Toshiba Plasma power supply buzz. red light blinking.

[fastline]

Toshiba 42HP95. They are well known for killing the Seine board I guess but they can be tested out by removing power from that board and that did not work. When power is applied, the PS will fire a relay on the board, bring up 2 fans, wait about 5 seconds, then kill the fans and throw the famous red blinking light.

I am still learning on power supply repairs. Not sure if this noise from the supply is normal or not. It is a buzz but only audible from about 2ft away if you are listening for it. I removed every load from the PS and it still makes the same noise. Coming from the inductors it seems. Bridge is good and never blew a fuse.

Also, I am NOT a TV repair guy. After testing the PS with no loads, I was going to reattach the plugs and when I tried reconnecting the Vsus plug, I got some arcing. I realize things were charged up and I did not connect it wrong but wondering if this is a poor practice and can damage anything? I am used to the old TVs where there was a service switch to drain the caps but these don't appear to have anything.

I am very much suspecting the power supply but honestly pretty overwhelmed. All caps "look" fine. Probably about 30 FETs on it so that will be fun.... Just not real sure what I might be looking for if that buzz is deemed an issue.

 

[tunedwolf]

I don't have a great deal of experience on Tosh Plasma's, but I'm guessing at a couple of diodes and FET's being goosed on the power board. I seem to remember them being on the end of a heatsink rather than in the middle. Check the 15V rail, it's pretty common for the cable decoder/ card reader to pull it down. Disconnect the 4 way plug going to it and see if the 15V rail reappears.

Don't run any switchmode power supply without a minimum load attached, simply put they don't like it. I only ever went to component level on Pioneer Plasma power supplies due to them blowing up every week (it was faster to just fix it than wait for a replacement board) but other than that, I just replaced the board, no hassle, warranted repair for the customer.

rgds

 

[fastline]

ESR meter on the way. I am still blown away over the price. You can get a Craftsman digital multimeter that is reasonably accurate to do about 50 functions for 50 bucks, or a meter that just does one function and I have to assemble the whole thing for 100 bucks!!! What is so special about this circuit?

 

[tunedwolf]

Its ability to measure the equiv series resistance of a capacitor without having to get your soldering iron hot...
Also quite handy to find those pesky little decoupling caps that insist on going short circuit...
Although, I think I would have spent a little more than that and bought an Atlas ESR80, but then I'm a snob when it comes to tools

rgds