Thief Issues (Pacific Novelty) *FIXED

Pac Man with dollar bills instead of dots.
 
Update — After a few weeks of no issues, I left town and the game sat idle for a couple weeks. When I came back, the tape player stopped reversing and the game started resetting into test periodically. I had to take apart the tape player since the tape was stuck. It had overlapped on itself I think because of the repeated reverse attempts (or the failed reverse attempts were because the tape was stuck?). Chicken or egg situation…

After I got the tape player sorted out, put everything back together and the game was now resetting more consistently. When it did boot, the graphics were partially garbage.
IMG_0579.jpeg

I cleaned and reseated the 8255 once more, which didn't improve things. When the game went back into test mode after I few minutes, I started wiggling connectors. When I got to the "power" 6-position IDC, the game booted back up. I turned off the game, and I pulled the board out and saw I had a cold solder joint in the 3rd position. After reflowing, it booted back up and no more resetting issues so far.

One thing I haven't been able to solve to get this thing to 100% is these small color dot artifacts that show up in the game after it's been warming for 15-20 minutes. I thought it might dirty legs on the color chips, but it's multiple colors, and I believe each individual chip controls a different color, so that seems less likely. Any thoughts?

IMG_0582.jpeg
 
Congratulations and job well done on getting the tape player and cold solder issues identified and repaired!

For the color dot artifacts, it looks like one (or more) flaky chips in the 4116 VRAM section of the Main / CPU board. There are 32 of them.

If you haven't already done so, carefully remove each one, clean the legs and apply DeoxIT before re-installing.

If the issue persists after that, the easiest way I have found to locate the culprit(s) is to apply heat with a heat gun, and/or cold spray. I use an inverted can of "Canned Air" computer dusting spray.

Heat each chip to see if it makes a difference, and then follow that with a round of cooling each chip. By doing this, you can usually identify which ones are at fault because the dot issue will worsen or improve with temperature.

The VRAM section is circled in this picture for reference. This is my parts board, and you will notice that three chips are missing. That's because they went to replace the bad ones on my working set of boards.

You can also order new ones from APAR.

IMG_3874.jpeg
 
Last edited:
I'm starting to feel like my Thief is possessed... Things were going great, and then the next day after addressing the cold solder joint, the game won't boot, not even into the random test cycle I was seeing before. After power cycling a couple of times, I get a dark screen or a pinkish version of the scrambled TV from Poltergeist. I'm thinking there is a core issue I haven't addressed. The voltages were solid when I tested them a couple weeks ago, but I'm planning to pull the game out (again) and see if how voltages look in different spots. On the tape head's forum, someone noted it could be an inconsistent 12v that was causing the player to struggle to reverse (rather than a mechanical issue). So there might be some kind of voltage issue I haven't found. I'm feeling like this is a PCB vs a Power Supply issue, but keeping an open mind. -- @Arcade2007 Any other suggestions or test points to key in on, please let me know!
 
How to exorcise evil spirits from possessed arcade games:

- Remove every socketed chip.
- Clean the inner and outer faces of the legs of each chip with a Dremel wire wheel brush
- Get some DeOxit, spray some in a small jar, and paint some on the legs using a small art paintbrush, then reseat the chip twice. (Get a Wiha prybar to make lifting chips easy.)
- Also use the wire wheel on all header pins (just buzzing it on the face of the pin that is exposed, which is where the connector plug makes contact)
- Also use the DeOxit on all connectors in the entire cab. Including everything that connects to all 3 game boards, all pots, and the ribbon interconnect connectors. I like to paint it on the pins of each connector using the same small brush as above.

The key is the Dremel wire wheel. There is 40 years of oxide built on on the tin legs of socketed chips, and all header pins. And it won't come off by just reseating. You have to remove it with something abrasive.

I do the above to every board I repair, before I start troubleshooting problems. And it eliminates a LOT of problems.
 
Last edited:
In addition to what @andrewb has already suggested, double check the solder joints on ALL header pins. You mentioned previously that you reflowed them. Reflowing means you need to remove all the old solder and reflow with fresh solder - don't just add new solder to the old, crusty oxidized solder. If a pin has been overheated, or operated long-term with an existing cold solder joint, you will need to carefully remove the oxidation from the pin itself with a small wire brush, or by scraping gently with an X-acto knife.

If you gently flex or twist the PCBs and you hear any popping and creaking, it's a telltale sign that you have oxidized pins and sockets.

You might well have a power supply issue too - so best to check that out as well - and all the PCB pins and cable-end connectors associated with the power supply cables.
 
In addition to what @andrewb has already suggested, double check the solder joints on ALL header pins. You mentioned previously that you reflowed them. Reflowing means you need to remove all the old solder and reflow with fresh solder - don't just add new solder to the old, crusty oxidized solder. If a pin has been overheated, or operated long-term with an existing cold solder joint, you will need to carefully remove the oxidation from the pin itself with a small wire brush, or by scraping gently with an X-acto knife.

If you gently flex or twist the PCBs and you hear any popping and creaking, it's a telltale sign that you have oxidized pins and sockets.

You might well have a power supply issue too - so best to check that out as well - and all the PCB pins and cable-end connectors associated with the power supply cables.


All excellent points. Especially the creaking comment, that one is very true. If you compare flexing the board before and after pulling, cleaning, and DeOxiting all chips, you'll hear a drastic difference.

So much of getting these old boards working reliably again is just cleaning all of the electrical contacts. People waste money on cap kits and other stuff, and neglect the #1 thing that affects all boards, which is oxidized and dirty contacts. (I also recommend washing all boards as well with a good cleaner like Krud Kutter or Greased Lighting, to flush all of the nicotine and other grime out of the sockets, and off of everything else.)

Another thing regarding power, be sure to test the 5V on all three boards separately (CPU, IO/Sound, and Coprocessor). And measure each voltage with respect to a GND point on the same board you're measuring the 5V on.

They each draw different amounts of current, and depending on how clean your harness and connectors are, you can see different values for the 5V on each board. If they are different, that's ok. You just want adjust the 5V to spread the difference out, so they're all at least 4.90V. (It's ok to have one a little low, and another a little high, you just don't want any too low or too high.)
 
Okay, the re-seat, Deoxit, and reflow project went fairly well.

Unfortunately, I broke a leg on heavily oxidized C8 on the coprocessor board. At the risk of sounding dumb, this chip looks important. I'm thinking this can't be replaced, unless I find another original, correct? Or can it be bridged to another spot on the board? It's the lowest left leg in the image below
 

Attachments

  • IMG_0604.jpeg
    IMG_0604.jpeg
    241.5 KB · Views: 11
  • IMG_0605.jpeg
    IMG_0605.jpeg
    498.9 KB · Views: 11
Last edited:
Depending on where the leg broke off (how close to the case), it is usually possible to clean up the remaining part of the leg and solder on another one from a donor IC. If it was just the thin, necked-down portion that broke off, then odds are good that you can execute this type of repair. This is the first option to investigate.

There are likely other options (burn contents to a new ROM, etc.) - but first see if the leg repair is feasible.

Can get you more details when I get home in front of my board set.
 
That's a PROM.

It's not an off the shelf part you can buy complete, it's something that you'd have to find a blank for, then get it programmed.

The best thing to do here would be to salvage that chip. There are ways to do it. The easiest one I do in these cases is mount the chip in a machined-pin socket, then file the side of the chip flat (just where the pin broke off), then solder a piece of stripped 30AWG Kynar wire to the exposed piece of leg on the edge of the package, to the corresponding pin of the socket.

There are threads about it here. Here's one with another way:


If you want to send it to me, I can fix it for you for a small beer fee.
 
If it's just the lower thin portion of the leg that broke, you can solder another whole leg from a dead chip to the stub that is left.

When there is no stub at all, that's when you have to get fancier. But if there's a stub there, just file it down to bare shiny metal (otherwise the solder won't stick, if it's covered in rust), then solder a new leg on.

If you need to get fancier, you want a machined pin socket, not dual wipe:

 
Okay, making lateral progress…. So got the chip leg fixed and the game booted on the first power. Some other observations:

- game doesn't coin up when it does boot, and the speaker buzz seemed a little louder than usual.

- after power cycling to test the power supply, the game is still booting intermittently & usually after a couple minutes of black screen or scrambled red

- PS voltages are good. Voltages between the CPU and I/O board are good

- noted 8155 on the bottom of the CPU is running a little hotter than other chips. I looked at pics of other boards just to make sure I put it back in the correct direction.

- 8255 voltages seem off on I/O board, nothing higher than 4.5v, most of the legs read 3.8v

- I was able to get the game to boot once to the I/O test screen, but it wouldn't go past the first screen of text announcing the I/O board test

- I did get the game to boot once by pressing on one of the EPROMs on the coprocessor board. It was odd because it skipped the test mode
 

Attachments

  • IMG_0609.jpeg
    IMG_0609.jpeg
    558.4 KB · Views: 3
Last edited:
That's the 'IO board driver test'. That just tests the IO board.

What about the other tests? (Particularly the main test where it checks the ROMs and burns in the video RAM.)

Also, have you tried reversing the ribbon cable? If not, try it. I've seen some that work in one direction, but not the other (presumably because they're bad, as it normally should not matter.)
 
Back
Top Bottom