Identifying Monitors

[SavannahLion]

OK, I have three monitors in various degrees of "clean" to "covered in goat ---steaming pile of meadow muffin---" (I'm not kidding about that). I decided to work on the cleanest one. Unfortunately, it's also the same one that was inside of a "Z" cab that came smashing down to the ground.  It's also the one that appears the most complete The others are missing what appears to be a small 2" x 3" with six pots assuming those are the same make and model as the clean one.

While examining the tube, I discovered the orange plastic collar at the very end of the tube is in pieces and the pins are slightly bent. I straightened the pins out and the board fits OK. But what was/is this orange collar thing? Can/should it be replaced?

Next, what the hell do I have?? I looked in all the places I can think of to find a model number but I can't track any down. There are several places where some stickers were removed. Perhaps model numbers? There are numerous Serial number stickers. Most say WG570106. There is a man' date of 1990 (others too but illegible). The largest marking on the main board is P538. Zenith tube. A big label identifying critical components on the main board which reads 69X1712-100. There's more. Lots more, but nothing stands out as a model number. Can anyone help in IDing this?

[SavannahLion]

Well, after examining everything I could think of. I wired the monster up, plugged in a board, did a few last minute checks and plugged it in.

Lots and lots of pretty blue arcing. Practically jumped out of my skin from the noise it made. Apparently, something really important did not survive the fall. It's a small black box with two knobs that has a line running from it to a suction cup to the tube. Since I know the tube has some nice HIGH voltage (what did someone on the boards say, 3,000V minimum?) through this suction cup, logic would dictate that this black box generates that voltage.

Dump ---Cleveland steamer--- that I am, I put the power switch opposite of the monitor, so yanking the power cord from the wall socket seemed prudent.

After swooshing away the smoke and ozone, I examined with my eyeball (I'm not interested in discovering how much voltage is packed away in there) there is a crack right across the top of the box. Not sure if it's really a result of the fall or just a defect. I'm guessing it's from the fall. Whatever, I'll need to replace it I guess. Any advice? Can I get the part or does the whole board need to be replaced?

Looks like I'm not testing the PCB's any time soon. 

[Kevin Mullins]

It's a small black box with two knobs that has a line running from it to a suction cup to the tube.

That sounds like the flyback transformer from your description.

The P538 main chassis seemes to come from a Wells Gardner 25K7193 (K7000) monitor.
The flyback should be readily available from someone like Bob Roberts, etc.
The flyback is a common failure item on those models.

Your best bet would be to do a cap kit, flyback and check the H.O.T and voltage regulator.

[SavannahLion]

Other than the Flyback giving me a free light show, are the K7000's pretty decent monitors to work with?

Your best bet would be to do a cap kit, flyback and check the H.O.T and voltage regulator.

I've heard other people mention HOT or H.O.T. I've even seen it mentioned on several repair sites, but I don't understand what that stands for.

[Kevin Mullins]

Yes, the K7000's are very reliable monitors, easy to work on, etc.

The "H.O.T." is the Horizontal Output Transistor.

[SavannahLion]

The P538 main chassis seemes to come from a Wells Gardner 25K7193 (K7000) monitor.

How weird, I could swear I Googled for P538 last night and nothing came up. Now I Google for P538 and I even get links leading back into this forum. 

Butter Scotch. Oh well, at least I have a better idea of what to look for now.

[Kevin Mullins]

http://www.wgec.com/service/bom_reference.asp

Second one down....... 

[SavannahLion]

I'm beginning to wonder if I should keep this particular P538 board, use this to scavange parts for the other P538, and buy a new one online.

I finally pulled the board out and took a closer look... and made some comparisons to the other P538. Turns out there's a whole other sub-circuit going on there. There's an extension near R22 that leads off to a mess of resistors and caps (this sub circuit was one of the focal points for the arcing from the cracked flyback BTW). Additional jumpers and resistors in several places which apparently this is meant to fix the vert adjustment.

With my limited electronics skills, I don't know if it's a good idea to try and work on a board experiencing so many problems to begin with.

What do you guys think?