Did I Just Blow My Monitor?

[Mario]

I have a 25K7191 powered thru an isolation transformer, which is connected to a power strip. It was all working fine with my PC (via an ArcadeVGA).

Today, I touched the monitor's metal harness and felt a shock. Worried about improper grounding, I cut open an extension cord and wired the monitor's harness to the ground wire of the extension cord, and then plugged this into the same power strip. When I turned on the monitor, I heard the buzz that told me that the monitor turned on, but then heard nothing. I don't see any glow, and I get no picture.

I confirmed that I still have power going to the monitor by checking the transformer's output. I noticed a fuse on the monitor chassis, and it looks OK. With subsequent tries, I still hear a slight buzz from the monitor, but then nothing (as before).

Any ideas? Thanks.

Mario

[Mario]

 

Oh, no!!!

I just plugged it in again, heard the monitor power up, and then heard sizzling and a loud POP!

Now I'm sure it's blown. What do I do next?

 

I should add that this happened with the monitor NOT grounded to the power strip as I had tried in my first post above.

Mario

[Harry Potter]

My monitor did the same thing a while back. I was told it was a flyback going to heaven.

[grantspain]

Very strange for something like that to happen,connecting your chassis frame to earth should not do that-the only way that could happen is if a componant(leg or case) is shorting against the metal frame,obviously before you connect an earth there wont be a problem apart from the electric shock but when you connect earth bang you have just shorted the whole thing out.
1.check under the chassis for any componant legs that are too long or bent over,look for any burn mark on the metalwork this will point to the problem.
2.check you have the correct HOT,sometimes people would put the wrong package transistor on which did not have an insulated body.
3.check for any split capacitors or maybe a burst electrolitic.

[Mario]

...
2.check you have the correct HOT,sometimes people would put the wrong package transistor on which did not have an insulated body.

Thanks for the response. Can you explain this in simpler terms? What exactly am I to look for?

Mario

[Q*Bert_OP]

Hook the monitor up with an Iso. X-FMR!!!!!!

[Ken Layton]

The flyback transformer is a high failure item that can fail at any time on this chassis.

[fredster]

Dude, never hook up a monitor without an isolation transformer to test it. Very few of them don't need it.

You blew your hot. At least the hot.

Now you can order a rebuild kit from Bob Roberts and try and rebuild it. My guess is that you needed a cap kit in the first place. Your X ray protection circuit was kicking in. The monitor fired and then died. That's a cap kit.

Get the full deal and replace the stuff in it. After that, make sure you have it grounded and hooked up to an isolation transformer.

Welcome to monitor Repair, Mario.

[Mario]

Dude, never hook up a monitor without an isolation transformer to test it. Very few of them don't need it.

I did use one! I stated this in my original email.

You blew your hot. At least the hot.

What exactly does this mean? What's blown? I looked at the chassis, and I don't see anything that obviously looks blown. If it's the flyback, as Ken suggests, how easy is this to repair?

Now you can order a rebuild kit from Bob Roberts and try and rebuild it. My guess is that you needed a cap kit in the first place. Your X ray protection circuit was kicking in. The monitor fired and then died. That's a cap kit.

Get the full deal and replace the stuff in it. After that, make sure you have it grounded and hooked up to an isolation transformer.

Welcome to monitor Repair, Mario.

I've got a second monitor. The other has lots of color smear, but I expect that the chassis is fine. Anyone know how easy it is to swap the chassis? I think it's the same type of monitor (I'll double-check when I get a chance).

Unfortunately, I blew the better of the two monitors. The worse one was still in a cab, so I was testing with the good one. I'll never do this again.  (at myself)

Mario

[grantspain]

If your monitors are exactly the same its very easy to swap,you have the following cables on pretty much every monitor ever built in the world ever-
1.mains in
2.rgb/signal in
3.scan coil plug
4.degauss plug
5.tube neck card earth
6.most important one-h.t lead to the tube(remember if its old to discharge first or you will be flying through the air)
7.neck card
If your not confidant doing this see if anyone on the forum is near you and get them to help,once you have swapped your first chassis its easy from then on,but please beware there are some pretty high voltages on monitors-i got a 30,000 a couple of years ago never been quite right in the head since,most modern monitors do not require the h.t to be discharged but you cannot take this as gospel because more than likely its gonna be the one you got that does.

[Mario]

Looks like I've got three choices.

As previously stated, I have two monitors. The one that was blown is a 25K7191. The other is a 25K7194 and has a poor picture (color bleed, low red color, for which I was told that the tube needs to be rejuvinated). So, do I:

1. Fix the blown monitor, which may need a new flyback, or maybe more. I don't know how to diagnose this.

2. Fix the poor-quality monitor, which may need a rejuvination (it had previously had a cap kit installed). I believe I'd have to call in a pro for this.

3. Swap the chassis'.

I'm guessing I'll go for the chassis swap as I have everything on hand. But I don't feel comfortable doing any of these.

Big question: are the chassis of the 7191 and 7194 interchangable? Is it a simple swap, or do I need to change anything?

Thanks, all.

Mario