Goodmans LD3265

Thread Starter

tom66

Joined May 9, 2009
2,595
Got this 32" LCD TV in for cheap.

The symptoms sound like bad caps but it doesn't seem like them as none are visibly bulging.

The TV will turn on only sometimes. Once turned on it works perfectly, not a problem in the world. But you will have to wait hours if not days before it is ready to work again.

I performed the soft-start modification, disabling the soft-start FET Q837 connected to pin #8 of the SG2525A. The set worked perfectly for 3 weeks, then died again, with a blinking front LED. I reversed the mod, now we're back to the original problem, it just won't turn on.

The only thing left for me to do is to buy a new power supply unit for the TV which is around £20. I'd like to avoid doing that if possible because it's kinda like giving up on a difficult puzzle!

The chassis is a Vestel 17MB22-2. I have the service manual available if anyone wants it. There are schematics included in the service manual.
 

debe

Joined Sep 21, 2010
1,320
Capacitors can be dried out & faulty they dont have to bulge. Check the circuit of the SMPS there may a resistor to kick start the powersupply. These can give trouble if gone higher in value. Can you post the powersuply circuit.
 

Jotto

Joined Apr 1, 2011
151
It probably uses a PMPS, look for a 47mf @ 50v volts it should be close the pulse width modulator. It could be a PWM and FET combined. There should also be a few 100mf caps that should be looked at. I wouldn't look at any cap over 1000mf at this point.
 

Jotto

Joined Apr 1, 2011
151
You get what you pay for. I would use good quality caps if you can get them. You want low ESR caps, long life or high temp.
 

Thread Starter

tom66

Joined May 9, 2009
2,595
You get what you pay for. I would use good quality caps if you can get them. You want low ESR caps, long life or high temp.
I recap secondaries always with high quality ones. I recap'd my LG 42" with Rubycon YXF, my 19" monitor with UCC KZG and my ethernet adapters with Panasonic and Nichicon low-ESR.

I found a power supply for £10, so I bought it. I gave in :p. I've been working on this bugger for weeks now - not been easy.
 
Thread starter Similar threads Forum Replies Date
R Analog & Mixed-Signal Design 32
Top