Well, I've just received my new Sansui AU-9900a - a wonderful, well-built machine! The stereo imaging is superb. It used to belong to a church and was driven only on Sundays, literally. But given it's age, I will be re-capping it soon and then I'll give it tune-up. Can anyone out there share their copy of the service manual with me? Many thanks.
xxxfarmerfranco@gmail.comxxx (delete the xxx before & after address)
xxxfarmerfranco@gmail.comxxx (delete the xxx before & after address)
Hi Black Gate,
Blindly "recapping" an amplifier only really helps when you replace the bad capacitors. It's certainly not going to correct the several other issues that crop up in older equipment.
I had a look in your user information, trying to discern your level of technical experience, but I see you haven't filled anything out yet. No insult intended, but I always like to see if someone knows how to service equipment rather than just swap parts. It gives me an idea how much damage may or may not occur.
I would caution other members to not take a soldering iron to anything unless the have some training (of some sort) and do know exactly what they are doing.
-Chris
Blindly "recapping" an amplifier only really helps when you replace the bad capacitors. It's certainly not going to correct the several other issues that crop up in older equipment.
I had a look in your user information, trying to discern your level of technical experience, but I see you haven't filled anything out yet. No insult intended, but I always like to see if someone knows how to service equipment rather than just swap parts. It gives me an idea how much damage may or may not occur.
I would caution other members to not take a soldering iron to anything unless the have some training (of some sort) and do know exactly what they are doing.
-Chris
Hi "Blackgate",
I have a AU-9900A too and was recapping it a couple months ago.
I discovered the advise Anatech (Christ) is providing is generally correct. For the 9900A, all you really need to be is change all the old electrolytic caps.
I managed to locate the service manual (from Rapid share) and the bias is 50mV - basically a Class-A int amp.
I did find the sound a bit too raw for myself so I changed the film caps on the pre-amp board as well as a few of the film caps on the driver board. Please note there are a two bi-polar caps on the driver board, a bi-polar on the psu board and another two bi-polar on the pre-amp board.
Also becareful when desoldering on the pcb(s) as this particular unit has pcb masks which are a little mis-aligned (compared to other Sansui's inmy collection). My best advise is to take a high-res pix of the pcb(s) - both sides, before you start.
I ran into a dry-joint issue on the driver board a couple times. The most troublesome incident was due to a joint which I loosen by mistaken on a resistor when searching for another hole. This cause the amp to go into protect on-off repeately. When I checked via multi-meter the problematic joint shows connectivity. Managed to correct the issue when I notice the problematic joint look a little higher than the neighbours.
Sounds like a valve amp now! In fact, it sounds so good I sold my AU-20000 and kept the AU-9900A!
I have a AU-9900A too and was recapping it a couple months ago.
I discovered the advise Anatech (Christ) is providing is generally correct. For the 9900A, all you really need to be is change all the old electrolytic caps.
I managed to locate the service manual (from Rapid share) and the bias is 50mV - basically a Class-A int amp.
I did find the sound a bit too raw for myself so I changed the film caps on the pre-amp board as well as a few of the film caps on the driver board. Please note there are a two bi-polar caps on the driver board, a bi-polar on the psu board and another two bi-polar on the pre-amp board.
Also becareful when desoldering on the pcb(s) as this particular unit has pcb masks which are a little mis-aligned (compared to other Sansui's inmy collection). My best advise is to take a high-res pix of the pcb(s) - both sides, before you start.
I ran into a dry-joint issue on the driver board a couple times. The most troublesome incident was due to a joint which I loosen by mistaken on a resistor when searching for another hole. This cause the amp to go into protect on-off repeately. When I checked via multi-meter the problematic joint shows connectivity. Managed to correct the issue when I notice the problematic joint look a little higher than the neighbours.
Sounds like a valve amp now! In fact, it sounds so good I sold my AU-20000 and kept the AU-9900A!
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