swep1neon

[pinball god]

My neon is dead and need confirmation of likely culprit. I ground the neon return black wire and no glow. Pinrepair tells me its the transformer. I test the voltage and I don't get 12v but 15.3 approx. I found a thread where a person has identical problems but was getting 13.2v. She found when the neon worked it was 12v and when it went over that it was dead. Unfortunately there was no solution on this thread, so I dong know if its still dead or not since 2011. Last time I tested the neon I used a 9v battery and it lit up but haven't tried it since.

What are your thoughts as I have replaced a transformer once already, switched driver pcb's with short term success. The good thing is the neon is no longer intermittent, but dead for a long time now. Or is it a chop on the driver pcb? I'm stumped.

[Retropin]

Neon units themselves last many many years unless they get broken or are very badly made and the process or removing contaminates hasn't been done correctly. The small little 12V transformers don't last nearly as long unfortunately.. but again, its dependant on manufacture.. some are better than others.. why don't you put another 12V across the input to test the transformer?
A simple visual test on the tube will give a good indication if its working or not.. any yellow/ brown staining up the inside of the tube is a sign of contaminates.. or any loss of the phosphor powder is a sign of a broken tube and subsequent loss of vacuum

[Retropin]

Just picked up on this:... The good thing is the neon is no longer intermittent

Intermittent is either transformer or supply fault... put 12V across it and find out

[pinball god]

Sorry guys misinformation. I grounded the neon and it fires up. So what does that mean?

[pinball god]

Did continuity from the socket (brn/wht) ground wire near neon to the plug end that goes to the driver pcb and it buzzes out for connection. So I reckon no broken ground wire. Does getting 15v plus on a 12v line be a concern?

[pinsanity]

neon is good - check
transformer works - check
neon fires when grounded so not a continuity/grounding problem - check.



Then the problem most likely lies upstream on the board - specifically the 2 chips that regulate the light saber.

Main culprit - ULN2803A at U35 on the power driver board
Accomplice - 74HCT574 at U34 on same.

[pinball god]

neon is good - check
transformer works - check
neon fires when grounded so not a continuity/grounding problem - check.



Then the problem most likely lies upstream on the board - specifically the 2 chips that regulate the light saber.

Main culprit - ULN2803A at U35 on the power driver board
Accomplice - 74HCT574 at U34 on same.

bugger. BTW is there any way of testing these chips or is it just a matter of replace and see if one or both fix the problem? Also is there a common reason why these go that must be addressed or I'll just keep blowing these guys? Thanks

[pinsanity]

Ideally with a logic probe.



Having said that, whenever I have had a neon problem on either CV or SW and I have eliminated all other components, 99% of the time it has been the ULN. I usually don't even bother to test the existing one just replace it with a socketed version - chances are the board has/is being shorted somewhere, that is the main reason for a failed ULN.

[pinball god]

Ideally with a logic probe.



Having said that, whenever I have had a neon problem on either CV or SW and I have eliminated all other components, 99% of the time it has been the ULN. I usually don't even bother to test the existing one just replace it with a socketed version - chances are the board has/is being shorted somewhere, that is the main reason for a failed ULN.

I was afraid you'd say that. The short, would it only be attributed to the neon circuit or any short what so ever. The latter will kill me.