(Topic ID: 212013)

TOM power issue. Need pointers!

By RigidCollision

1 year ago

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  • 12 posts
  • 4 Pinsiders participating
  • Latest reply 1 year ago by RigidCollision
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#1 1 year ago

Hi guys,
I have TOM that I have been running for 15 years. My greatest purchase!
Today I powered it on and I got a scrambled display, transformer hum, a single *bing!* and then nothing. No lights on the play field or header. No apparent power to the play field at all, no further sound. I think the scrambled display is power related. It's a new colour replacement screen.

The machine has not been moved, is in awarm and dry environment etc.

Fuses all seem fine. I am stumped where to start investigating further.

Any tips would be greatly appreciated.

Kind regards,

#2 1 year ago

Are you getting 5 volts to the cpu?

#3 1 year ago

Hi Tony,
At the moment I am not sure. I have LEDs on the boards lit which I know isn't the same but may be an indication of power. As you can appreciate in 15 years I have rewired and changed components, connector blocks, solanoids etc but I have never had a power issue before and so have no idea where is safe/applicable to test for voltages (my electrical safety and general skills and tools are ok).

#4 1 year ago

If you have a meter check the power driver board for the 5 volts. There is a 5 volt test pin on the board.

#5 1 year ago

Pin 32 on the WPC rom any good?

#6 1 year ago

Found it...
TP2 5v is reading a fraction under 5.
TP3 12v is just under 12

#7 1 year ago

And TP1 ?

#8 1 year ago

TP1 is 13v.

The symptoms are repeatable. E.g every time I power up I get the *bing* and scrambled screen with no power as described above.

#9 1 year ago

Check the wires in connectors at J116/117/118.
And does J606 have both voltages ?


#10 1 year ago

Checked 116,117,118. Can't see any obvious loose/disconnects, no scorching. No signs of obvious degradation/dirt/corrosion

Tested 606 with its plug connected.
12v unr = 13v
5v = 4.8v
Checked ground was OK.

#11 1 year ago

Check your ribbon cables

#12 1 year ago

Ribbons all checked. I have noticed that the blinking LED which indicates the CPU is alive is not blinking and it doesn't change anything if I remove the two data cables from the cpu board and boot the machine.

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