Amp Guys! Help on ordering Pots, Resistors etc...

[Guest]

I'm going to change the input jack (It's sloppy and worn down) and while I'm in there maybe also the plastic pots and install a real Jewel Light on my Pro Junior. Before touching anything I have to drain the caps on it.

BTW, I will keep the original red led inside the new Jewel and will not wire a jewel light lamp in there. No need to do extra hassle with that since I want it red anyway

Well, according to the "Unofficial Fender Hot Rod Guide" http://studentweb.eku.edu/justin_holton/caps.html you can discharge the caps by using a resistor to connect the caps + and - poles together. A question though, is the discharging done to every cap or are they wired so that doing it on one will drain everything?

So, I need a resistor... the UFHTG points out that I need a "Xicon 25K 10W Cement Power Resistor". There aren't exactly any Radio Shack around the corner in this country so I'm best of ordering. I found this finnish amp builder webshop where I'm thinking about ordering pots and such from. I can't find any 25k 10W resistors... Am I a lousy searcher or do they not have any?

Webshop link:
http://www.uraltone.com/kauppa/index.php?language=en&XTCsid=7c0bad3d4844337a922b444c4628c882

Could you also help me with which pots I need to order. Log/Audio, 250k/500k etc?

So basically I need help with the following on my orderlist:

1x 25k 10W resistor or a resistor with a value that discharges the Pro Juniors caps to a safe level.

2x CTS Pots

1x Switchcraft jack (I have that allready)

1x jewel light and holder (I know which)

3x push back clothwire spools (three diffrent colors, I know which)

Would be awsome if you guys could help me out on this! It will be my first work on a tube amp.

 

[kmcguitars]

Re: Amp Guys! Help on ordering Pots, Resistors etc...

The way You describe discharging caps in your diagram it a new one to me? I prefer to use a Alligator clip with one end on the + side of the cap and the other I touch to the chassis w/t the resistors (i.e. Ground) Techs can discharge all caps at once, But this is not a good idea for D.I.Y.ers. There are many vendor's online to get parts from. www.hoffmanamps.com ,www.tedweber.com
BTW, Read up some more B4 you discharge your caps. Pay attention to safety warnings.

 

[greco]

Re: Amp Guys! Help on ordering Pots, Resistors etc...

I am just learning electronics and am building my first "big" project..... a Champ clone tube amp.

There are many ways to discharge caps.

The resistor you are looking for is a power resistor and you don't need to go to the trouble/expense of getting it for the
amount of disharging you will need to do.

The advice I was given was to wire (don't use very light gauge wire...I'd go to about 14 or 16 stranded) a 100 watt light bulb socket between (with a bulb ) to two leads with alligator clips on each end. Then just do as the diagram shows.

Others might offer a variety of suggestions. I'll be reading with interest also.

I would do each cap (mainly the large ones) by itself, I'm not so sure that all caps can be discharged at once...this is news to me.

Please read up on this (as advised by kmcguitars) for your safety.

Dave

 

[greco]

Re: Amp Guys! Help on ordering Pots, Resistors etc...

Bump

Hoping that an amp builder, EE, etc. comments also as safety is an issue.

Thanks

Dave

 

[Guest]

Re: Amp Guys! Help on ordering Pots, Resistors etc...

Another bump for this thread!

Also, what CTS pots should I used?

 

[greco]

Re: Amp Guys! Help on ordering Pots, Resistors etc...

You will probably need to replace the pots with the same value as the amp has now (it will be written on the back of the pot...eg 50K, 100K, etc).

I think that you should use audio/log taper (not linear) but I'm fairly sure that this isn't too critical.

You might also need to get pots of the same diameter if space is limited on the chassis panel. CTS pots (for guitars) are about 25 mm. in diameter

Still hope the you get comments from others that are more experienced/qualified.

Good luck with the mods.

Dave