HELP !! Right Channel distortion G 8000

MJ Clemmer

Well-Known Member
Hello guys, JUST recieved the G 8000, looks GREAT BUT ... when I hooked her up, the right channel sounded distorted, turn it up a bit (to about 5-6 watts) and the "protection" kicked in. I let it reset, then turned the balance all the way to the "left channel ONLY" and turned it up, SOUNDED GREAT, goes WAY UP THERE with No problems. I tried to move the cd player to another input and got the same result. But when I hooked it up to the PHONO 1 and 2, it was real bad on BOTH sides....Im lost and dont know what to do. I am SUPER bummin ! PLEASE is there anyone that has an idea what is wrong, and if its gonna cost a ton to fix. I have been waiting for a unit like this for years and am SO glad to get one, but not in this condition. look at the E bay item, and you can see that it says "EXCELLANT CONDITION WITH ALL INPUTS AND OUTPUTS are working fine"! So if anyone can help or assist. I would be forever greatful.... Gonna e mail the dude that sold it to me now Is there anyone near the Milwaukee WI or Chicago area that fixes these? Man I am despert.... thanks again and check out the link....I dont think he was right on this one...


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3092477618&sspagename=STRK:MEWN:IT&rd=1 Thanks again for ALL of the input that I have recieved from all of you SANSUI GREATS ! I hope to hear from ya soon...Michael... (a Bummin Michael...)
 
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I'm interested in the reply here, I have a Luxman that's doing the same thing - even though you have exibited GROSS smiley abuse. Christ, I can hardly look at the post.

Cheers,
Russ
 
This has been tested to the best of our ability and all inputs and outputs seem to be working fine.

That's what it says, probably a unit that has travelled some and could use a good cleaning! Check your selector switch...
 
NO. Do not connect a high level output to a phono input. You will overdrive the amps.

Now, back to the distortion. You need to get a moderate signal - preferable an FM station, and switch to MONO. Is the right channel still bad? Or is it now OK?

Set all controls to the NORMAL or DEFEAT position; esp. the tone controls. They are gererally a major source of noise and distortion in a G-8000 (probably any G-xxxx) and in the defeat position you should hear no crackle or distortion.

Try that first and report back. Then I'll outline my "switch & control mashing" routine.

Paul

PS: It took about 3 to 4 weeks for my G-8000 to settle down after cleaning and the use of my "daily switch & control masher" routine.

Now it noise-free and singing like a bird.
 
Ill give it a shot and let you know how it turns out. I didnt know about the phono jack with the cd player. Could that have caused the problem?...Ill get back to you after I try all of your suggestions...thanks for the help...Michael...
 
Lol!! The phono input is designed to take the teeny-tiny output of a moving-magnet cartridge (on the order of 2 to 5mV, or 0.002V to 0.005V) and amplify it to something usable. The gain factor is huge, and there is a fair amount or equalization that takes place to restore the proper frequency response (RIAA phono curve).

A CD player puts out a signal somewhere around 1V or so...or about 500-times what the phono input is designed to accept.

I believe you can interpolate the rest.;)
 
Well that might explain the REAL BAD NOISE that came out of it when I turned it on..LOL... I guess I get the DUMB_ass of the week award... Michael...:withstpd: I DID learn something this week anyhow... Do you think its a BAD praoblem, of a fixable one? I know this is HOW you PAY for your mistakes....Michael....
 
Do you think its a BAD praoblem, of a fixable one? I know this is HOW you PAY for your mistakes....Michael....

I feel it's unlikely you would do any damage to the amp by overdriving it (briefly, I hope) with a large signal into the PHONO input. Now, your speakers, on the other hand, may well have reached the smoking stage rather quickly :D


Typically, those output transistors are rated for the rail voltages they run on and usually fail due to circuit component failures rather than being directly over-driven.

Echowars would have a more definitive answer for this - I'm using engineering principals only. We all know how often that works :cool:

Paul
 
Originally posted by Morden2004
NO. Do not connect a high level output to a phono input. You will overdrive the amps.

Now, back to the distortion. You need to get a moderate signal - preferable an FM station, and switch to MONO. Is the right channel still bad? Or is it now OK?

Set all controls to the NORMAL or DEFEAT position; esp. the tone controls. They are gererally a major source of noise and distortion in a G-8000 (probably any G-xxxx) and in the defeat position you should hear no crackle or distortion.

Try that first and report back. Then I'll outline my "switch & control mashing" routine.

Paul

PS: It took about 3 to 4 weeks for my G-8000 to settle down after cleaning and the use of my "daily switch & control masher" routine.

Now it noise-free and singing like a bird.

Ok, thanks for the info....I tried EVERYTHING that you stated and it still has the distortion in the right channel. It also will STILL go into the protection mode when using the right channel , its goes into the mode at about 4-5 watts....,Im ready for the next part of my schoolin..... Thanks again...Michael...

PS: I will NEVER AGAIN hook up anything to the PHONO inputs, BUT a PHONO, (i said that to myself 100 times today)...LOL
 
If it goes into protection mode at some level, like 4-5 watts, but not at low levels then I suspect that the BIAS is off on that channel -or- there is a driver circuit problem. Once it exceeds the maximum current allowed the protection circuit kicks in and shuts 'er down - thankfully! A BIAS value that is out of spec will do that. Most of the time it can be corrected by the BIAS adjustment.

You need to do the BALANCE adjustment (described earlier - o VDC on the speaker outputs) and the BIAS adjustment both of which require a service manual and a DMM.

Paul
 
Disconnect the speakers and put a decent meter set to read DC voltage on the output terminals. With the spring speaker connectors on the 8000, you might have to make small 'speaker leads' to get a connection (depending on what type of leads the meter has). Set the input to 'Aux' with nothing connected to it.

Anyway, look at the DC offset on the channel that is acting up. Observe it with the volume at minimum, and watch it as you slowly increase the volume level. Ideally, it should be 0.00V. In reality, few amps manage that without circuitry to monitor it and constantly make corrections (called a DC Servo). If you see less than 20mV ('+' or '-', it's absolute value we are concerned with, not the sign) then that's decent. I'm not going to parrot all the info in the DC Offset thread, but anything over 100mV is cause for sonic concern, and at 600mV to 1.5V or so the protection will kick in.

If you don't have a decent digital meter, go buy one. Ought to be a standard item for every household.

Rpt back with your findings.

(I suspect blown components on the driver board if severe distortion is noted, but offset is a starting place...)
 
Originally posted by Morden2004
NO. Do not connect a high level output to a phono input. You will overdrive the amps.

Now, back to the distortion. You need to get a moderate signal - preferable an FM station, and switch to MONO. Is the right channel still bad? Or is it now OK?

Set all controls to the NORMAL or DEFEAT position; esp. the tone controls. They are gererally a major source of noise and distortion in a G-8000 (probably any G-xxxx) and in the defeat position you should hear no crackle or distortion.

Try that first and report back. Then I'll outline my "switch & control mashing" routine.


So now Paul, can you please tell me what the switch and control mashing routine is? I'm having the same problem with my G8000 right now. Thanks. I also pm'ed you.
 
Well, that cleaning routine is as follows:

1) With the unit unplugged, clean all the pots and switches (and those PRE OUT/MAIN IN jumpers) using a good contact cleaner like Do-Oxit.

2) With the unit still unplugged, work each and every control, switch and jumper several times - but not overly fast or aggressively. Remember, these are vintage units and we don't want to break things. Just make sure you have cycled everyting through all positions and ranges a dozen times or more.

With the power back on; and volume set LOW and a pair of not-so-important speakers connected :p: continue .....

3) Work all switches as above thru several cycles; for pots (volume, balance etc.) I usually run a few cycles with NO pressure on the shaft, then a run a few cycles with a gentle PULL on the shaft (don't pull the knobs off :D ) and then a few cycles with a gentle PUSH on the shaft. This is necessary to put more mechanical pressure on the wiper arm so that it wipes more effectively while in the cleaning cycle.
NOTE: You may have to re-apply contact cleaner if, after a week or two of #3, the problem(s) do not appear to be getting better.

I do this every day until all signs of channel drop-out, scratching volume noises and switching static is gone.

It can take anywhere from a couple of days (my AU-999, for example was noise free on the 3rd day) or a couple of weeks (my G-8000 took nearly three weeks of this procedure) to become bug free.

If there are circuit problems (e.g. DC Balance is off or BIAS is incorrect) then this proceudre won't cure that. But by getting all the mechanical components clean and noise free you can then better assess the remaining problems.

Good luck!

Paul
 
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Thank you SO much,ALL of you. I am going to try everything that ALL of you told me to do. I will get back to you guys and let you know the outcome. THANKS SO MUCH......Michael...
 
Paul, I followed your advice and guess what? My sansui G-8000 is again singing the blues. First I cleaned the radio twice but still no go, then I tried your step no. 3, which is pull and push on the shaft while running it into a cycle and did it about 10 times. And what do you know, the right channel came alive and wham! it's singing the blues again. So now I'm a very happy camper and thanks to you. YOU DA MAN PAUL!!!
 
Originally posted by henter04
Paul, I followed your advice and guess what? My sansui G-8000 is again singing the blues. First I cleaned the radio twice but still no go, then I tried your step no. 3, which is pull and push on the shaft while running it into a cycle and did it about 10 times. And what do you know, the right channel came alive and wham! it's singing the blues again. So now I'm a very happy camper and thanks to you. YOU DA MAN PAUL!!!

Wow! It really works :D (just kidding - I know it works because I've been using this trick for 30 years).

Good work!! Congratulations.

Now, don't stop doing this just because you have daylight down that tunnel - keep it up for a few days because the oxidation and crud is still there. You have managed to wipe a connection thru it but a program of daily "rub and scrub" will ensure that this baby sings for a long time.

Paul
 
I have to clean my G8000 periodically also. It seems to be the only weak point of an otherwise outstanding receiver. The fact that I have it in the basement doesn't help either! I have found a new cleaner which does a really good job on cleaning the controls: Greentree Generation 2000 super Contact Cleaner, available at www.mcmelectronics.com. I follow it up with De-Oxit.
If cleaning doesn't work, I am in Cleveland, OH and I can fix it, so PM me if interested.
 
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