PT and resistors question....AB763 to Dumble conversion

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tsl602000
Posts: 103
Joined: Sat Mar 03, 2007 10:47 am
Location: Netherlands

PT and resistors question....AB763 to Dumble conversion

Post by tsl602000 »

Hi all,
I'm almost done building a D'Lite with 6L6 tubes and a choke, but I have a few questions.
Unfortunately my 6 month old TAD (German) PT died all of a sudden after working appr. 30 hours. I'm looking at a Hammond 290DX:
http://www.hammondmfg.com/guitarLine.htm, which is supposed to be a direct replacement for a Bassman PT. Would this PT be ok?

Also, do the resistors on the power cap board have to be 2 or 3 watt? Someone mentioned me the 1watt resistors will be just fine too.

On the D'Lite layout/schematic there's a 3W/220K over the B5 20uF cap. On all the other ODS schematics I have this resistor isn't there. Should I use this resistor for a 6L6 amp?

Thanks!

Coen
tele_player
Posts: 311
Joined: Sat Sep 29, 2007 3:27 am

Re: PT and resistors question....AB763 to Dumble conversion

Post by tele_player »

The CX or DX would do fine.

There's a simple formula for calculating power dissipation in a resistor(V*V/R). In this case, V is the voltage drop across the resistor, and R is the resistance. You'd choose a resistor that's higher than the result of that calculation.

The 3W/220K is sometimes referred to as the 'FET simulation' resistor. Its job is to load the last stage of the power supply about the same as the FET circuit, which is omitted in the D'Lite. It's not related to which power tubes you use.
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tsl602000
Posts: 103
Joined: Sat Mar 03, 2007 10:47 am
Location: Netherlands

Re: PT and resistors question....AB763 to Dumble conversion

Post by tsl602000 »

Thanks tele Player!
That answered all my questions!
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