New Amp Day - StewMac Mojotone '65 P-Reverb Princeton Reverb Assembly & Review

[jonfields45]

From my 1975 High School Year Book:



That's me on the left holding a '73 natural ash, maple board, Strat. If you look carefully to the left of the baritone sax you can just make out the silver panel of my late '60s Princeton Reverb. That amp was perfect. It had just the right touch of distortion when loud enough to solo. The first seated trumpet could also improvise a solo, but the electric guitar is so much easier to rip out a ton of notes. It was a real kick at the time playing for high school assemblies.

[jonfields45]

I've finished the chassis prep and next comes the main and bias eyelet boards.

Not a work of art, but hopefully electrically correct...

[Bluside]

Looks like you are doing a very professional job. Keep the pictures and progress reports coming.

[jonfields45]

After some distractions, a tiny bit of progress (bias eyelet board):

[Glennwillow]

Originally Posted by jonfields45

I've finished the chassis prep and next comes the main and bias eyelet boards.

Not a work of art, but hopefully electrically correct...

Having spent a lot of time in electrical labs at TI (Texas Instruments) in my early working days as an engineer, I think that looks good!

- Glenn

[jonfields45]

The instructions call for complete population of the eyelet board before soldering, but the single connected jumpers fall off and flop around, so I am checking to make sure those eyelet holes are fully populated and soldering just them as I go along.

[SalFromChatham]

This thread is making me twitch and convulse.

It take me 3hours to put together a simple IKEA purchase that they say should take an hour.

Barbie is more handy than me.

[clintj]

I believe Fender would fully populate the boards, then flip them to solder and add the flying leads as they went. The shape of solder joints on vintage eyelet boards are backwards from what top soldering would produce.

[jonfields45]

Originally Posted by clintj

I believe Fender would fully populate the boards, then flip them to solder and add the flying leads as they went. The shape of solder joints on vintage eyelet boards are backwards from what top soldering would produce.

Makes sense to me. When I do the full eyelet board soldering the back side will be a lot easier to access.

[abn556]

Years ago that would have been a fun project. Now my eyes are not good enough for that kind of work.

[jonfields45]

The main eyelet board is complete. I'm confident the components are in-spec, placed correctly, and soldered OK. I am concerned that the single connected jumpers that don't go through a board hole for extra support were subject to too much handling and might break. Between using a stripper (and trimming the many cloth strands with cuticle scissors) and spinning the wire under an X-acto knife, I settled on the knife. I definitely prefer stranded silicone insulated wire and even PVC insulated stranded wire over this period correct solid core lacquered cloth wire. The green ground wire is heavier and strips more easily.

[clintj]

That insulation is what's known as cloth pushback. You push it back to expose the inner conductor for soldering, no trimming required.

[MCDEMO1]

Great looking work !

I built the Stew Mac '59 Deluxe amp a couple of years ago. Both MojoTone and Stew Mac do a fantastic job with their instructions, but I also populated the board and soldered by section as I went along.

I had two problems with the build:

1) the estimated length of some wiring sections were too short and there was not enough wire supplied with the kit - luckily I had some on hand.

2) Two of the mounting screws on the front baffle for the speaker were not in the correct positions. Way off in fact. I was not about to start taking the MojoTone built cabinet apart, so I contacted SM and they immediately sent me a new cab in exchange. I had painted the interior of the original cabinet black, but ended up clear coat sealing the replacement. I think I spent more time overall in treating the tweed covering than on anything else.

Aside from those two things everything went very smoothly. If I was younger I'd be very tempted to tackle the MojoTone Brownface Vibroverb kit.

I also went the Etsy route for my ID plate for the DeLuxe:

[jonfields45]

Originally Posted by clintj

That insulation is what's known as cloth pushback. You push it back to expose the inner conductor for soldering, no trimming required.

The instructions suggest stripping which keeps the cloth out of the solder joint. But I do use shielded cloth push back to wire guitars and in that application the pushback is truly handy, in particular with the shield.

[clintj]

Whoever wrote that likes doing things the hard way. I just push it back a quarter inch or so, so the cloth is clear, then slide it back down to the joint when it cools.