LC TDK PSU issues

[Jon183]

Hi everyone,

I have a TDK supply that has a really strong burning smell and gunk all over. I am going to send off for all the caps on the right side on Friday and give it a thorough clean. Just wondering if there is an issue with CR4 and what part it is, the smell seems to come from that part.

 

[techknight]

i think it is a zener diode, and if its heating up its shorted. 

If it is shorted, then there has to be a reason why. if the power supply doesnt work, then the mitsubishi PWM IC is probably dead with it. 

 

[Jon183]

i think it is a zener diode, and if its heating up its shorted. 

If it is shorted, then there has to be a reason why. if the power supply doesnt work, then the mitsubishi PWM IC is probably dead with it. 

The system is lifeless and does nothing at all when switched on with this supply, have to share my good astec one between my LC and LC475.

 

[Jon183]

Macintosh LC TDK 699-0153 recap list:


C5



180μF 385V



C8



8.2μF 50V



C60



47μF 25V



C55, C52, C51



1000μF 10V



C56



56μF 25V



C54, C53



270μF 25V



C64



270μF 10V


Pretty sure its accurate, haven't really double checked it though.

 

[Jon183]

Recapped it, working now, I will test it with a multimeter after I recap my iici logic board.

 

[marmotta]

I have recaped my psu but random work or not... anyone know the code of the component IC55? Is at left of diodes... my component not have any word on it!

 

[marmotta]

This is under red cross

 

[marmotta]

I think is a thyristor, but I'm not sure

 

[superjer2000]

Recapped it, working now, I will test it with a multimeter after I recap my iici logic board.

Did you also replace the diode or anything else or just do the recap?

 

[Jon183]

Did you also replace the diode or anything else or just do the recap?

just recapped, it worked for a bit but died a few days later

 

[marmotta]

just recapped, it worked for a bit but died a few days later

You can verify the code of IC55? You would do me a big favor

 

[Jon183]

You can verify the code of IC55? You would do me a big favor

sorry, I cant read what is on it

 

[marmotta]

sorry, I cant read what is on it

I use a phone with max zoom and led light.... or is total black?

 

[Jon183]

I use a phone with max zoom and led light.... or is total black?

I did exactly the same, sadly its way too faded out.

 

[marmotta]

I did exactly the same, sadly its way too faded out.

Damn! You can't read "TYN"? :-(  

 

[marmotta]

Help!!!!!!

 

[techknight]

Its a voltage regulator. Without xray vision I dont know which. 

Easiest way to find out is measure it for shorts first, if there are none, then attempt to power on the supply and measure the input vs output voltage. thats how you tell if its bad or not. 

 

[marmotta]

Its a voltage regulator. Without xray vision I dont know which. 

Easiest way to find out is measure it for shorts first, if there are none, then attempt to power on the supply and measure the input vs output voltage. thats how you tell if its bad or not. 

Can be a CT7912? Positive or negative? ....the old component is destroyed, I tested it same as thyristor and is died...

 

[marmotta]

This can help?