WPC95 resets and LEDs flicker then blow

[robm]

On the Monster Bash i did the playfield swap, a lot of the LEDs have gone - a lot of the time they seem to flicker for a while, then just not work, put a new one in and it  works fine (they are Ablaze 3's) although may blow later again.

What could cause this - if it was a short in the wiring, i would have thought the fuse would blow (all correctly rated), and it seems to be happening on a few different circuits (both GI and feature lamps)

It is also resetting a bit - particularly when the knocker sound is generated.  I will replace D7,D8,D9 and D10 and C9 and C1 - anything else to check and would these two problems be related?

Thanks

Rob

[Strangeways]

Do you have another Driver board to swap out ? The use of LEDs should not cause the problem(s) you describe unless one LED has an internal short - but it should be blowing a fuse, not other LEDs.

While troubleshooting, I'd revert back to standard bulbs where possible. What are the test point voltages ?

[beaky]

i agree with the above.

you may have a faulty transistor in the lamp matrix.

it is easier to identify faults in the lamp matrix with standard lamps installed, it will make it easier to see if they have to much voltage going to them.

also make sure that all the plugs are installed in the correct place on the driver board.

[robm]

Thanks for the tips so far - unfortunately i have no other WPC95 games to try a board swap

How much voltage is too much voltage going to the lamps?  Would the problem most likely be a lamp driver transistor or something else?

Will have a good look at it tomorrow.

[beaky]

you should have around 5.5 to 6.5 volts for the lamps.

when you say "they flicker" do you mean they go bright and dim but don't turn off?

try unplugging J119 before turning the machine on in case the plugs that go to J119 and J123 have been swapped around and try it again, the little pieces of plastic that block the key holes may be missing and you may have them plugged into the wrong plugs.

J119 should have the following wires on the plug
pin1: red - green
pin2: red - green
pin3: key (no wire)
pin4: red - blue
pin5: red - blue
pin6 to pin 9: No wires

J123 should have yellow wires with a different coloured stripe on each wire going to it.

J121 is not used so it should not have anything plugged into it
the wiring code in the manual states that J123 has only 8 pins but the picture of the board shows nine pins.

If this fault has only come up after a playfield swap it possibly could just be a plug plugged into the wrong place.  if the pieces of plastic that block the key holes are missing it would be quite easy to get some plugs mixed up.

I may be wrong but it's something i would check.

[dj10555]

You could check that the input voltage jumpers are set for 240V AC.

regards Derek

[robm]

You could check that the input voltage jumpers are set for 240V AC.

regards Derek

Nice work Derek.  As the machine has a new owner, i cant check everything straight away (he is 1/2 hour away and a sparky, so has a very good understanding of most of this stuff).

But i have just checked some of my photos from the tear down and i am 99.9% certain it is set for 200v (ie: black wire pin 1-11, white 4-10, black 3-6), whereas the wpc-95 schematics show the 220v settings to be black wire pin 1-11, white 4-10, black 3-9.

So i'm assuming if we just  change the black pin 6 to pin 9 connection, it will take it to 220v.

Whether this has any bearing on the problems i am unsure, but i guess try it first then get TP voltages.

When i tested them yesterday they were very good - ie: 5.12, 12.04.  I replaced all the diodes on the power driver board, plus C9 and C1, as well as jumpered the GI diodes so they are bypassed.  The machine still did a reset when the knocker sound was generated, and the 5v stayed at 5.12 during the reset.  Then it played for an hour without a reset, then did it again.....


Beaky - thanks for your tips - will double check these when i can

Rob

[Homepin]

Rob, if it is set for 200V and you apply 220~240V, the secondary voltages will be WAY higher than the machine expects.

If we say the input is nominally 230V then that is 15% higher than the tapping is set for at 200V. This translates to the secondary voltages being AT LEAST 15% higher (there are many other factors that come into play but for the purpose of this discussion this is close enough).

I would say this is your problem for sure.

[beaky]

after you set the transformer up for 220 / 240v and if it still resets try replacing C31 capacitor on the CPU board (100 Uf, 25 volt) 

[robm]

Thanks for the help guys, hopefully its all sorted.

After jumpering for 220v, the rate of LEDs blowing (one of the 3 in each of the bulbs would go first, then the 2nd, then the last one would flicker and die) has slowed heaps - there have been one or two but i am assuming that they were stressed, and had/have a very shortened life?

In terms of the reset - was an unrelated problem, the RAM chip had a loose socket, we discovered this by pushing down on the CPU board, then isolated to the RAM.  New socket, and all sweet.

Plus - i used a desolder station for the 1st time and am amazed at how awesome they are - i ordered one that should turn up in the next few days, so looking forward to some breakdowns so i can use it!!