Author Topic: 17PW26..... (Read 4757 times)

tom66 · « **on:** October 16, 2011,10:27:34 »

These power supplies...... !!!!

Anyway, I have one of these power supplies in a Wharferdale TV. When plugged in main cap reads 322V, standby rails are good at 5.05V/3.38V, blue LED glows. Then I press the button, main cap ramps to 388V (PFC), then collapses (main board switches it off), stby rails are good but main rails are completely dead maybe a few hundred millivolts. With PL803 disconnected PSU doesn't switch off (forced on as STBY line is low), main cap stays at 388V, but still no activity from main outputs.

I tried the TV with another PSU (17PW15) which was close enough (though still has problems - intermittent on/off with other TVs), and it worked fine.

Originally when turned on the main cap wouldn't ramp to 388V and there would be clicking noise from stby trafo. That was a dead diode D823 now replaced. Then stby rails were there but still no PFC. So I replaced the resistors R817,R818,R819 and that part is working. Then I bought a repair kit for it to fix the no startup problem. Recapped electrolytics on all the primary side except 33u/50V C840 but will shortly replace that too. Replaced C877/C878 polys. Still no luck.

Any idea on what to check?

Mulja tv repair portal · « **on:** October 16, 2011,10:27:34 »

ProDave · « **Reply #1 on:** October 17, 2011,03:20:18 »

A tip with these PSU's

Put the PSU on the bench with just the mains plugged in, and all output connectors disconnected, and the PSU should (if working) fire up to "on" mode with all outputs working.

Makes fault finding a lot easier.

Service manual can be downloaded free if you google, with a good fault finding chart

tom66 · « **Reply #2 on:** October 17, 2011,04:29:51 »

Yep I tried that. Well I had it in the TV but I disconnected all outputs. The rails are all dead maybe hundreds of mV each. When the TV tries to turn on, a faint whistling sound is heard for 2-3 seconds (this continues forever if all the connectors are unplugged.)

Mulja tv repair portal · « **Reply #2 on:** October 17, 2011,04:29:51 »

sparky · « **Reply #3 on:** October 18, 2011,06:50:03 »

hi
if checking psu with all plugs disconnected make sure you have
good connection on the board for you - lead on meter
dave

heidiau · « **Reply #4 on:** October 19, 2011,06:41:18 »

hello, have a nice day!

Turnip · « **Reply #5 on:** October 19, 2011,11:17:15 »

Hi Heidiau

Wot - with a Vestel : must admit recently have found worse turkeys - Chris.

Mulja tv repair portal · « **Reply #5 on:** October 19, 2011,11:17:15 »

Mulja tv repair portal

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