One more-Toshiba shuts off after 20 mins. No sound nor picture

[jimdandar]

I have a Toshiba 32AV502R, 3 yrs old, that shuts down after 20 minutes or so; no picture, no sound. It will come on again after about 45 minutes and repeat this cycle.

I took the back off after it failed, the capacitors seem fine, but noticed a 3 second interval of buzzing coming from the power circuit board. I was able to isolate the sound that came from the circled part on the attached picture using the rubber tubing only of a stethoscope. This part does not buzz when the tv set is working.

I am going to replace this part, but can anyone tell me what it is so I can order one? Thanks.

[jimdandar]

Re: One more-Toshiba shuts off after 20 mins. No sound nor picture

OK, let me try with the attachment.

[tom66]

Re: One more-Toshiba shuts off after 20 mins. No sound nor picture

It is a transformer, unlikely to be the problem: more likely is some part of the power supply is shutting down. Have you tested if the supply voltages stay stable or drop out?

[jimdandar]

Re: One more-Toshiba shuts off after 20 mins. No sound nor picture

I am a neophyte electronic repair person. I can test for power, but do not have the knowledge to answer your sugestion. Any other thoughts? Thanks for your patience.

BTW I lived in Whittlesey, near Peterborough, for a year and a half a few decades ago.

[tom66]

Re: One more-Toshiba shuts off after 20 mins. No sound nor picture

Do you have a digital multimeter?

[jimdandar]

Re: One more-Toshiba shuts off after 20 mins. No sound nor picture

Yes

[tom66]

Re: One more-Toshiba shuts off after 20 mins. No sound nor picture

I don't live in Leeds normally - just doing a 4 year Electronics Engineering university degree. Though I am liking it for its TV market - if I don't manage to break the screens while working on them .

OK, near the connectors going from the power supplies to the various boards in the TV (one the main board, with the video inputs on it, and one the inverter, which makes the bulbs light up) there may be a label indicating what the individual pins do - can you read off what this says if it is present?

[jimdandar]

Re: One more-Toshiba shuts off after 20 mins. No sound nor picture

left of the connector p802 gnd. above the connector +24 vaud GND +12vcc +5vcc. to the right power acd dim inv

[tom66]

Re: One more-Toshiba shuts off after 20 mins. No sound nor picture

It's hard for me to see, but is is clear to you what pins are +24V, +12V etc? Can you check these pins for the voltage when the TV is working and when it fails? To check the voltage, set your meter to DC 200V, place the black probe in the chassis of the TV (any exposed part of the metal frame is good), and probe each pin individually - you may need to stick the probe in the place where the wire goes. Also, make sure positive lead is in Volt/Ohm (horseshoe symbol) and negative in COM.

[jimdandar]

Re: One more-Toshiba shuts off after 20 mins. No sound nor picture

I am testing the pins on the upper left of the circuit board in the picture. This doesn't make sense to me but the only voltage readings I get are 5.0 from the three 5 volt pins. I get 0.00 from the 24 and 12v pins. I reconnected the connection and the tv is working fine. I will send readings when it overheats. Thx

[RON_CET]

Re: One more-Toshiba shuts off after 20 mins. No sound nor picture

here's some material which might aid in helping you troubleshoot

[jimdandar]

Re: One more-Toshiba shuts off after 20 mins. No sound nor picture

Thank you. I will digest this tomorrow. It looks very helpful.