I have a System 1 Dragon with the solnoids not working that i'm trying to fix.

First off, the game boots and enters attract mode. I can coin up and start a game.

If I plug in any of the coils they lock on, including all the 3 tones. The relays do not lock on but do not function. All CPU controlled lights are working correctly. When first working on the machine, the coils were fine but after 5 mins of leaving the machine idle the issue started. I've since swapped in another CPU and another driver board which displays the same issue.

Here's additional info:
- Connectors have been repined.
- Cap C17 on the CPU has -11.84 V. Is that good enough?
- I doesn't seem like solenoid buffers Z6/Z7 are the issue (because I've swapped out the whole CPU and driver and the issue is still present.)
- Momentarily gounding one of the relay transistor tabs fires the relay.
- A battery is not installed and the 0-10 audits have junk values.

Can anyone offer any insight into what the problem might be? Thanks!

The -12v is a little low, do you its within acceptable range?

I've swapped in a different power supply which produced -12.1V and the problem still persists. So since I've tried a different CPU, driver and power supply and the issue remains, I don't think i'm dealing with an issue in the board set.

I've checked the bridge rectifiers, they seem fine. Wiring and sockets and pins seem all in very good condition.