MRC AH101 Transformer repair

I'm sure it's fixable, worst case a drill or Dremel tool removes the breaker.

Wish I could get to the breaker.  Cant get the dang thing apart.  The  screws/bolts that hold the outer case on, must be case hardened.  A file/drill or even a cutoff tool wont touch it.   They are cone shaped with 3 slots.  The heads are .275" o.d x .140"  thick taper to a point with no shoulder.  Cant get a pair of vise grips on em.   Bought this thing on craigslist for $50 to use just for lights and accessories.  Apparently 1 breaker controls both variable voltages.  Might have to get the torches out!!  lol.  Any ideas would be appreciated.

bob

I'm hard pressed to think of any metal that bolts would be made of that I can't cut with a Dremel fiber reinforced cutoff wheel, it's hard to believe there's no way to remove them.

What exact head do they have?

They are shaped like a big philips screwdriver with 3 shallow slots.  Cone shaped. O.D. is .275" x  .140" deep.  Comes almost to a point. No shoulder. The sharp angle of their shape is the bad thing.  45 deg.  Never see anything like them.  Hard as #$%.  Fine Mill file wont even make a mark.  Force a cutoff tool on them it breaks. I took a small sharp chisel and taped on one of the slots. Didnt move.  Dont wanna pound on it, mite break a board or a solder joint.  Time for the torches.  LOL

Bob

Sounds like the tri-wing driver pictured above.

Visit your local Harbor Freight and buy the 33pc IIT Security Bit Set.

Included are a few tri-wing bits.

Just noticed this thread. I looked at one of my AH101's. The case is held on  with what looks like a male tri-wing screw. It would take a female driver to remove them. I have the set GRJ posted. It only has 4 male tri-wing's, no females. I looked at my much larger Craftsman driver kit, it has no female tri-wings either.

AmFlyer posted:

Just noticed this thread. I looked at one of my AH101's. The case is held on  with what looks like a male tri-wing screw. It would take a female driver to remove them. I have the set GRJ posted. It only has 4 male tri-wing's, no females. I looked at my much larger Craftsman driver kit, it has no female tri-wings either.

Ever had a problem with the breakers AmFlyer?  The fan comes on ok.   But 1 minute later the breaker trips.  Recovers real quick.  Dont know what size breaker it is. Must be real weak to trip with less than 60 watts.  Manual says 100Va variable.  Friend of mine has 2 of these and he run 2 PW F3's on same line for around 90 Watts.  More power than either 1 of my old ZW's.  But a PITA for sure.  .  Accessory side 70Va 14 watts  continuous and the 10Va work ok.  Guess thats why it was only $50.  Took a voltage reading b4 I bought it.  All gave advertized readings.  Never considered a bad breaker.  Like John said I bet I can get a replacement breaker if I could get the #$%^&^%@#% open!  Might have to take the grinder to it.  Thanks AmFlyer and GRJ.

I have three that work without issue. I only use them for one month a year on the Christmas layouts. I suspect at most each layout loop draws 5A plus the 10V and 14V accessory loads connected. The AF trains do not put as heavy a load on the transformer as Lionel trains can. There are frequent derailments when the children are running the trains. Breakers work fine, they are tested more than I like. Much prefer them to the original AF transformers. Nice to be able to walk around the layout with the hand helds.

The tri-wing pattern shows the slots on an eccentric,  These are not, they are straight.  They look exactly like the "holt" screw pattern or the "torx T-8 screw pattern except they are male.  Everything on the net show those patterns as female.  Like " lands and grooves " in a rifle barrel John except straight.  MRC has the market cornered!  I have no way post a pic.  If I said "pretty please" amflyer would you post a pic of one?  thanks 

bob

Best I can do with the iPhone hand held. 

Thats perfect Tom.  I appreciate ya.  Hopefully someone has had to deal with these type screws before.   Thanks again Tom.

Bob

I never saw those screws before.  I had two of the MRC Pure-Power 270 models, and they had standard screws.  Truthfully, I suspect those may be pressed in fasteners, they look nothing like any screw that I've ever seen or heard of.

I am also 100% certain that I could remove those with the Dremel fiber cut-off wheel, they're not diamond plated.

According to Mid-state Bolt & Screw website they show a female screw thats called HOLT screw pattern.  Looks exactly like this screw xcept it female.  I took a small chisel and hammer and finally got one to turn out enuff to get a pair of vise grips on it. Its a screw alrite, app 3/16" long.  Like a self-taping screw style thread, There are 10 of these.  Im afraid to keep hammering on it for fear of breaking something insude.  Gotta be a female type bit around somewhere to turn these things out.  Dont know what they are made of John but they are hard as H. Tried to cut a slot in front of one with a Dremel wheel.  Thought I could then use a gun-smith type screwdriver.  To hard!  Frustrating!

Bob

http://www.mutualscrew.com/hol...-bits-17956/top.html

Can't really tell the size you would need.

Gene Anstine

My eyes might be deceiving me but those two bits look like a male driver for a female headed fastener. However this site does have the fasteners that are used on the AH101. They are not Holt, they are called Theft-Pruf. They also have the socket drivers but they are by size and are not cheap. I would guess these to be #4 screws but never took one out to verify.

AmFlyer posted:

My eyes might be deceiving me but those two bits look like a male driver for a female headed fastener. However this site does have the fasteners that are used on the AH101. They are not Holt, they are called Theft-Pruf. They also have the socket drivers but they are by size and are not cheap. I would guess these to be #4 screws but never took one out to verify.

Good luck getting 1 out Tom.  The OD is .275,  9/32"? 6.8mm?  I recollect seeing a commercial that had a nut driver set that was just the opposite of an EZ-out.  It gripped the od of a rounded off nut.  That mite work if you could find 1.  

Bob

I have no plans to disassemble the case. If I did I would order the Theft-Pruf #4 driver for  $15.64 plus tax and shipping and use that. 

Thats not gonna work Tom.  Guess Ill guess take a diamond grinder to em. 

I believe these are Trident security screws, the removal tools (not sure of the size, maybe #4, 6, or 8?) can be found here: 

<http://www.tannerbolt.com/prod...Y-SOCKETS-TOOLS.aspx>

Bill in FtL

Thanks Bill,  I believe Ill try one of those.  Thanks again Tom and John and Gene  for all your help.

Bob

Sounds like the best solution. 

I cant find a cross reference of the numbers to find replacements.  There is no name of vendor.  I assume its made in Japan cause other parts have japan on them.  How does one find a replacement for these?  Thanks

Bob