K7500 help needed

OU Flight

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Working on a Golden Tee Fore 2005 with a K7500. Game plays blind with no picture and no neck glow. When powered on I can hear the static from the tube like it is trying to power up.

Is there a flow chart to work this threw? I've got the WG manual pulled up, but still a novice at monitor repair.

I went to check the B+ voltage and it measured slightly above 0. Don't know what it was because I got distracted by the burning smell and saw R301 glowing red hot.

Where should I start on this one?

Thanks,
Joe
 
Pull the chassis, replace the caps, test the HOT, VR, U601, R303, D302, inspect the flyback and all pots, look for cold solder - then try again.

And make sure the game is set for med-res...
 
Thanks, couple of questions:

Which cap kit should I order from Bob, the Combo kit or the Alternate kit?

The monitor was working, so I'm pretty sure it is set for medium res. How do I check? couldn't find that in the WG manual.

Im assuming the VR is a voltage regulator. Where is this one at?

Thanks
 
The cap kit should be the K7500 kit. I think bob combines the kits for those 4 models. Not sure what the alternate one is.

The res is changed on the GT PCB via dip switch.

It's the transistor mounted on the metal wall right next to the filter cap...
 
Thank you for your help Modessitt. I really appreciate it.

Like I said I am a complete novice with this and am trying to figure this out.

PCB is set correctly for Med Res.

Not sure how to test some of these items that you directed me to.

I tried looking it up on here and google, but just having a hard time figuring out how to test the HOT and VR.
No idea on how to check U601.

I ordered Bob's cap kit today and these parts so they would be here if I need them. He did not have any 1.2 OHM 5% 2W MF resistors though. Can I replace these with a similar resistor or do I need to find the exact ones?

Thanks for your help.
 
Tell me if I am doing this correctly. Testing the HOT, multimeter in diode mode, one lead in the top of resistor where the screw is and then check the 3 legs with the other. Looking at the transistor, the left leg and center leg both show resistance and the leg on the right beeps shorted. Is the HOT good or bad?

Thanks
 
Just discovered that about half of the components on the board show shorted when looking around with the meter. What is the best way to trace down a short and is there a particular component that may have failed and caused that shorted circut?
 
Tell me if I am doing this correctly. Testing the HOT, multimeter in diode mode, one lead in the top of resistor where the screw is and then check the 3 legs with the other. Looking at the transistor, the left leg and center leg both show resistance and the leg on the right beeps shorted. Is the HOT good or bad?

Thanks

Put the black lead on the center leg. Put the red lead on each of the outer legs. If it beeps or is close to zero on either, replace it (with an insulator if necessary). If you get something between .400-.700 on both, then it is good.

Just discovered that about half of the components on the board show shorted when looking around with the meter. What is the best way to trace down a short and is there a particular component that may have failed and caused that shorted circut?

You have to make sure the parts you are checking aren't low resistance (anything under 10 ohms can cause a beep), something that measure as a short normally (coil, inductor, transformer), or you aren't getting a false reading through another part (pull the part and check again).

The easiest way to track down where the short is on a pcb is to remove the part you get the short reading on (after making sure it isn't shorted) then use the schematic or follow the traces to find all the parts that connect one side to the other side of the part you get the short reading on (you should still measure a short on the empty holes). Then start pulling one leg of each part on those traces until the short reading goes away, testing after each removal. Once you find where the short reading is coming from, check that branch of the trace until you find why you get a short reading (shorted part, transformer in circuit, low-resistance part, etc)...
 
Thanks. That explains the shorts I was finding. They were all resistors. I'll get this down eventually. Thanks for walking me through.
 
Just finished the cap kit. Out of the entire kit only about 6 caps on the board showed good when I checked them with the ESR. It amazes me that this monitor was working at all before it went out. I had one or two caps that didn't match up on values and I didn't replace because I wasn't sure if they were compatable. I'll get the numbers tomorrow.

I now have some life to the monitor. It has a vertical collapse. Just a line running horizontally across the screen.

Where should it go with this one now? Any parts in particular that cause this? I still have the D302 and U601 that I got from Bob but not installed yet.
 
Changed R120, R303, D302, and U601 and now it is completely dead. No more horizontal line or really any sign of life. Game plays blind and votage is reading 120v AC at the plug on the chassis.

Looking at the WG repair guide for No Power-Dead:
Q101, Q704, D101, D102, D104, R880, and R120 test good.

I do not know how to test U101, T701, T700, and U701.

I couldn't find Q703 on the board. Have to go back and look again.

R104 is a 10K and is reading 13.2K. Do you think that one would cause the total shutdown?


Here are the votages at the test points:
TP103: 1
TP104: -33
TP105: -1
TP106: 1
TP200: 0.83
TP201: 0
TP202: 23
TP203: 0
TP205: 0

Any sugestions? Thanks,
Joe
 
TP202 (B+) is the important one. It's too low. Check that C107 and C155 are oriented properly, and that none of the pads are wiggling with the part. Then check R100 for proper value and good pad/trace connection.

You can always get a couple alligator clips and attach them to a lamp plug, with one connected to ground (heatsink of U601) and the other to TP202. Turn the lamp on, then power up the chassis. If the lamp lights, and your B+ is about +117-118, then your PS section is good and the problem is with the load (deflection circuit)...
 
Ok, I think I'm throwing in the towel on this one. Modessitt, are you taking on any new projects or anyone know how the best place to send it to is?

Joe
 
Ok, I think I'm throwing in the towel on this one. Modessitt, are you taking on any new projects or anyone know how the best place to send it to is?

Joe

If Mod doesn't want to do it you can always send it to WG for repair.
 
Just an update. After letting this monitor get the best of me I finally broke down and sent it off to Wells Gardner. They charge a flat rate of $100 and did an excellent job. Now I have a nice clean completely working board. Headache over.
 
Just an update. After letting this monitor get the best of me I finally broke down and sent it off to Wells Gardner. They charge a flat rate of $100 and did an excellent job. Now I have a nice clean completely working board. Headache over.

I wish I'd done that with mine. I spent far more and essentially ended up with a monitor that I had to junk.
 
I wish I'd done that with mine. I spent far more and essentially ended up with a monitor that I had to junk.

I know. I wish I had done it from the start. I spent about $20 in a cap kit and some misc parts, no luck. Bought a chassis off here for $50 in hopes of replacing this one. Didn't work. Then figure in hours upon hours messing with it.

I still want to learn more about fixing them, because I love fixing things myself.
 
Just an update. After letting this monitor get the best of me I finally broke down and sent it off to Wells Gardner. They charge a flat rate of $100 and did an excellent job. Now I have a nice clean completely working board. Headache over.

How did you go about contacting them for repair? I have a k7500 that is dead and I know nothing about repairing them. A local op will do it for $100 but if its the same price to send it off to WG, i'll probably go that route instead. I looked on their site quickly but didn't see anything about repair service other than warranty service.
 
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