Ampeg BT-15

UnDx3_bassist · #1 08-12-2010, 11:58 AM

Hello all,
I bought a '69 BT-15 last night, I am the second owner.
I have a question about the glowing faceplate, mine will not light up. I have popped open the chassis to look but everything looks okay. What do I do?

christw · #2 08-12-2010, 12:03 PM

It had a seperate light bulb IIRC. It may just be burned out. Wait for one of the real Ampeg guys like JimmyM to chime in.

beans-on-toast · #3 08-12-2010, 12:18 PM

That amp had what they called an electroluminescent panel. Hard to fathom but they applied 300 volts AC to the thing to get it to light up.

There should be two wires from the transformer connected to the panel. One of the wires goes through a 0.25A fuse. Your best bet would be to check the fuse first.

JimmyM · #4 08-12-2010, 12:21 PM

Quote:

Originally Posted by christw

It had a seperate light bulb IIRC. It may just be burned out. Wait for one of the real Ampeg guys like JimmyM to chime in.

you mean david beans on toast. he's way more experienced than i am. i've never even seen a bt-15 in person. i started the portaflex club with the express purpose of attracting people like him to talk about them so i could learn something

beans-on-toast · #5 08-12-2010, 12:49 PM

Please don't embarrass me like that Jimmy.

TB would be a dull place without you keeping the momentum going and challenging all of us.

UnDx3_bassist · #6 08-12-2010, 01:52 PM

Thanks for the info, the fuse is i dont even know. It looks like there is a fuse there with no insides. :/ There is a lone red wire coming off of the mini-circuit board where the fuse hits the board. I dont know where/what the wires goes or does.

UnDx3_bassist · #7 08-12-2010, 02:05 PM

Alright, I figured I ought to show you what I'm looking at.

Those two red wires (I think) should be spliced together...correct me if I am wrong.

I think someone undid it for some reason...I dunno.

JimmyM · #8 08-12-2010, 02:09 PM

Quote:

Originally Posted by beans-on-toast

Please don't embarrass me like that Jimmy.

TB would be a dull place without you keeping the momentum going and challenging all of us.

thanks david, and i'm sorry, but talent and skill like yours deserves acknowledgement now and then. i'll try to keep it to a minimum, though

beans-on-toast · #9 08-12-2010, 02:49 PM

I started writing this before you posted the pic. The image is blurry and it is hard for me to see where the two red wires are from. For sure someone was working on it.

The fuse looks like it is the panel fuse. It has what is called pigtails on it -- wires at each end that you solder to. Again it is hard to tell from the pic. These type of fuses are still available but can be harder to find. Check locally first then mouser.com, newark.com or digikey.com

Try to trace the circuit.

There are two wires going to the panel. One should connect directly to the power transformer. The other should go to a fuse and continue from the other side of the fuse back to another wire on the transformer. I don't know what the wire colors should be so I can't help there.

If the two red wires are from the power transformer, you can test them with a multimeter set to AC volts. You should read around 300 volts.

Assuming all the wiring is in place, the easiest thing is to just replace the fuse. It saves a lot of work testing it. The fuse should have a fine wire inside. It is hard to see. If it is blown, there will be no wire inside. Replace it with a 0.25 amp, 300 volt or higher voltage fuse.

You would normally test the fuse with a multimeter meter. Remove the fuse from the circuit. Set the meter to the lowest ohms setting. Put one probe on each end of the fuse. If it is burnt, it will read infinity. If it is good it will be a very low resistance or zero.

If you can't easily remove the fuse. Get an inline fuse holder from a place like radio shack. Install a .25A fuse. Securely clip the wires onto each side of the amp's fuse. This is a temporary measure that will bypass the old fuse and allow you to test the panel and see if it lights up.

Note that this is a 300 volt circuit and is very dangerous to work with. If one of the wires slips off it can come into contact with something inside the amp and can damage something else. It can also kill you.

sedan_dad · #10 08-12-2010, 04:02 PM

Attachment 177295
Pretty cool looking when it's working.
I have one.
Attachment 177296
I use mine for my practice amp .

giacomini · #11 09-02-2010, 10:31 PM

Sorry to hijack the thread, but can anyone answer me about the portaflex cabinets? Were all of them sealed or did they make ported ones too?

Vintage-Blue · #12 09-03-2010, 04:02 AM

None of the Portaflex cabinets were sealed - they were all ported.

giacomini · #13 09-03-2010, 06:57 AM

Quote:

Originally Posted by Vintage-Blue

None of the Portaflex cabinets were sealed - they were all ported.

Thanks! I was wondering that because I got a B3 model, the one with a single 15" and a ported cab and I just bought a VT Bass pedal to try to get sorta the Portaflex sound out of this SS Ampeg.

I guess if the cab construction is close enough to the original the modeling will act better... But I know that pedal is supposed to emulate the SVT.

BTW, JimmyM, how do you compare that portaflex setting in the VT Bass to the original thing? I remember you posting about the SVT settings, not the fliptop.