Tuning-Up a G-6000

EdwardHallman

New Member
Hello all! I'm a proud owner of a Sansui G-6000 Receiver. My father purchased it back in 1979 (I believe) while stationed in Okinawa, and it's aged pretty well. It's only physical defects are insignifigant: All of the bulb lights are burned out (which I actually like; it makes nighttime listening easier), and the right channel meter is broken. It plays everything really well and sounds great, especially with my old Bose 901 Active Equalizer attached to the NR Adaptor port.

Earlier today, I decided that I wanted my right channel power meter back, so I decided to swap the broken one in the right channel meter's place with the signal level meter. I never listen to the radio, and even if I did, I figured that the tuning meter would be informative enough for me to get homed in on my target station. The meters seemed to be exactly the same, and the swap went perfectly.

(A bit of background information:) I used to have problems with the G-6000 shutting off automatically from when the volume was too high, a feature that was built-in for a good reason. Unfortunately, my desire for loud music coupled with my overclocker's instinct forced me to open it up in an effort to disable or loosen the auto-protect. I figured that if there was a switch or a potentiometer for that, it'd be one of the six pots on the vertically-mounted board labeled "driver unit".Turns out I was wrong. Surprise, surprise. (The board was split in two, and symmetically mirrored on either side, so I only messed with the pots on the left side.) Anyway, when the pots didn't do anything beneficial as far as auto-protect goes, I just put them back to their original position (or very close to their original position, rather), and hoped for the best. None of them did anything to the sound or the stereo as far as I could tell, so I just decided to call it a failed experiment and close the thing up.

I'm faced with a new problem, though. I know it's just an insignifigant annoyance, but I'd like to fix it up if it's at all possible. Both of my channel meters work, but the left one isn't nearly as reactive as the right, and it also seems to be much "looser" than the right. It turns out that at least two of the three pots on either side of the "driver unit" board directly controlled the meters. (I'm still unsure what the third did; it's offset from the rest, and it doesn't seem to have any affect upon the meters, so I'd love to figure out what its purpose is.) Knowing that the two potentiometers controlled the meters, I figured that setting them to be exactly the same on either side would make both meters exactly the same. I desoldered the right side pots, took measurements, and resoldered them without changing their values. When I desoldered the left side's pots, however, their total value wasn't exactly what the right side's pots were; in fact, the 2.2k pot was 500 ohms less than the other. I tried setting them up proportionally, but that didn't work. After about two hours of tweaking the pots to get them to exact values (to the ohm), I just ended up resoldering them and doing it approximately. How frustrating.

So, the purpose of that unnecessarily long post was simply this: I was wondering if anyone here knew exactly how to get the meters on a Sansui G-6000 to behave a certain way. If anyone could give me some insight, I'd really appreciate it!
 
Assuming that the meter you swaped in is really identical to the one that broke (cant speak to that) then yes there is a procedure for calibrating your meters. It sounds to me like you need to get a service manual and do a service on that reciever. Service manuals for vintage gear are frequently sold on ebay and there are several web sites that specialize in them as well. Sorry I dont have the links handy....but google will surely bring them up.

But to do the service you will likely need some equipment you dont have. For example, I believe the service manual for my kenwood ka-9100 integrated amp says a signal generator is required to calibrate those meters. Yours may vary of course. Best of luck to you.
 
I actually found the complete schematic diagrams for my G-6000 this morning, and believe it or not, the text is in ENGLISH. This is amazing.

So it turns out that the two pots on either side that directly affected the meter on the driver unit board are labeled as "Center DC 0v Adjust". The third pot on either side is labeled "Bias Current Adjust". Could someone tell me what that third pot would do?
 
Actually, they came with the receiver itself. I dug the box out of storage and buried under some styrofoam packing, there was a single sheet of paper, which was exactly what I needed. Turns out that the two pots that I was looking for were on an entirely different PCB that was mounted on the front panel and obscured by a few bunches of wires. I set the others back to normal and everything seems to be working correctly now.

Forgive me for not doing this earlier, but thank you very much for your response yesterday, RhinoFly. I really appreciate it, and I guess in my excitement this morning, I totally spaced thanking you for it.
 
Originally posted by EdwardHallman
So it turns out that the two pots on either side that directly affected the meter on the driver unit board are labeled as "Center DC 0v Adjust". The third pot on either side is labeled "Bias Current Adjust". Could someone tell me what that third pot would do?
You are going to screw yourself counter-clockwise if you mess with these adjustments!!

If you already have, then you best learn how to set them back to original before you fry a speaker, your amp, or both. These pots have absolutely nothing at all to do with adjusting the meters.
 
If you already have, then you best learn how to set them back to original before you fry a speaker, your amp, or both. These pots have absolutely nothing at all to do with adjusting the meters.

I've already put them back to their original position (down to the ohm). The thing that really surprised me about my receiver was that the pots used were actually very inaccurate; for example, one pair was rated at 2.2k ohms, and the first in that pair had an actual resistence of 1.9k ohms and the second had an actual resistence of 2.6k ohms. When I put the pots back into their original positions, I got the resistences accurate to within an ohm or two, but with discrepencies like that, I would think that I could have been a couple hundred ohms off without making a big impact upon the stereo's performance.
 
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