v2000 distortion - HV section?

Bullwinkle

Member
Joined
Sep 10, 2009
Messages
859
Reaction score
8
Location
Rochester, New Hampshire
I have a fully working asteroids with a G05-802, but I also have a 2nd board and 2nd monitor (v2000) that are not working properly.

I have capped the faulty v2000 (including the C100 & C101 as one of them had failed) and replaced the deflection bottlecap transistors & checked for shorts. Leaving the good pcb board in the cab, I place the v2000 in and get the following result:

monitor_distortion.jpg

The B&W Vector Monitor Guide (point 17) says that if video information is distorted (letters and figures are "crinkly") check the 90v power supplied by the EHT unit, if that looks good check the electrolytic caps... well, I've replaced the caps during the cap kit so it's unlikely that's it. Does the pic look like the "crinkly" the guide speaks of?

thanks,

Tom
 
I'm not sure I understand the "2nd board and 2nd monitor (v2000)" reference.

I assume the picture you posted is from the V2000, but is it connected to the "2nd board" as in a 2nd Asteroids board? or is it connected to the known-working 1st Asteroids board?

It's helpful to know if the issue is with the board or the monitor.

I recently worked on an Asteroids with graphics issues (different from yours) that turned out to be related to the adjustment pots on the game pcb...
 
I'm not sure I understand the "2nd board and 2nd monitor (v2000)" reference.

I assume the picture you posted is from the V2000, but is it connected to the "2nd board" as in a 2nd Asteroids board? or is it connected to the known-working 1st Asteroids board?

It's helpful to know if the issue is with the board or the monitor.

I recently worked on an Asteroids with graphics issues (different from yours) that turned out to be related to the adjustment pots on the game pcb...

sorry..i tried to be clear and failed miserably. It is a known working asteroids board that works perfectly with my G05-802 .. this is what I get when I swap monitors and use my v2000. I can swap them back n forth without moving the game board pots and the G05 works perfectly, the v2000 gives me the image in the pic.
 
Are you swapping entire monitors or just the boards from the monitors? if you swap The -802 and V2000 are compatible, so you can swap just the HV cage or just the deflection board - as you narrow it down. Just remember that if you swap the deflection board, you have to change a wire position on the big connector on the edge of the deflection board...
 
I was talking about swapping entire monitors, but I have moved the deflection boards around but now that you say that, I'm not sure what was paired with what. I will swap boards around when I get home to see if the problem remains with the v2000 HV & tube or moves to the G05 HV & tube. if the problem remains, I'll swap the HV units just to make sure the problem moves. At least that will narrow it down.

I do know that on the v2000, after capping it, I powered up and blew F100 & F101, checked the brand new bottlecaps (after the fact..shame on me) and yup.. one was shorted to the chassis. Pulled it out..pushed it back in and made sure I had no continuity. I figured that would have toasted the transistor, but I plugged it in and tried it anyway..and you see the results in the pic. Now I will swap stuff around to see if maybe that has anything to do with anything, but it seems as though that transistor is fine (as I'd expect a collapse if it had died)

As for discharging these monitors, I've read something where you place 10 resistors in series in order to discharge these properly, is that necessary?
 
Find the plug to that transistor, then use your meter to check between the wires to that transistor. Compare it to the other on the monitor of the same type. you may have a problem with it. Usually if it's shorted enough to blow fuses, then it's bad. I usually just do a quick check to see if they're shorted to the frame, and if they're not, then I test the monitor. Of course a recent 6100 repair showed me that doesn't always work, as 4 of the 6 were shorted when testing at the wiring. it's possible that transistor only failed partially. you should replace it just to see. Easier than swapping boards...
 
OK, I swapped the boards around and the "crumpled" font and squashed screen stayed with the power supply. So both deflection boards work fine. I changed the bottle cap that shorted and the issue remained. I also tested the holder for the bottle cap and it was fine, but I also resoldered one of the connections as looked a bit iffy. No affect on the issue. Looks like the problem is in the HV section.

The tube itself takes about 30 seconds to show anything and that's with the brightness and contrast cranked up...which doesn't seem right either. I do have another HV diode on the way, but I'm wondering if it's possibly just an adjustment of the pot in the HV section.

Should I just wait for the diode to show up?
 
I don't think so. The diode failure usually exhibits in blooming, and that's not your problem. If it's been capped fully, then check the diodes and transistors on that board. Maybe a burnt (or discolored) resistor...
 
Looks like a linearity problem to me. Can you make a pic of it with the diamonds test screen ?

Might be just the pots on the deflection board.

What tube brand is on the 2000 ?
 
Looks like a linearity problem to me. Can you make a pic of it with the diamonds test screen ?

Might be just the pots on the deflection board.

What tube brand is on the 2000 ?

Here's the Diamond Test screen:

test_screen.jpg

And here's a pic of the label on the tube:

tube.jpg

I've had this deflection board in the G05-802 and it worked fine. Any ideas based on the pics? I'm very unfamiliar with vector monitors.. is it possible this is a tube issue? I do have a BK 467 i can test it with.

I should mention that this deflection board has had the two large ceramic resistors removed and jumpered. But as mentioned, it works fine in the G05-802
 
Last edited:
The image is too big. Not a huge deal, but over-deflection can hammer your power supplies harder than necessary. Try reducing the X-gain and Y-gain pots on the game board until the entire test image fits on the screen. You should be able to see all 4 corners of the rectangle. And try adjusting the linearity pots. You should be able to get a really good diamond pattern with nearly straight lines.
 
Last edited:
Just what I expected an Amperex tube. These have a poor reputation... The dimness of the tube is notorious acording to what i have read....

The diamonds look better than I had expected though and that has nothing to do with the tube AFAIK.

I dont have experience with adjusting the pots on the deflection board, so far all those I worked on had good linearity.
 
Just what I expected an Amperex tube. These have a poor reputation... The dimness of the tube is notorious acording to what i have read....

The diamonds look better than I had expected though and that has nothing to do with the tube AFAIK.

I dont have experience with adjusting the pots on the deflection board, so far all those I worked on had good linearity.

I do have a G05-801 here...doesn't have a deflection board, but I could try putting the tube with the current HV and deflection boards and see what happens. Can I use the HV section of the 801 with the 2000 deflection boards or are they completely different? It's either tube or HV as the deflection board used in the pictures worked perfectly in the G05-802 I had here.
 
afaik the 2000 and g05 parts are exchangeable.

At least thats what the BW vector faq says, if you havent yet, you should really read it:
http://www.crazykong.com/tech/bw_vector_monitor_faq.pdf

I actually have that printed out.. which is why I asked about the HV section as I know the 801 2-board set is not compatible with the 802 or v2000 (which are interchangeable)... I was just wondering about the HV section alone, but the voltages are a bit different (56 or 74vac for the 801 and 60vac for the 802 or v2000). Was wondering if the 56v vs 60v would work. I'm not inclined to try it without knowing if 60v would be too much for it. I may just swap the tubes to see if it's a tube issue.
 
Back
Top Bottom