Magnavox 50MF231d 37 Blown Fuse/supposedly solid green light when turned on

[garry7263]

Re: Magnavox 50MF231d 37 Blown Fuse/supposedly solid green light when turned on

I pulled out the Ysus board and checked the cap the kid put in, what a mess

[tom66]

Re: Magnavox 50MF231d 37 Blown Fuse/supposedly solid green light when turned on

Oh dear ... wow. I'd be amazed if that works at all. Remove all of the solder and resolder it.

[garry7263]

Re: Magnavox 50MF231d 37 Blown Fuse/supposedly solid green light when turned on

I pulled it out but unfortunately i only have the other capacitors that the guy gave me. The copper pad on that side was missing, which I guess her thought he could just solder the two leads together. I soldered the one leg to the other side if the board as that where it should connect to. Here is a pic of the repair.

[tom66]

Re: Magnavox 50MF231d 37 Blown Fuse/supposedly solid green light when turned on

That should work.
Next, see my previous tests:-

Vs is much too low. Please set this carefully to the panel rating (+/-1V)
Ve, Vset and Vsc are also very wrong, and will need to be set within +/-2V.
Check in a dark room: does the plasma panel glow slightly?

[garry7263]

Re: Magnavox 50MF231d 37 Blown Fuse/supposedly solid green light when turned on

it wasn't working at all. There is some discoloration to the back of the board and I checked the row of chips and they all tested just about exactly the same. I will install it and check to see if anything comes up.

Tom, Should I adjust the voltages after putting the board back in, or should they be adjusted before I connect the X and Y boards?

[tom66]

Re: Magnavox 50MF231d 37 Blown Fuse/supposedly solid green light when turned on

They should be adjusted with all boards installed.

[garry7263]

Re: Magnavox 50MF231d 37 Blown Fuse/supposedly solid green light when turned on

Boards installed, unit clicks twice then once. Then everything shuts down and I lose all voltages. There is a green LED that starts flashing 5 times.

The top most board is encased in metal and has two solid green LEDs inside.

the board under that has two LEDs, the LED closest to the connector glows solid, but there is another LED under the AC in that flashes constantly.

If either the X or Y boards are disconnected, the power does not shut down. The LED on the power board glows solid. I kind of lean towards the X and Y board being ok. I think that when both boards are connected, it draws too much current and shuts itself off due to some component not being able to handle the current.

[garry7263]

Re: Magnavox 50MF231d 37 Blown Fuse/supposedly solid green light when turned on

Come to think of it, that is probably why the voltages were so far off from where they should be.

[garry7263]

Re: Magnavox 50MF231d 37 Blown Fuse/supposedly solid green light when turned on

I am off to get parts to make an ESR meter today. I think I will go through power board component by component.

[garry7263]

Re: Magnavox 50MF231d 37 Blown Fuse/supposedly solid green light when turned on

I had to put this away for a while. I am just getting back to it. I went through the Y-sus and found two rows of diodes shot near the black connectors. Also found the other cap near the replaced one was on its way out as it now shows a bulged top.

I ended up getting another Y-sus board and checked those diodes and they measure good. I dont want to put in a new board and kill it, so I need to know how to check for a bad Y-buffer.

Before, it would turn on and then shut down right away. Unplugging either the X or Y board would allow the power to stay on. Should I be looking at replacing the X-sus also ?

[garry7263]

Re: Magnavox 50MF231d 37 Blown Fuse/supposedly solid green light when turned on

This is what I found when going through this board so I got a replacement

that is .001 VDC in diode mode

[garry7263]

Re: Magnavox 50MF231d 37 Blown Fuse/supposedly solid green light when turned on

I need to know how to test the buffers to make sure they will not destroy the new board. Can anyone show me what pins I need to test and the best way. I think Coppel had a blog, but he says to test in diode mode but comes with an ohm reading and that doesn't make sense to be since ohms is resistance and diode test the flow of current. I have a Fluke 79iii

I have tested from a ground by the blue caps, get readings in the 4.7Mohm range on all the connector leads that go to the panel

I just want to make sure I don't kill the new Y-main and I do not have a lot of cash to replace it again but I might be able to scrounge up enough to get some new buffers