G-8000 Popping Noise

The boards are easy to work.
The shields are different and should be installed with the full covered one on the right. As looking at the set.
What transistor is causing the issue?
Some will use freeze spray. Others will replace one at a time. Or you can replace all of them.
Any method will require setting the amps Bias and offset.
And it's good practice to balance the amp by matching the same components on the other channel.
If a transistor is acting up, it's likely the others came from the same batch and the issue will come up again sooner or later.
A start would be to eliminate any cold solder connections on the board. Reflow all of them.
 
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A start would be to eliminate any cold solder connections on the board. Reflow all of them.

Being it appears to have been worked on in the past, recapped at least. Double check all the connections on the suspected boards for a cold solder or broken lifted traces. The latter an all to common occurrence even for the experienced with good equipment, more so for the lesser skilled.


Barney
 
Try cleaning the pins with the Markthefixer pencil eraser trick. Do a deoxit cleaning on the female ports. Can anyone tell the OP if this unit has any of the transistors on the board are part of the "worst" transistor list and whether it would be a good idea to replace them? You have one of the greats there. I was given one for free by AKer Madhattter; so my only cost was shipping from Washington State. I spent the money and sent it to CDFixer in California for a rehab. When you get this all straightened out, you will be very happy. All work you are doing will give you a great knowledge base in you head. A great thing to have. Enjoy.
 
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None of the amp's driver boards transistors are standout's for known trouble.
I'm not sure how I would begin to isolate/repair the issue.
If that's what it ends up looking like (Transistor(s)).
All listed transistors have good Fairchild, or On Semi equivalents.
 
Reads like a troubleshooting guide/flowchart that Sansui forgot to add to the service manual.
So what is it, a passive or an active component? we shall see.
 
Well I can't seem to add photos. I created an album and added the pictures to it but then it said I didn't have any in there. Maybe I have to wait awhile? I was a bit disappointed to see that the sight is downsizing my hi-res pictures even though I got them under 10 meg. I'm not sure if anyone will be able to spot anything I'm not seeing but I'd at least like to see if someone can. I'm not at all comfortable with rewetting all of the solder connections. It would be great practice for me and I even have a new tip for my Weller butane but this is not a board I really want to practice on! Can anyone tell me what might be wrong with my photo posting?
 
Seems to me that some transistors were replaced, can you read the transistors labels?

Check the solder for hairline fractures and I can't see very well but check the this points.

DSC_4295.JPG
 
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Hipocrates, that spot at the bottom left was some of that yellow goo that I flaked right off. I see nothing on the top spot. Generally speaking, all of the solder joints look pretty darn good to me. Where would I read any transistor labels? The transistors are the little things with colored rings right? I don't see any writing on them. And what would FR (R17, 20) be? I assume it's some component on the board. That's right folks, I pretty much know nothing at this level.
 
Umm - unless I am mistaken - looking at your pic #4291 - it looks like there are some Hitach 2SC 458's in that board - could this be correct? Could thse be subs someone later dropped in? If this is correct then these are most likely to be your culprit. They are the "boxey, slopey" looking square transistors - very distinctive-looking. can you check their numbers?

untitled.png
 
And what would FR (R17, 20) be?
Those are fusible resistors usually fails... so you have to replace it for metal film, R15, R20(location) the value is 150Ω 1W (i think)... those can cause some problems.
the transistors are the little back boxes with three legs
red circle--> transistors
yellow circle---> "fusistors" (pet name for fusible resistors)

Probably one of those buggers is messing around.

DSC_4291.JPG

More info here on this masterpiece

http://audiokarma.org/forums/index.php?threads/bipolar-junction-transistor-testing-basics.43186/

Note. those units once properly reconditioned are awesome... so you could consider that.
 
Considering it very strongly. Just trying to get a feel for what has already been done/needs to be done. It's very clean inside.
 
Well I'm off on vacation for a couple weeks so this has to be back-burnered. In the mean-time I'm going to try and pick up a used Fluke 77IV to replace the cheapo units I've been toying with for many years. Then I'll see if I can do anything useful with it. Happy holidays everyone!
 
Just an FYI: I caution about using freeze spray on some parts of the driver board, specifically the input FET. Hitting some devices will cause such a large change in gain that parts downstream can be damaged, or at a minimum the unit will go into protection. A current-limited supply (such as a DBT) is required before attempting this.
 
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