Strange red plating tubes on new build

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SoulFetish
Posts: 211
Joined: Wed Apr 03, 2013 1:50 pm
Location: Norwood, MA

Re: Strange red plating tubes on new build

Post by SoulFetish »

We’ve all been there. In fact, i just did this the other day in an old… bassman or Pro reverb, I can’t remember.

It was one of the Silverface models with the 160R cathode resistors and AC shorted cathodes. Anyway, I installed a 1 ohm resistor in cathode to ground, and continued with the repair. When it cam time to test, I noticed the output looked like garbage, with obvious imbalance. The top half of the waveform had significantly less gain. Did all the obvious tests- swapped output tube positions, new phase inverter, measured PI load resistors, etc.
Those all checked out fine. Turns out, the supplier packed a 100 ohm resistor in with the bag of 1 ohm resistor s. So, When I grabbed two out of the parts drawers, I didn’t even notice it when I was soldering it in.
SoulFetish
Posts: 211
Joined: Wed Apr 03, 2013 1:50 pm
Location: Norwood, MA

Re: Strange red plating tubes on new build

Post by SoulFetish »

jabguit wrote: Tue Nov 02, 2021 11:43 am
SoulFetish wrote: Tue Nov 02, 2021 3:38 am Dude, you are measuring across a 0.1 Ω resistor. I suspect that when you install proper 1 Ω resistors in place of those, it will all make more sense

(brown-black-silver with gold band as the tolerance)
brown/black/gold/gold
I was trying to tell him to look again, brown-black-silver was what he installed
jabguit
Posts: 250
Joined: Tue Aug 18, 2020 11:53 am
Location: NC
Contact:

Re: Strange red plating tubes on new build

Post by jabguit »

SoulFetish wrote: Tue Nov 02, 2021 11:50 am
jabguit wrote: Tue Nov 02, 2021 11:43 am
SoulFetish wrote: Tue Nov 02, 2021 3:38 am Dude, you are measuring across a 0.1 Ω resistor. I suspect that when you install proper 1 Ω resistors in place of those, it will all make more sense

(brown-black-silver with gold band as the tolerance)
brown/black/gold/gold
I was trying to tell him to look again, brown-black-silver was what he installed
10-4
I was trying to tell him what he needed.

cheers,
Jack Briggs
Briggs Guitars
SoulFetish
Posts: 211
Joined: Wed Apr 03, 2013 1:50 pm
Location: Norwood, MA

Re: Strange red plating tubes on new build

Post by SoulFetish »

Teamwork 8)
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