I've seen this issue on a couple of games lately. The 5v power supply is near or exceeds 5v in both cases. For whatever reason I'm getting a 200mv+ drop between the CPU board's 5v input connector and the game ROM.

Fish Tales
Driver board J114: 4.97v
CPU board J120: 4.97v
Game ROM: 4.76v
210mv drop

White Water
Driver board J114: 5.07v
CPU board J120: 5.06v
Game ROM: 4.83v
230mv drop

Both games are resetting frequently. I've never seen anything like this, usually it's at the driver board itself or the connectors going to the CPU board. The only cap I see measures 5.05v across and I also reseated the ROM with no improvement (WH20). Could the ROM socket possibly be the culprit? I am aware they cause all sorts of issues at times due to their design. Or could the issue be more difficult to track down/repair? If the latter is true then I will simply opt for the cheaper and more stable WPC 5v mod.

I replaced the CPU board in White Water with one of the same part number. The 5v supply has improved slightly and the resets are not as frequent, but I'm still seeing a large drop between J210 and the game ROM. There is no drop in the initial vcc section stemming from J210 in the schematics prior to the break in the drawing...

J210 5v rails (2x): 5.06v
Game ROM pin 32 (vcc): 4.85v

schematic.png

Following the schematic tracing backwards from the ROM...

W4: 5.05v
W5: 4.85v
W2: 4.85v

The above appear to be test points on one side of a zero-ohm jumper at each location. I tested these jumpers and there is no drop across them. I moved the game ROM and batteries over from the old board. Suspecting a battery problem, the VBATT side of W5 reads 4.11v when the game is off. The batteries need to be changed, but I don't see anything odd with those and the game is currently keeping memory.

However, I did notice something strange with the 1.5k resistor at R3. One side reads 5.04v, but the other reads 4.97v. For comparison I tested across R96 and R97 near the top of the board and got only a 10mv drop across them, even though they are both 1.5k as well. I am pointing to the low side of the resistor in the second photo. Is this normal?

fr_245.jpgfr_246.jpg

I'm getting a steady 119v at the wall outlet. This is the only machine resetting, but it doesn't seem to be an issue apart from the CPU board as the voltage coming in at J210 is a healthy 5.06v. I'm also considering a possible issue with the game ROM... that's the only other thing I carried over from the old board.

Any ideas? Do I just need to send it to Clive? I have two boards doing this and don't want to spend money having them both repaired if it's something simple.

Yeah I'm in the dark as much as you are here. Again, I'm thinking it may be a chip on that board dragging the voltage down but the game ROM is the only one I see with a vcc input. And if that's the case I will send it off anyway.

I will try the original board in another working machine and see if the problem follows.

Ok so I got some readings on two more games that do not have reset problems and the results are interesting...

TAF
J210: 4.97v
ROM: 4.77v

BSD
J210: 4.85v
ROM: 4.63v

So that 200mv drop to the ROM is normal. Next I'll be investigating the driver board. Thanks for the help.

Since I have already replaced the caps and regulator on the driver board and the issue is not connections between boards (5.06v coming in) I opted for Kahr's board. Now I am getting 5.15v to the CPU and 4.91v at the game ROM. No more resets!

Well of course, that's the first approach I took. The first thing I did was replace key components and that worked great for a few years. Then it started acting up again, and it was just the MPU board resetting (which is the main drag on the 5v power supply). If it were my game I would go through the machine 100% but as operators we don't have the time. The game is a high location earner.

The funny thing is I tested voltages as low as 4.79 on another game and that one does not reset at all.

I changed it already, as a lot of people suggest.

Yes. I had to run a jumper afterwards for C5.