Film-Tech Forum ARCHIVE: How To Repair A Strong 61-984000 Transformer

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Posted by Mark Gulbrandsen (Member # 72) on 10-28-2005, 06:58 PM:

The Strong 61-984000 transformer is inside of all new style Strong 1-3kw Xenon switching rectifiers and serves as a step down 220 to 120 volt AC transformer.

This transfomrer powers the lamphouse's AC requirements and the rectifiers low voltage internal control circuitry. I've had a couple of them fail lately even though they are protected by a 3 amp circuit breaker!! Turns out there is a simple thermal fuse on the primary thats there more than likely for UL rating and this thermal fuse opens if there is a short circuit present on the secondary even before the circuit breaker on the rectifier has a chance to pop and protect it. There must be a heck of a long delay on that breaker! Anyway its very easy to repair this transformer and keep its UL rating at the same time, it costs less than 1.50 in parts and about a half hours time. List on this transformer is just under $200.00!!

You will need an NTE-8096 Thermal fuse, a pair of wire cutters, a crimp tool,a medium flat blade screw driver, and some GC Electronics Radio-TV Cement. You will not need a soldering iron!

Start by prying off the side of the transfomrer that the primary gos into as shown in the photo, the side with the part number on it!! Be careful not to split the side into two pieces. All of them I've repaired so far have come off cleanly and release at the side tabs.

The thermal fuse is located right under the first layer of insulating paper . Cut through it very lightly and carefully with a sharp razor blade and pull the paper back enough to get at the fuse and clip it out.

You should be at this stage.....

Then strip 1/4" of insulation from the two wires. Then form the new thermal fuse and leads into a U shape and then crimp it in place to the two wires with the rings supplied with the new fuse.

After you have the new fuse in place power up the transformer(preferably from a variac) to be sure that its working ok. After all is known to be well again take some of that GC Radio-TV Cement and goop it all over the fuse and insulating paper and weight the paper back down over the fuse and let the glue dry.... my the aroma from that glue certainly is good [Big Grin]

.....

After the glue has dried use some more of that great smelling GC glue to cement the transformer cover back in place and you're ready to return the tranny back to service.

Mark

Posted by Pete Naples (Member # 761) on 10-29-2005, 02:54 AM:

I usually replace those before the rectifier is installed, as they will fail in spectacular fashion at an inoportune moment. All the ones I've seen fail were most definitely deceased beyond repair! Strong really ought to get it into their heads that European voltage does NOT peak at 220v, in the UK we're on something like 230v +-10%!

Posted by Mark Gulbrandsen (Member # 72) on 10-29-2005, 09:30 AM:

Pete,
Never had them fail like that, the ones I have had fail were from things inside the lamphouses that became shorted. Of course the fuse always blows first to protect the circuit breaker! Should we say that this is the weak link in the Strong product....

Mark

Posted by Steve Guttag (Member # 268) on 10-29-2005, 03:14 PM:

Strong has addressed that by switching over to Fuses instead of the circuit breaker in their switching power supplies (as well as high-reactance.