Princeton Reverb: Couple easy questions

[DennisM]

I'm converting my PRRI PCB to hand wired.

1.On the 10pf, 250pf and 500pf, silver mica or ceramic disc? Or does it matter?

2. On the cap on the bias board, I'm having trouble finding a 25/100. Can I use a 50mf/100v instead without any problems?

3. What kind of tool do you use to tighten and loosen the big nut on the pilot light assembly? Danged if I can get anything on it.

 

[Supertwang]

1. I’d prefer silver mica
2.I think some Fenders have 100uf/100v bias cap so I’m pretty sure 50uf should be fine
3. I use soft-jawed plyers to remove the jewel light and regular small channel lock plyers to remove the light fixture nut

 

[elpico]

It matters more with the little caps than the big ones IMO. Ceramic can be more problematic than mica, but both can work fine.

You can use a bigger bias supply cap. This is a decent one.

 

[DennisM]

1. I’d prefer silver mica
2.I think some Fenders have 100uf/100v bias cap so I’m pretty sure 50uf should be fine
3. I use soft-jawed plyers to remove the jewel light and regular small channel lock plyers to remove the light fixture nut

Thanks. I just screw the jewel light on hand tight. I'll have to try the small channel locks on the big nut on the back.

 

[GotA24Fretter]

1.On the 10pf, 250pf and 500pf, silver mica or ceramic disc? Or does it matter?

They'll perform nearly identically. A good quality ceramic cap is cheaper and more reliable than a low quality mica.

If you insist on mica, use heat sinking and work fast when installing them.

2. On the cap on the bias board, I'm having trouble finding a 25/100. Can I use a 50mf/100v instead without any problems?

The reissue you're reworking uses a 100μF. I've heard of cases where bias under filtering add hum to the signal. If you're going to use the same transformers, then expect to need to add a second cap to the bias input leg of the Intensity pot.

3. What kind of tool do you use to tighten and loosen the big nut on the pilot light assembly? Danged if I can get anything on it.

Tonecraft makes a specialty tool for this, but I'd imagine an adjustable wrench crows-foot would work fine, but better an appropriately sized open ended crows-foot.

 

[Pete Farrington]

.On the 10pf, 250pf and 500pf, silver mica or ceramic disc?

Ceramic caps aren't one thing.
There's maybe half a dozen different ceramic dielectric materials used, the particular one used for any particular cap depends on value, voltage, size, tolerance, voltage and temperature stability (coefficient), and microphony.
One cap product line might use different dielectrics to cover the range of values and voltages.
So to have a clue about what you're buying, the manufacturer's info must be checked, which means using a serious vendor that bothers to supply that info.

Ceramic capacitor - Wikipedia

en.m.wikipedia.org

I just screw the jewel light on hand tight.

Whatever you end up using, it must be tight and secure. If the lamp assembly moves / rotates, the heater supply might get shorted to the chassis, which will cause trouble and, if there's a grounded heater CT, might wreck the mains transformer.
Even if tight, it's good practice to line the inside of the chassis around the lampholder with some type of insulation.

 

[Nicko_Lps]

I'm converting my PRRI PCB to hand wired.

1.On the 10pf, 250pf and 500pf, silver mica or ceramic disc? Or does it matter?

2. On the cap on the bias board, I'm having trouble finding a 25/100. Can I use a 50mf/100v instead without any problems?

3. What kind of tool do you use to tighten and loosen the big nut on the pilot light assembly? Danged if I can get anything on it.

It seems that your questions are already answered and i agree with all the answers but...

Why would you ruin the PCB to make it handwired? A pcb is generally better in terms of noise until it starts to self destruct because our tube amps have excessive heat that they cant handle for too long..

My humble idea is leave it as it is, when your PCB starts failing, you kick in and make it hand wired

 

[sds1]

1) COG/NP0 ceramics are the best choice for these smaller values IMO in terms of cost and stability

2) 25uF, 50uF are legacy values, today you will more easily find 22uF, 47uF. 100uF is probably the right move here though

3) https://www.tonecraftaudio.com/fender-style-jewel-nut-wrench