Magnavox 30MF200V/17 Won't Power Up

[kevinm34232]

Happy Father's Day to all you Dads out there!

This TV is an oldie (Sept. 2004), have had sitting here for a bit.. Thought for sure it would just be bad caps for once..

Full info: 30MF200V/17, Chassis LC4.6U AA, Serial YA1A

Symptom: Power LED goes RED GREEN ORANGE RED - Won't power on.

I got the service manual for this chassis, and it says to jump 2 pads on the main board which I did, to get error codes. This did not work. So I'm not sure what the problem is.

I checked the voltage regulators on the main board and they all were good, I beleive the 12V is the one that drops out the rest stay up, Ill have to double check it.

There is no backlight, but a brief flash of light when you shut it off.

Since I can't get any error codes and there is no obvious problems, I don't know what to think.

Im wondering if the LED pattern means anything though.

[retiredcaps]

Re: Magnavox 30MF200V/17 Won't Power Up

Thought for sure it would just be bad caps for once..

Not likely with Rubycon caps. The days of just bad caps is less than 10% now.

I got the service manual for this chassis, and it says to jump 2 pads on the main board which I did, to get error codes. This did not work.

How did you jumper it? Maybe you didn't jumper it long enough?

[kevinm34232]

Re: Magnavox 30MF200V/17 Won't Power Up

I dragged solder across the pads so it's permanently jumpered for now..

[tom66]

Re: Magnavox 30MF200V/17 Won't Power Up

It may need to be removed as it is powered up per the instructions, as a two step process.

[kevinm34232]

Re: Magnavox 30MF200V/17 Won't Power Up

I can try that, wasn't sure if that was meant just not to damage anything since it disables protection..

Here are the codes, it looks like most of the codes are main board/software related doesn't it?

[retiredcaps]

Re: Magnavox 30MF200V/17 Won't Power Up

I dragged solder across the pads so it's permanently jumpered for now..

That would not have been my interpretation of the instructions.

[kevinm34232]

Re: Magnavox 30MF200V/17 Won't Power Up

Well started from strach with the power supply board. It looks like the section for the 12/24V is OK as those voltages come up breifly, and then go down after TV shuts down.

But there is a high voltage line going from power board to sub power board/standby&audio board. It says it should be 263V but I only have 70V.

I have 161VDC across each of the large caps. 320VDC at bridge rectifier.

Was wondering if you guys can help determine why the voltage is low. Thanks!

[tom66]

Re: Magnavox 30MF200V/17 Won't Power Up

320VDC at bridge? In USA? You sure?

[kevinm34232]

Re: Magnavox 30MF200V/17 Won't Power Up

Yea, I am confused by this setup with the second board that has the standby circuit and audio amp..

I saw this voltage doubler thought that was the reason.

[tom66]

Re: Magnavox 30MF200V/17 Won't Power Up

Ah OK -- that makes sense. 320V is fine.

What connector # has the 70V on it which should be 263V?

[kevinm34232]

Re: Magnavox 30MF200V/17 Won't Power Up

It's connector 1306 brown and blue wire from main PS to AS board as seen in post 7

[tom66]

Re: Magnavox 30MF200V/17 Won't Power Up

70V is definitely bad then. What is the voltage across capacitor 2503?

[kevinm34232]

Re: Magnavox 30MF200V/17 Won't Power Up

About 160V

[tom66]

Re: Magnavox 30MF200V/17 Won't Power Up

So, measure the voltage drop across 1401 (looks to be a fuse), what do you get?

[kevinm34232]

Re: Magnavox 30MF200V/17 Won't Power Up

1401 is a glass fuse, there I get 70V

[tom66]

Re: Magnavox 30MF200V/17 Won't Power Up

70V across fuse, that is, red probe one end of fuse, black probe other end, volts DC?

[kevinm34232]

Re: Magnavox 30MF200V/17 Won't Power Up

No I was measuring red probe on fuse and black to hot ground..

I get 0VDC across the fuse

[kevinm34232]

Re: Magnavox 30MF200V/17 Won't Power Up

I found 6506, which is a 4 pin IC, pins 1 and 2 which are the AC pins have 120V, the DC pins 3 and 4 have 159V.

[tom66]

Re: Magnavox 30MF200V/17 Won't Power Up

Well, this doesn't make sense: you've got 160V across the cap, 70V after the fuse, and yet the fuse has 0V drop. Are you using cold ground or hot ground for your ground point? Pin 2 of 1306 is your hot ground.

[ben7]

Re: Magnavox 30MF200V/17 Won't Power Up

It would make sense if it is a bad solder joint...