Hi all,

I bought a Dr Who which wasn't working and am trying to bring it back from the dead. I've replaced 4 fuses and after switching it on the following can be observed:

- everything is dead on the playfield/backglass, no lights at all
- the left ramp diverter coil locks on, and activates diverter
- scrambled line on the DMD, nothing else
- LEDs D19 and D21 are constantly lit on the MPU board
- low hum from the speakers

I've checked the power driver board LEDs and they seem to be correct. I've tried re-seating a lot of cables, checking all fuses are ok, pushed on the MPU, and booting the MPU with only power connected - but nothing seems to have an effect.

Next step was to try the MPU board out of my CFTBL but I'm worried I fry it.

Any ideas would be greatly appreciated!

Cheers.

Brilliant advice!

Should I desolder the coil as a precaution?

Will also measure that 5v supply. Then swap the U6 into my Creech board and report back.

It's not the ribbon Pinball Maniac40.

Swapped over the MPU board from CFTBL and inserted the DW U6 chip.

It behaves fine with only J210 connected (D19 goes out, D20 flashes). But with all cables connected it does the same as the original (D19 and 21 permanently on).

The original board didn't work in CFTBL so definitely needs some repair.

Mmmm.... any ideas?

Ok got the game to boot!

Used my good MPU board, and left all the ribbons connected to it apart from the two to the DMD driver board. Game booted, passed the test mode and all the lights started cycling with audio- excellent!

In the excitement I didn't notice the coil was still locked on and it started smoking - this needs sorting.

So it looks like the issue is with the DMD board. I think I have a spare so will try swapping it out. I've never read that this board could stop a game booting before?

Bit more progress in getting this thing working...

Swapped out a DMD board and it booted up ok, so this board was somehow preventing the game from booting which is interesting! Looking at the attached photo the R7 resistor looks in bad shape.

So game now boots but there are problems with the trap door solenoid locking, which suggests a shorted driver transistor. Then also the TARDIS popper and left time expanded pop-out are not working, so maybe also TIP36C transistor issues.

Does anyone know if the resistor and diode also need to be replaced? Or at least checked out?

20190321_134725 (resized).jpg

Thanks man, I'll get to work on them. Just to be clear, by ICs do you mean the legs on the chips?

Cheers for that. All three transistors are TIP36C, Q72/78/80 I think. The fuses check out ok, and there is about 45-50 volts at the coil. I would love it if I only had to change one, but I cant figure out what else could be the problem.

I think you can test those transistors but you gave to remove the power board, so that's the next step.

No, they were connected. Now I'm thinking I haven't measured it properly... they share the violet/yellow wire, and as the trap door locks on there must be voltage there right? I desoldered the power to that coil for the time being.

Thanks again for the tips!! Locked on coil is now disconnected at the smaller wire.

All the voltages checked out ok. I took the power board out and the reason why those other two coils (on pins 4 and 5) were not firing became quite apparent:
20190322_175247 (resized).jpg