Another Ceronix 1492 problem...

[bs27r1b]

Hello,

New here but not a complete Newbie to this kind of thing.  I have been in the vintage arcade hobby for several years and now there are some gaming machines leaking into my collection.  I got a draw poker machine with a "non-responsive" Ceronix 1492 monitor.  I re-capped it and boom it worked great!........ for about 10 minutes...  then it lost its marbles and was flickering, rolling, the screen was split horizontally and then it deteriorated to just a bright blue horizontal line.  I was almost proud of myself for a minute there!  for the 10 minutes of joy it looked great, nice and crisp and colorful.  Anybody have a good guess and where to start?  Thanks in advance for any info anyone might offer.

[Chris-socal]

Hey there,

The first thing I would look at is the Vertical IC. Using diode check,  Put negative probe on pin 1. Now put red to each of the other pins. You should get diode or slight continuity but none of the pins should short to pin 1 or ground. This doesn’t prove it works, it just identifies shorts.

I don’t have a lot of experience with Vertical collapse on these but I would also verify all caps are polarity correct. It can happen to the best of us.

If you don’t find anything there check the HOT. middle pin negative, outer pins should check like diodes.

Check voltage regulator. Doing a diode check doesn’t prove anything unless its shorted. They can pass this test fine but not work. The best test is to put a meter on it when powered on.

If there is a line Im pretty sure the flyback is working.I assume when you powered it on it was in the game so it was isolated. You didn’t plug it into line voltage did you?

Let us know what you find on these first checks.


Chris

[bs27r1b]

Thanks for the reply..   Yes it is in the game while testing.  I will check those points out this weekend.   If there was a cap polarity problem would it have worked perfectly for the first 10 minutes?   Now that I think about it it didn't fall apart until it was power cycled once. 

[Chris-socal]

That depends on the cap and the day of the week. Some caps will flat out explode, some might function for awhile until they die internally. Do you have a capacitor tester? Personally I would replace the cap but if I didn't have a spare and it tested o.k. I would use it.

There is a 10uf cap on the PRA-H board, its a surface mount cap, if you have an ESR tester you might be able to determine if that one is shorted without removing it. You can replace it with a regular cap if necessary, it looks funny but it works (Pic attached, see red arrow in middle of pic). If you can take a clear picture if the board from above I can look to see if anything looks abnormal. These boards have the + printed on the top side so you can pretty easily spot a backwards cap.

Chris

[bs27r1b]

Checked my polarity on the replaced caps.. all good.  from what I can tell from the schematic the IC you are referring to is the LA7851 chip right next to that board you pointed out in your recent pic.  Here are the readings i got with a diode check with my black probe on pin 1........

[Chris-socal]

I don't see anything indicating a short so it could be good. It could be bad but not shorted too.
 
Check the voltage regulator and MPSA64 in the color board section. pics attached. Same thing, it doesn't really matter what the readings are as long as they aren't dead short. We are only trying to spot the obviously dead.
If you look in the NLG File System there is a troubleshooting log, I don't recall if it has Vertical Collapse but it might be worth taking a look.

Chris

[Chris-socal]

Wait, no you are looking at LA7851, that's not the vertical IC. The vertical IC is in the middle of the board, 8 pins in one row. LA7830.

[bs27r1b]

Well here is a crazy update....  I fired it up and got the bright blue horizontal line and then my phone rang.   While I was on a 10 minute work call I watched it come back to life in the exact opposite order it died!   first some flickering, then some rolling with a split screen and then it settled down and looks good...  Weird.....

[Chris-socal]

It looks like the flyback is turned up too much.
Lower knob on tne flyback.
Did it have white lines when you first powered it on?

The FB could be dying too.

Chris

[bs27r1b]

No white lines,  that picture doesnt really do it justice.  In person it is really crisp and clear with good color.  it is hard to take a picture of the screen, I get a black vertical bar through the pic if I try and take it straight on.   For me it is more about the challenge of the repair then the game itself so I have been racking my brain trying to think of what component would behave that way   

[Chris-socal]

If it does this every time something isn’t right.
Do you have another 1492 you can connect to the game to verify its a monitor problem?

When I take pictures and I cannot get the camera out of sync I film a few seconds of video, then I do a screen capture of that.

There aren’t many components that wear out, they are typically working or not.
The flyback is definitely suspect.
Look real close at the solder joints for the yoke connector pins, if those crack they can cause flickering, loss of video, etc.
there might be a resistor out of spec.

Chris