Lg50 pc1d

[Cornboats]

I have trouble fault finding a fault on psu board YPSU-JO12B.

Changed shorted Q855 SD20N60 power fet

Symptom-fuse keeps blowing.



All other Power fets tested ok.

removed Relays RL101 & R102 & tested ok

removed C603 & c603 power capacitors and tested ok.

removed diode D601 and tested ok.

Last time I tested the thyristers TH01 blew up as well as flowing fuse.



Any help would be welcome.

[selldoor]

Re: Lg50 pc1d

Pictures might help and using the lightbulb in series trick would save keep blowing bits.

[munirutech]

Re: Lg50 pc1d

did u hear the click of the relay before the fuse goes off

[Cornboats]

Re: Lg50 pc1d

Munirutech

With the large caps C602 & C603 removed and the diode D601 removed the relays energise but when fitted back fuse blew and Thryister Tho2 burnt and cracked.

D602, Q602, Q601, Q606, Q607 Bank of fets and diodes are still removed so at least I know this section is ok.

Selldoor

I haven't tried the light bulb trick- Could you illuminate?

Many thanks for taking an interest.

[selldoor]

Re: Lg50 pc1d

I haven't tried the light bulb trick- Could you illuminate?

HAHAHAHAHA I assume that is a joke?


See here
https://www.badcaps.net/forum/showth...ght=light+bulb

If you search there are various mentions of it.

Also google light bulb series test will give lots of hits

Serious about the pics though - I know its dark and difficult to get good pics but we tend to like pics on here - someone ( not me) may recognise the circuits and suggest what causing the problem.

[munirutech]

Re: Lg50 pc1d

hi

i tried googling the power supply model but could not find what am expecting to see,try to take a close image of the psu and a close image of the rf filter section of the psu to see what you are dealing with

[Cornboats]

Re: Lg50 pc1d

http://www.cornelissen.talktalk.net/...v/LG50psu1.jpg
http://www.cornelissen.talktalk.net/...v/LG50psu2.jpg
http://www.cornelissen.talktalk.net/...v/LG50psu3.jpg
http://www.cornelissen.talktalk.net/...v/LG50psu4.jpg

I've got some pictures for you today.

The red scribble says "Blown" and marks location of thyristor TH101.

I haven't done the light bulb series test yet.

Hope these are some help.