Repairing a k7401

[trueno92]

I have no idea what im doing...
It WAS doing this faint clicky thing but it went away after 8-9 seconds.. b+ are still glued down, chassis is pretty mint otherwise... never knew if it worked when i got it... no neck glow..

There is this grey 2 prong comjng off the tube that im guessing is for service.

Anyone gta centric that services these?

[nagamitsu]

Ticking may be electricity grounding/arcing somewhere, broken traces, bad flyback. My G07 monitor has same/similar symptom. Is considered high voltage shutdown.

Tim

[Chazzman]

Chris (Electronic Federation) can likely help you out.

[Gonemad]

The 7400 series can be a pain. I've done one or two of my own in the past. Sounds like something in the HV section. Would do a capkit and possibly has some other failing components. B+ is a pain because of the amount of glue some used to keep it in place. If you have no experience, you are safest to send it out.

[Rickn]

Ok, likely the 2 wires form the tube you spoke of (and I emphasize 2 wires not 4) are coming from the degauss coil that is mounted on the "bell" of the tube. They should be of no consequence to your problem as long as the insulation on the coil has not been exposed and shorted to ground. If a very quiet ticking noise, likely the regulator (Q101) but it may have been taken out by a few caps, or a shorted HOT (again a few caps) hope this helps?

Rick

[trueno92]

Thanks for the warnings, gents. Im taking heed!!

So i see a lot of mention here and elsewhere about cap replacement and im all good with that having experience on vintage solid state receivers.. but i dont have a scope that would measure the resistance over the total circuit. I dont mind replacing them, but i would like to test the tube to make sure its worth my while...

Also i dont have the correct power cord, so i ghetto rigged the plug that looks like DOD (ac power input) with the D Facing down on the flat sides, into a computer power cable, direct to AC power. that should work, but i just dont want to do anything too stupid!

[Electronic Federation]

Cap replacement will most likely not fix that issue. If you don't have alot of experience with that chassis you should really send it in rather than make it alot harder to repair and more expensive.

To effectively troubleshoot that problem you need to isolate the power supply section and put a load on it to see if your issue is in the power supply or deflection circuit.

If your going to attempt the repair yourself shotgun everything, flyback , caps, horizontal output transistor etc. That's your best shot at being successful.

Your welcome to send the boards in for repair. Pm me for more details or if you just need advice.

Thanks

Good luck.

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