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Look for missing signals to the ZMC2... There's one that tells it which 8 bits to shif out and if it's stuck/missing, you'll get that kind of striped screen. It's one of the low numbered pins.

OK, when you power it up, how many bongs do you hear? Just one? When you turn the test mode DIP on and go into the sound tests, what sounds / effects do you hear OK? Which are bad?

Who wants to repair them? I'll do some work on them like replacing the 3 dead tactile switches, but I don't have a good source for the europin connectors to undo battery damage... I'm also not going to try to fix horribly corroded edge connectors. To me these represent a Q-Sound chip to sell to...

Have you replaced the supercap in the audio section?

Thanks, but I've only had to replace the A-01 and B-xx chips.

Now you see it... Now you see the other... I ordered "20 AMD 27C400 EPROMs" and received 16x Hitachi HN27C4000G-10, 2x Hitachi HN27C4000G, and 2x ST MX27C4100... Did OK on the lot and they came blanked. It did take some work to get all the paint off though. Overall, was a good buy...

Check connections between the A and B board near the Z80. If it can't connect properly to the sound ROM and the 2 SFX ROMs on the B board you'll have issues. Also check the sockets and those 3 ROMs for corrosion. Clean the legs of the ROMs if needed.

These are pins from the PALs to the chip on Crime City. I'm thinking one (pin 5) would be for a /CS (Chip Select) or similar function for accessing the I/O chip as that's an output on the GAL. Pin 11 is an input so it is possibly an /INT (interrupt) coming from the I/O chip. I haven't taken...

You probably have a Tantalum cap that is shorted. Common issue. An ESR meter can be used as a high frequency milliohmmeter to find the tantalum cap with the lowest resistance across its leads. If you have a multimeter you can check reisistance (with the power off) of the disconnected PCB to see...

Is the volume up button stuck on / shorted on?

Thanks guys! I have more out on the PLD Archive.

Hey folks, Had a bit of a bitch of a Crime City on the bench. Two stuck inputs and a sound subsystem in watchdog. Fixed it, but in the midst of doing that I reversed the pinouts for two of the customs: TC0220IOC - I/O Controller IC TC0140SYT - Sound Subsystem Controller IC The I/O controller...

Yes. It won't do anything. No ROM code to run on the two CPUs since there's no B board and no sync pulses since there's no C board.

Check the resistance between +5v and the edge connector pin for Player 1 start. Compare it to Player 2 start. That will tell you if you have an open trace or open resistor pack.

That's actually a Z80A. The A simply means it's tested and will run at 4MHz. The part number is Z0840004PSC that last 4 is the speed rating. You'll see some with 6 and 8 as well for 6MHz and 8MHz speed ratings. Don't feel bad, I thought the same for a while until I looked up the data sheets. :)

No. The +5v is fixed at +5v (+/- the voltage set by tinkering game owners)

Yeah, that one is a problem in the battery backup circuit. Look around / under the HC32 chip and make sure the little 1/8 watt resistor (22k) is not open. As for the one watchdogging... check for a bad BIOS but other than that it's usually either a bad RAM, bad trace, or battery damage issue...

It's good that you used a 5v cap as the charge circuit on the NiCd is a 470 ohm resistor connected from 5v to limit current. Check the datasheet for the cap to see if there are charging limits on current that you need to observe to help prevent early failures of the capacitor (shorts...

Check around the battery for damaged traces from battery leakage. Check continuity to the CPU and each other of the Backup RAM for the address lines. Data lines are individual with one chip connected to the lower 8 bits and the other to the upper 8 bits of the 68000 CPU. If the /CE and /OE...

If it was the MV4 I'd say replace the PRO-C0 chip. Not sure which one has the functionality of it on the 4F...