Pvm-1953md horizontal output transistor

[Popester]

How about showing us some pictures of them now working?

[freakaftr8]

I'm stumped. It's a 60hz AC crawl in the pic like a humbar. All caps are changed out. And iys definitely the power supply. I've never seen this on a solid state or SMPS device before. Its acting like dried out electrolytics. Could a transformer cause this? I mean there are smoothing circuits designed to filter out AC currents in the DC path but maybe too much to filter out?

If anyone as ever run a microwaves near a monitor or a tv, This symptom I am having is almost identical to it. When just the ost menu is activated before you apply video source the menu is pulsing in-and-out rapidly on the sides in pretty stable to the center when you run video, it has a subtle crawl to the picture and you can visually see light hum bars like a 60 cycle draw moving up-and-down screen. That symptom is more indicative to what I'm used to like my old CTC 16 with dried out electrolytics.

[freakaftr8]

Originally Posted by Popester

How about showing us some pictures of them now working?

These two pics are when I first picked them up.. 2nd is when I got the 1st one working with low grid voltage hence the smearing. Have both power supplies out of the monitors right now still trying to figure out this crazy crawl in the picture on one of them in have the other 1 out using as comparison is soon as I put everything back together I'll take pictures but they both have remarkable pictures!

Kind of makes me feel bad about blowing up the CRT in my KV2643R but I'm certain that CRT was on its way out.. But it is funny how low grid voltage will also give you the symptoms of something that may look like a worn CRT when in fact it was just low voltage on the drive transistors..

[Electronic M]

If the power supply uses Zener diodes for regulation and or a comparison voltage for an adjustable regulator then maybe one opened and the hum it would usually suppress through loading/regulation is getting through...

[freakaftr8]

Good call. Even thou the comparison between boards seen the same on all diodes, I may lift a leg to measure.

Btw here are some pics..

If you notice the monitor in the back is the one with the supply issue. You can see it on a snapshot. the edges are pulsating in and out.

Pardon the mess.. The wife and I are working around my mess and creating another by getting all the Christmas lights out..
Yay me.. get to hang lights...

[freakaftr8]

My scope is picking up excessive ripple on the 117v output. tbw other boards output is minimal. Barely noticable on the scope. The ripple is also jittery when no video is displayed. Just the OSD. When video is displayed the jitter slows down and just barely moves up and down on the scope.

I'm having an obvious filtering issue. There are shunt capacitors but all read good. There are two LFT line filter transformers located at T601 and T602. With an ohmmeter they read ok. I'm sure if thay had internal damage I wont be able to tell just by a measurement thou.

Trying to figure out what the freewheeling device is used and how its applied here.