Sansui AU-9900A EQ Board F-2691 in AU-9900? (F-2570)

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Segasonic91

Active Member
I want to replace the EQ/Phono board in my AU-9900. I found a F-2691for sale, which is the board for the AU-9900A/11000A. The board and its contents look to be almost identicle across both as are the connection pins on the board. Is this compatible with the AU-9900?
 
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Hyperion said:
Why? - what's the problem?
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I have been having a lot of problems with the original.

Although I was unsure if that was due to the 798 replacements I installed. I matched transistor pairs, but could not get both "E" legs in the holes, so I soldered one leg to the other. I had continuity to where it should go, but was still unsure if soldering the legs was an effective way to replace the 798's. I notice the F-2691 only has two of the bastard things, not four.

Damned thing finally came out of protection (I had replaced caps on the power and output board as well) Phono was dead when I tried it initially with foil intact, AUX was working so I put the old 798s back in, and it went into protection. When I took the 798's out again was when the foil came off. It was stuck to the legs of the 798 and would not come off. I am using a desoldering station at 300c, contact for 5 seconds or less. I have had no problems before this board, I think the foil on these, being so small are especially delicate and brittle from age.

Just tried it to see if AUX is working, and it was still in protection. I noticed I had not turned the power point off last time I checked it. After a few hours, it will usually come out of protection but go back into protect mode as soon as it detects the phono input being used. I thought replacing it might be a good idea because the one in it has given nothing but problems. It sounded like crap when it DID work, although I know other factors could effect that. At this point, pretty much all caps have been replaced apart from tone controls. It came out of protection when I recapped and changed 725/1313 transistors on the main output board. I do not have the other transistors for that board at the moment. I detected nothing bad from them when tested, but I still want to replace them.

I just want this rotten thing to work, it cost me a fortune over 2 years ago and has gotten no use. I am ready to chuck it at the moment. Just won a Pioneer SA-9800 (9500) from Japan for ¥16,000. Once it arrives, I am ready to just get rid of the rotten thing.
 
I will add that I am amazed the phono board worked at all. I did not realise until I started working on it, but the phono (and power) board had been recapped before. The thing was, every single thing in it was the wrong value. Much higher uf than it should be and much higher voltage. Some were lower uf as well. The bi-polar caps had been replaced with 2 470uf/160v caps, it was a mess. Just another lie from the seller when he told me it had not been touched and was all original.
 
ivandezande said:
The 9900/11000 are not hard to get going. Recheck your work or get it to someone who knows these units better.
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You are right, it shouldn't be hard to get going but this thing is one problem after another. What about the 798 replacements I mentioned, is soldering the middle legs together of the two KSA trasistors sufficient? As I said I have continuity, but I do not know if they are working as they should. There were two replacements on the phono board, obviously from when proper 5 leg replacements were available. I left those in and only changed the old originals. I ordered the remaining transistors I need to replace everything on the output board as it was after I recapped it, is when it initially came out of protection. I was still getting horrible pops though.

I am still no closer to knowing if the 9900A board will work in my 9900.

EDIT: Hmmm, I guess not. The connection pins are different afterall. There are two spaced pins on the left and one on the right vs one each side on the original.
 
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Segasonic91 said:
You are right, it shouldn't be hard to get going but this thing is one problem after another. What about the 798 replacements I mentioned, is soldering the middle legs together of the two KSA trasistors sufficient? As I said I have continuity, but I do not know if they are working as they should. There were two replacements on the phono board, obviously from when proper 5 leg replacements were available. I left those in and only changed the old originals. I ordered the remaining transistors I need to replace everything on the output board as it was after I recapped it, is when it initially came out of protection. I was still getting horrible pops though.

I am still no closer to knowing if the 9900A board will work in my 9900.

EDIT: Hmmm, I guess not. The connection pins are different afterall. There are two spaced pins on the left and one on the right vs one each side on the original.
Click to expand...
What I do to make the dual’s is hold the two new transistors together with a pliers, and solder the very top of the two touching legs. Cut one of the double leg off, and there you go.

I’m guessing you have a bad connection, solder bridge, etc.
 
ivandezande said:
What I do to make the dual’s is hold the two new transistors together with a pliers, and solder the very top of the two touching legs. Cut one of the double leg off, and there you go.

I’m guessing you have a bad connection, solder bridge, etc.
Click to expand...

Great, thank you for that. I will do that and swap them out. I keep thinking that the wires connected to the relay board from the phono board was what caused the lack of sound from the phono board when it was working at first. But I checked continuity and there was no problem. I will check everything over again.
 
Well, checked over the boards again last night. I re-soldered the black wire to the board that slots into the relay board. I also got the 100uf/10v bi-polar caps yesterday so I put those in the output board and also replace 3 of the 4 DS-430 diodes. I could not get the wires soldered to the same spot as one of the diode legs to come off, so I left it.

Checked it again and heard the "CLICK" of the relay. Plugged my CD player in and had sound. It lasted about 2 minutes before it went back into protection. Turn off then on again and it clicked. Same thing happened. Third time I tried it, I started getting the horrible, loud pops and crackling through the speakers so I left it.

I also just tried the phono input and get NO SOUND still. Could that be because of those 798 replacements I made up not working?
 
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