I just got a <400 play HUO TZ that has handed me several issues despite functioning normally in situ during the pre-purchase inspection. I’m asking for help troubleshooting the below issues, all of which I'm hoping have a common cause.

- Flashlamp voltage (TP7) shows 1.2V (even when powered off for several hours), jumps to ~30V when flasher bulb #28 is plugged in.
- Flasher #28 (inside ramp flasher) remains continuously on when an LED flasher is plugged in and will remain dimly lit after turning off the machine.
- All other flash lamps function normally when flasher #28 is plugged-in and will turn off within about 10 seconds when #28 is unplugged.
- Incandescent flashers plugged into #28 do not illuminate, however they will turn on/off all other flash lamps, as described above.
- The mini-playfield magnetic flippers no longer work during game play or tests.
- Gumball geneva mechanism no longer works during game play or tests. Applying voltage to the motor lugs causes motor to spin the mechanism.

Power Driver Board Test Results:
All 6 LEDs on the board lit.
Unregulated 12V (TP1): 14.4
Regulated 5V (TP2): 4.8
Regulated 12V (TP3): 11.9
Zero-Cross 0.4V (TP4): 0.4
Coil power 70V (TP6): 77.4V (fluctuates between 69 – 89)
Flash Lamps 20V (TP7): 1.2 (30V when FL#28 plugged in)
18V (TP8): 18.1
All fuses pass continuity check.

Any help is greatly appreciated!

Lostcause

Might you be thinking of the 8 High Power PCB Assembly (A-16116)? In this case, I'm fairly certain the opto board isn't the issue.

Eric_S

I am familiar with issues caused by low CPU voltage and ribbon cable problems, my Judge Dredd was a prime example. In this case, the issues present as something else entirely.

Also, while I suppose header pins are worth looking at, the game is essentially new and the pins have almost none of the stress cycles seen on a typical machine. Moreover, I suspect a header pin would more likely cause intermittent functionality, as opposed to the predictable and highly anomalous behavior seen to affect the 20V accessories.

If I were to guess, I’m going to focus on the fact that TP7 is 1.2V but jumps to 30V when flasher lamp #28 is plugged in. This circuit should be closer to 20V and the circuit has commonality with many (all?) of the non-functional components. I'm just not adroit enough to know what could cause this...

It turns out J124 had accidently been plugged into J128 during the installation of an OCD board. Problem solved! Thanks everyone for the troubleshooting suggestions!