Monitor acts like it shuts off and on real quick?

[modessitt]

I've circled the most common areas for bad solder on the K7000. The small circle in the middle is probably the biggest culprit. If any pad moves even the tiniest amount when reflowing, then assume that it is no longer connected to the trace, and use either a clipped component leg or piece of insulated wire to connect it to the next point on the trace:

 

[KevinMullins]

Since your symptom looks like a vertical deflection/collapse problem I added a couple spots to check the solder joints on.

The vertical IC and the yoke header pins.

 

[Ohmerone]

What about voltages
you can learn alot more about whats happening in the circuit.
Try dividing the Power supply from the Hv circuit..

I pulled a chassis that had no flyback or HOT and pluged it in
and monitored the voltages.
I was able to measure B+ voltages and drive signals from the Ic
to the vertical and horz-drive signal to the base of the HOT
My B+ was around 150 on both sides of the resistor??
I added the bulb to output side of the resistor and the voltage
drop to 129.3 so you can troubleshoot the regulator on it own.

I did have a case where i had shutdown and i added the bulb
to the output of the VR, my voltages was 150 and and only dropped to 140
so i replaced the VR. and the voltage dropped to 130.vs
the inside pins of the VR measured Low ohms.
Here are some pictures to get an idea of what i mean..

 

[vicjw66]

Don't overlook the possibility that the power supply is faulty.

 

[ArcadEd]

I didn't realize there were more posts in this thread, sorry about that.

I still have the issue and here is what I have done.

Gone over the entire pcb several times sucking solder checking and putting new solder on bad area.

Cap Kit

New Fly Back

New resistors at 91, 92 and 93

Replaced IC3

The problem seems more spread out now, but still there.

Now when you say check power supply, you mean my switcher could be causing the issue? I didn't even think it could be that. I will swap that out asap.

Ed

 

[ArcadEd]

Well, changed power supplies (switcher) with no effect. Same issue.

I put it on the rejuventator just to check for leakage and do a clean and it seemed to make it better, but the problem is still there so I don't really know. It's so random.

It seemed to happen less frequently when I adjusted all of the color controls down and set them each at 1/2 a turn. But again, I have no idea if it helped or not.

Maybe I should start getting ready to ship the chassis to someone to look at.

 

[cadillacman]

youve gone too far to give up now..

dont know if it pertains or not but unsolder r101 check it, check the traces, then reinstall it. ( cant remember if thos ends up on the horiz or the vert on this monitor)
but like i said unsolder AND CHECK THE TRACE UNCERNEATH of r101. R101 and other components in that same area tend to cook bad. SOmetimes r101 solder will look fine, but once you unsolder it, you find the trace underneath has tarnished completly black.

but worth a check man.

Have you measured the b+ on the monitor yet? I doubt its an issue, but should be checked before you go too much further.

if you give up, mod, myself, chad at arcade cup, or mabye even chris25810 would probhably tacke it.

 

[jay]

The power supply (DC) has nothing to do with the monitor.

 

[ArcadEd]

The power supply (DC) has nothing to do with the monitor.

Yeah I know, I was curious if it was causing the pcb to flip out. Going for everything here .

I will check r101. I know I unsoldered most of the board, including 101 to check. Not sure if I replaced 101 or not, I will have look at the chassis again.

 

[vicjw66]

The power supply (DC) has nothing to do with the monitor.

????

Well the WGK7501 in my Gauntlet Dark Legacy sure feels differently. I couldn't figure out why the monitor kept shutting off randomly. Nothing I did to the monitor would fix the problem until I changed out the original switching power supply. Now it works fine.

 

[THE COUNT]

????

Well the WGK7501 in my Gauntlet Dark Legacy sure feels differently. I couldn't figure out why the monitor kept shutting off randomly. Nothing I did to the monitor would fix the problem until I changed out the original switching power supply. Now it works fine.

The OP's chassis is powered from the power cord through an isolation transformer. If a power supply was causing a monitor issue, it would be because the game PCB wasn't getting the proper power and therfore not making the correct outputs to the monitor.

 

[ArcadEd]

My R101 reads at 6.34k. It is removed from the pcb.

Is that correct?

 

[cadillacman]

6.8k 5% and i think 3 watt

6.2k is a little low( common on those as they age, resistance gets lower and lower runs hotter and hotter) might cause issues later on but that aint your issue i dont think anyways

how do the traces/solder pads look?any cracks or black tarnished traces?

 

[ArcadEd]

No, I have gone over it all a few dozen times, nothing is jumping out at me.

Here is another picture. If anything jumps out, let me know.

Here is a higher res picture
http://www.arcadeinabox.com/stuff/70001.jpg

 

[Buffett]

the solder joints for r101 look like they need redone and you do have r101 there it looks like its missing from the bottom pic. also all the traces-pads by ic3 look to be bad or missing check them for continuity. and run some jumpers to make shure.

Peace
Buffett

 

[ArcadEd]

Yeah, I still had my r101 removed for testing when I took the picture.

The IC3 solders are all new, and look bad in the picture. I went ahead and tested for continuity as well, all checks out ok.

 

[ArcadEd]

I am going to measure voltage on Pin 6 of IC3 and see if there is any change when it collapses.

 

[ArcadEd]

OK, as suggested I monitored voltage on Pin 6 of IC3.

It's steady at about 53.9v. When the monitor collapses I see it spike to 54.9-55.5.

Does that help at all?

Thanks.

 

[THE COUNT]

That is 2x what it should be. It should be around 24volts. Isn't that 24v supplied by the flyback????

 

[ArcadEd]

Now I tested this AC, should this be tested at DC voltage?