Tokens Only Main Banner
Main Page Image

Posts Tagged ‘Repair Log’

Repair Log: Space War: 081209

Thursday, November 5th, 2009

Patient: Vectorbeam Space War UR
Technicians: Mark H, Bill K and Chris M
Problem: Slightly shaky graphics during game play.
Troubleshoot: After discussing the problem with Mark H, I pulled the monitor and got it over to his place for testing. He didn’t find any issue with the monitor and suspected the ribbon cable, which I hadn’t brought along. Apparently the ribbon cable is a common failure point on the old Vectorbeam and Cinematronics games, similar to those crappy MCR ribbon cables that are always brittle and prone to failure. Good idea to just replace it. Here’s the old red ribbon cable attached to the monitor/pcb. (more…)

Repair Log: Warlords: 081409

Wednesday, September 9th, 2009

Patient: Warlords upright
Technicians: Bill K and Chris M
Problem: Continuous tone with intermittent screeching noise. Volume must be turned all the way down to play the game comfortably. Listen to this sound bite on You Tube and you’ll get the idea.
Troubleshoot: We first attempted to swap in a known working AR II board, but there was no change. Next step is to check the audio oscillations to see where they are originating from. We checked the audio test points on the pcb with an oscilloscope by hooking one lead to the test point and the other to ground. This was the resulting square wave display.

Warlords UprightWarlords UprightWarlords UprightWarlords UprightWarlords Upright

The scope leads were then connected to the sound test points on the AR II, with the same result, except the square wave was amplified (larger). This ruled out the AR II pcb as the cause of the problem because the oscillations were the same. The noise was originating from somewhere else. We had to take a closer look at the schematics which I didn’t have on hand, but could easily find at the arcade archive. The schematics show that the audio section on the pcb can be traced back to leg 37 on the pokey, a likely culprit as they are known to fail. Quick history of the name…”The pokey is an I/O chip used by Atari in many of the classic era games, its name comes from POtentiometer and KEYboard, as it was commonly used to sample (ADC) potentiometers (such as game paddles) and scan matrices of switches (such as a computer keyboard).” – Wikipedia. We powered down and swapped out the pokey with a known good chip, but there was no change. Isolating pin 37 on the pokey, responsible for audio output, also gave us the same wave display result on the o-scope. This ruled out the pokey.

Warlords UprightWarlords UprightWarlords UprightWarlords UprightWarlords UprightWarlords Upright

Since it appeared that the pokey was good, the likely problem was now with the audio portion on the pcb. That was all we could do at this point because I didn’t have any of the audio amp chips on hand to replace or piggy-back onto the existing chips. Bill took the board home to change out the chips and capacitors from the audio section. I took this opportunity to lay the game down and add some gliders (levelers with nylon). This would allow me to move the game around a lot easier without damaging my floor like the metal levelers do.

Warlords UprightWarlords UprightWarlords Upright

Picked up the repaired Warlords pcb from Bill along with a spare pcb Bill had on hand, just in case. Installed the original pcb into the game and fired it up. Same problem with absolutely no change. Installed the spare pcb and got the same noise issue, but at least I was able to verify it was working and also potentially rule out the pcb as the noise problem. At this point I was a little irritated and because I use tokens to run my game room, the coin door on the cab was open to allow me to easily add credits. I closed the door a little rough and got a fluctuation in the sound, interesting. Opened the door and noticed the sound fluctuated as I moved it around. Jiggled the coin door wires and got the same changes. So now it appears that the connection to the coin door is the issue. With so many wires and connectors to check, this is going to be a pain. Bill stopped by later that night to poke around at the coin door. He moved wires, jiggled coin mechs, pulled on coin shutes and then moved the slam switch. Huge change occurred. Bill pulled the leaf apart on the switch and the sound vanished, bingo!

Solution: Slam switch on coin door was closing/sticking with door movement causing leaf switch contact and the horrid sound. A simple piece of blue tape between the switch contacts keeps them from closing and the sound is gone. I guess it pays to check ALL the simple solutions before running the repair gauntlet, but at least I learned a few things.