G-9000 Repair

I sure do, I have a small shop in Apple Valley. I've been repairing and building since getting out of the USAF in 1992.
 
I used to get my HiFi repairs done from an ex USAF guy in Apple Valley several years ago. He had a shop loaded with vintage stereo equipment in an industrial park not far off of Happy Trails Hwy, and I believe the cross street may have been Quinnault, but not 100% sure. I was real impressed with the huge speakers he used to test the Nikko receiver I brought to him for repairs. You don’t happen to be that same guy, are you?
 
If it was years ago that was Marty, I forget the name of the business. I'm only a couple of streets over from where he used to be, the next street east of Quinnault. I have a small shop inside of a warehouse that used to be filled audio gear, lots of Japanese Kabuki speakers but that was only a couple of years ago.

I just remembered Marty's business name, Bear Electronics. does that sound familiar?
 
I can’t remember the name of his business but It was around 10 years ago since I’ve been there. The first time I went there was to buy a pair of Ohm speakers he was selling on eBay. The room where these speakers were was chock full of amps, receivers and speakers, audiophile heaven... I was met by him and an Asian gal (his wife?) and bought the Ohms from her. I lived in Palmdale but had a work assignment at the old George AFB, which is now SCLA, so that was a close drive for me.

I was hoping you were him because I wanted to know if those massive speakers were still there. I have a thing for big speakers...
 
That sure sounds like the same place I work now, that owner sold everything and left in 2015 and I took over the warehouse then and still have my shop there. Was the shop in the main warehouse or in an office? If it was in an office I was the tech there at that time. I opened the shop while working for the old owner in April of 2012.
 
The workshop was in the back. I’d walk through the front door and I seem to remember there was a glass case at the narrow entrance. There was wall shelving there on either side with amps, receivers and speakers. To get to the actual workshop, I had to walk down a narrow hall to the back. I believe there were two rooms, one on either side in the back. One side had the test equipment, the other side was where those large speakers were. They weren’t tall, a bit shorter than Cornwalls, but just as wide and definitely deeper.

I think my last visit was back around 2010 or 2011.

Sorry for taking over the thread. Hopefully the OP responds soon and let’s us know where he lives and hopefully it’s near you so you can get the business.

I see you like GAS equipment! I recently picked up a clean Ampzilla from AKer Rmac with one crackling channel I need to repair.
 
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Well that sure describes my shop so it hasn't been as long as you think. It has to have been after April 2011 as that's the way the shop was set up until May 2015. Those old speakers were JBL L200s I think. Yes, I like James Bongiorno equipment and just love to work and rebuilt anything SAE, GAS, or SUMO. Unfortunately I don't get to see much of it unless it's my own stuff. Just finished up a ground up rebuild of an SAE2600 for someone in MN and have his 2400 in for a rebuild now. Are you going to repair your Ampzilla yourself? I just got one of mine going not too long ago.
 
Yup, after confirming online, those really were JBL L200 speakers. I’d remember them anywhere. Marty told me he didn’t care too much for the sound of them, but he wouldn’t sell them to me, LOL!

Yes, I plan on restoring the Ampzilla when I have the opportunity. So many projects, so little time with having a full time job taking me away from the restoration work.
 
Marty was Bear Electronics, long gone by the time Ebay got started. The man you are thinking of is David, he was married to a Filipina. I was/am the tech here since April of 2011.

Craig
 
Marty was Bear Electronics, long gone by the time Ebay got started. The man you are thinking of is David, he was married to a Filipina. I was/am the tech here since April of 2011.Craig
I'll tell you that I'm guessing at most of the human issues, as It's been a few years since all these transactions took place. I just recall that I thought it strange that a female had control of this empire of audiophile equipment, then a man shows up and takes control of the sale. Whether that man was David, Marty, or Craig, I couldn't tell you honestly. LOL! All I know is the sight of all that stuff is what got me re-fired up into the audiophile business.
 
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this is Hank in Colorado! i just recapped a G-9000 for a customer. I used Bourne trimpots from Mouser. The 100ohm was part #652-3296P-1-100LF, and the 1K ohm was # 652-3296P-1-102LF. Top mounted adjustment and near perfect fit. This 9000 would not come out of protection with the old pots and the tricky adjustment. Follow the instructions and set DC offset at 0Vm then adjust the bias to 5mv, then readjust DC Offset to zero, it will have risen to about 30mv after setting bias. Do not readjust Bias!
 
Hank, the #652-3296P-1-100LF is 10 ohm. What he needed was 652-3296P-1-101LF which is 100ohm.
Can you or Ketamine explain what you set the new trimpot to before you started testing? I mean, should I just turn it all the way until it clicks and then rotate it 12.5 times and start from there? is there another better way to do it?
 
Can you or Ketamine explain what you set the new trimpot to before you started testing?

Bourns multi-turn trimmers are set at the factory to half track resistance, that is how everyone receives them. There is seldom any reason to turn them one way or the other before adjustment in-circuit, despite what the SM says in the adjustment procedures. Adjusting to the wrong extreme (either maximum or minimum resistance), is an easy trap to fall into, and can easily cause component damage before it is realised that it is set the wrong way. This is because different circuits either require minimum resistance for minimum bias, or maximum resistance for minimum bias, but having the trimmers initially set for half resistance seldom causes problems.
 
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Thank you John :)
are the two areas I marked in red where I should measure Bias?

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are the two areas I marked in red where I should measure Bias?

Yes, that's it, you need to adjust for 16mV - with the meter set to read 'DC mV'. In the above diagram it usefully shows the polarity for the meter connections. (some people get worried when they see a negative reading for this on a digital multimeter - it just means the connections are reversed - it is the magnitude of the voltage i.e. '16mV' that is important, whether positive or negative. ;))

You should make an initial setting after 5 minutes warm up, keep monitoring and adjust again after 30 minutes. During this time it should remain quite steady, but will likely drift very slowly in one direction or the other (up or down).
 
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