XM501 Vertical Problems

troxel

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Working on a Sea Wolf and recapped monitor with Bob's kit. The screen is scrunched between the bottom 2/3. The top 1/3 is just black. Wondering if it's a cap that wasn't included in the kit. I haven't worked on a Xm501 before and open to any ideas. Thanks!
 

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Working on a Sea Wolf and recapped monitor with Bob's kit. The screen is scrunched between the bottom 2/3. The top 1/3 is just black. Wondering if it's a cap that wasn't included in the kit. I haven't worked on a Xm501 before and open to any ideas. Thanks!

Have you tinkered with all the pots on the frame and the chassis? ... mainly the ones on the chassis.

I don't mean just randomly turn them, because one of them controls B+ voltage, but there's another one that does vertical size... I'd start with that one and see how it goes?
 
I adjusted the vertical size and the two-thirds of the screen just gets smaller. I cranked it up all the way, and that's the picture I took. I will check transistors hopefully tonight. Any other thoughts?
 
Checked transistors and all tested good in circuit. Any other items to check?

Also, noticed that the anode was smoking. I have smelled something burning even before the capkit and could never find it until tonight. Any ideas on that? It usually happens after the game has been on for a bit.
 
I am going to try and clean and reset the anode and see if that stops the smoke.

Any ideas on the vertical size issue?
 
Checked some voltages and got the following:

Pin 7 = 34.3 Vdc
Pin 19 = 18.5 Vdc
Pin 25 = 34.7 Vdc

Checked Q13 out of circuit and tested fine. However, tested the HOT and the emitter and base were shorted. Pulled it out of circuit and it tested fine, but the connectors were still shorted. Would this have anything to do with the vertical height?

Any ideas?
 
Checked some voltages and got the following:

Pin 7 = 34.3 Vdc
Pin 19 = 18.5 Vdc
Pin 25 = 34.7 Vdc

Checked Q13 out of circuit and tested fine. However, tested the HOT and the emitter and base were shorted. Pulled it out of circuit and it tested fine, but the connectors were still shorted. Would this have anything to do with the vertical height?

Any ideas?


No idea, but looking at the schematic... if C25 is goofy it could cause a short? Same'sh with C24 and R44?

Run the video out to the RCA video jack on a TV set to double check to make sure it isn't a board issue? Video out from the board to the center of the jack, and GND from the board to the outside of the jack.

... I'm pretty much grasping at straws here. Sorry no one else is chime'ng in.
 
R44 is shorted. It's a 2.2 ohm 2w, ww. Does it have to be a wire wound resistor or can I use a different type of resistor such as a metal film?
 
You could use a different type but apart from the fact that it's rare to see a standard resistor rated above 1W, the wire-would ceramic types are going to dissipate heat MUCH more effectively and last longer.
 
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