Ceronix 1793 Cuts Out after a few minutes

[jay]

Clean the edge connectors on your 3902 board. Thats likely a physical problem.

[Justin]

It doesn't have an edge connector. They are normal pin socket connectors.

[Chris-socal]

You can check all that because you need to know that the connections are good but I still say things aren't resolved on all the traces and PRA boards. If you have a color out or bad connection it will make all kinds of noise and make all colors mess up. Because the auto-bias is trying to correct there is all kinds of stuff taking place...which isn't good.  You have made good progress and the fact that you now have an image proves my original point...it's traces or solder joints.

On the PRA boards themselves there can be bad connections where the pins connect to the traces on the board. When this happens you need to scrape the coating off the board until you see silver and run a solder bridge, it's hard to do because the plating on the board is a different metal than the pins so the pins soak up all the heat. Picture attached of a PRA schematic.  I highlighted a few examples of the area I'm talking about ....not these pins specifically but the contact point. Every time the PRA is bumped or removed there is risk of a pin losing contact and it will drive you insane. That's what happened to me. LOL

Also, I was looking at the picture of your remote board, are those pots tight or are some of them loose?  These monitors do NOT like pots with bad contacts. Bad contacts on the pots are as bad as problems with traces. Ceronix monitors don't like trace or contact problems. It drives auto-bias crazy.

Traces on certain generations of Ceronix monitors are horrible. They might look good... Member Badbuad can attest to the amount of time spent trying to fix traces only to give up and swap in a new/used board. These boards don't generate a lot of heat so they don't show age like other boards do.

Chris

[Justin]

I'm beginning to figure that out about traces. I just hand wired all the traces on the blue PRA with 38awg enameled copper wire and a microscope. I was so excited to put it in and see blue come up too but now I have no picture again. But at least the screen isn't all blue or all red, right.

I still hear the popping/arcing in the back but I can't for the life of me figure out what it is.

Any ideas on why I would suddenly lose all video out?

[Justin]

Couple more things to add sorry:

When I shut off the monitor I can now see blue in the flash as it powers off. I'm hoping this is good.

The pots are pretty loose. Some are looser some are tighter.

I remembered you asked if I added solder to the yoke connector. I avoided that because I tried to reflow one of the degaussing coil pins and the thing fell right out of the board and it was a PITA to get back in

[Justin]

I'm sorry, I don't like putting these posts in a row but I have something to add:

I just adjusted the G2 voltage back up to manual spec (290V) and I get a guess which color now screen... It's Green. This monitor is playing with me.

I guess I will look at the green PRA now.

[Chris-socal]

Don’t go all extreme, check the traces with a meter and look closely. Replace those that are questionable. My point was not to dismiss solder joints and traces when working on a Ceronix.
I wouldn’t re-wire everything.
Its possibly a transistor on one of the colors.
Clearly you are working in the right area.
You might want to ask one of our supporting stores if they have a 1793 neck board.

Chris

[Justin]

I was looking for a neck board but I'm not sure where I could even find one. The screen is now blue again and it's hitting the fault shutdown again. Back to the beginning. I did however catch a small whisp of smoke from the blue side of the neck board but nothing looks burnt. I'm about ready to throw on the towel and try sending it to Alan. I sent him an email to see if he had any tips for me but haven received a response yet.

[Chris-socal]

Im sure K-Lar or Midwest slots will have a neckboard. But yes, sending in a board that is this complex is probably a good idea.
You leaned a lot about it, which is great.

I believe you have an SVGA….it looks like it has 7 video input pins, am I correct?
I have seen both variations, I know they both use a 7 pin housing but one of them uses all 7 pins and the other has an empty 7th position.
I don’t know if a vga board will work in an SVGA machine. Hmmm.

Chris

[Justin]

The schematics called it a VGA that why I thought it was, I could be wrong. It says CPA4243.

Really disappointed that I couldn't get it going. My thought is if I can get a neck board I'll try swapping that, if/when that doesn't work I will see if I can send it to Alan at KLar unless there is someone closer to me.

I emailed Alan to ask for pricing.

Do you know of any vendor specifically that I could get a neck board from?

[Chris-socal]

No one stocks parts like this except shops that support older equipment. Many shops quit supporting CRT altogether.
K-Lar or Midwest slots is best bet. Go to the home page of NLG and send a message to every supporting vendor.

Are you sending email to klar.slotrepair@gmail.com ?

I might have one in storage, I will look this weekend.

Chris

[Justin]

That would be amazing! Thank you, I'll look to see how many pins are populated in the connector.

[Justin]

Its been a while, but I have an update and a new issue:

I have got all the colors back!

Unfortunately it cannot be that easy. Now I have lost sync. Looks mostly like I lost Horizontal sync, but I'm not sure. I will upload the videos to google drive and attach a link.

If anyone knows where to look it would be greatly appreciated. I doubt I blew an IC as it was working prior to fixing the blue channel. It displayed in just red and green.

https://drive.google.com/drive/folders/1brAlgNoaYqjOKYGnH6OyS7Vr4m0fpm0O?usp=drive_link


From Moderator: I'm adding screenshots from videos 1 and 2 in case the Google drive link goes away at some point in time.   

[Justin]

 

Finally. Bad solder joints on the H PRA. Now on to troubleshooting the sound on the IGame board

[jay]

Very nice.

You should put the old caps in to see where the original problem was (kidding).

[Chris-socal]

Oh you got it!
What did I tell you…solder joint, solder pad, trace.
Repeat, solder joint, solder pad, trace
Repeat!

Did you finally succumb to using a magnifier?

[Justin]

I had the microscope out!

Ok so it's mostly fixed. It works fine, but the horizontal width does not take up the full screen at max. It also sometimes will make 1 single snap noise (arc) and the screen gets dim then comes back up working fine. I can never see where the arc is but I don't think it's the flyback because it's just 1 spark

[jay]

You could always stuff bits of flash paper through out the board.
When it arcs you should see a puff of smoke and maybe a bit of fire so you can easily locate it......

Yes.... You can start the start the petition at anytime to have me thrown off the forum     

On a serious note - it could still be a capacitor popping. I have had that before, generally too much current for it.
Given that you just ran a cap kit through it - my suspicion would be a cold solder joint.

[Justin]

It's just weird because it recovers on its own. I don't even have to reboot it.

[Chris-socal]

I think you completed a cap kit, right Justin? On a Ceronix board this symptom isn't really a symptom of bad capacitor, it would have to be out of circuit or so far out of tolerance it reads like a resistor.

Here is my long-winded list of things to check.

1. The Green ground wire that goes to the neck board. Look really closely at the pin and solder joint on the board. Inspect the green wire for a break in the insulation. It gets brittle and can crack. Put shrink tubing on it if you find a crack. That wire is not high voltage.
2. This can still be a solder issue on one of the PRA boards. That neck board has a LOT going on. If there is a variable joint, some of those leads shut the board off if they don't have continuity.
3. Take a look at the neck wires where they connect to the yoke board. You might have to remove the plastic cover. Some of those have caps or resistors under the white cap. Look closely at the solder joints where those yoke wires connect. Sometimes one of those thin wires is hanging on by a thread.
4. I hate to say this because it's a bad problem, but there is another member who is dealing with a very similar issue on his 1492 and I originally proposed that if a cap kit and solder flow doesn't solve it, it could be the yoke windings. He has done all kinds of work and behind the scenes he has since told me he thinks it might be the yoke windings after all. He found a dark spot.  If you look real closely at them sometimes they burn through and start arching, it will be a dark spot in the windings. You have very few options to fix this, you might get lucky and be able to lift the burned winding and slip a piece of insulating material under it...but when there is one there is two. They are usually real tight so you can even try the last ditch option of breaking the write, put an insulation pad down, then insert a jumper in the break. I'm just saying this in case it is the yoke windings. You are describing this problem exactly.
5. Hasn't this board done this from the beginning?  It really could be the flyback. Inspect the wires going to 2nd anode and to the neck board look really closely. When the flybacks arch they sometimes jump to the frame or to a heat sink close by just for a moment, then recover. A lot of flybacks that leak still work. They just occasionally arc. Be careful, when Ceronix flybacks arc they arc good! Right through your hand to whatever is on the other side. Keep one hand behind your back. It hurts if it goes through your fingers but you are touching the chassis with your other hand, it's a whole other thing. 
6.  Pull the cover off the neck board socket and make sure the solder joints are good where the wires press in. I bolded neck board because I want to be sure you know I'm not saying Yoke board again. Two different things.

Chris