Should the pins of a new flyback be "hot" when installing it??

Robomayhem

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Should the pins of a new flyback be "hot" when installing it??

I was putting a new flyback (MRCFT 249) in a Neotec NT-2701 and while soldering one of the pins my right hand (holding the solder) touched the metal frame as the iron was on the pin and there was a small shock/zap at the tip of the iron and the current came up through the solder and got me. Thankfully it did not hurt my Hakko, but now when I plug the monitor in I get the start up static but no neck glow. Did this zap short the flyback? And why would it zap in the first place.
I have done at least 20 fly replacements in various monitors and never had this happen..

Any thoughts?
Thanx.
 
Most electrolytic capacitors on the board could hold some charge, even after the monitor is off for a while. It's possible that as you were making the connection, you got a short circuit path between one of those capacitors and your flyback pin.

It takes around 25,000 volts to jump a 1/4" gap - what type of gap did you have?

Also, with the cold weather, you could have had a static discharge.

I'm not sure that would be enough current to fry a fly (ohhh! nice play on words there). I'd suggest re-flowing the fly again.

Did you replace all the caps, or just the fly?
 
I capped it probably 4 months ago, and at that time the fly was performing properly. But a week ago or so the focus started drifting so I ordered the new one.
Curiously the fly still has voltage at the pins as I got my hand close to the pins while re-installing it and it gave me that fuzzy feeling...
After the playoff games I will pull the new fly and put the old one back in and see what happens.

Thanx
 
I had a weird situation about 10 years ago, working on a REIL (Runway End Identification Light) at an airport. The report was the strobe wasn't working.

When I powered it up, the strobe flashed once, and then not again. I figured I had a bad cap, so I unplugged it, and discharged the cap.

Since the cap in this case makes a "Big Blue" look like a tiny blue, I checked and discharged it again.

"Spack!"

So I discharged it again.

"Zot!"

This went on until I got a nice big resistor, and bridged the connection points.

The resistor got warm, and the cap finally stopped trying to shock me.

It was a bad cap. (Bad Cap! Bad Cap! Go to your corner!)

I'm not sure how an inductor like a fly could store a charge, unless it has an integral cap.

From reading these forums, I have learned that cap kits don't always come with the "big caps" around the fly.

I think you have a bad cap in the board. It would be a fairly big one.
 
Makes sense - despite being a "compatible" flyback, the values are going to be a little bit off. On a monitor as sensitive as this, you may have to tweak the shutdown a bit.

What's the B+ voltage?
 
No - your little "zap" did not fly your fryback (see what I did there?). As stated, you got a little discharge from a cap. I've sometimes see the grounding of the soldering iron plug cause a cap to discharge when I've touched a pin with the soldering iron.

BUT - a zap could fry the HOT or something more delicate, so check all that stuff. Most caps will discharge on power down, so a cap holding a charge usually means something wrong in the circuit. An example of this would the G07 filter cap that holds a BIG charge when the small fuse blows due to flyback or HOT failure...
 
Well turns out the B+ was at 137v, and once I dialed it down to around 113v I got a picture :)
Now the issue is that the pic is extremely blue. Thinking it is probably an issue with the neckboard. Also, it seems the chassis is actually a NT-27E, even thought the neckboard says it is a 2701.

Thanx for the help guys, I appreciate it.
 
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Yeah, I worked on a 27E that also said 2701 on the neckboard. Apparently the neckboard is universal...
 
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