NEC DM-2710 Professional Video Monitor Repair

[Shibby]

Originally Posted by Electronic M

On a linear supply, the AC cord connects to a large 60Hz power transformer the secondaries of which are rectified.

On a switch mode supply, the AC cord connects to a diode bridge and some LARGE capacitors...Then to a switching transistor a small high-frequency transformer and some additional smaller rectification and filtering.

The idea of switch mode is the higher freq the smaller and cheaper the trans, and regulation and protection is built in by design.

Here you go (PWC-3529)
https://i.postimg.cc/ncp41dql/Power.png

[Electronic M]

Originally Posted by Shibby

Here you go (PWC-3529)
https://i.postimg.cc/ncp41dql/Power.png

Thanks, a link to a page that only says "500 Internal Server Error" is just what I always wanted.

[Jon A.]

Originally Posted by Electronic M

Thanks, a link to a page that only says "500 Internal Server Error" is just what I always wanted.

Had I known that I would have gladly given you those I've found.

Seriously though, it'll probably work later on, we just have to wait the bloody things out. I'd like to be able to reach through the screen though and do a hard reset on the server.

[Electronic M]

Originally Posted by Jon A.

Had I known that I would have gladly given you those I've found.

Seriously though, it'll probably work later on, we just have to wait the bloody things out. I'd like to be able to reach through the screen though and do a hard reset on the server.

Snickers, I asked for that didn't I...

[zeno]

This set will have a switching supply.
The flyback ( FBT ) is probably good. Normally they short
& no HV will come up or it will go into overcurrent SD or self destruct.
NEC monitor switchers were a large module very well shielded.
A look inside may turn up more bad electrolytics.
If its marked on the PCB you can look for the HV B+ supply & see if
it goes above spec ( typicaly abt 120 VDC ) before SD.

good luck
Zeno
LFOD !

[Shibby]

Originally Posted by zeno

This set will have a switching supply.
The flyback ( FBT ) is probably good. Normally they short
& no HV will come up or it will go into overcurrent SD or self destruct.
NEC monitor switchers were a large module very well shielded.
A look inside may turn up more bad electrolytics.
If its marked on the PCB you can look for the HV B+ supply & see if
it goes above spec ( typicaly abt 120 VDC ) before SD.

good luck
Zeno
LFOD !

Thanks for that info Zeno. I really do hope that the FBT is still good because apparently this is some kind of top secret experimental government component that doesn't even exist on paper. As you can see from my previous post i'm starting to think I might be in the clear there but only time will tell. Will be on the hunt for more bad components tonight.

I did measure the B+ and from what I saw it was slightly over spec. This is assuming that I was measuring correctly and had the right numbers. It may or may not have been within tolerance though. I don't remember the service manual giving me a +/- tolerance number but I might be misremembering. Either way I intend to repeat my measurements with the variac if needed so I can see how the voltages are behaving before shutdown.

You seem to know a bit about NEC monitors. Do you know anything about this specific model? I cant seem to find a single thing on it and was extremely lucky to find the service manual. Only one site seemed to have it and yes I did have to pay for it. It just seems to be very very uncommon and I'd love to know more about it. If it helps any the guy I got it from took it from a security company that he had worked for when they were throwing it out.