K7000 P447 is this veritical collapse?
- Thread starter boy141
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boy141
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Tested
didn't get a chance to buy parts for the lightbulb test. something to do tomorrow between meetings .
Pins on the yoke header pinpads test fine using continuity. Followed green and yellow wires to other side of the board. did continuity test - works.
didn't get a chance to buy parts for the lightbulb test. something to do tomorrow between meetings .
mecha
Well-known member
what's a light bulb test going to achieve? it's a linear power supply, you have B+ voltage. if you have 170V on the regulated B+ side probably means the deflection section isn't connected to it, the power supply is unloaded. if you barbecued the D18 pads you need to fix them. is D18 connected to the first yoke header pin where the red wire would normally go?
what solder are you using? I've seen it many times before, it smells like it has charcoal compound. lol
what solder are you using? I've seen it many times before, it smells like it has charcoal compound. lol
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You look like you missed a part.
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I think those are the yoke header pins, I thought the same thing when I first saw it lol.
@boy141 When you say: "D18 black band is facing away from the metal heatsink." does that mean the black band is closer to the "middle" of the board, or closer to the outside edge? Just to clarify.
D18's solder pads look ok to me. Just an FYI, diodes short not go open.
It sounds like the flyback is not energizing at all. So yeah it would be nice to be able to test a flyback, and you can use a ring test, but that requires a special piece of equipment.
So, this could be a couple things:
- Flyback is bad (this is very suspect because of the issue you had before, the original white knob flyback is installed, and ya if it's cracked it's on it's way out. If you have another flyback this would probably be a quick easy cheap test).
- Flyback is not receiving reference voltage because of:
- Xray protection pot. It's right underneath (in your pic) the green and yellow wires by the vertical IC heatsink. If this got bumped, broken or something it would shutdown the monitor and give the symptom you are having.
- A lost connection from your B+ supply to the flyback primary.
- Test the b+ pot, probably by removing it out of circuit, trying to remove the glue if I could. If I couldn't, I'd be replacing it.
- I have extra k7000 flybacks, so I would just substitute a new one and re-test.
- Check for missing connections on the b+ rail to the flyback primary.
mecha
Well-known member
for all the doom and gloom about white knob flybacks, which I'll echo once more is just something perpetuated by people that literally sell flybacks, there's a metric shit ton of these in actual arcades still operating in that condition. not people's basements or bathrooms, but in commercial settings where they were intended to operate for many hours a day.
also K7000s have fixed voltage regulators, there is no B+ adjustment. that's the shutdown pot. while it may be true it could've gone bad, this monitor was actually running before it got monkeyed with about 8 times too many.
while it's true the K7000 is like the Chevy 350 smallblock of monitors, they do require a fair amount of work to make right.
I just subscribed to the mecha2001 youtube channel. Unlike mecha, mecha2001 knows what he's doing.
mecha
Well-known member
mecha is a terrible person. people say he's mean.
He's not mean, he just doles out heaping servings of tough love. It's what's made me the man I am today.
I still replace cracked flybacks though.
boy141
Member
We are back. I really remember why I hate working on chassis. Less of a headache to swap out.
I replaced the flyback with one from arcadepartsandrepair. The B+ still reads 170v.
I unsolder D10, and the tube does NOT come on.
Solder D10 back in circuit.
Measured cathode side of D12 - .002-.007 volts DC.
Going to go through the same checklist and see what i miss.
Anymore ideas?
I replaced the flyback with one from arcadepartsandrepair. The B+ still reads 170v.
I unsolder D10, and the tube does NOT come on.
Solder D10 back in circuit.
Measured cathode side of D12 - .002-.007 volts DC.
Going to go through the same checklist and see what i miss.
Anymore ideas?
I would do morph/Mike's lightbulb test to see if you are getting something other than 170v on the regulated side. Just to make sure your regulator isn't damaged. I just had mine fail in a way that it would test fine out of circuit with my meter. Pins 1 and 4 were not testing short, and the rest tested just fine. I replaced the regulator because everything else was testing good and that solved the problem. I put the suspect regulator back in and the high voltage would not turn on. It was probably triggering the X-ray protection.
As far as I know, and that's not saying much, since the heater voltage comes from the flyback and the X-ray protection is being triggered then you won't get heater voltage and, therefore, no neck glow.
If you have a spare regulator I would just toss it in. If you don't, then isolate the high voltage section and put a load on the regulated B+ to see if it will hold at 123v.
As far as I know, and that's not saying much, since the heater voltage comes from the flyback and the X-ray protection is being triggered then you won't get heater voltage and, therefore, no neck glow.
If you have a spare regulator I would just toss it in. If you don't, then isolate the high voltage section and put a load on the regulated B+ to see if it will hold at 123v.
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