Wpc-s Power driver pcb cooking

[pinball god]

Hi Rob,

Bit hard to tell from that photo.  With power off and the machine unplugged from the wall, that jumpering plug can be simply unplugged and removed from the machine.

Being a young fit whipper snapper, if you look closely the numbers are actually molded onto the plastic so you can check it 100%.

If you're like me, a magnifying glass the size of the hubble telescope helps.

Thanks mate all good. Pin 1 is actually with tab on the bottom positioned at bottom right not left so jumper settings are ok. Helped me heaps mate thanks

So back to wondering why pcb is getting hot?

[beaky]

if the voltage to the lamps are correct then it could be:
A: Some of the G.I. wires have been wired incorrectly (wires on the plugs that go to playfield and back box G.I.s) and there are more lamps on one or more of the circuits than there should be. (hot plugs)
B: Bad solder joints on fuses, Faulty fuse holder or faulty fuses. (hot fuses)
C: when the new plugs were installed the pins in the housings were not crimped properly, or the headers were not changed or the headers were not soldered in correctly (hot plugs)

You will need to check if the wires were fitted in the correct positions when the plugs were changed. If all the wires are correct and the voltage is correct it comes down to faulty parts / or workman ship.

I have just recently fixed a wpc driver board with a burnt G.I fuse holder, all the plugs and wires showed no signs of heat stress, it just came down to either a faulty fuse, fuse holder or bad solder joint.

[pinball god]

if the voltage to the lamps are correct then it could be:
A: Some of the G.I. wires have been wired incorrectly (wires on the plugs that go to playfield and back box G.I.s) and there are more lamps on one or more of the circuits than there should be. (hot plugs)
B: Bad solder joints on fuses, Faulty fuse holder or faulty fuses. (hot fuses)
C: when the new plugs were installed the pins in the housings were not crimped properly, or the headers were not changed or the headers were not soldered in correctly (hot plugs)

You will need to check if the wires were fitted in the correct positions when the plugs were changed. If all the wires are correct and the voltage is correct it comes down to faulty parts / or workman ship.

I have just recently fixed a wpc driver board with a burnt G.I fuse holder, all the plugs and wires showed no signs of heat stress, it just came down to either a faulty fuse, fuse holder or bad solder joint.

Quick question prior to checking these out. I have LED's on all the PF inclduing GI's. Although the problem was from the start I have added a couple of LED's to the PF. This shouldn't cause an issue????

Also the BG GI's have always been the problem going out.

[beaky]

if its only a few leds it should be no problem.

I have seen G.I circuits fail like this with age and general use.

Just a few hints and tips below, depending on what you decide to do.

When you repair or replace the board you must make sure the pins are crimped correctly on the wires and they of a high quality.

If you repair the board check that the remaining G.I. fuses are not corroded on the area that is contact with the clip on the fuse holder. if they have replace the fuses and check if there is any corrosion on the fuse clips on the holder, if it has migrated to the fuse holder clip then replace the fuse holder. any corrosion between the two surfaces can cause resistance which creates Heat. The heat in time may cause a dry solder joint which creates more resistance and more heat until the plastic melts on the fuse holder and the board is damaged by the heat. I have seen the end result of this many times.

Also re flow the solder on the remaining fuse holders, if the joint looks like it has become a dry joint it is best to remove the old solder first and then resolder, you will get a better connection this way.

And don't forget the headers, make sure they are in good condition, if the solder joint has over heated it may better to replace the header because the solder some times won't take properly to the pins.
If any of the headers need replacing then replace with the high temperature type headers and make sure you flow the solder right through the board so there is solder on the top and the bottom solder pads around the pins. 

[pinball god]

 Quick update. I measured voltage some GI globes on the Tom and got 7.8vac. I would have expected 6.8v there abouts ???

Could this explain the cooking? And where do I look now? Thanks

Also just went to remove the pcb and found J121-7 fully burnt header and connector pins. So this explains the out GI's but not why they keep burning.

[pinball god]

Replaced J121 header & connector and voltage now 7.2vac all globes working but still concerned about the voltage

[Homepin]

Replaced J121 header & connector and voltage now 7.2vac all globes working but still concerned about the voltage

It is VERY difficult to get an accurate AC voltage reading unless you have a VERY good meter. I wouldn't be too concerned about a reading of 7.2V

[Marty Machine]

Silly question, but are your GI leds correct "AC leds" and not "DC leds"???
....meaning, the 'AC" ones have an internally fitted diode-rectifier to ensure AC becomes correctly polarised DC on the Led?? if DC leds are put in the AC installation, they'll cook and overdraw current.
( excuse my ignorance, as i haven't used Leds on pinnies myself, and perhaps ALL pinny leds are "AC ready"??? ).

Maybe pull all the GI leds out and re-measure the AC volts, does it rise from 7.2 upto 8 or 12 or something?
Perhaps place 1 led-at-a-time back in the GI, while monitoring the multimeter for an obvious drop caused by a dodgy led????

my 20c ;-)
MM.

[pinball god]

Silly question, but are your GI leds correct "AC leds" and not "DC leds"???
....meaning, the 'AC" ones have an internally fitted diode-rectifier to ensure AC becomes correctly polarised DC on the Led?? if DC leds are put in the AC installation, they'll cook and overdraw current.
( excuse my ignorance, as i haven't used Leds on pinnies myself, and perhaps ALL pinny leds are "AC ready"??? ).

Maybe pull all the GI leds out and re-measure the AC volts, does it rise from 7.2 upto 8 or 12 or something?
Perhaps place 1 led-at-a-time back in the GI, while monitoring the multimeter for an obvious drop caused by a dodgy led????

my 20c ;-)
MM.
[\quote]

Ahhhhhh yeah, didn't know there were different types and all bought from pinney suppliers. I can do the checks but this problem has been around (I reckon) from purchase when only candies used. This may be misleading but I did notice soon after purchasing that one globe was missing from the backbox. Being finicky I had to put a globe in. I think after that the connector cooked not long after and the first header/connector fixit occurred. When the GI's go, it tends to be in the back box.

[pinball god]

Major update guys.

The GI's are still working fine but I thought I'd do a GI test and got interesting findings that may give someone an explanation of why my board keeps frying. This will help me greatly to maybe solve the problem once and for all.

I found that strings 1 & 2 remain on while testing all GI's individually and they also do not dim. They stay at full strength on even when testing say string 3.

Also when testing string 4, it increases in intensity until setting 4 where they flicker like there's a bad connection until I go to setting 5 and 6. So each time I get to intensity 4 this occurs. Btw strings 1 & 2 are still on at this moment

Any ideas?

[Homepin]

Shorted Triacs....

[beaky]

are u doing the tests with leds or incandescents? leds will flicker in the way you have explained when used in the g.i. circuits.

as far as the g.I.s not dimmimg at all it may be as home pin has said or other faulty components on the board

[pinball god]

Thank you guys, I will put in another pcb and see if these problems disappear. Btw will these problems cause connectors etc to overheat?

[beaky]

as far as i know no, it should not cause an overheating issue.