Hitachi GMK Pony Mark IV won't power

LWK · Post by **LWK** » September 5th, 2015, 12:24 am

I am finishing up a restoration of a cab I bought dead. I have the power supply kicking, so it plays blind now (woot)

I have this weird issue with the monitor when it is plugged into the machine, it will not power. Here is a video of my issue with the monitor plugged directly in *eek*:

http://youtu.be/31poVygNSvQ

I do not own a blue ring tester, so I cannot diagnose the flyback. Maybe some transistor is blown, any help is appreciated.
I plan to recap the entire thing, but can a issue like this be caused by capacitors? It sounds like its trying to power but some component is preventing it.
Also, in a picture is a arrow pointing to a connector that has no other connector to it. I figure it was a scroll led addition that has no bearing on anything.

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Here are pictures:

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LWK · Post by **LWK** » September 5th, 2015, 12:25 am

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LWK · Post by **LWK** » September 5th, 2015, 12:48 am

Wow, so get this, when I plug the monitor into the cabinet, I get nothing, when I plug the monitor and cabinet AC out into a extension cord together, they work perfectly. Could this entire thing be some grounding issue? Maybe my isolation transformer is wonky? Maybe my cabinets 5v/12 etc switching supply is the problem? I've tried plugging the monitor into my kyotaro cabinet area and got nothing there either. I'm really confused.. I honestly don't know what the hell the issue is. Worst case scenario I just bridge them to a extension cord that exits externally, but I'd prefer not to do that if I can make it stock. Thing is almost at the finishing line and then I can upload a entire video of its restoration! Flyback is fine. Originally it was squealing and then it stopped and just runs fine. Seems intermittent, cap kit?

EDIT; Replugged, it is now back to that squeling sound, a few plug ins and it can work again. Is the flyback toast =/

LWK · Post by **LWK** » September 5th, 2015, 5:52 am

Few more videos. It's working, but it squeals for some time and then when I replug it, it works fine, I can see a picture and everything.... What would cause a issue like this?

https://youtu.be/UZUjkZxLFyo

https://youtu.be/kqxAc55rMUE

sorry my audio sucks, this camera is no good.

Post by **grantspain** » September 5th, 2015, 9:37 am

check for bad solder joints first,caps could cause it so could the flyback

LWK · Post by **LWK** » September 5th, 2015, 10:15 am

I reflowed the entire board, neckboard to, it had the issue before, changed nothing. It has all its original capacitors. Shotgun?

Post by **grantspain** » September 5th, 2015, 12:56 pm

tbh you need to prove where the fault lies,either power section or deflection

you would need to isolate the flyback from circuit and add a dummy load on the b+ line,if it starts every time then issue is most likely flyback

LWK · Post by **LWK** » September 6th, 2015, 5:54 am

so desolder the flyback? where would I hook the light bulb to test? Keep in mind it always powers on when plugged into a wall. And it whines sometimes, but it runs.

Post by **grantspain** » September 6th, 2015, 9:08 am

if you mean you just get a high pitch whistle but always get a picture then its just a noisy linearity coil

LWK · Post by **LWK** » September 6th, 2015, 9:17 am

Flyback has no visible damage either. But I just dont get why when I plug it into the cab plug internally it will not power. Think maybe the caps in the cabs switcher are bad and it's preventing it? I can't see how it'd play blind without it working. Funny enough, the cabs light doesn't work either. Maybe check the switching psu's wires continuity? When I first fired on the PSU, it didn't start at all, it looked fine and after a reflow and cleanig it would. Am I just reawkening the electrolyte in the caps themselves,and its running real half assed? Course, light could just be a bad bulb. No idea. Only makes sense that something is bad in that section.

Post by **grantspain** » September 6th, 2015, 9:58 am

description of the fault is as clear as mud

is the monitor starting up every time you power on?
if no then its probably some caps on the chassis leaky

LWK · Post by **LWK** » September 6th, 2015, 10:56 am

Starts up every time plugged in directly, but when it is plugged in the cab, nothing.

LWK · Post by **LWK** » September 7th, 2015, 2:34 am

https://www.youtube.com/watch?v=wcRf16y ... e=youtu.be

Got it for 250$ delivered dead. I'm a happy dude right now.. The work was intense, and I **** hate the inside of this cab. It's anode cup accessibility is such dog crap, that I mounted the monitor upside down and switched the cable for easier access... I had this issue where the cab would not power at all when plugged into the cab itself, but worked when plugged into a standard outlet. Turned out the plug box had a wire that broke off it, and after running a continuity check, I fixed that to!

Just need to earth it and get a new bulb and work on the control panel a bit more. Having the control panel attach to the front is just idiocy. Also need to adjust the contrast.

Hitachi GMK Pony Mark IV won't power

Hitachi GMK Pony Mark IV won't power

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Re: Hitachi GMK Pony Mark IV won't power

Re: Hitachi GMK Pony Mark IV won't power

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Re: Hitachi GMK Pony Mark IV won't power

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My dead pony mark IV is kicking now