MOD 102 Kit not powering on at all. Any suggestions?

[martin manning]

I'm probably missing something, but aren't the two tips on that type of jack only supposed to touch with nothing plugged in? Wouldn't jumping a wire between the two keep them connected with a cable plugged in? Or is that not an issue?

Correct. The guitar signal would be permanently shorted to ground.

[Stevem]

Correct.
I misunderstood.
I thought you where trying to get one jack soldered right to another one which can take a ton of heat.

[vipor3D]

The layout could be modified to correct the issues that have been mentioned here. You could also play around with the operating points on the preamp tubes to get a feel for how that works.

When you say change the operating points of the preamp tube, are you referring to changing the bias? If so, would that mean just switching the cathode bias resistor?

[martin manning]

The cathode resistor Rk and anode load resistor Ra, along with the supply voltage, determine the operating point, and the cathode resistor bypass capacitor Ck determines frequency response at the low end. Right now both stages are using 100k Ra and 1k5 Rk, center-biased and fully-bypassed with a 22u cap for full range frequency response and maximum headroom. Increasing Ra increases gain, and un-centering the operating point will bring clipping and distortion on sooner.

[vipor3D]

The cathode resistor Rk and anode load resistor Ra, along with the supply voltage, determine the operating point, and the cathode resistor bypass capacitor Ck determines frequency response at the low end. Right now both stages are using 100k Ra and 1k5 Rk, center-biased and fully-bypassed with a 22u cap for full range frequency response and maximum headroom. Increasing Ra increases gain, and un-centering the operating point will bring clipping and distortion on sooner.

I spent some time reading up on the operating point and think it makes more sense to me now.

I've also made some mods/upgrades to the amp over the past few days and these have really improved the sound of the amp and made it super quiet compared to the buzz it had before.

Most mods are from the Mod 102 to 102+ conversion. The mods I've done so far are:
-The filter cap mod (Changed the two 22uf filter caps to 47uf and changed the 22k 1w resistor between them to 10k 1w)
-The filament hum/virtual center tap mod (Added two 100ohm resistors to the two lamp holder solder lugs and removed the connection between pins 3&4 on V2)
-I replaced the input jack with the shorting connection issue and did the input grid resistor mod (Removed wire from input jack to pin 2 of V1 and replaced it with 33k resistor)

In addition to the MOD 102+ conversion mods, I also rewired the power cord, fuse and switch so that the switch is now between the hot and the PT. Finally, I changed the bypass cap on pin 3 of V1 from 22uf to 1uf to tighten up the bass end based on a suggestion I read online. I really like this change as the low-end was very loose and "flubbery" before.

I added a picture of what the guts look like now. I've tried to clean up some of my wiring, but still have a way to go there...

[martin manning]

Good progress! I don't know what your sources of information have been, but this site is one of the best: https://www.valvewizard.co.uk Download the Triode Gain Stage document for info on the small signal stages.