EagleTG
Active member
How does anyone work on these things? Every time I touch one, things go badly. These chassis are the devil, Bobby Boucher. THE... DEVIL...
Flash back a few months. Trying to get a resistor on a K7000 chassis (Medium res, Super Sprint) to stop desoldering itself. Give up, swap another K7000 chassis into the cabinet. (Click here for link to thread of dispair.)
New chassis was working like a champ. Started showing signs of flyback failure (cracks in the flyback, white knobs, would lose focus as it heated up). (Link to me being here recently on another monitor.)
Order new flyback, install it. Check all the caps while it's out, looks like it's been recently capped, nothing shows bad on ESR. Decide to rejuve it while it's out of the cabinet.
Back in the cabinet, B+ is reading ~160v. I go over the board (been there a thousand times), find a bunch more bad solder/traces. Replace traces/reflow solder. Same situation. Repeat at least 6 times.
Following the flowchart, remove D10. Monitor comes up with image. Tube must still be good, right? I didn't kill it on the rejuve. (Which in hindsight, should have been done as a separate step. I should have confirmed the monitor was working post flyback replacement first. I know for next time.)
Re-attach D10, replace C57 (it was testing marginal anyway). Find a few more (@&#^$%@) bad solder connections. Been jumpering them as I go, thought I had them all resolved.
Caps next to HV shutdown pot test very good on ESR, have been recently replaced anyway.
I swapped in another (known good) voltage regulator as that's the next step in the flowchart. Still does the same thing.
At this point, I've been over the chassis solder and traces with a fine toothed comb, I don't suspect any additional problems (but who really knows with these chassis). Yet, this thing is STILL in HV shutdown. Still reading ~160v on the resistor, still powers up when D10 is disconnected.
My question is, can a potentially defective new Flyback cause HV Shutdown? Looking at the schematic, I'd believe it could. Any suggestions on what else to try at this point? I kept the old fuzzy flyback for the possibility of throwing it back in to see what happens. I've read a few things about bad flybacks right out of the box, this one was from ArcadeCup (obviously a trusted flyback source).
And I've reviewed the sticky on K7000's repeatedly, but maybe I missed something.
Thanks in advance for any help on this one. If it's not obvious, I'm beginning to really, really hate the older K7000 monitors. They make the quirky connectors on the K4600 seem like child's play. (And with that, for some reason the K4600 is still one of my favorite monitors to work on... not sure why.)
Flash back a few months. Trying to get a resistor on a K7000 chassis (Medium res, Super Sprint) to stop desoldering itself. Give up, swap another K7000 chassis into the cabinet. (Click here for link to thread of dispair.)
New chassis was working like a champ. Started showing signs of flyback failure (cracks in the flyback, white knobs, would lose focus as it heated up). (Link to me being here recently on another monitor.)
Order new flyback, install it. Check all the caps while it's out, looks like it's been recently capped, nothing shows bad on ESR. Decide to rejuve it while it's out of the cabinet.
Back in the cabinet, B+ is reading ~160v. I go over the board (been there a thousand times), find a bunch more bad solder/traces. Replace traces/reflow solder. Same situation. Repeat at least 6 times.
Following the flowchart, remove D10. Monitor comes up with image. Tube must still be good, right? I didn't kill it on the rejuve. (Which in hindsight, should have been done as a separate step. I should have confirmed the monitor was working post flyback replacement first. I know for next time.)
Re-attach D10, replace C57 (it was testing marginal anyway). Find a few more (@&#^$%@) bad solder connections. Been jumpering them as I go, thought I had them all resolved.
Caps next to HV shutdown pot test very good on ESR, have been recently replaced anyway.
I swapped in another (known good) voltage regulator as that's the next step in the flowchart. Still does the same thing.
At this point, I've been over the chassis solder and traces with a fine toothed comb, I don't suspect any additional problems (but who really knows with these chassis). Yet, this thing is STILL in HV shutdown. Still reading ~160v on the resistor, still powers up when D10 is disconnected.
My question is, can a potentially defective new Flyback cause HV Shutdown? Looking at the schematic, I'd believe it could. Any suggestions on what else to try at this point? I kept the old fuzzy flyback for the possibility of throwing it back in to see what happens. I've read a few things about bad flybacks right out of the box, this one was from ArcadeCup (obviously a trusted flyback source).
And I've reviewed the sticky on K7000's repeatedly, but maybe I missed something.
Thanks in advance for any help on this one. If it's not obvious, I'm beginning to really, really hate the older K7000 monitors. They make the quirky connectors on the K4600 seem like child's play. (And with that, for some reason the K4600 is still one of my favorite monitors to work on... not sure why.)
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