wg4600 blowing x603 at powerup

[cw]

Not sure whats going on.. fresh cap kit all the way around..   diode x603 is blowing at powerup.  It has toasted one trace from the ac into the coil filter l601.  At this point I am not sure if the replacement diode is doing the job, I picked up what was suppose to be the nte equivalent which is a nte116. It is rated at 600v and that does match the description of the diode in the manual......

any help with this would be great...

[Ken Layton]

Sounds like you are not using an isolation transformer to power the monitor. The 4600 series REQUIRES an isolation transformer for power. Never operate this monitor diecrtly from a wall outlet.

[cw]

iso is in place ...   Testing in a working time pilot..

[Ken Layton]

Is the isolation transformer wiring to the monitor correct? Only the monitor should be connected to the secondary (output) side of the transformer.

Your symptoms are exactly what happens when there's no isolation.

[cw]

wiring is all in place and unmolested... its all original and works with a g07 that i hook up..

[Ken Layton]

There are two things to check:

Unplug the degaussing coil. Sometimes it can get pinched and short to the frame.

The width coil can rotate in it's holder and short one of it's terminals to the frame. Make sure this isn't happening.

[cw]

I did try the degaussing coil but no luck.. the width coil is check with every reassembly having to solder the wires into and what not...but I will keep an eye on it on the next reassembly...  I really am not sure about this nte 116 that I am replacing x603 with..

thanks for the help Ken

[grantspain]

is your original fault this diode blowing?have you replaced it more than once?

[cw]

yes as far as I can tell the original problem was x603 shorted... I pulled the part numbers of the diode. Dropped it into the nte cross reference and got nte 116.  Its blown three times in a row now.. So something is up...

[grantspain]

and its not blowing the fuse as well?

[cw]

no its not...

[Kevin Mullins]

Since X603 is part of the bridge rectifier section of the power supply, I would try to isolate that section  from the rest of the chassis. Looks like pulling R701 should do that.
Then double check ALL the diodes AND resistors in the power supply section. Something is either dead shorted OR wide open.

And just to clarify....did you try it without the degauss coil plugged in?
(just wanted to double check what you meant by "did try the degaussing coil but no luck")
Because even if the coil itself is good, sometimes the PTC that turns it on and off will get "stuck" in the on mode (for lack of better terms) and this could be causing the overload of the power supply section since the coil is only supposed to be on for a second or two and then turn off. With the coil unplugged then could narrow it down to the either coil or the PTC.

NTE116 appears to be a 1A 600V diode......
When I crossed 201X3130-109 on the NTE site I came up with an NTE125.
But RM-2AV came up as an NTE580.
 

[cw]

yes I did unplug the degauss coil to check to see if it was shorted... I will pull a leg on r701 and see if I can narrow the search...   thanks