I could get involved but I cannot always reply as I am busy with a project knee deep.
To me getting involved is to see to it that you get the amp running. That takes a lot of reading, looking at pictures, studying the SM and all that.
And it takes a lot of time from side.

I can input pointers from now and then but I cannot promise I will be here always due to the work I am currently doing.

 

For now check Q574, Q572, Q573, D574, D573, D576 and c575 for Shorts.
And Remove fan and use a variable supply starting from 0 to not more than 5V to see if it works.
If not find one of that size and voltage.

Normally the fan operates when it detects Audio at speaker terminal.
The more volume the higher the RPM.

AFAIK the Amp does run if fan fails but will go into protect at high volume is the fan is not working even without heat build up.

I need to know the current condition of the Amp.
You can power up the amp with other units disconnected I believe.
If not powering up with units disconnected, connect ones by one and check. Normally it works together with tuner.
Post your complete findings.
And yes if it powers up, can you hear the relay clicking after a second or two ?

 

And Remove fan and give 12V to it to see if it works.

From the circuit, I don't think it is a 12V fan. Does it have 12V written on it?
I believe it is more like 3V. Don't blow it up with 12V.

 

Nope....12V. As far as I have seen.

 

Why do you say that? Is it written on the fan?

 

Mostly...I have seen 12V on technics.

But it could be a 5V one.

 

@AlbertHall.
Thanks my friend, fan should be less then 5V.
I corrected my post

 

I believe D573 is a 3.3V zener (it is difficult to find data on these parts) and that limits the voltage fed to the fan.
Also read this thread on the same motor: http://www.badcaps.net/forum/showthread.php?t=6577

 

Hello,

here are my findings. I didn't power up again (just jet), can do if required. When i did do so i felt everything was working well, though i didn't play anything. with respect to the fan I do remember that after the cleaning of the fan and at power up the plastic of the fan did seem to make a noise, like the propeller was touching something. So i'm pretty sure the fan motor is working as well. I opened it again and it doesn't state anything more than the model and date stamp.

With fan connected I checked all required. note the DMM default value is 1. When I connect ‘the other way’ it shows briefly a value of app 1800 than returns to the default. Vice versa it shows an consistent value, see below.

Q572 1020 one way, 1 the other, 1070 on middle leg, on inner leg 960
Q574 1020 one way, 1 the other, can’t reach middle leg
Q573 I tried all combinations I could think off and the only value I got was when connecting the middle and inner leg then it shows gradually runs from 1950 to a consistent 1990. All other combinations show 1

D574 838 one way, 1 the other leg
D573 1077 one way, 1 the other
D576 024 both ways
C575 024 both ways

Two bonus ones ;-)
D575 433 one way, 1 the other way
R575 1950, and 1 the other way.

What do you guys think? THe Q573 is suspicious but does show at least one value.

 

Q573 has internal resistors so it will read something like that.
You need to find some way to reach the middle leg of Q574 to check if it is shorted to one of the other legs. Perhaps wind some stiff bare wire round the meter probe and bent at right angles to the probe?

 

Or find a part of the circuit farther up the line that you can connect to. If this unit has been sitting for a spell, those electrolytics may be dried out and throwing off all voltages. Should use ESR tester and check them out.

 

You need to find some way to reach the middle leg of Q574 to check if it is shorted to one of the other legs. Perhaps wind some stiff bare wire round the meter probe and bent at right angles to the probe?

So I did. Q574 reads 1037 on the outside legs and similar value outside leg with middle leg. All other combinations read 1 after a second or so.

 

I did power up twice for a second and the fan made a small movement. All clicks where as I remember. The R573 starts smoking up again.

 

Or find a part of the circuit farther up the line that you can connect to. If this unit has been sitting for a spell, those electrolytics may be dried out and throwing off all voltages. Should use ESR tester and check them out.

Not sure how to do this and what to do specifically. An ESR is not part of the DMM I believe?

 

ESR is a separate type of meter that can test the series resistance of capacitors. Sometimes the capacitance may show up good but the ESR might be high creating problems when the cap is being used

 

Is the R573 smoking with the fan removed ?

And is it possible to measure voltages ?

 

... Suggest that you replace the electrolytic capacitors in the power section, as posted by Alex_C, previously. It is unlikely that you will get the unit working properly if you don't. These parts seem to have a limited lifespan .

 

It's not that I do not agree on replacing caps but they are darn good caps.

 

I second the suggestion. This fixes many power supply problems. But even if it doesn't it extends the life of the device because those capacitors will eventually fail. I resisted this brute force recommendation for a long time but after building an ESR meter and fixing a few things by replacing electrolytic capacitors, I have become a believer. The meter was satisfying, but really it's faster and cheaper and more effective in the long run to just replace the caps.

 

Changing the PSU caps may be a good idea but it's not going to stop this resistor getting charred.
Does the fan run nicely on 3V? If not it may be the problem.