(Topic ID: 315961)

Pinball Pool light diode

By jmbit

73 days ago


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  • 13 posts
  • 4 Pinsiders participating
  • Latest reply 72 days ago by Tuukka
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diode (resized).png

#1 73 days ago

Hello,

Game Pinball Pool - Pinball Pool

Wondering if you somebody can tell me the diode number that exists towards the back of the machine and ties to the lamps, they are clear. Picture attached.

diode (resized).png

#2 73 days ago

Think I found it. Wanted to pass on to others looking. 1n270 diode.
Great resource for finding some answers http://www.pinrepair.com/sys1/ this guy is awesome!!!

#3 73 days ago

Those are the switch diodes there are no lamp diodes on system 1.... not a matrix.

#4 73 days ago
Quoted from slochar:

Those are the switch diodes there are no lamp diodes on system 1.... not a matrix.

slochar thank you, would that prevent the light form going on from the switch?

#5 73 days ago

Which light, which switch? Bad connectors?

#6 73 days ago
Quoted from BorgDog:

Which light, which switch? Bad connectors?

BorgDog I'm having issues where the 5,6,7,8,13 aren't going on when the drop targets are triggered. I've replaced the transistor, I've upgraded the board to a Pascal PI-1X and see the single back to the board. Pascal has suggested replacing IC chips but doesn't make sense the new board would need 6 new IC chips so all of the light chips...

Picture attached.

IMG_7915 (resized).jpg
#7 73 days ago

The playfield mounted diodes are for switch matrix, not for lamps.

And the lamps are not controlled by playfield switches, but the switch is read by CPU, which then lights lamp if needed. If you have problems with controlled lamps, check your driver board.

If drop target switches are not detected by the CPU (use the diagnostic switch test) then there might be problems with some diodes being open. Reset (pull up) all drop targets and then test the diodes with your multimeter diode range. You should see infinite resistance (usually shown as 1. or OL on your meter) in one way, and with the test leads swapped the diode threshold voltage of about 0.1-0.3 volts. Maybe a good idea to disconnect playfield switch cable from CPU board before these measurements. And of course do this with power off!

#8 72 days ago
Quoted from Tuukka:

The playfield mounted diodes are for switch matrix, not for lamps.
And the lamps are not controlled by playfield switches, but the switch is read by CPU, which then lights lamp if needed. If you have problems with controlled lamps, check your driver board.
If drop target switches are not detected by the CPU (use the diagnostic switch test) then there might be problems with some diodes being open. Reset (pull up) all drop targets and then test the diodes with your multimeter diode range. You should see infinite resistance (usually shown as 1. or OL on your meter) in one way, and with the test leads swapped the diode threshold voltage of about 0.1-0.3 volts. Maybe a good idea to disconnect playfield switch cable from CPU board before these measurements. And of course do this with power off!

Thank you Tuukka I have checked the diodes yesterday and looks like a few of them are bad imo. I'm getting 0L both ways on those specific diodes. (so bad). When I close the switch on the diode does see voltage go across it. So I'm going to start with replacing one of those diodes and see what happens.

#9 72 days ago
Quoted from jmbit:

BorgDog I'm having issues where the 5,6,7,8,13 aren't going on when the drop targets are triggered. I've replaced the transistor, I've upgraded the board to a Pascal PI-1X and see the single back to the board. Pascal has suggested replacing IC chips but doesn't make sense the new board would need 6 new IC chips so all of the light chips...
Picture attached. [quoted image]

Does it score when those drop targets are hit? if it's not scoring then the lights won't light either, in which case it may be the diodes, or the switches, or the connectors. the 8 has not been hit in your picture as the 8 light by the captive ball would go out when the other goes on.

5, 6, 7 are on the same column on the switch matrix so if any one of those is messed up it could cause all those not to work.

#10 72 days ago
Quoted from jmbit:

I'm getting 0L both ways on those specific diodes. (so bad). When I close the switch on the diode does see voltage go across it.

Yes, the OL both ways definitely looks bad and diode needs to be changed! If you can't find 1N270 diodes, usually 1N4148 will work fine. The nominal threshold voltage is greater, but in the switch matrix, current is so small that the actual threshold is low enough to be just fine.

#11 72 days ago
Quoted from Tuukka:

Yes, the OL both ways definitely looks bad and diode needs to be changed! If you can't find 1N270 diodes, usually 1N4148 will work fine. The nominal threshold voltage is greater, but in the switch matrix, current is so small that the actual threshold is low enough to be just fine.

Tuukka that is very helpful! will replace and hopefully I'm finally good to go! Thank you!

I can get the 1N4148 this weekend. I can track down the 1N270's as well but will take a week. Think the 1N270's should be put in vs the other ones? Shouldn't hurt the PI-1X4 board?

#12 72 days ago

I tested with the 1N4148 Diodes and it fixed the issue however found this on the PI-1X4 FAQ:

1N270 diodes have a threshold between 0.2 and 0.3V and my boards are made to drive only this type of diode.
Schottky diodes are a perfect replacement, eg. BAT42 BAT43 BAT85..

1N4148 1N4004 1N4007 diode have a threshold between 0.6 and 0.7V. This means that the switch matrix circuitry may not be functioning properly if they are used. it's a problem which is too often overlooked when the original diodes have to be changed.

Going to change them out and see if everything works good.

#13 72 days ago

With low currents, such as in the switch matrix, the threshold voltage is also lower. 1N4148 will probably work but of course the original would be the best choice.

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