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Sansui TDC2075A (CRT TV) has no power or standby lights.

MobiusOne

Jun 8, 2022
17
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Jun 8, 2022
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Checked all fuses, replaced a bad resistor and MOSFET and still dead.
I think it's a power supply issue but unsure WHAT issue it has. I removed and tested the large black cap with my digital meter and it seemed to be fine gaining charge and doing as good cap would from the videos I watched.
Now I can NOT find a service manual for this TV but found one for this Memorex which uses the same VMC2938 board and the TV looks almost the exact same





PCB Images 1
PCB images 2 (Ignore the last image
 

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Bluejets

Oct 5, 2014
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No standby LED says standby power is down.
This is normally the 5v power required to get everything up and going.
Some knowledge of switchmode prower supplies is required to be able to trace just where the problem lies.

If you want to try to fix yourself, without a circuit diagram for that model, some of the repair videos on youtube or other online resources showing typical smps with no standby power would be a good place to start.
As always, these are dangerous pieces of mains powered gear given your lack of knowledge.

For example, when you say "tested the large black capacitor with digital meter"...how exactly did you manage that?
 

MobiusOne

Jun 8, 2022
17
Joined
Jun 8, 2022
Messages
17
No standby LED says standby power is down.
This is normally the 5v power required to get everything up and going.
Some knowledge of switchmode prower supplies is required to be able to trace just where the problem lies.

If you want to try to fix yourself, without a circuit diagram for that model, some of the repair videos on youtube or other online resources showing typical smps with no standby power would be a good place to start.
As always, these are dangerous pieces of mains powered gear given your lack of knowledge.

For example, when you say "tested the large black capacitor with digital meter"...how exactly did you manage that?
Tried looking online and I followed guides with sets having similar issues and they don't really help all too much unless you can point me to one. And I tested the large 200v cap just like in this video using the ohms settings since my meter doesn't have a capacitance mode.

I am aware of the danger of the CRT's charge and on a different model I have already gotten experience on how to discharge it.
As for the MOSFET it was bad but after replacing nothing has changed... no power whatsoever
 

Martaine2005

May 12, 2015
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Capacitors may still charge a little with a multimeter by using the meters battery.
ESR is the correct method to check electrolytic caps.

Martin
 

MobiusOne

Jun 8, 2022
17
Joined
Jun 8, 2022
Messages
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Capacitors may still charge a little with a multimeter by using the meters battery.
ESR is the correct method to check electrolytic caps.

Martin
I don't have a way of getting an ESR meter for my 200v 680uf but I also tested the voltage coming out of it while plugged in and It read about 160v
 

MobiusOne

Jun 8, 2022
17
Joined
Jun 8, 2022
Messages
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I was referring to the power supply, not the tube.
Im taking precautions with properly discharging PSU components. Even worked on the one in a smaller CRT before but this one has a DVD player and VCR so the board is much more complex and Im unsure to what part could be bad
 

Bluejets

Oct 5, 2014
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Im taking precautions with properly discharging PSU components.

That wasn't what I was referring to either.
Location was correct but I was referring to any live testing.
A fully charged cap in that area will definetely give you a wake up call, that's for sure.
However, the same point with the circuit powered up will lay you flat with zero wake up if you don't take the proper precautions.
There should be no reason to work live.
Show some sense and heed the warning.
 
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