Blue dipped ITW caps (salvaged from Fender PA head SF)

ElectronAvalanche · Post by **ElectronAvalanche** » Sun Jul 03, 2011 4:12 pm

Hi gang,

before using some of these in my 70s Hybrid I thought I ask if somebody has used these in Dumble style circuits.

I tried them in the past, but could not for the life of me find anything special.

The caps are marked ITW and are sort of like Blue drops from a 70s silver-face Fender PA 100 head.

Thanks for any info on these!

Electron

Structo · Post by **Structo** » Mon Jul 04, 2011 4:27 pm

Most likely polyester.

I remember someone saying that the earlier polyester molded caps sounded different (better?) than the currently made Orange Drop polyester caps.

I would probably try them after checking for leakage.

ElectronAvalanche · Post by **ElectronAvalanche** » Mon Jul 04, 2011 5:17 pm

Thanks Tom!

but how to test leakage? I have a scope somewhere and a VM of course.

I searched the web and testing seems to be a bit of a hassle. I could use clips and hang the caps in my other amps from a B+ and then test for DC leakage with my VM?

Leakge has to be tested at operating voltages right?

Cheers,

Electron

thyx · Post by **thyx** » Tue Jul 05, 2011 2:26 pm

Yep. One end to a B+ of working voltage, the other end to a VOM set to read voltage. Depending on the internal resistance of the VOM, you shouldn't see anything more than a fraction of a volt. Those blue-drop caps are actually pretty good in terms of reliability and being non-microphonic.

groovtubin · Post by **groovtubin** » Wed Jul 06, 2011 1:53 pm

ElectronAvalanche wrote:Hi gang,

before using some of these in my 70s Hybrid I thought I ask if somebody has used these in Dumble style circuits.

I tried them in the past, but could not for the life of me find anything special.

The caps are marked ITW and are sort of like Blue drops from a 70s silver-face Fender PA 100 head.

Thanks for any info on these!

Electron

NO problem using them sparingly in my builds, like the pi secondary feed, and hrm ts..

ElectronAvalanche · Post by **ElectronAvalanche** » Thu Jul 07, 2011 7:20 am

Hi all,

thanks for the tips! I will try them in the PI and TS for this build!

Cheers,

Electron

ChrisM · Post by **ChrisM** » Thu Jul 07, 2011 2:05 pm

Thanks for this thread! Just got a bunch the other day, didn't know if they were any good.

renshen1957 · Post by **renshen1957** » Thu Jul 07, 2011 2:45 pm

ElectronAvalanche wrote:Thanks Tom!

but how to test leakage? I have a scope somewhere and a VM of course.

I searched the web and testing seems to be a bit of a hassle. I could use clips and hang the caps in my other amps from a B+ and then test for DC leakage with my VM?

Leakge has to be tested at operating voltages right?

Cheers,

Electron

Hi

Check out ebay for a tube powered capacitor tester (Heathkit). These work at B+ voltages.

Best Regards,

Steve

The Amp Garage

Blue dipped ITW caps (salvaged from Fender PA head SF)

Blue dipped ITW caps (salvaged from Fender PA head SF)

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