Tech: Black Widow PCB resetting

jehuie

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So I bought the internals to this Black Widow and since I happen to have a complete BW, I decided to try out the monitor and PCB to see what they do. The good news is: The monitor looks great and works great. Colors are bright. Very good deal on that thing.

The bad news is: The PCB is a no worky. I've never seen one behave this way so thought I'd ask here before proceeding with troubleshooting the thing. As soon as I fired it up I heard a loud and fast clicking which I thought was the counter clicking through rapidly like a machine gun. But I turned out to be mistaken....it was actually a mechanism in the coin-door itself that was repeatedly clacking like that. Apparently it's a coin-lockout mechanism. And for each click, both player start buttons are flashing at the same speed. And there's no display at all.

Is this a watchdog kinda behavior? Any tips on what to do to check it further? I can start blindly swapping chips to it from the working board at least for the ones that are in sockets. But that seems not very elegant!

Someone has suggested that I need to check the voltage at the PCB which I have not had a chance to do yet. I know my other board works fine in the cabinet but I'll check that anyway.
 
It could well be the watchdog, hopefully you've got a logic probe you can put on the reset pin of the CPU (verify you're getting a clock signal while you're there). If it's resetting constantly I would try swapping the CPU's if they are socketed. Once you have proven the CPU works then the next step is to test the ROM and RAM. If they are both good then you have a logic fault and this is where things begin to get difficult to diagnose.
 
I think you are are on the right track by testing the voltages 1st.

I don't own a BW board but if it's anything like a Tempest board, then the voltages are adjusted on the board itself using the test points on the board.

If the voltages were/are set too high, it could have already fried the CPU. Do as the previous poster said and check RESET on CPU with a logic probe. I think Atari also used a 6502A on that board??

Have you D/L'd the manual on BW?

-Muel
 
Haven't downloaded the manual yet. Just got the thing and have been running a bunch of different directions this weekend with other projects. Really? The +5 is adjusted at the board somehow? I've never heard of that.
 
There are no pots on the game board to adjust voltage (same goes for Tempest). The only voltage adjustment is on the AR board for 5 volts.

The game board pots are for adjusting XY size and alignment

Mike



Okay, I'm speaking for a Tempest, but yes... there are pots on the PCB to adjust the voltages - they are not on the power supply.

On a BW, I believe that there are trimpots at locations R187, R189, R192. You'll have to figure out what they actually adjust.

Here's the manual:

http://www.arcade-museum.com/manuals-videogames/B/BlackWidow.pdf

-Muel
 
So the voltage was fine at the board. I went and swapped out all the big chips (CPU, AVG, etc) from a known working board and it did the same thing. Then I swapped in all the roms as well as another chip (EAROM ER-2055) from the known working board and....it came up and ran! The graphics were a bit wonky so I did some adjusting with the various pots on the board and, at first, it was looking pretty good.

But then suddenly the graphics went way off...you can see that the game is playing but the graphics are seriously hosed. I took a pic and I'll try to get it uploaded shortly to show you what I mean.
 
Here's some pics. The first is the cross-hatch pattern and the others are during game play:

7174761009_0e5a71f679_b.jpg


7359986546_b9a1b5085a_b.jpg


7174760509_cdac4f90a8_b.jpg


Any ideas on where to start? Maybe one of the pots I was adjusting is flaky?
 
It's not uncommon for boards that have not been powered for years to suffer secondary failures.

Based on the photos I would doubt its just a bad pot

Mike
 
It's not uncommon for boards that have not been powered for years to suffer secondary failures.

Based on the photos I would doubt its just a bad pot

Mike

So a chip that's been sitting unused will become weaker somehow? Or is it more like a cold-solder issue likely? Or is it one of those deals where it could be 8 million different things?
 
I'd put my money on a failed chip in the video output section.... But it could be upstream of the DACs as well
 
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