Battlezone Too bright and cant turn brightness down

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Battlezone Too bright and cant turn brightness down

So i just spent the last month getting my Battlezone to work and got it all down to just a monitor problem now. The monitor is extremely bright and i cant turn the brightness or contrast down at all. I cant leave the machine on in fear of it burning a hole in the middle. Is this a vector board problem or deflection board problem? I tried a different tube and it does the same thing so i know its not the tube. The monitor is 19v2000. Any tips? Bad deflection board? I did the field mod and replaced r101 with a thick wire. Thanks in advance!
John
 
You might start by reading up on the B&W vector FAQ: http://www.crazykong.com/tech/bw_vector_monitor_faq.pdf

The brightness issues are discussed, as well as the (monitor's) Z-amp.

Regarding how to test the (PCB's) Z output: Easiest way is to hook it up to a known working monitor. Not everyone has one... There is a test point in the board labeled "Z OUT". Find it and a "GND" test point. If you have access to an oscilloscope, use it to monitor the signal (with DC coupling, you should see it stepping between 1 and 4VDC). If not, use a DMM in AC voltage mode. You might expect to see (very) rougly 1VAC (RMS) here. It'll vary depending on that the game is drawing, but the point it that it shouldn't have 0V AC (i.e. be straight DC). If so, it's not "moving" and the game board would appear to be at fault.

There is also a Z-amplifier circuit on the monitor, and a number of other potential causes. Check all of your edge connectors, pins/contacts, etc. between the PCB to the monitor. Check/clean/replace the contrast and brightness pots (R514 & R517, I think).
 
Thanks for the tips!

I can vouch for trouble shooting a brightness issue with a DMM...I had a z-out issue with our BZ PCB that did what something similar to what you have. Our z-out would measure a steady .5v one time and a steady 1.5v the next. Turned out to be the 74LS399 at location H8.

I described what I did on the 1-25-2010 update here...
http://www.vidiotarcade.com/battlezone.html

Good luck! :beerchug:
 
Ok so im getting a steady 1VAC on the z out when the game powers on an goes throught the attract mode. Is this a good sign? SHould I start looking at the deflection board?
 
Ok so i threw another battlezone board in the cab and the same exact problem. So its either a power supply problem or deflection board problem. I will let you guys know when i get the rebuild kit for the deflection board. Also i hooked up an asteroids monitor and same thing. (Same deflection board, I only have one.)
 
Alright, good. You have eliminated the PCB as the source of the problem. All signs point to the monitor (assuming the wiring harness, and connectors are good).

Before digging into the monitor board, I'd verify that the 1VAC of Z-signal is making it all the way to the monitor. You can check it at the monitor 12-pin connector. Should be pin-1. Look for corroded or otherwise bad pins. If it's there then the edge-connector, harness, and monitor connector are OK, and it's time to look at the V2000 PCB. I'd start by looking very closely at the header pins for harline cracks in the solder joints (the pin with the z signal on it). Randy Fromm has the schematics for the V2000 here: http://technical-department.servegame.com/monitor_schematic_diagrams/wg_v2000.jpg You can trace the Z-signal from pin 1, around and into the z-amp circuit. There is a description of it in the full manual (http://arcarc.xmission.com/PDF_Monitors/Wells Gardner V2000_Manual.pdf page 11).

Are any of the neons on the board lighting? Have you checked the HV unit outputs (esp the 95VDC)? Is Q504 or Q503 shorted? Just throwing out ideas here... That FAQ mentioned earlier may also have suggestions.
 
Thanks for more tips! I will be doing more diagnostics tonight when i get home from work. I have a nice extra set of battlezone boards now if anyone is interested once i get everything working perfect. Thanks for all your help everyone. Anybody need a battlezone power supply? I have one that works but is kinda dirty.
 
Also i noticed sometimes the spot killer LED comes on and off even though the games is displaying properly (Just extremely bright) None of the other "christmas tree" lights ever come on.
 
None of the other "christmas tree" lights ever come on.

That's a Good Thing. Those neons are there to prevent the K and G1 (I think) voltages from getting too high. If they're lighting, it means something is wrong.

Regarding the spot killer LED, I don't know if I'd sweat it right now. The spot killer circuit is there to turn down (i.e off) the brightness (Z) if there is no X or Y activity (i.e. is the game is hung or otherwise not moving the beam around). You kinda have the opposite issue... can't turn down the brightness/contrast. That reminds me, old pots can cause problems. The contrast & brightness pots... turn up back a forth fully a few times, blow 'em out with canned air, spray contact cleaner in 'em... then turn them all the way down. Along with cracked solder joints at headers and old electrolytic caps, nasty old pots are high on the list of common problems with these guys. Oh, and let us know if you've got that 80-90VDC (edit--s/b 90-100VDC) coming back from the HV cage to the deflection board.
 
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I dont know what i did but i keep blowin fuses on the deflection board. i will let you know after i re cap it and replace the reisitors and other stuff and add the right fuses. Kit should be here tomorrow.
 
Ok put the cap kit in, put some new components in and still too bright. Also im gettin 98 Volts back from the HV cage. Is that too much? How can i reduce it? Thanks
 
Ok put the cap kit in, put some new components in and still too bright. Also im gettin 98 Volts back from the HV cage. Is that too much? How can i reduce it? Thanks

That sounds OK to me. I see that I typed 80-90V earlier... that was an error. The V2000 schematics note a nominal 95V, and the G05 schems show 90. 98V sounds close 'nuff to me.

I guess we're back to the Z-amp circuit... which doesn't have too many components: a couple of pots, two transistors (Q504 & 503), a diode (D506), a few caps, and some resistors. I supposer I'd check the transistors for shorts, and any caps which weren't in the kit (again checking for shorts)...

You re-flow the header joints while you were doing the caps? Have a chance to clean or replace the pots?
 
I cleaned the pots and tested them with my meter, when i turn them the resistance varies alot. Not sure what the right resistance should be though. It would be nice to get a list of all the right values on them. Looks like I will be making an order through digikey. By the time im done ill have a brand new deflection board!!! i already replaced half the components. Better safe than sorry i guess. Thanks for the help again.
John
 
I reflowed alot of stuff, some of the metal was peeling up so i scraped the green stuff off and made some new solder lines with the extra wire cut from the caps when i put them in. I also bought a few of those little round yellow caps
 
Its Fixed

Ok so there is a resistor next to the brightness pot (R518) that is supposed to be 470K. i replaced it with resistors that had half the value. I finally put in a 240K resistor and boom its all fixed. i can turn the brightness up and down perfectly. The video looks amazing now. Thanks for all yout tips and help!
John
 
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