mich

question about polytone amp
« on: June 08, 2005, 11:08:30 AM »
greetings,
does anyone know how the power transistors on a polytone amp are configurated?i cant seem to find them on the pcb,and the schematic shows connections with wires where the transistors should be-i figured they could be separetad from the pcb-alone on their hitsink or something like that.can someone confirm?

oh,and another one...-if someone here had this amp,did it have a switch for voltage selection?(110v/220v/240v)
i have a bunch of wires coming out of the transformer's primaries-and ill try to feed the pair with the highest dc resistence the 220v we have here in spain...sounds logic?

thanks.
"Tubes gone - darkness,darkness,darkness no colour ,no contrast." - Joni Mitchell


NewYorkDave

question about polytone amp
« Reply #1 on: June 08, 2005, 11:15:48 AM »
It's been years since I've worked on a Polytone--and it's an experience I would rather forget--but I do recall that the output transistors are mounted off-board, on heatsinks.

Wear gloves and a dust mast if you don't want to be scratching/coughing for the rest of the day from the fiberglass inside the cabinet.

mich

question about polytone amp
« Reply #2 on: June 08, 2005, 11:48:24 AM »
thanks ny dave,luckily im only ataching the power amp section wich i got on ebay to a polytone preamp that i built.....so no scratching and coughing for me....but its good to know they have fiber....ill put some in my cabinet too.....
"Tubes gone - darkness,darkness,darkness no colour ,no contrast." - Joni Mitchell

mich

question about polytone amp
« Reply #3 on: June 08, 2005, 03:12:45 PM »
o.k,i got the transistors, but they have only 2 terminals...i dont have any expirience with these....what do i do with my C,B,E? :shock:
even the 2 terminals are not marked with base ,collector or whatever.....what to do?sorry if its an ignorant question,but i cant seem to find any info on this.....
thanks
"Tubes gone - darkness,darkness,darkness no colour ,no contrast." - Joni Mitchell

NewYorkDave

question about polytone amp
« Reply #4 on: June 08, 2005, 04:00:42 PM »
For anyone who doesn't know, we're talking about TO-3 cased transistors.

The case itself is the collector terminal.

As for the other two terminals, here's a mnemonic I learned years ago which has always helped me:

"The Base is on the Bottom when the Leads are on the Left."

(This is as you're looking at the transistor from the bottom, with the leads pointing directly at you).

mich

question about polytone amp
« Reply #5 on: June 08, 2005, 04:36:21 PM »
got it.
what about the isolation from the heatsink?any pointers on that?
thanks
"Tubes gone - darkness,darkness,darkness no colour ,no contrast." - Joni Mitchell


 

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