1962 Ampeg Portaflex B-15N

[xtian]

Amp on my bench from--wait for it--Guitar Center. Yes, they made good on their promise to send me work, because they have no local techs to work on their stuff. Manager wants to keep it as stock as possible.

In the third shot, what is that disc? An internal fuse? It appears on the schematic between the wall plug and the fuse (legend says, "100 ohms cold, .99 ohms hot"). Replace it? Remove it?

Notice the name "Louie Ramirez" scratched on the shield plate. Famous vibraphonist and percussionist?

And for your viewing pleasure, dig the fully MacGuyvered fuse meant to solve the missing fuse cap problem!

[tictac]

That disc thing looks like an ancient version of an inrush current limiter.

If you look at some of the newer Fender amp schematics they have the part number for the newer version of these devices... like CL-blank-blank....

TT

[cbass]

You mean the foil wrapped fuse didn't fix it?
I'm shocked that always fixes it

[dorrisant]

Nice shots... Still waiting to see one of these up close.

Tony

[Stevem]

Yup, current inrush limiter, these would go bad in tube type TV sets all the time, and that one is well on its way out!
And yes, in Fenders they are mostly blue in color, and even the silverface champ and vibro champ has them.
That 10 watt cathode resistor is one item that I always step up to 15, and since those transformers cost a ton to replace, a in line fuse on the OT center tap is another little change I make also on all of these potted tramsformer amps!

[Smokebreak]

I had the opportunity to fix one of these up a couple months ago. Really really good sounding guitar amp. Still on my list to build one.

[Milkmansound]

I use CL-60

[xtian]

I use CL-60

Excellent! Thank you.

[xtian]

Yet another reason this amp is making my jaw drop: All original, Ampeg-branded tubes.

[tony hunt]

Very, very cool amp there.

Louie Ramirez, yes - that reminded me of his track - "Love it Up"
www.youtube.com/watch?v=WcYhvn5R9ew&ind ... QX91u4LEU7
I had that LP for a while, until an ex-GF threw all my collected vinyl on the bonfire.

[xtian]

This damn thing is shocking me...AFTER I put the 3-conductor power cord in! My outlets are wired correctly and properly grounded, my green earth wire is firmly connected to chassis, and I cannot measure any stray AC on the chassis or switch bats.

And yet! I was shocked once when I used one hand to seat the rectifier--fingers on glass, thumb on chassis--ZAP!

And a second time with one hand on the input cable shield, and the other brushed the control panel--ZAP!

Seriously, WTF?

[xtian]

Great gravy. Some bastard rewired the 8-pin "safety" speaker connection incorrectly. This scheme is supposed to "make" the HT center tap connection to ground, but now that CT current is running thru the speaker.

Exciting, you bet.

[xtian]

Done. Dominated.

Had to fashion a replacement 8-pin plug because the old one was beyond repair. Also had to replace Volume 2 pot after sudden drop in volume revealed a bad pot.

I must say, I thought Everett Hull hated distortion. But this thing sounds AWESOME with my SG and the volume dimed. ROCK!

[Jack Hester]

Here's the thermistor that I've been using on my Ampeg restorations, as well as my recent breadboard build:

http://www.mouser.com/Search/ProductDet ... 22-12103-B

It's 120 ohms, cold. At max current, it drops to .9 ohms. And at 50% current, 2.25 ohms. Rated for 3 amps.

Jack