As-2518-32 sound card star trek

What happens to the game if you boot the game with the sound board connector off and get it into attract mode and then connect the sound board up?

When you say "all voltages are present" did you test some voltage points on the sound board as well?

Did you try to just disconnect the speaker or just disconnect the volume pot? I would test the speaker first. It could cause strange voltage behavior if it's bad/shorted.

There could be resistance caused by cracked/cold solder points, in turn causing a voltage drop only "sometimes".

Look at back side of the connector pins on the sound board to look for cracked/cold solder joints. If there is a connection "almost making contact", it can cause voltages to act crazy. Also worth checking voltage points on that board and directly on the MPU as well both with and without the board connected. My suspicion is that some issue on the sound board is causing the 5VDC or 12VDC to drop in the game.

Or, if the voltage is just barely able to boot the machine, adding the additional power required by the sound board could cause your problem. Rebuilding the power transformer/rectifier supply could be in your future if that's the cause.

I totally agree with Snyper.

The MPU only sends solenoid signals to the sound board and maybe one enable line from mpu j1. Your issue is likely a voltage drop caused by a failed component in the sound board or overall poor connectors.

The sound board creates its own voltages from 43v and 12v. When the sound board is hooked up, see if your overall 12v and mpu 5v drops low.

Can you "pin out" the sound prom and any other socket-ed chips on the sound board to confirm connectivity through the sockets onto the backside of the board? I have had two older Bally sound boards like this and they just needed new sockets.

I've spent quiet a bit of time with the soundboard schematics lately...
I'd say you could have a bad U2 or Q3... but given there are 10k series resistors on it... even a bad chip shouldn't cause the MPU to not boot.

is the sound board is loading the powersupply. C5 short?

Sure it could. The PROM on that sound board runs all the sounds in the game. If it's dead, or the socket is bad, it will not work at all… There will be no sounds. I've had it happen to me twice.

These sound boards still have some life with a bad or missing sound PROM. It plays the notes in the correct rythum, just all the same pitch.

That's strange. I once discovered a bad socket on a Harlem sound board… Tested it with a Star Trek sound board, and both boards were silent. Replacing sockets on both boards got them working. It could be that solder was reflowed over the pins at the same time but on one of the boards, I specifically remember reflowing solder, testing the board, it not working (silent), than replacing the sockets and they both worked perfectly thereafter… I wonder if two pins being shorted on the PROM or PROM socket could cause this type of issue.

game turn on MPU goes into lock mode, green led goes out and game will not start up.

You missed my point. He said the game wouldn't boot with the soundboard installed. IE something was shorting the MPU lines. As I stated; a resistor is in series with the Latch and the prom isn't even attached to the mpu pins... so the board must be loading PSU, not the MPU.

Given the game works without speaker would lead me to believe the culprit may be the LM380 chip loading the power supply.

I didn't miss anything. In post #4 the OP got the game booting with the sound board fully connected. C'mon catch up! J.K.

It sounds like the game's MPU randomly locks up with the sound board connected. Try to determine why... Get it booting and safely shake the crap out of the MPU/head/sound board banging/tapping everywhere. It could help point to a bad socket or component on the MPU.

Regarding the sound board issue, you should follow the steps below if you've confirmed the voltages are good. (you confirmed this in your above post). If you've replaced the suggested components below, I really don't know what to tell you other than to look for a working board on ebay. They aren't that expensive.

Are you certain the MPU is pushing the correct sound signals out to the board? It honestly still sounds like an MPU problem.

from pinwiki:

4.12.1 AS-2518-32 & AS-2518-50 Sound Board Troubleshooting

12v regulator section:
Check for 67 volts on the positive side of C17. If missing replace CR3. If positive side of C17 is the same as TP4(43v) replace C17 and CR3.

If 12v is too high, check Q1, R22, CR4, and C18.

Clock Generator:
U1(4049) can fail. Check for about 2.5vdc where R3 and R5 meet. (On my functioning -50 board, I see .8vdc at this point) If voltage incorrect replace U1 which is a 4049 hex inverter. If still incorrect suspect U4 which is a 4526B programmable 4 bit counter. The 4526 can be purchased from vendors such as Mouser or Digi-Key.

Amplification / no sound issues:
First, make certain that the cabinet speaker is present, connected, and functioning. If an audible hum is heard from the speaker, then the amp is working. Next, check both pots. It is best to replace them if they are the originals (typically blue or black thumb wheel pots). Measuring across the two outer legs of the pot is the total resistance (10k). Measuring from the middle leg gives a resistance with regards to how the pot is adjusted (a value from 0 ohms to 10 kohms depending on the pot's position).

To check the amplifier at U9 (LM741), look for about 2vdc at U9 pin 2. (On my functioning -50 board, I see 6vdc at U9 pin 2. Before replacement, 12vdc was seen when it wasn't functioning.) If voltage is missing, replace the amp.

If you can't figure it out and want it repaired I can do it for $50 including parts (except for a bad PROM which would be extra) plus return shipping.

IIRC if your hearing a constant tone; I'd check the solenoid connect to the sound board. Constant tone means the 555 timer isn't triggering or being held high. The 555 triggers a ramp pulse which causes the tones to be raised in pitch and the returned to "zero".

The PROM plus digital logic "always" output the tone with the 555 timer enabling it's output.

If the rest of the sound board is working; I'd think the tone should change when new data is being sent to the board. IE you should hear the Power on chime sequence without "pauses" between the notes.

Also; you could use the Pinball Sound board tester to "test" on the bench.
http://pinball-mods.com/blogs/?p=361