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1000x Distortion

N

Nick T

New Member
Hi all,

I've been lurking here for the past few weeks trying to nail down some Gremlins in a 1000x that was passed down to me. Right now it sounds pretty distorted.

So far this is what I've done to it:

Detoxed all the Pots and Switches.

Recapped the driver amp block

Replaced the coupling capacitors

Replaced the c458 transistors on the driver amp block

I've run a signal through the Main In, and it sounded just as distorted as using the Aux and Phono inputs.

Anyone have some advice?
 
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Thanks for the reply!

I'll check those capacitors again and report back. Where should I place my leads in order to check the mid-point voltage?
 
I'm almost 100% sure it's not the buttons at this point. After I put a signal into the main in input, I was still getting the same Distortion. None of the switches work when you have it in Main In.
 
petehall347 said:
what voltages do you get at every output transistor case with respect to chassis ground ?
Click to expand...

Measuring the voltage between the ground and the top of each Power Transistor, I got exactly 32.2V on one pair of them and between 33.2V and 33.8V on another pair.
 
there is the problem then . one of each pair should be about half the voltage of the other .. check the grounds first .
 
petehall347 said:
there is the problem then . one of each pair should be about half the voltage of the other .. check the grounds first .
Click to expand...

Awesome. Just to be clear, I put one of the leads on the ground on the back of the receiver and the other on the top of the transistors (the collector).

Is it possible that these have gone bad and just need to be replaced? I'm not exactly sure what I should be looking for on the ground connections.

I really appreciate all of the help.
 
petehall347 said:
for example ..f1180a driver board check voltage from chassis to pins 2 and 17 .
Click to expand...

So at the base of each transistor (801, 806) I'm getting around 3.5 volts. At the collector it's close to 17 volts.

I don't think this is what you were looking for. Do you know which transistor numbers I should be checking?
 
Last edited:
base emitter voltage would be more useful . p.s lost me when jumping to here from checking grounds . unless you mistook the line on the schematic as a trace ?
 
petehall347 said:
base emitter voltage would be more useful . p.s lost me when jumping to here from checking grounds . unless you mistook the line on the schematic as a trace ?
Click to expand...

Yeah I mistake your instructions haha. The grounds are both fine. I got an even 0V when I checked each.

The base emitter voltage is .6 V in each, I'm pretty sure that the main board is in working order.
 
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