Mitsubishi VS50703 no start up

[slinteriors]

My mitsubishi VS50703 will not start up. Starts to power up but shuts back down after about 20 seconds. Any ideas would be a great help. Havent opened it up yet, Dont have a service manual. anyone have one. Thanks

[lcaillo]

First thing to look for on this one is a coolant leak. Next would be bad capacitors in the power supply and the low voltage regulators. More info about what it is doing when it comes up and shuts down would be helpful.

[slinteriors]

No eveidence of coolant leak. I have checked the boards . The main fuse was blown next to the cord. The other 3 are ok. Nothing happens except the green power light lights up then it clicks the relay and goes off. I dont have a schematic for this set. do you know where the regulators are located? I appreciate any suggesstions. The Horizontal output transistor seems okay not shorted or open.

[slinteriors]

does anyone have the service manual for the VS50703 they could email me? I cant seem to locate the correct one. I found one for VS60603 which looks simallar but my model isnt listed in the manual. Any ideas. Thanks. I tried holding menu and imput but no blinks. Just green light for a second when i hit power then it clicks and the green light goes out.goes out

[lcaillo]

The service manual is available from Mits parts, or from several pay sites online. The online sites where you can download manuals are not authorized to do so, so you never know what you are getting, though many people have had success getting them cheaper this way.

If the green light comes on the main regulator is likely running. If you can't find the regulators, chances are pretty good that you will not have much success troubleshooting the set yourself. You need to check the ESR and capacitance (or just replace) on all of the filter caps in the main PS secondary and on all of the low voltage regulators in the set. You can identify regulators by the heat sinks, though other semiconductors will also have heat sinks.

[slinteriors]

Okay I have found 1 bad capacitor near the vertical transistor. Replaced that and have high voltage and the tubes light but I am getting a vertical line about 1/2 inch wide across the screen with some wavy convergence like lines then it shuts down. Still cant get it to blink any codes. The capacitor had leaked some residule about the size of a dime right near the vertical transistor could this be a conduction issue between the transistors terminal and PCB runners? I have downloaded 3 service manuals so far but none list my specific model . Is my model a VZ9 chassis?

[lcaillo]

Check the connections at he connectors on the yokes. The pins sometimes have cracks in the solder joints on the vertical. If that is not the problem, you could have a bad vertical output IC, or still a problem with a regulator circuit. A schematic and a scope are likely needed unless you want to shotgun it.

[slinteriors]

resolderd the pins. If i leave the vertcle yoke plug unplugged i have audio and a wider verticle line with all 3 tubes lit. If I plug the verticle yoke plug back in i have no audio and just a razor thin red line. but either case it shuts down, it does stay powerd up longer if i leave the verticle yoke unplugged however. This is where I am at now.

[lcaillo]

Do not run the set with vertical scan failure. You can easily burn the phosphors. If you don't have a scope to trouleshoot you could try changing the vertical output IC, if it has the supply voltage that it should.

[slinteriors]

I found a shorted diode in the vertical section replaced that and i know have evrything functioning perfect except it looks like the red yoke has been rotated as does the blue the image is just a little out of alignment . The convergence controls work but the red image looks off center as does the blue. looks like it needs to be twited back counter clockwise about an inch. Any ideas on how to go about doing that. The set runs fine except for that.