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G8000 with no sound

thesaint

thesaint

Active Member
I thought I would get this started after doing as much reading as possible as I could on the
G8&9K. First time in the Sansui forum, so hopefully with expert help we can get this awesome G8000 back playing again!
I wanted to try to eliminate all the try this and try that and give as much useful info as possible before just posting, it doesn't have output.

The unit passed dim bulb test. Turns on and flashes in protection as it should and goes green with audible relay sound! I have checked and cleaned every glass fuse and they all check out good.
Tested dc offset at the speaker terminals, L = +1.3v and R = +71.9v, I know not to worry about this as it can be adjusted later.
Both spk A&B have visual and audible relay engage/disengage when turned on/off.

One of the most common things told is to clean the connected/separated switch. I have done this now 3 separated times on as many days to the maximum. There is no way that switch is not clean. I next dismantled the face and all knobs and went to town cleaning every pot and lever on it. As mentioned repeatedly in past threads, I know I may have to do it again before buttoning it back up when completed.
Went ahead and checked every board with a molex and pins and cleaned them all. They were all really tarnished!

Tapped on relays when tuned to a strong fm station and when using music through AUX, no change.
Tried pre amp out rca to amp in with the switch on disconnected and didn't get anything. Also tried the reverse of that and with the G8000 as the amp, also nada.

In the cluster of the 3 relays, I can hear and see them function. I noticed there is 4th buried in there and do not know what that is for or if I should be able to hear it as you can not really see it.

I hope I have exhausted all the "obvious" and am ready to take some direction on how to proceed with this.

This is from an original owner and it worked fine up until he put it in closet about 8 months ago. It also has never been serviced which seems remarkable to me.

Pre-thanking all that can help someone newish and my first sansui.
 
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thesaint said:
Tested dc offset at the speaker terminals, L = +1.3v and R = +71.9v, I know not to worry about this as it can be adjusted later.
Click to expand...
I am not an expert but first thought is R = +71.9v looks like you have full +Rail voltage passing through. Are you sure that is Volts or did you mis-read your meter and it is Millivolts? I don't think the Speaker Protection Relay should allow that to happen. But if this is the case, you probably have a shorted Output Transistor. Others with more experience on the G series will probably chime in.
 
Good deal. Sounds like your protection circuit is working properly. The fact your not getting signal on Preamp Out to an offboard Amp or Offboard Preamp into Amp is not giving any output on the G9K is a concern. I'll try to look at the schematic later tonight or someone else may jump in. Double check if there is a tape monitor engaged. If you had a scope you could try to trace an AUX in signal to see where it drops out.
 
First, you need to diagnose whether the problem in the main amp or in the preamp. Connect your phone directly to the main in. Before switching on the receiver make the volume of your phone to minimum. Switch on the receiver and gradually increase the volume of your phone to check whether you are getting sound or not. If you get normal sound the problem is in the preamp section. If you don't get any sound in both channels problem obviously in the main amp. To rule out the preamp has no problem you need to connect the pre-out to the main in of another unit and check the sound.
 
I did this check previously both ways and didn't manage to get anything.

I just tried my phone in the main, switched to cap coupled and could faintly hear it out the speaker, no matter the volume.
I will also retry the pre out into another amp to see what I can get tomorrow.
 
Re-tested signal into amp with switch set to separated cap coupled, extremely faint sound coming out not matter the volume setting. Re-tested the pre-out with the same setting on the separated switch, and nothing. Tried these both on different equipment just to make sure. I really would have thought that with no sound the dim bulb test and the protection feature wouldn't work so well.
 
yes, all testing and test have now been don on full mains.
The 8000 turns on, goes green and lights up as it should. Tunes stations strong on fm. There just seems to be no one home?
 
Even though I cleaned and tested all the glass fuses, I went ahead and replaced with new at the same value, some were rather gross and somewhat corroded.
Doubled checked all the molex connectors I pulled and put back on. As I have had only one test spk connected on the left channel I switched it over to right just for the hell of it. Started to get very faint distorted sound out of the right on any source. Decided to tap on the relays and the faint distorted sound started to cut in and out. Although still nothing on the left.
Could I have at least found one problem? Bad relay/corroded relays?
 
Yes, sorry, forgot to write that. Different speakers and its the same for both spk A and spk B, just the distorted sound out of the right.
 
So your saying that because it exhibits the same exact symptoms on spk A and B, it can be be the relays, even though when you tap on them the faint distorted sound comes and goes in and out?
 
Went ahead and 2nd round deoxit every switch, pot and lever followed up with faderlube. Also for my own curiosity popped the speaker A relay cover off and gently cleaned the contacts. That was a crazy amount of cleaning! No change in operation. Nothing out of L and low distorted sound out of R on A or B spk. That's with Fm or AUX.

What is next and where to go from here?
Thanks
 
I have the service manual downloaded and I'm ready for direction on what to check or test. I would like to fix the problem before doing any restoration that should be done.
Thanks
 
best place to start is the power supply .if that's not right nothing else will be .
make a list of the voltages and check against the schematic
 
Since this is my first Sansui and the boards differ substantially from pioneer, apologies for not just being able to crank out readings of you are all used to seeing posted.

This is the F2809 board
These are all the pins I could find to get a reading.

1. +41.65v
2. -41.7mv
3. -68.0mv
4. +1.2mv
5. +.5mv
6. +61.22v
7. -62.0v

10. -58.33v
11. +58.59v

16. -8.97v

20. +.4mv
21. +.0695v
22. +23.33v

29. +2.0mv
30. +2.5mv
31. +0.4mv
32. -88.0mv

35. +1.4mv
36. -88.0mv
41. 0.0mv

Do I have to get readings on molex connectors C,D,E,F and G? Do I have to get readings from F2806/7 boards?
 
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