Ampeg B15NF Fliptop Blows Fuses

[Leo_Gnardo]

Leo - I'm in Walpole, Mass.

Drat, I was just a skip and a jump away, visiting relatives in Sudbury last weekend. Might be back there around Christmas.

And thank you for taking the time for such a detailed and concise answer. Actually everyone who has responded to the thread has been great, I sincerely appreciate it!

Why thank you! We have quite a good brain trust here on MEF, it's quite unlike anywhere else I've looked. The Amp Garage similar but it looks like that website is fading unfortunately.

[earache]

So I have ordered and received a new power transformer from Fliptops.net and I am wondering if any of you who have had this problem - the mounting holes and the wire pass-thru holes don't line up with the replacement!

The potted lugs sticking out of the replacement transformer are off location as much as .100, and the bunch of wires from the replacement transformer don't line up with the hole in the bottom of the chassis. I've had to file the chassis holes out and even have used a sheet metal nibbler to enlarge the hole in the chassis where the wires pass thru.

Also - it's a huge PITA working on this amp in general, as the all the tube sockets are riveted to the chassis and are then soldered directly to the circuit board. I didn't want to undo all of that so I used a Dremel to grind out the holes

To repeat - anybody else encounter these same issues?

[SoulFetish]

So I have ordered and received a new power transformer from Fliptops.net and I am wondering if any of you who have had this problem - the mounting holes and the wire pass-thru holes don't line up with the replacement!

The potted lugs sticking out of the replacement transformer are off location as much as .100, and the bunch of wires from the replacement transformer don't line up with the hole in the bottom of the chassis. I've had to file the chassis holes out and even have used a sheet metal nibbler to enlarge the hole in the chassis where the wires pass thru.

Also - it's a huge PITA working on this amp in general, as the all the tube sockets are riveted to the chassis and are then soldered directly to the circuit board. I didn't want to undo all of that so I used a Dremel to grind out the holes

To repeat - anybody else encounter these same issues?

Hey, I'm in Norton MA. I'm happy to help you out if you want to bring the amp by. I have the metal fab tools to make this a little easier and worked on a B15N not too long ago. Iremember it being a pain in the ass retrofitting some parts. PM me if you want.

[earache]

SoulFetish

Thanks for the kind offer, but it's all sorted out and working great!

I dont understand why Fliptops.net makes a direct replacement part that doesn't directly fit without modification.

Thanks to all for the help, you folks are always great!

Also I took loads of photos inside this amp so I am happy to share any gut shots on request.

[Leo_Gnardo]

I dont understand why Fliptops.net makes a direct replacement part that doesn't directly fit without modification.

Doubt that Fliptops actually make the transformer & enclosure, I expect they have a contractor who does that. Maybe the poor fit is the result of translating US measurements to metric & back? Or the deep-drawn steel pot is the only thing they can find that's "near as possible" to original. In any case, after your experience I'll continue my mad scientist method of melting out old bad trannys & repotting in original cans. Takes a lot of time & concentration, but it's sort of fun & never a problem re mounting pot enclosure studs.

[earache]

Leo G

Do you have a fixture that holds the threaded mounting lugs in the correct position while you are repotting the transformer?

It does sound like "mad scientist" work, but maybe not so "mad" after all because it cost $229 plus $16 shipping for that power transformer that didn't fit. What does it cost you in materials to repot a Portaflex transformer?

[earache]

Oh my, I just saw that Fliptops.net is just starting to repot old transformers as a service. I woulda saved at least $30 if that option existed a month ago.

https://www.fliptops.net/catalog/p-1...mps#attributes

[Leo_Gnardo]

Do you have a fixture that holds the threaded mounting lugs in the correct position while you are repotting the transformer?

No the lugs/studs don't move so they slide right into their former chassis holes. I wind a couple of nuts onto the studs to keep glop from collecting in the threads while removing the old transformer. Count on the nuts getting covered with potting glop, likely they'll be discarded. I've tried using tape, the stickum doesn't hold when the transformer is heated up. Might try plumber's teflon tape next time. It's cheap, very thin, has no stickum. Nothing like a low cost experiment.

[QUOTE}What does it cost you in materials to repot a Portaflex transformer?[/QUOTE]

I use (expensive) beeswax, that's the costliest part besides the new iron. Others may wish to use ordinary paraffin wax or some other magic goop. In any case figure 5 bucks for wax, maybe a dollar's worth of white modeling sand, 3 bucks worth of black wrinkle paint (a third of a can), half a dollar's worth of charcoal briquets to melt the original potting tar/wax out. Time consuming is what it is. Oh yeah there's the transformer let's not forget. For a PT, depending on which one you choose say $60 to $100. $150+ if you insist on Mercury iron - I never have. Similar for OT's.

When figuring expenses, don't forget shipping dead potted transformers to Fliptops. I don't know if they include painting the box with wrinkle black as part of the deal. If you like the "distressed" look, never mind.

Waiting for the right weather conditions is also a factor if doing your own. Calm damp weather is good for the transformer hibachi. Tar smoke goes straight up so neighbors don't get alarmed, nearby vegetation won't catch on if the potting tar catches fire. Doesn't hurt to have a hose or fire extinguisher ready to hand. Calm dry warm weather for wrinkle paint. It won't wrinkle if conditions aren't right, believe me I tried and nothing else will do. If you have a proper spray booth might have a go at it in there. Too much humidity though, and it'll be a bust.

[g1]

Did you contact fliptops about the fitment issue? Is it possible there are more than 1 version of stock transformer?
I should think they are aware of the issue, but you never know. They may appreciate a heads-up.