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Sansui 9099db. Very quiet output.

C

CFroelich

New Member
Hello all. I’ve recently picked up a 9090db free off the curb when it was waiting to be picked up by the garbage man. I thought “no way is this even going to power up”, but I brought it home and blew it out with an air can. Checked all the fuses I could find with a multimeter and they all showed continuity. So I crossed my fingers and plugged it in. Lo’ and behold it fired up and sound came out of the speakers! However the sound is very muted. There was very little scratchy sounds when I played with the knobs and buttons, and a can of DeOxit later, almost none of that. However, it is still very quiet. Like a 2 watt stereo. Everything else seems to work. The volume knob gives a linear increase of sound from zero to the muted max. Balance knob works. Tone controls adjust sound as you would expect. I hear a difference when I adjust the Dolby knob. It’s the same with the headphones. Everything works, it’s just very muted. Tried A, B, and C speaker terminals. Speakers are known to be good. I tried different jumpers from preamp to main. Same result in the AUX and Tape inputs.

When I touched the jumpers very loud hum and suddenly AM radio was coming out.
 
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Did you try a different preamp with the amp section?

Also I wouldn't run it much until you restore the driver board, unless you like fried output transistors.
 
ivandezande said:
Did you try a different preamp with the amp section?

Also I wouldn't run it much until you restore the driver board, unless you like fried output transistors.
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I’ll try that today. I’ve got a Marantz 2226. If I run the preamp from that into the main IN on the 9090db (and vice versa) and I get good sound in one of those configurations, that should help pin down my problem, correct?
 
CFroelich said:
If I run the preamp from that into the main IN on the 9090db (and vice versa)
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This is a good idea, but I advise you not to do the vice-versa part of this if you find the power amp section of the 9090db works correctly. As what you will be doing is feeding a potentially faulty pre-amp (9090db) into a working Marantz 2226 power amp - with the possibility that you might damage the Marantz. Just accept that you have found a fault in the 9090db pre-amp - if that's what the results of your test shows, and take it from there. ;)
 
Hyperion said:
This is a good idea, but I advise you not to do the vice-versa part of this if you find the power amp section of the 9090db works correctly. As what you will be doing is feeding a potentially faulty pre-amp (9090db) into a working Marantz 2226 power amp - with the possibility that you might damage the Marantz. Just accept that you have found a fault in the 9090db pre-amp - if that's what the results of your test shows, and take it from there. ;)
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Ok. Thanks for the heads up.
 
From the New Zealand school of crappy audio incorporated, dont forget - use crappy (but working) gear to test this unit till it is running, ie:

- crappy speakers,
- crappy sound source (phone, CD player) with volume control to run a quiet signal into the "main in" poweramp section,
- crappy power amplifier to run from the preamp of the sansui unit into this, to test the sansui pre section.
 
slimecity said:
From the New Zealand school of crappy audio incorporated, dont forget - use crappy (but working) gear to test this unit till it is running, ie:

- crappy speakers,
- crappy sound source (phone, CD player) with volume control to run a quiet signal into the "main in" poweramp section,
- crappy power amplifier to run from the preamp of the sansui unit into this, to test the sansui pre section.
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Speak for yourself mate.........:yikes:
There is no need to do that, you verify its working correctly before plugging it in and then you do not have to worry about all those shenanigans...
 
AlTinkster92 said:
Shucks I can't believe someone would throw that out for the trash man.......good grief! Hope you get it working! AL
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I know! Minimum value (as is) is $600 and if I figure out how to fix it myself I’m going to have a $1K receiver for very little investment! I’m just getting into this and I’ve really gotten lucky. Some of my finds so far are a Realistic LAB 420 FOR $20. The Dual 1019 for $85. 4 monstrous HealthKit speakers for $40. Some Scott B-10 speakers for free. The most expensive thing so far is my Marantz 2226B for $185. It’s been super fun going on the treasure hunts. I only know what to look for because of AK forums.
 
slimecity said:
From the New Zealand school of crappy audio incorporated, dont forget - use crappy (but working) gear to test this unit till it is running, ie:

- crappy speakers,
- crappy sound source (phone, CD player) with volume control to run a quiet signal into the "main in" poweramp section,
- crappy power amplifier to run from the preamp of the sansui unit into this, to test the sansui pre section.
Click to expand...
Well, Hyperion had a good point and I stopped by goodwill and picked up a mid-90s Yamaha Natural sound receiver for $5 so I’ll be using that as my source and maybe an amp for the Sansui preamp as a last resort. Such good advice on AK.
 
CFroelich said:
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OK. Here is what I did. I hooked up the new cheapo Yamaha as a pre-amp into the main IN of the 9090db and can get crushingly loud music. :rockon:. So the problem is not the amp. Is there any benefit of hooking this up in reverse?
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No. The Sansui preamp (or maybe something else within) *needs* to be repaired. You have established the power amp works. Since the volume control and tone controls seem to work, the issue may be in the Dolby board. Now it's time to get a *GOOD* tech in your area to repair it. A "newbie" (no offense) isn't going to have the required skills for it. Where are you located?
 
Skywatcher said:
No. The Sansui preamp (or maybe something else within) *needs* to be repaired. You have established the power amp works. Since the volume control and tone controls seem to work, the issue may be in the Dolby board. Now it's time to get a *GOOD* tech in your area to repair it. A "newbie" (no offense) isn't going to have the required skills for it. Where are you located?
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I’m near Reno NV and there is no one local. Closest techs are in Sacramento so if I have to have it fixed by a pro, I’m probably going to send it to QRX
 
CFroelich said:
I’m near Reno NV and there is no one local. Closest techs are in Sacramento so if I have to have it fixed by a pro, I’m probably going to send it to QRX
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Perhaps there is someone from here on AK close to you that would be willing to take a look at it. But if not, QRXrestore is a good place to send it.
In the mean time, you could try cycling a few switches (with the power off). When switches don't get used much at all, the tarnish builds up on the silver-plated contacts. Start with the TAPE1 switch and work it about 50 times to help scratch some of the tarnish off the contacts. Then cycle to Dolby switch, then the selector switch trying it out in between each switch, then move to the bass turnover switch. See if anything changes at all. If there is any improvement, then the switches will need a thorough cleaning. It's quite a task to clean them properly, though some have had (limited) success spraying Deoxit D5 and working them. But that only helps for a short time. If there is no improvement, then likely the passthrough joints on the Dolby board need "fixed", or it has the old green ribbon cable in the Dolby board that could be bad. But in any case, it needs a thorough diagnosis to determine the actual cause.
 
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