Help with G-22000 AMP Protection

tder1

New Member
Hey There ! Finally picked up an Amp for my 22K, Been using the front end through an old Pioneer, The wealth of knowledge here may be able to help. After careful and proper assembly won't come out of protection. I'm not an expert but can usually find my way around. I found F1 and F2 blown and the right channel relay is not pulling like the left. The dust cover is missing for the relay so perhaps that blew the fuses? Changed the fuses, all others good. Powered up, The fuses didn't blow but the relay is still not pulling and no power light on the amp. Still in Protection BTW, Did some work arounds and I know the left channel works. Any Ideas ?
 
Start with the basics...check the DC offset on each channel. This will have to be done on the PC board somewhere, since the speaker relay will not be closing and the speaker terminals will not be connected to the amp output.
 
Hi Guys, Well after 2 Years of my 22000 sitting in the Shop untouched, won't mention, I finally had enough and picked it up. Lucky it was still there. Iv'e been thru quite a bit myself Resistors, Transistors, New Caps on the Driver, and the polarities are correct, but i'm held up and perhaps you can just give a general idea. No Right Channel. Pull the driver and it comes out of protection and plays Left. I have all good voltages at the driver plug but when I plug in the driver it stays in protection and my 78V on pin 2 drops to 24V both sides + and -. I cant see anything wrong. Driver Board? Power Board?
Any steerage would be appreciated. Thanks in advance
 
What is the DC offset for the right channel? This would be a good time to use a dim bulb tester. If the outputs are shorted, the soft start resistor could overload. The DBT will help prevent that. If you don't have a DBT, google it. There is a lot of information available on how to build and use one. Once you have that, put the driver board back in and connect everything. Measure the DC offset voltage at the copper coil on the power supply board.

- Pete
 
Mine looks OK when driver boards are attached (DC offset 0V Bias 15mV)
When driver boards are removed there were DC offset was 9V!!!
We replaced TR 10 11 12 13 14 and problem solved. These was testing OK, but I guess they was out of spec.
 
I've been on a DBT 100W the whole time so far for about a week. I had left floating at -5 +3 mv and right at 0mv without 2901 in. If I put it in it wont pull the 2nd start relay in. I had problems frying R34 on 2901 so thats when I checked all the trans ,diodes and resistors on 2901. I believe I took all the fuse resistors out. Transistors changed, 1,2,4 on 2903. 10 on 2901. I thought changing 10 would take care of it. It measured good before i changed it. Nope.
This may help cuz the DBT may have been masking problems. I took it off the DBT this morning and immediately blew fuse #2 to one of the blue leads and fried R34 on 2901 again. Short somewhere it seems ? Idea what I should look at?
 
Have you checked the output transistors? You have to remove the heat sinks to get to them.

- Pete
 
I had just pulled them all on that side before i tried it off the DBT. I checked them and they all look good. I have several sets both Sankens and OnSemi's.
 
As far as I can see now all I have left is the sort of the blue PS wires blowing fuses. Can someone just give me a little direction to find the short?
Had to rebuild the driver again. Turns out whoever worked on it before had T03 In backwards. You know, Check and Double Check!
 
Not sure what you mean by "the sort of the blue PS wires". It's not likely anyone is going to have one open to match that visual description. You need to reference schematic points so we can follow you. What fuse is blowing, what board are you on, what does the sort of blue wire connect to?

- Pete
 
Point Taken. Sorry. After working on this for weeks i take a lot for granted,I have all the Docs and can usually figure them out. From the right channel power supply there are a bank of wires that plug into F2903 Rt Channel Power Supply that are fused with 10Amp glass fusses. white,purple,red,blue, I am blowing fuse 01 and 02 for the blue wires 55V only when off the DBT. I realized my stated voltages above are low because im on the DBT. They are actually normal when plugged off the tester. Without the driver Board 2901 plugged in I have 89v at 39 and 46 at the connector for the driver board on 2903. as soon as I plug in the 2901 board those 2 drop to 54v and R34 on 2901 gets very hot. There is a short somewhere having to do with the 55v power supply somewhere downstream. I don't want to throw too much at once. I need to find what is blowing my 01 and 02 Fuses on 2903 first. Thanks for your patience. I'm way below some of the extreme knowledge you guys have with this stuff but as a collector I need to be able to work on them. It did me no good to leave it with a Tech. for 2 years and have nothing done. Its a crap shoot.
 
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Do not mount driver boards or connections to output transistor until all other boards are working. I mean until it comes out of protection, keep driver boards and output transistors away.
You can also remove power connections on the 2903.

So,
1 remove both driver boards,
2 remove yellow-brown, purple-blue connections and yellow on both 2902 and 2903 (these connects the output transistors)
3 remove white reds purples and blues on 2903 (cables from transformer)
if 2902 is working properly it should go green, (also 2903 should be partially work)
when you see green, mount transformer cables (3), if you can still see green mount driver boards, at this time it goes green if they are also working but you will not be able to set bias. finally you can connect output transistors and make adjustments.

This step by step troubleshooting helped us a lot.
 
Wow, That is one heck of a receiver. Lot's of things going on.
Remove the blown board and go through it completely, checking ALL the transistors, diodes and resistors for values. Check ALL the outputs in that bad channel for serviceability.
Lift one leg of the resistors and diodes when checking.
Don't worry about the ceramics or coils.
Buy a DCA55 for checking the transistors. Well worth the money considering you are saving money by fixing it yourself. And the built in value of that set!
Do not take any short-cuts. Take good notes on what you checked. Take your time. There are no easy fixes. There is no single component fault.
Do not continue to plug the set into the house without going through the DBT.
Install new correct value fuses and use the DBT until the set responds with both amp driver boards installed and a dim bulb.
If you don't at least do the above tasks, find another tech to fix it for you.
This is not a set for a beginner.
 
Just awesome direction guys, thats what i'm looking for. I'll give it a try and get back. Thanks alot.
 
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