10uf 25v 10uF 35v 555-RFS35V100ME3#5
C607 47uf 10v 47uF 16v 555-RFS16V470MG3#5
C608 47uf 10v 47uF 16v 555-RFS16V470MG3#5
C609 33uf 6.3v 33uF 25v 555-RFS25V330MG3#5
C610 33uf 6.3v 33uF 25v 555-RFS25V330MG3#5
TR601 XA495 ZTX795A 522-ZTX795A
TR602 XA495 ZTX795A 522-ZTX795A
TR603 2SC458 KSC1845FT 512-KSC1845FTA
TR604 2SC458 KSC1845FT 512-KSC1845FTA
TR605 XA495 ZTX795A 522-ZTX795A
TR606 XA495 ZTX795A 522-ZTX795A

Filter Block (F-1208)
C717 10uF 25v 10uF 35v 555-RFS35V100ME3#5
C718 10uF 25v 10uF 35v 555-RFS35V100ME3#5
TR703 XA495BL 2SA640 522-ZTX795A
TR704 XA495BL 2SA640 522-ZTX795A

Tone Control Block (F-1209A)
C719 10uF 25v 10uF 35v 555-RFS35V100ME3#5
C723 47uF 10v 47uF 16v 555-RFS16V470ME3#5
C729 33uF 25v 33uF 35v 555-RFS35V330ME3#3
C733 47uF 10V 47uF 16v 555-RFS16V470ME3#5
C735 10uF 25v 10uF 35v 555-RFS35V100ME3#5
TR705 XA495 ZTX795A 522-ZTX795A
TR707 XA495 ZTX795A 522-ZTX795A
TR709 XA495 ZTX795A 522-ZTX795A

Driver Block (F1282)
VR801 5k Ohm 5k Ohm 652-3296P-1-502LF
VR803 1k Ohm 1k Ohm 652-3296P-1-102LF
C801 1uF 50v Mylar 2.2uF 250v Poly MUNDORF71332 (Purchase from Parts Connexion)
C807 22uF 10v Bipolar 22uF 35v Bipolar 647-UES1V220MPM (50v would be a tight squeeze)
C809 100uF 25v 100uF 35v 647-UKZ1E101MPM
TR801 XA495G ZTX795A 552-ZTX795A
TR803 XA495G ZYX795A 552-ZTX795A
TR805 CDC8002-1 ZTX694B 552-ZTX694B
TR807 CDC8002-1 ZTX694B 552-ZTX694B
TR809 2SC984 *KEEP IF WORKING*
TR811 CDC8002-1 ZTX694B 552-ZTX694B
TR813 CDC9002-1 ZTX795A 552-ZTX795A (Will this work?)
TR815 2SC680 *KEEP IF WORKING*
TR817 2SA566 *KEEP IF WORKING*

Power Block (F-1293)
C021 1000uF 10v 1000uF 16V 647-UPW1C102MPD
C022 1000uF 10v 1000uF 16V 647-UPW1C102MPD
C023 100uF 50v 100uF 63v 647-UPW1J101MPD
C024 100uF 50v 100uF 63v 647-UPW1J101MPD
C025 4.7uF 50v 4.7uF 50v 647-UPW1HR47MDD
C026 4.7uF 50v 4.7uF 50v 647-UPW1HR47MDD

Ripple Filter Block (1230A)
R003 68ohm 3w 68ohm 3w 756-W21-68RJI (Smaller wireround type to keep heat off capacitors)
C006 220uF 50v 220uF 63v 647-UPW1J221MPD
C007 100uF 50v 100uF 63v 647-UPW1J101MPD
C008 100uF 50v 100uF 63v 647-UPW1J101MPD
C009 100uF 50v 100uF 63v 647-UPW1J101MPD
C010 220uF 50v 220uF 63v 647-UPW1J221MPD
TR001 2SD223 *KEEP IF WORKING*

SP Protector Block (F-1334)
C903 220uF 10v BPEC 220uF 16v BPEC 647-UES1C221MPM1TD
TR901 CDC8002-1 (B, C) MJE340 or ZTX694B 522-ZTX694B
TR902 CDC8002-1 (B, C) MJE340 or ZTX694B 522-ZTX694B


Other on Chassis
C002 4700uF 50v 6800uF 63v 647-LKG1J682MKNS
C003 4700uF 50v 6800uF 63v Nichicon Super Trough 40x100mm
TR819 2SC111 MJ15001G 863-MJ15001G (outputs)
TR820 2SC111 MJ15001G 863-MJ15001G
TR821 2SC111 MJ15001G 863-MJ15001G
TR822 2SC111 MJ15001G 863-MJ15001G

F001-F006 4A Quick Acting Fuse
F007 4A Fuse (100~127v)

 

[gslikker]

hmm did you check the length of the big capacitors, do they fit with the case on? Otherwise you would have to cut the metal to enable stick-through?

 

[stopkidding]

Yes. Those super through caps are quite long, 100mm. I got them for my au-666 build, but unfortunately didn't check the size and now they don't fit... :-(

 

[stereofun]

Very nice cleaning job - that's the right way to begin.

I'd recommend the MJ21194g's as outputs - they are twice as fast with only half the capacitance of their predecessor the MJ15001.

Welcome, we look forward to see your progress.

 

[Robisme]

hmm did you check the length of the big capacitors, do they fit with the case on? Otherwise you would have to cut the metal to enable stick-through?

You are correct, those won't fit. I used the LKG1h682MKNS. 50V 40mm X 80mm.

Rob

 

[Skip Lunch]

Thanks everybody! I meant to measure and remedy the large caps but spaced it last night. I found mostly 35mm diameter instead of 40. I think the stock caps are 40x70mm

You are correct, those won't fit. I used the LKG1h682MKNS. 50V 40mm X 80mm.

Rob thanks! I'm going to amend my draft and add these to my list with the outputs recommended by Stereofun.

 

[Robisme]

The originals I pulled are 40mm X just about 80mm.

Rob

 

[AnalogueBen]

Hi @Skip Lunch, how did your build go?

 

[Skip Lunch]

Hi @Skip Lunch, how did your build go?

Hey Ben! Apologies I have left you guys out of my build. It's on the back burner but I am still working on it. There is a couple errors I found on the parts list and that I will update you guys on soon enough with some progress.

 

[AnalogueBen]

Hey, well that'd be interesting to know about the finds. Awesome your still working on it