Space Duel pick-up first tests

Area69

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I recently obtained a Space Duel which had clearly been sitting for ages with the usual ancient and thick layer of dust over everything internal.

Overall in great cosmetic condition, only needs Simple Green to remove it's protective layer of nicotine.

Monitor has been replaced at some point with one from a Tempest, as I can clearly see Tempest burn. Matching serial numbers on everything but the PCB, so that's been swapped out at some time also.

Rather than plug it in and see what happens, like I would've done years ago, I uplugged the power to the monitor, and the two edge connectors, and tested the voltages at the AR2 after having a good look over.

Everything checked out as would be expected, with the unregulated voltages being higher and the 5v at the + side of C1 being almost spot on. Voltage to the monitor is 50v-0v-50v. I even go to the edge connector and checked at those pins, all good.

Next I cleaned the edge connector fingers with a fiberglass pencil, and then the various connectors on the AR2 get the Deoxit treatment, check everything again, all good.

So I plug the pcb back in, place my DMM probes in the 5v and GND test lugs on the PCB and hit the power switch, 7V! WTH!

I turned it off right away, but what the heck? How am I getting 7v on the board, whenever I just verified 5v from the AR2.
 
ARII over-voltage when logic board (load) is attached can be attributed to blown sense resistors (i.e. higher impedance than 10ohms).
 
I pulled the AR2 and began testing some of the resistors in that circuit. R29 should be 10 Ohms but reads as 13, R30 also 10 Ohm reads as 14. The others seem ok, except for R7 shows as 7.5k in schematic but reads as 3k. I don't see any of the usual burned or brown looking spots on this board, it actually looks minty fresh. I'm testing these in circuit, so maybe not actually correct readings.

Also checked the +10.3V at the AR2 for AC and got a reading of 0.3 so I'm thinking the big blue is good enough to leave alone for now.

I have a couple of new 2n3055s, so I'm going to replace that this evening, just because.
 
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R29/R30 values should be fine. When they are in the 100's or Kohms, you get over-voltage. Next would be to test the harness.
It is also possible the 2N3055 is faulty. If it has a 1980 date code, most recommend to change it with a part from a known vendor/distributor (don't use electronic components from ArcadeShop).
 
Make sure you are using the correct test points, and that the test points are clean.

Also, you could try turning the 5V down all the way to minimum before plugging in. Not to operate it this way permanently, but just to do some more troubleshooting, to get more information.

I've never seen an AR act quite this way, so it's a bit curious.
 
I've seen this - on the bench - several times.
Each time it was high-impedance sense resistors.
Seems to regulate with no load but goes OV when loaded.
Sometimes the sense resistors pass a visual inspection and are not burned.
Such is the importance of using a quality DMM to accurately measure the device.

And I've seen more bad LM305 controllers than 2N3055 pass-transistors. LOL :)
 
Last night I swapped out that 2N3055 and today the voltages are good at the board. Getting a solid 4.9V

Checking around the board, the 15V and -15V are good. I have steady red lights on the control panel though. So I cleaned and reseated all the socketed chips, but no change. X and Y are both 0V, now that I'm testing them for AC. Seems like my last experience with something like this was a Tempest, and I used my logic probe to listen around the xy section until something stood out.

I have the Cabinet here at my shop and my tools at home, so it looks like I'll be loading this up to take home soon.
 
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Is the board playing blind?

If it isn't, it isn't going to be the XY section. You need to get the CPU section working first.

Next thing to do here is boot the cabinet up with the test mode switch already flipped on before you hit power. Then listen for any RAM error codes, and listen to hear if it completes self-test (which you can tell if you press any of the control panel buttons and hear beeps.) If that's the case, self-test is working, and there may be ROM errors preventing the game from booting.

In that case, test the XY outputs again, and if they are safe, connect the monitor and ONLY boot back into self-test to see the error codes. Then shut down and fix them. Do NOT flip out of test into attract while there are still error codes, as it can blow your monitor.

Never boot a vector game into attract mode with the monitor connected, until you are 100% sure the game is playing blind, and there are no errors in self-test.
 
Good Point, I just finished reading over your 6100 startup guide pdf.

Thank you for that.

I've been so caught up in Vector concern, I didn't think about the simple stuff. The speakers have been dead silent, no beeps, nothing but hum in or out of test mode.

For now I can verify the ROMS. I may or may not have a 6502 I could pull from some rando board on a shelf.
 
Ok, good.

Keep in mind that it's possible to get cases where you have no sound (either due to a bad AR, bad speaker, or bad audio section on the game board), where you won't hear any RAM error codes. But not because they aren't there, you just aren't hearing them.

So it's important to make sure the rest of your audio section works. (Ideally by sticking another good board in the cab, if you have one, which will verify the speakers and AR.) Otherwise you can think there isn't a problem, when there is.

The key to troubleshooting these is divide and conquer. Verify what parts of the cab and game board are ok, one by one, and narrow down where any issues might be.
 
After testing the ROMs, I found two that didn't identify correctly. One of the Vector roms at 106 and the other at 201. As luck would have it today, I had blank spares of both types of chips (one is only 16k) on hand, and flashed them with the correct ROM data. Now they all verify @ ROMident and Arcade Restoration as version2 space duel.

Still no joy. Just a quiet system with the electrical hum, and solid lights at the select buttons.
 
Got a logic probe? If not, time to get one. It won't fix everything, but it'll let you get more insight into what's going on, on the board. It's the next tool up from a DMM.

Elenco LP-560. $25 on Amazon.
 
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