fired it up and smoke comes out of PT

[Tillydog]

http://www.scribd.com/doc/2474233/Match ... ar-Effects

oh well. i guess its just a $50 learning experience at this point. time to make a light bulb thingy next!!!

Both of the bridge rectifier schematics on that page are wrong !

(Hi!)

[Alexo]

http://www.scribd.com/doc/2474233/Match ... ar-Effects

oh well. i guess its just a $50 learning experience at this point. time to make a light bulb thingy next!!!

Both of the bridge rectifier schematics on that page are wrong !

(Hi!)

Man, that's messed up!!

[wsaraceni]

Thanks guys. Foe what it's worth. The file I got was the same as the linked wrong one. Mine came from schematic heaven.

Thanks

[Drumslinger]

man that sucks. I've burnt a transformer in the past. it's a learning experience and we move on. i use the light bulb limiter method on my builds and it works great. as Merlinb suggested, check the transformer for shorts.

[FUCHSAUDIO]

If the heater line has a center tap on it, and you put a bridge on it, you'll upset it.... Not to mention some potential wiring errors to and from the bridge. Recheck that area well, and look on E-bay for a variac.

[wsaraceni]

andy, here are the specs on the transformer

269EX 43 115 60 380V C.T. @ 71ma. 6.3V @ 2.5A - X5

i should be good to go if i just fix the bridge correct?

also, if i was to use a variac, what brand/type would work well.

[FUCHSAUDIO]

who made it, got a spec sheet ?

[wsaraceni]

hammond 269ex

http://www.hammondmfg.com/pdf/5c0026-27.pdf

[FUCHSAUDIO]

So, it has center tapped filaments...that, plus the miswired bridge is the cause for the fry up.

[FUCHSAUDIO]

What are you trying to do with this winding ?

[wsaraceni]

the sheet says the secondary has CT but not the filaments. unless im looking somewhere wrong.

[wsaraceni]

What are you trying to do with this winding ?

believe it or not, it started because i had a 269ex transformer sitting around. i looked for a project to use it and ended up finding the matchless vibrobox/hotbox combo. then i decided to just do the vibrobox.

so after getting the parts to finish it up. i ended up frying the part that started it all.

here is the schematic of what i am trying to do (the correct schematic)

http://www.prowessamplifiers.com/schema ... robox.html

[selloutrr]

The Eico 1073 is a great variac.
AC and Amp Meter.

I modified mine, by adding larger external Western Electric 6" meters

I paid under $100 back in 2004

[Gibsonman63]

Not to highjack the thread, but I haven't figured out why I need a variac. I built an amp, restored a few and recapped about a dozen amps, but I have always just tested them with the light bulb limiter and then plugged them in and let them run for a couple hours.

Am I missing out on something important?

[jelle]

Variac is for controlled slow startup. Say 5v start voltage, then meter everything. Slowly increase and measure. Your filter caps will like it too as they are slowly reformed.

Jelle