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Mr Bob
Mr Bob, Technician
Category: TV
Satisfied Customers: 6
Experience:  ISF trained, provide repair and calibration advice to DIYers at online HT and HD sites.
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I have a mitsubishi Model VS-70707. After moving the set and

Customer Question

I have a mitsubishi Model VS-70707. After moving the set and plugging it back in; it let me know the power was interruped, I then go to the menu to program the channels and while doing so the power goes off. I have unplugged the tv and the set does the same thing. PS: the set was mfng. October 2000. THANKS!
Submitted: 8 years ago.
Category: TV
Expert:  Chuck Williams replied 8 years ago.



So if you try to turn it on, does it do anything, or does it click on for a couple of seconds, then click back off?



Customer: replied 8 years ago.
It will do just what you said
Expert:  Chuck Williams replied 8 years ago.

Then try to turn it on, and then when it clicks off, go up to the front panel and press the INPUT and MENU buttons together for at least 6 seconds.


This will cause the front panel LED to flash a sequence of two numbers. For instance, if the set is working correctly with no problems, the LED would flash once, then twice, then pause, then repeat a few times. Find out what yours does and get back to me.



Customer: replied 8 years ago.
It will not power on unable to complete your previous instructions.
Expert:  Chuck Williams replied 8 years ago.

Oh. Well, I'm afraid it's having a problem with the stand-by power supply. The good news is that this may be a simple problem. If you have electronics experience, you might be able to fix this yourself, but it sounds like you'll need to hire a tech.


By the way, you're sure it's plugged into the power, correct? You might try unplugging it for 30 seconds, and then plug it back in, and see if it works. If it doesn't, it's definitely broke.



Customer: replied 8 years ago.
should I remove the back to access stand-by power supply. tell me more because I'm very capable . PS: I have three women I'm trying to please.
Expert:  Chuck Williams replied 8 years ago.

The standby power supply is a part of the main power supply and is on the Main Board, which is on the right side when viewed from the rear.


First check the fuse, it's near where the power cord comes in.


If that's good, check for 12 volts DC at TP12VS. If that's not there, you're going to have to pull that board out and troubleshoot the primary (hot side) of the power supply. Look for a broken solder connection on that side of the power supply, because it's rare that this set has major power supply problems.


You might consider contacting PTS Corp. and seeing if they can rebuild the board for you.



Expert:  Mr Bob replied 8 years ago.
Sounds like it is getting worse. Initially it would go into protection, now it won't respond at all, or even turn on?

Shutting down after turn-on often involves the convergence circuit, usually needing ICs replaced and a fuse or 2 as well. But if it now shows no life at all...

You might want to observe very carefully whether there is coolant leakage or damage on any of the boards. The 5-number Mit models have been rife with coolant leakage, in both the HDready and SD units, starting when they went from 4-number to 5-number model numbers.

To do so, unplug your set, remove the front cover down below, and with a small flashlight shine its beam onto the boards and look for either the gleam of liquid, or the dried signs of corrosion from liquid that has already dried out. Sometimes you have to use a mirror to look down inside a big heat sink to see the damage.

Also feel for the lowest edges of the metal cowlings that encase the CRTs hanging directly above the boards, as the outer 2 cowlings are slanted and the lowest corner is where the leakage usually drops out, and onto your boards. If you feel a drop of liquid that is clear but feels like anti-freeze, then you have had coolant leakage from your CRT(s).

If your brown board has coolant on it, that one's single layer and chances are it can be saved. If the green board, that's a multi-level board and it usually bites the dust. PTS won't work on them if they have coolant leakage damage.

If it's the green bd you may find one online, but they are NLA from Mit, on that old a set.

I have always been able to save the brown single layer boards, but the green ones can only be saved under certain conditions, and by someone willing to strap any faulty conn's of the 2 layers together, hardwire, in the coolant-saturated zone. Hopefully that zone does not contain any ICs, as that usually cinches the deal, and not the best direction.

Either way, chances are you'll need a pro in on this one.

Mr Bob