My new G6000 was just delivered this morning and i did the usual dc offset check before giving it a listen. 198mv on the left and 34mv on the right. I plugged in some headphones with a cdp hooked up to the aux input and i have no sound. Nothing on fm, am or tape. All inputs are quiet. No sound from the speaker terminals either. I'm not sure where to start on this one. It is in great cosmetic shape and i would really like to get this one fixed and put into service. Can anyone point me in the right direction? (it cost me a hundred dollars so i cant just write it off).

After checking around with my meter i found that there is no power getting to the preamp or the tuner. I ordered the service manual for it today but wont see it until next week. There is no power going through the 4 fuses on the power supply board either. If anyone has any advice i would be really glad to hear it. Thanks in advance.

Is there power coming out of the transformer secondaries?

Chill till you get the manual. Too hard to see what's up without it.

Chill till you get the manual. Too hard to see what's up without it.
Good advice. That is what i will do.

After checking around with my meter i found that there is no power getting to the preamp or the tuner. I ordered the service manual for it today but wont see it until next week. There is no power going through the 4 fuses on the power supply board either. If anyone has any advice i would be really glad to hear it. Thanks in advance.

Bummer. When you get the manual I may be able to help. Recently fixed a G-6000 and sent it back home in a cheerful mood. I have the SM here.

Paul

If it is a bad transformer, does anyone know if the transformer from a G7500 will work in it's place? There is one on the auction site right now and it has just over 1 day to go.

If it is a bad transformer, does anyone know if the transformer from a G7500 will work in it's place? There is one on the auction site right now and it has just over 1 day to go.

Don't jump to conclusions until you (we) have done some basic troubleshooting. A blown transformer is likely the last component to go on a G-6000 because the unit is adequately protected by fuses - unless, of course, some dimwit had jumpered those before you got it. :sigh:

Hang in there. We'll have it singing soon enough. :thmbsp:

Paul

Cool. I'll chill and wait. Thanks everyone!

My friend what can you expect for $100.00 dollars? Not Much. :nono:

if one out of a sansui g 7000 will work i have two of them for parts

if one out of a sansui g 7000 will work i have two of them for parts

I'm still waiting on the service manual but i'd be willing to bet that a G7000 power supply could be made to work. I'll let you know what i find out. Thanks!

Ordered it from Optimum Business Solutions and it is pretty nice. Good high res scans that should print really well. With manual in hand i did some testing and foud that all of the transformer taps are working as they should. There are three taps coming off the transformer at 40vac, 33vac and 7.5vac and all read dead on. I followed the path and have power after the rectifier diodes but that is where i need a little help. The schematic only gives voltages at certain places and i'm a bit leery about sticking my meter probe in some of those places because it's really tight.

Bias read 184mv on the right and 86mv on the left and after following the manual and turning the adjustments counter-clockwise i was only able to get them down to 22mv on the right and 48mv on the left. That is with both adjusters turned all the way counter-clockwise. Still no sound though.

I figured out why the tuner didnt work. The shaft that goes through the selector switch had slid backwards and was not seated in the front part of the shaft anymore. So it was never turning when you turned the knob on the front. I slid it back in and am now able to tune stations on the tuner but i still have no sound. While checking out the driver board i found that the transistors do not match and 2 resistors on one channel are the wrong value. I am going to pull the transistors this weekend and test them and see about getting the correct resistors. Pics below.

If i have bias voltage present, dc offset present, and a verifiable input signal but no sound that would tell me that the driver board is functioning. Maybe not correctly, but functioning. This got me thinking about what else could cause a no sound situation. Is it possible that the fault might lie in the equalizer board or maybe the tone board? Or could it be that the volume control is dead? When you turn on the power the lights come on, the tuner signal strength meter jumps up to about four and the speaker relay clicks. If i have the headphones hooked up i hear a slight hum that is unaffected by manipulation of controls. How can i test the volume control to see if it is operating as it should?

Hi Noprayer,
Your pics shows lots of fuse resistors and dropping resistors to be checked and is the relay clicking? no contact no sound, Next are those transistors with heat sinks. Hope the transistors and resistors your'e planning to pull out are not originally intended or factory installed as you will notice if it was by Sansui's solders or someone has touched or altered on it and installed a wrong values.

If you mark the position of the bias youv'e turned, the better if not I would rather put on the middle position to protect the power transistors in case it works normally, and readjust later as per the service menual.

Hope you fix it!! :banana: :banana:
regards
arsenio

If i have bias voltage present, dc offset present, and a verifiable input signal but no sound that would tell me that the driver board is functioning. Maybe not correctly, but functioning. This got me thinking about what else could cause a no sound situation. Is it possible that the fault might lie in the equalizer board or maybe the tone board? Or could it be that the volume control is dead? When you turn on the power the lights come on, the tuner signal strength meter jumps up to about four and the speaker relay clicks. If i have the headphones hooked up i hear a slight hum that is unaffected by manipulation of controls. How can i test the volume control to see if it is operating as it should?
Your deduction is a valid one...

The volume can be cold-tested with an ohmmeter, or you can follow the signal with a scope.

Just for grins i hooked my t-amp up to the tape out and lo and behold i DO have sound. Does this tell me that the pre-amp is functioning? And where would a person look next? I did test the volume control and got some strange readings. The meter is set to the 2000k scale and at zero volume the meter read zero. But when i turn the volume control up it goes to around 25 at 1/4 volume then down to 13 at half volume, back up to around 25 at 3/4 volume and a steady 3 at full volume. I'm not sure how to interpret those readings. Any insights? Thanks in advance.

You might have been measuring from the loudness tap. Or not. Can't quite see what ya did from here... :no: :)

Certainly you'll get output from a tape monitor...it doesn't go but through a couple of switches, and probably through no active circuitry, so it isn't much of a test.

You might have been measuring from the loudness tap. Or not. Can't quite see what ya did from here... :no: :)

Certainly you'll get output from a tape monitor...it doesn't go but through a couple of switches, and probably through no active circuitry, so it isn't much of a test.

I measured from one outside leg of the volume control to the center leg. I was able to identify the loudness leg and i did not use that in my test. If i flipped the probe to the other "outside" leg i get the same behavior, but in reverse. Zero ohms at full volume and 3 on the meter (200k range) at no volume. I hope this helps and is the correct way to test. I'll post some pics after work tomorrow.

If you're measuring 3 ohms, then there's a problem. If it's something else, then you will have to figure out what your meter is telling you. If you can't, then maybe time for another meter...?

Honestly, I think that you're barking up the wrong tree. Volume pots go bad, but I don't see anything that you've posted that makes me think that that's what has happened.

Check all supply voltages first...regulated and unregulated. If that's good, then it's time for a signal trace with scope and generator.

I set up some time with my friend kenny and his scope on sunday and he said he should be able to help me figure this beast out.

I took the beast over to my friend Kenny's house today and started probing with his scope and a signal generator. We got as far as verifying signal into the tone board and no signal out of the tone board and then the probe for his scope broke. GRRRRRRR!!!!!!! It's pretty old and he said he was wondering when this was going to happen as it had been repaired once before. We ordered a new probe and will continue with the troubleshooting next weekend. So, to sum it up, the problem lies somewhere in the tone board. I'll update more next week.

The new probe arrived yesterday and this afternoon i headed over to Kenny's to get educated on oscillascope usage and Sansui troubleshooting. In short order we had the problem down to a missing -30v power supply to the tone board. This was caused by a shorted zener diode on the power supply board (zd602 if anyone cares). From what i learned today this shorted zener would not allow the voltage regulating transistor for the -30v (for the tone board) to turn on thereby causing the tone board to stop functioning correctly. (I hope i remembered that correctly) He checked the driver board and advised me to replace the driver transistors with matched pairs since the existing ones do not match and are leaky (whatever that means) and the cause of my high bias voltage. So now i order some parts and next weekend i will put it back together in what i hope will be working condition. Thanks Kenny!

Getting close...

FWIW, you won't be able to properly check the drivers with them installed in the board. Too many alternate routes for current to take during a test. If they were checked while still soldered to the board and you were measuring some oddball readings during your tests, the transistors should be removed to confirm this. If they measure OK when removed, then they are likely fine.

...all speculation since I don't know what he did or how he tested.

Getting close...

FWIW, you won't be able to properly check the drivers with them installed in the board. Too many alternate routes for current to take during a test. If they were checked while still soldered to the board and you were measuring some oddball readings during your tests, the transistors should be removed to confirm this. If they measure OK when removed, then they are likely fine.

...all speculation since I don't know what he did or how he tested.

The regulating transistor and the driver transistors were all pulled and then tested. He said the readings for the driver transistors were strange but the transistor for the -30v supply was fine. Finding that the transistor for the -30v supply was fine is what made us pull the zener for that transistor and test it.

Well, after a couple of weeks of other duties we were able to finally get the zener diode into the G6000. IT WORKS!!!!!!!!! An 11 cent part made the difference. Since i orderd the driver transistors we put those in too. We left it sit on for about an hour and went back and adjusted the bias and offset (offset= 1.5 left 2.2 right, bias= 4.5 left 4.5 right). Right now i am listening to "The Wall" through the ADS speakers i picked up awhile back and i am PLEASED! Thanks for all the help and advice and a special thanks to my good friend Kenny, Who taught me alot while troubleshooting this beast. This one is a keeper!
:banana: :banana: :banana: