5e3 build - fuse keeps blowing

[AppleScrappler]

many thanks! I probably will just switch that PT out and save this one for the inevitable build of a deluxe reverb or something.

intermodulation distortion? sounds fancy. if you don't my me asking... what do I do to put negative feedback on the output section?

[ThermionicScott]

many thanks! I probably will just switch that PT out and save this one for the inevitable build of a deluxe reverb or something.

380-0-380 is too high for a DR. (It would use that Weber PT as well.) I'd save the Heyboer for a 2x6L6 build of some kind.

intermodulation distortion? sounds fancy. if you don't my me asking... what do I do to put negative feedback on the output section?

That's the kind of distortion where two tones add and subtract to produce new frequencies, even in a "clean" tone. Sounds good with power chords, but not with complex chords. The way I'd implement it is to remove the cathode bypass cap on the second gain stage, then attach a 56K resistor between the "hot" side of the speaker jack and the top of that cathode resistor.
If this makes the amp squeal, reverse the two OT primary leads.

- Scott

[AppleScrappler]

380-0-380 is too high for a DR.

That's the kind of distortion where two tones add and subtract to produce new frequencies, even in a "clean" tone. Sounds good with power chords, but not with complex chords. The way I'd implement it is to remove the cathode bypass cap on the second gain stage, then attach a 56K resistor between the "hot" side of the speaker jack and the top of that cathode resistor.
If this makes the amp squeal, reverse the two OT primary leads.

- Scott

ohhh yes that's the mod I did. I'm pretty excited about it. for now I strung a bunch of diodes together to drop the B+ (it's around 378 now) and switched the cathode resistor. I have to wait for my brother to mail me the other PT from my house. I'm too excited about testing the new mods to wait! thanks Scott! huuuuuuge help!

[ThermionicScott]

ohhh yes that's the mod I did. I'm pretty excited about it. for now I strung a bunch of diodes together to drop the B+ (it's around 378 now) and switched the cathode resistor. I have to wait for my brother to mail me the other PT from my house. I'm too excited about testing the new mods to wait! thanks Scott! huuuuuuge help!

Oh cool! Some Fender amps included a negative feedback loop around the tone controls, so that's what I thought you were talking about earlier.

I'm a big fan of that Weber Deluxe-style PT. Not only is it good for tweed and blackface Deluxes, it's perfect for the pre-1955 2x6L6 Fenders that used cathode bias.

- Scott

[No457 Snowy]

Hi AppleScrappler,

I had a similar high B+ with my 5e3 build. The power tranny in my amp is the Mojo/Heyboer 761EX (354-0-354) and I was getting a 450V B+ (Also running on 240V wall voltage here in Australia). I mounted 6 X 12 Volt/5watt Zeners in series on a tag board, leaving plenty of room between them and left nice long leads running from each diode to the next to help dissipate some heat. I mounted the board on the side of the chassis with a Nylon standoff and ran the whole assembly in series with the Red/Yellow centre tap wire to Ground. I now get a B+ of 380V with that setup and so far everything seem OK, not too much heat etc, I figured spread over the 6 diodes all mounted on the board and spaced nicely should be fine, I guess time will tell.

Cheers,

Snowy

[ThermionicScott]

Whoops, I need to amend what I posted earlier. The #22772 you have should work for your Deluxe-y things, but it's too low in current capacity to use in 2x6L6 designs. It's the #25130 PT that I really love.

- Scott

[AppleScrappler]

I'm actually experimenting with both of those mods Scott. I simply copied the feedback loop of the tone controls of other fenders like you mentioned but the output feedback loop is what I'm working with now. i was confused about which one you were talking about at first! I gotta get my terms down!

[AppleScrappler]

Yeah Snowy, for the moment I strung 6 10v 5 watt diodes and left the leads long and made pretzels out of them to dissipate heat. It's temporary just to see how much the voltage drops but I was thinking of doing something just like you described if I want it in there permanently. thanks for the info!

[No457 Snowy]

Here's a pic of how I mounted my Zeners, seems to be going OK.




Snowy

[AppleScrappler]

Wow thanks for the pic! that's a very clean job you did. Mine looks like a pretzel factory. I'm gonna go to ratshack and get a board and give that a shot. thanks again!