Having problems with the left side pre-out it’s approximately tracking 15 to 20 W less than VU meters right side it’s not the actual amplifier itself. I switched to pre-out and problem follows amplifier channel. Not only am I having lower wattage in the left. I lost complete bass on my right channel. Anybody have any idea before I start taking this thing apart to save me some time. What may be wrong? Have you guys experiences before?
Sansui 9090 DB Pre Out Issues
- Thread starter Tunes 68
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The signal path through the preamp is complected. There are many points where a little dirt can cause that kind of dropout. At the very least, all the controls need to be cleaned. You may be able to narrow it down by "exercising" the controls. Move all the controls and knobs back and forth a few times.
- Pete
- Pete
Is there anything else you have done during the troubleshooting this issue? Let us know so we don't make suggestions which you've already completed.
Greek 7005
New Member
I’m not sure if my reply went through before it looks like it didn’t. I tested it through the mono switch and vu meters remain the same wattage. In stereo we lose power. The problem with the right channel with no bass still persists. That’s all I did at this point.
Thanks
Thanks
petehall347
the brandy coffee man
try the loudness
Are you helping the OP?
I would clean all the switches once more. Some will actually need to be removed and opened up to clean properly. I know that sucks but sometimes sits the only way.
And Yiasou!!!
Athanasios
I just started tinkering with it. I pushed in the mono switch and both meters are reading the same wattage. I did try switching to tape inputs besides auxiliary input and still experiencing the same issue. As I mentioned before I cleaned all the potentiometers really good along with exercising them. the next thing I’m about is to take the radio apart and start checking the tone board possibly?
will do
Thanks
OK update after eight hours of pain staking work. I repaired the Dolby board. Pinned all the pass through now working perfect perfectly. output levels all correct the only thing wrong nowid that when I switch from auxiliary to a.m. to FM I get a popping sound out of my speakers both channels. I have a spare 9090 tuner assembly. I plugged it in and there’s no popping the chassis works flawlessly. I found two bad transistors on the tunet board and one back cap. I thought that was my aha moment, but it wasn’t. I’m still getting a popping more work to come. has anybody ever experienced that. ? It’s only when I switch it from AM to FM to aux I get that popping sound. Everything else works just great. I also rebuild the power supply of the tuner assembly.
Crickets?
It is when you switch from the tuner, Am or Fm to aux when the popping occurs? I'd look at any coupling cap from or to the switch that leaking would put DC on the switch contacts. I am not looking at the schematic.
Greek 7005
New Member
Hi, yes that exactly what’s happening, I did check those carefully. Frustrating
Are there any other steps you've completed during troubleshooting of this issue? Please let us know so we can make better recommendations and not recommend actions which you've already completed.
Hi, I just spent a hour on it and found tr 10 defective and are TR 11 ok, I pulled both out and tested and dim bulb lit up very bright. Need to replace with a good substitute and find out what else is bringing this circuit down.
The original is a Sony C1636. Do we have a good substitute for this?
Gross parameter search at Digikey turns up 2N5089 as a possible alternate, but you definitely need to evaluate application as usual.