Matsushita TM-202 blowing fuse

[sandmanx]

I picked up a Pole Position that was playing blind the past weekend. When I opened it, I was greeted to a fried flyback. I ordered one and a cap kit from Bob Roberts and installed it tonight. This was the first time I replaced a flyback, but it seemed straightforward.

There are 2 fuses on the board, one is 4A which does not blow, and the other is a 1.5A fuse which is blowing on startup. I'm still fairly new to the hobby, and don't know where to troubleshoot from here. Does anyone have any ideas?

I'd rather not swap monitors with one of my other games for now as they are in my house and Pole Position is in the garage at this time.

 

[sandmanx]

I worked on this a couple of times this weekend, and it's still blowing the 1.5A fuse on startup. I replaced all the burnt wires from the flyback blowing up, and I did unplug the degauss coil and no change. From what I've read it could be related to the degaussing circuit or the HOT, but I don't know how to test to find out potential problems with these. Can anyone point me in the right direction?

Here is a pdf version of the service manual: http://arcarc.xmission.com/PDF_Monitors/Atari Monitor TM-202 1st Printing Matsushita 19in.pdf

 

[sandmanx]

The HOT was bad, and I just replaced it. Now it's coming up with neck glow, but still not displaying anything.

I measured B+ and it's at 132V and won't go any lower with the adjustment pot, but will go up even higher. It should be at 123V.

So starts my next adventure in what is quickly becoming the monitor from hell.

 

[Alpha-tron]

Have you checked the resisters in figure 16?
part of the votlage control goes a voltage divider through R811 R812 R813 R815.

I would be checking there first espically if the voltage is on the high side.

Maybe the D804 Zener diode.

Good luck

 

[sandmanx]

Have you checked the resisters in figure 16?
part of the votlage control goes a voltage divider through R811 R812 R813 R815.

I would be checking there first espically if the voltage is on the high side.

Maybe the D804 Zener diode.

Good luck

The only thing I checked was Q801, which I found base and emitter to be shorted. I didn't check anything further down the line yet, but I'll check everything else in the circuit as well.

Thanks for the feedback, as I'm still not exactly sure how to follow the logic on circuit diagrams.

 

[sandmanx]

I replaced Q801 and R811 and now B+ is at 121V and won't adjust, and still no picture. I'm about ready to take a sledgehammer to this piece of shit!