Need help with caps for new Express build

[lgehrig4]

I'm starting a new Express build. So far it is just in my mind but I did pick up a small lot of NOS caps (Mallory PVC, CDE) hoping that some would be the correct values for this project.

I think I may have 4 different caps that I can use but I need to make sure.

Starting with my Mallory PVCs. Whats written on the caps are close, but not exact to the parts list I downloaded here.

Parts list I have
.002 .0022
.022 .02

Are these what I need? I've built a JTM45 but I am not a tech/engineer so it's little things like this that leave me scratching my head. My gut says I have the right ones.

Next up is a Mallory Electrolytic

Parts List I have
Mallory 25V/22uf Mallory 25V/25uf

This close enough?


Last question is for one of the silver micas. I know I have the correct one, but I don't know which it is the way it's written on the cap

Parts List I have
500V/500pf 500V / 3000 +/- 5%
510 +/- 5% 500AE

Which is the 500pf?


Thank you!
Jeff

p.s. where can I purchase the correct caps for this project or other proven brands? I want to stick as close to the originals as possible. I've already decided on Pacific tranformers based on what I've read.

[Colossal]

Hi Jeff,

Welcome to the forum. Not trying to just pick on you right off the bat, but the search function will answer all of your questions. There is a vast, vast amount information that will keep you up for 3 weeks straight reading if you don't mind not sleeping.

Also as a primer, check out the AmpGarage Trainwreck Files section. This is the one-stop shopping spot where specifications documents are posted that answer the questions that most everyone joining and wanting to build a Trainwreck ask. Once you have read every thread in the Files section, then start searching to answer the questions that are generated after reading the files.

Trainwreck Files section:
https://tubeamparchive.com/viewforum.php?f=3

Everything you need to know:
https://tubeamparchive.com/viewtopic.php?t=5691

Mallory PVC caps and Pacific transformers:
http://datasheet.octopart.com/PVC16115- ... 111029.pdf

PVC series polyester caps are completely out of production, long gone. All of the easy to get last stock is now gone. RJ, a member here is your best bet for any remaining stock as well as Pacific transformers. He was our primary source but he has taken a hiatus so I'm not sure if he is doing business but you can reach him here:
http://rjguitars.net


Yes, your Mallory 22uF/25V are fine for cathode bypass. If you want to build an Express, don't change any part values. Use exactly what is on the schematic get it working, then tweak. Not quite sure what you mean by 'which is the 500pF' (post a photo). A typical 500pF mica will say 500 ± 5%.

Good luck!

[lgehrig4]

I understand what you are saying and believe me I've done my fair share of searching and printing.

I have the shcematics, diagram and parts list. I wanted to know if the values written on my capacitors were the values needed. For example I have a .0022 and the parts list calls for a .002. Is that considered the same value? I know it may sound like a dumb question to most here but I don't have a background in electronics and don't know if older caps or different brands have slightly different ways of printing values on their caps. These are little things you learn along the way that you won't necessarily find in a book or the internet.

As far as the PVCs I did know that they were discontinued, but I was hoping there were stashes like mustard caps and NOS tubes.

[M Fowler]

Yes that is close enough value in caps.

I got mine from rjguitars and I rarely see these PVC caps even at surplus houses. Unless someone bought out rj he should still have some caps.

I might have enough for one build as well I can look.

Mark

[lgehrig4]

Thanks Mark that would be great! I had actually emailed rjguitars. I'll just take it slow and grab what I can find. I want to take my time because there are still things I need to learn about this build. The JTM45 I built came out great but from what I am reading this one can be finicky. Love a challenge though

[M Fowler]

I got an email from rj yesterday so he's still kicking around the shop.

Keep me posted and I'll see what I can find.

[lgehrig4]

He replied to me and it sounds like he only has chassis so I'll pretty much be needing everything else. If you find some stuff you don't mind selling let me know. I'll keep watch in the emporium here, the gear page and Ebay. No rush.

[M Fowler]

okay I'll get back to you.

[M Fowler]

Here is what I have on hand:

PVC .022/600v have 2 you need total of 4

PVC .0022/600v have 1 you need 1

PVC .1/600v have 3 you need 3

Mark

[lgehrig4]

Sent you a pm

[M Fowler]

Got it and right back at you

[lgehrig4]

Ok, so I was finally able to view that Mallory data sheet (computer issues). So there is a .002 and .0022. In your experience would that .0002 make much of a difference in an Express build?

I'm surprised there are values so close together. Don't caps in general have tolerances that would make that little of a difference in value a non-factor anyway?

[Reeltarded]

It makes a 100% difference in what side of tolerance you are going to land on.

Coupling... Yes. It will make a difference that you probably won't care about even a little bit, unless you think an Express already sounds kind of thin.