Dreams destroyed by Battlezone

[Deadly]

R29 burning up is usually indicative of a poor ground (As Dokert suggested cleaning the finger board.)

I've noticed on the vectors it's not a bad idea to add extra grounds (create a triangle.)
Run a ground from ISO to PCB to Monitor then monitor back to ISO. Kind of overkill but if that edge connector ever starts to lose it's ground from the edge connector it'll have two other places to pull from.

My .02

 

[discostu]

R29 definatly burned up due to a poor connection but it was caused by my right elbow bumping the harness...please believe me, elbow hit harness then R29 turned to smoke. With that said the new resistor is doing fine and all test points on all pc boards show proper voltages. I Rung out the harness that connects the auxilliary to vector board and it meters fine even with all sorts of tugging, the connections at the boards meter fine and the harness in place also meters fine from board to board. I am rebuilding the connectors for the edge of the pc boards, its a royal pain in the a$$ but seems like a good idea. There is a new BZ high score card and big blue is brand new. Metered all the x and y pots on the evctor board and they seem to provide ggod continuity and smooth operation. There ar 12 volts present at the Xout and Yout test points but the spot killer is still active and only a small, 2"diagonal line can be seen in the top left corner of the monitor. If the rebuilt edge connectors do not help then I will be out of ideas :-(

 

[DarrenF]

R29 definatly burned up due to a poor connection but it was caused by my right elbow bumping the harness...please believe me, elbow hit harness then R29 turned to smoke. With that said the new resistor is doing fine and all test points on all pc boards show proper voltages. I Rung out the harness that connects the auxilliary to vector board and it meters fine even with all sorts of tugging, the connections at the boards meter fine and the harness in place also meters fine from board to board. I am rebuilding the connectors for the edge of the pc boards, its a royal pain in the a$$ but seems like a good idea. There is a new BZ high score card and big blue is brand new. Metered all the x and y pots on the evctor board and they seem to provide ggod continuity and smooth operation. There ar 12 volts present at the Xout and Yout test points but the spot killer is still active and only a small, 2"diagonal line can be seen in the top left corner of the monitor. If the rebuilt edge connectors do not help then I will be out of ideas :-(

Sound like you've done some good things:

Rebuilt and checked out the AR board, check.

Rebuilt the PCB edge connectors, ongoing? You doing both (there's one at the main PCB and the Aux board)?

I forget if you said you've re-flowed the joints at the interconnect headers or not; or if you've checked/rebuilt the interconnect connectors. Be wary of the interconnect, mine had cracked joints on both ends and wires hanging on by a single strand (or less).

Big Blue, check. HS/rom-saver kit, check.

So, does it play blind now? (i.e. can you insert a coin, press start, and head the game sounds, even with the monitor disconnected or non-working?)

The 12V at X-out and Y-out... that AC? I forget what's "normal" there, I can put a meter on mine tonight for comparison. (I'd expect near nil DC, as it goes pos and neg and 0 is the center of the screen.) Did you mention having an oscilloscope earlier? If so, you should be able to put it into X-Y mode and use it as a vector monitor (w/o Z control).

 

[discostu]

I was expecting to see ac at x & y out but instead I have 12vdc. I do have a scope but I'm a novice at implementing it, when I hook both probes up to x and y out I just get a line across the screen, hooking up to either or just shows a solid 12v line. I havent yet flowed the solder joints at the harness connections mostly because I'm starting to suspect a problem between the DAC and output. I will be done with the vector board finger connector tonight, the auxilliary board connector will have to wait, the work has been brutal on my back (just had back surgery last month) so I need to pace myself.

 

[DarrenF]

I had a meeting last night, and didn't get a chance to turn on a video game, much less hook a DMM to BZ. I'll try again tonight...

No problem being a novice with the 'scope. None of us were born knowing how to use one. A general guide is here: http://www.doctronics.co.uk/scope.htm Every scope is a little different, but most have plenty of similarities. To use it as a vector monitor, you'll need to figure out how to put it into "X-Y" mode, where the horizontal position doesn't move at a specified rate (as it normally does; selectable ms per division), but it is instead controlled by the 2nd channel input. On mine, it's at one end of the dial for selecting sweep speed. Some scopes apparetly have a button to enable X-Y mode. Set the other dials to maybe 2 or 5V/div for starters. Switch the coupling to GND, center your beam, then switch each channel to "DC" coupling.

If not getting any video output, I'd want to first verify that the digital (MPU) portion of the board is running before diving into the output DACs and amps. Of course, if it "plays blind" then it IS running, and I'd agree with your approach of looking at the video output bits. If it's not playing blind, or if it's "watchdogging" constantly, then there may be no real expectation of video output. "Watchdogging" is a feature Atari built into the game, whereby if something goes wrong and the code goes off the tracks, the game will reset rather than "hang." This game code is written such that a particular "address" is written to periodically (many times a second, actually). A hardware counter gets restarted each time this happens. If a certain period of time elapses without this particular "address" being written to, it resets the CPU chip (rebooting the game). It's pretty easy to tell when an Asteroids is constantly watchdogging, because the LEDs in the start buttons blink a couple times a second. I'm not sure of an easy way with BZ. Personally, I'd stick a logic probe on the reset pin of the 6502 and see if it's pulsing or not. (Not sure if you have a logic probe... your scope can also be used to check this, once you get up to speed using it.) In any case, my advise is to ensure that the game is running before worrying about video output.

If you're near NE Florida, I can give you a break and come over to crimp on some of those split pins for ya

 

[discostu]

I was wondering what the watchdog feature was on these games, thanks for the info. I finished the lower connector last night, it had no affect as expected, also reflowed the interconnect headers and replaced the harness and a sad looking lf13201 without any affect on the video. I do have a couple of bad electrolytic caps (meter as a short) so I will replace them but I'm not holding my breath. I just hope the problem isn't in the monitor, I get anxious around those uber leathal voltages. Thanks for the offer Darren but I'm way up in Connecticut where splicing itsy bitsy wires and inhaling solder fumes is still better than going outside.

I'd like to give an adda boy out to Bob Roberts for his great communication, ubelievably fast shipping and fantastic selection of obscure parts, thanks Bob! Ditto for Mike's Arcade, professional and lightning fast. Just wish my game was working..sheeeit.

 

[DarrenF]

That's the jist of the watchdog. Oh, and it can be disabled by jumpering the "WD DIS" (I think that's the label) test point on the PCB to GND. But usually disabling it doesn't make things any better...

Don't be disappointed that rebuilding the edge connector didn't "fix the game". Trust me, it needed to be done. The burning resistor on the AR board indicates that it was needed; even if you bumped the edge connector... a multi-Watt resistor doesn't burn up in an instant, it had to have been carrying significant current for some time. Re-pinning is time well-spent. As is re-flowing the interconnect headers and fixing up the connectors there.

I'm guessing that was a 74LS132N you replaced...

Don't be too afraid of the monitor. The only dangerous bit, IMHO, is the 12kV at the business end of the HV transformer, the HV diode, and under the anode cap on the CRT (aka "sunction cup"). As long as you don't go probing under it you should be OK...

I took some DMM readings on my (working) BZ (all during attract mode... sorry, didn't do test mode):
1) at X-OUT test point (relative to GND); 3-7VAC (mostly 3-5VAC) during attract mode, only 1.9VAC with high-scores on screen. +/- about 1VDC.
2) at Y-OUT TP (rel to GND); 2-5VAC (mostly ~3VAC) during attract mode. +/- about 1VDC.
3) -15 TP; -15.2VDC
4) +15 TP; +15.1VDC (note 3 & 4 are for the X&Y output amps)
5) +5V DAC TP; +5.045VDC
6) -5V TP; -6.28VDC
7) +12 TP; +11.73VDC
8) Z-OUT TP; 0.5-0.9VDC, 0.7-1.2VAC

All readings made with a Fluke 112 "True RMS" DMM, FWIW.

To see if your CPU is resetting (watchdoging), watch pin 40 (of the 6502 CPU chip). It should remain high (+5VDC) at all times after start-up. If it's dropping periodically, that's a watchdog reset happening... The reset doesn't take very long, so you may need either a fast-updating DMM, or a logic probe, or a scope, to see it happen.

 

[discostu]

Thanks for checking! I'll compare my measurements tonight. I found one of the problems was a poor connection at one of the lf13201's (switching IC in the analog section), it may be a bad socket or lousey soldering but after some twisting and tugging I now have deflector chatter, no more spot killer and ugly looking graphics if you turn the brightness up to it's max setting. So one set of problems has given way to another set as the images are both super faint and crooked, especialy the high score screen.

 

[DarrenF]

Ahh... stupid me. I havn't had any issues with those analog switches (the LF13201) so I wasn't familiar with them. Looks like those guys are in some sort of windowing circuit that blanks the beam when vectors would go off-screen?... but I'm not certain.

Well, sounds like you can be certain now that the MPU is running, since you're getting vectors output (even if they too dim and wonky).

So now that you can see SOMETHING on the monitor, what do you have in test-mode? Beeps (bad RAM)? Number on the left side of the screen (bad EPROM)? T, H or L in the upper right corner (aux board problem)?

 

[discostu]

Well its been a while but a lot has been done to my stubborn Battlezone. The abscence of an image was due to all 3 lf13201 switching ICs being bad, once replaced I had my image back. Thats the good news, the bad news is the screen is prretty much still a mess as the left side seems to droop considerably and the test screen is impossible to get centered and the squares are all different sizes and shapes. Moving vectors are the most distorted.

So far I have rebuilt the A/R II board, replaced big blue and the bridge rectifier, replaced all the x&y trim pots on the vector board, replaced all 4 bit slice ICs in the "math box", replaced any op amps in the analog stage and replaced ALL electrolytic caps on both boards. For a while I have suspected one of the DACs but there are 3 of them and they aren't in sockets, any thoughts on what my next step might be??

 

[DarrenF]

Welcome back. Sounds like you've made some nice progress. Good work on the LF13201s, sounds like those were causing the beam to be blanked all the time, which is why it appeared very dim.

At this point, some pictures of the display you're getting would be very helpful. Sounds like there's still some game PCB issues, but not sure if there are monitor issues on top of that. Pics would help judge.

When entering test mode, do you get a single very short tone, or a series of of low tones followed by a longer high tone? Bad RAM (indicated by the latter) can certainly cause wacky vectors to be drawn. Also, I don't know how bad the display is, or if you can tell if there's a letter being displayed in the upper-right corner (T, H or L). If so, there's a problem with the aux board (math box).

If your RAM is all good & the math box is kosher, then your idea is valid: the next thing upstream would be the DACs. They aren't particuarly cheap & plentiful, so I'd recommend trying to determine if they're bad before doing shotgun style replacement. The only way I know to do that is with a logic probe. What you'd be looking for are digital lines stuck high or low, rather than pulsing. Having a known-good PCB is helpful; I'd be glad to probe my BZ DACs and report which pins are doing what...

 

[discostu]

Here is a picture of the test screen, it looks considerably better in the photo than the flesh. After replacing the x&y pots on the pcb things leveled out a bit but there is still some sag on the left side of the screen as well as some intermittent shakes. To think this board was supposed to have been refurbished at one point. I see arcade chips sells only one of the DACs is there a source for the Am6012?

 

[DarrenF]

The Real Bob Roberts sells AM6012s, $11 a pop. I'm not sure you need one, though. That looks pretty decent to me.

You need to adjust your "BIP"s. Pull out page 02B of the schematics, and read the text in the upper center entitled "Adjustment of R73 and R74". Then find the pots on the PCB labeled X-BIP & Y-BIP. Adjust them in test mode per the instructions. That _should_ improve the alignment between the cross hatch and the bounding box. If it doesn't, I'd say time to start looking at the monitor (perhaps a cap kit). If you get the BIPs dialed in better, details on adjusting image size and position are on the right side of page 02B (short version: adjust size with pots on the PCB, adjust position with rings on the monitor neck).

If your vectors sometimes just appear "noisy" or "jiggly" (but don't look altogether "wrong"), I'd say consider the pots on the monitor chassis. They get dirty and cause intermittent "noise". I had this problem on both Asteroids and BZ. Bob Roberts also sells pot kits for both the G05 and the V2000 monitors (not sure which one you've got):

G05 Deflection Bd Replacement Pot Kit (6) $9.00
V2000 Deflection Bd Replacement Pot Kit (4) $6.00

 

[airlair]

I know this may sound a little ridiculous, but I recommend that you take a good eraser and clean the pcb edge connector where the harness connects. My BZ mini did the exact same thing you are describing once and I did this and it fixed everything. I clean my Tempest once a year as well.

 

[discostu]

I ran the eraser over the finger connectors early on without any results but they do look better at least. The monitor was supposed to have been recaped recently, the deflection board looks pretty good and the caps appear to be nice new Elna's but the quality of work is dubious since I have no idea who did it. The only "basic" repair I kinda skipped was replacing the Aux board side connector, the main pcb connector has been repined and replaced but since the job was such a ball buster and yielded no benefits the top connector was somehow overlooked ;-). Moving images seem to have the most problems thats why I replaced the bit slice chips, hmmm.

 

[DarrenF]

...the main pcb connector has been repined and replaced but since the job was such a ball buster and yielded no benefits...

I don't think it was without benefit. Your AR board thanks you for the effort.

The Aux edge connector has 30% fewer pins But if you want to minimize the effort, only re-do the +5V & GND pins (1, 2, A, 22 & Z). But I don't really think you have a problem here, 'cause no mathbox error is reported in test mode...

If you feel good about the electronlytics in the monitor, then consider the pot replacement (on the monitor deflection board). Or at least blow them out, twirl them back and forth, spray some contact cleaner in them...

If moving images seem to have the most problems, I think we could better judge what the problem might be if you made a video (in gameplay mode) and posted it on YouTube.

 

[Jeff F]

If you feel good about the electronlytics in the monitor, then consider the pot replacement (on the monitor deflection board). Or at least blow them out, twirl them back and forth, spray some contact cleaner in them...

I've started to replace monitor pots as a SOP now since I've had more than a few act up lately. Seems like 25-30 years may be the limit for these.

 

[discostu]

What do the deflection board pots do exactly? How should I go about adjusting them? Can the deflection board be removed without discharging the HV portion of the monitor (so as to prevent death)? My deflection board has small tubes installed on it, similar to some of the soviet miniture tubes from the 70's and 80's , is that normal? I love tubes, my amp of choice is a SE tube amp but I'm not sure they belong in an arcade.

 

[DarrenF]

Hehe. The pots I'm talking about are for linearity adjustment. (There are also brightness & contrast pots on there.) There are two linearity pots on a Wells Gardner 19V2000 and four on a Electrohome G05-802. If they're old/dirty, they cause intermittent "jumpiness" (for lack of a better term). I'm not suggesting that they need adjustment (the BIP pots on the game PCB did need adjusting, though), I'm suggesting that the linearity pots may need replacement. BTW, you'll want to determine which monitor you have then get and read the manual for it: http://arcarc.xmission.com/PDF_Monitors/

The HV portion of the monitor (the HV board) doesn't retain charge, nor need discharging. It's the CRT itself that is a giant capacitor and needs discharging. If you were working on the HV board, then yes you would need to discharge the CRT before removing the anode cap (which must be removed to take out the HV unit). To answer your question, yes the deflection PCB can be removed pretty easily. Just carefully unplug all of the connectors going to it, then use a 1/4" nut driver to take out the screws. There's nothing dangerous here as long as you unplug the power first.

I think the tubes you're referring to are neons. There should be 3 of them; they look like Christmas tree lights. They're protection features. They clamp the G1 or K voltages if they get too high due to malfunction. Thus, they should not be lit if your monitor is working normally.

I have an Elekit TU-879S tube amp in my arcade for tunes. Very nice kit to assemble, and sounds nice too.

 

[discostu]

Thanks again DarrenF and others, I have the deflection board out and its in very good shape except for the linearity pots which are the color of rust. I only have two trimmer pots so I was a little confused when I read the g05 should have four, looks like my board revision has a fixed resistor in lieu of the other pots. My schematic says the pots are 1k but I'm not sure what wattage rating so I'll grab the beefiest pots available. Thats pretty cool running your audio through a tube amp, mine helps warm the dining room, cheaper than oil at $3.70 a gallon

I still have a feeling the video problem is in the pcb as moving, 3d images suffer the worse effects. Its as though all my tanks, cubes and pyramids are going through withdrawls, fidgeting and squirming around even when stationary, I'll try to get a shot of it.