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Hoffman Amps Forum image Author Topic: Help Indentifying Capacitor  (Read 3597 times)

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Offline whoops

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Help Indentifying Capacitor
« on: December 25, 2016, 09:54:19 pm »
Hi,
can you help me identify which type of capacitor in terms of "Dielectric Material" is the own shown in the attached picture?

I'm unsure if it is a Paper type or Polyester.

It's fitted in a mid 60's Gretsch reverb unit. The same type capacitor was used by Valco in Gretsch and Supro amplifiers.
The capacitor has "Standard" written. I dont know if "Standard" refered to the brand or to capacitor type.


Thanks

« Last Edit: January 10, 2017, 10:06:15 pm by whoops »

Offline dunner84

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Re: Help Indentifying Capacitor
« Reply #1 on: December 25, 2016, 11:49:34 pm »
I had the same ones in a 1950s Masco.. the wax type and the one you have in the photo. Sorry I can't help with the dialectric.

Offline whoops

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Re: Help Indentifying Capacitor
« Reply #2 on: December 26, 2016, 11:32:02 am »
This one I'm not sure if it's surrounded by a hard wax, or if it's a polyester type.
« Last Edit: January 10, 2017, 10:06:37 pm by whoops »

Offline Willabe

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Re: Help Indentifying Capacitor
« Reply #3 on: December 26, 2016, 03:55:02 pm »
Why do you want to know?

Offline whoops

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Re: Help Indentifying Capacitor
« Reply #4 on: December 26, 2016, 08:36:42 pm »
A lot different reasons.
Learning, curiosity and because I'm doing a service in a Gretsch unit I have and it's good to identify the caps that have an higher failure rate compared to others.

Are you familiar with these "Standard" capacitors? Any info to share?

Thank you

Offline HotBluePlates

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Re: Help Indentifying Capacitor
« Reply #5 on: December 27, 2016, 04:58:00 pm »
Never heard of "Standard Capacitor" but it sounds like a typical gimmicky name for the 40's & 50's.

Do you suspect the 1µF cap to be bad?  If so, you could always pull it out & cut it open (use rubber gloves in case any goo inside is hazardous).

For its size you know it's not electrolytic.  Could be metallized paper, could be a plastic film.

Offline sluckey

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Re: Help Indentifying Capacitor
« Reply #6 on: December 27, 2016, 05:09:56 pm »
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline whoops

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Re: Help Indentifying Capacitor
« Reply #7 on: December 27, 2016, 11:58:07 pm »
Never heard of "Standard Capacitor" but it sounds like a typical gimmicky name for the 40's & 50's.

Do you suspect the 1µF cap to be bad?  If so, you could always pull it out & cut it open (use rubber gloves in case any goo inside is hazardous).

For its size you know it's not electrolytic.  Could be metallized paper, could be a plastic film.

Well the unit is from 63, so I suspect from components drifting the values like resistors, and caps drying out, leaking, etc.

For the Resistors I'm just tracing the circuit with the schematic and measuring their value. I found some differences between the circuit and the schematic, could be due to later revisions in the schematic or in my unit, could also be production mistakes .

As for the Caps, I replaced all the Electrolytic caps already, the Filtering caps were long gone.
I left the Ceramic caps and two 1uf 400v "Standard" red colour caps (the one in the picture).
So to answer you question I don't have a particular reason at the moment to suspect this cap besides being and older unit so it's nice to be suspicious and measure everything while restoring in order to minimize future problems.

I dont have my ESR meter at the moment, but I can measure them for ESR, Capacitance and Leakage in the next days.

If this cap is Wax in Paper I would replace it in a pinch.
« Last Edit: January 10, 2017, 10:08:15 pm by whoops »

Offline whoops

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Re: Help Indentifying Capacitor
« Reply #8 on: December 28, 2016, 12:04:39 am »
Here's the perfect replacement for that cap...

https://www.tubesandmore.com/products/capacitor-musicap-400v-polypropylene-coupling

LOLOLOLOLOLOLOL

it's 13 dollars, but it's a MUSICAP!!!!!

Well, I have locally an old distributor of Philips electronic Components, they have a big stock from 30 years ago NOS parts, they never updated the prices in the last 20 years. So I can get Philips MKT Film capacitors for 13 cents, much better than 13 dollars. LOL

Although being high quality the Philips MKT are not Musicaps, but at least they are Orange, and it seems that people say that Orange coloured capacitors sound amazing!


Sluckey let me know if you need some Philips MKT capacitors, Polysterene or Polycarbonate.





Offline sluckey

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Re: Help Indentifying Capacitor
« Reply #9 on: December 28, 2016, 05:10:18 am »
Quote
it's 13 dollars, but it's a MUSICAP!!!!!
Oh no. The price starts at $13. The one you need is $21.95.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline whoops

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Re: Help Indentifying Capacitor
« Reply #10 on: December 28, 2016, 08:21:13 am »
Quote
it's 13 dollars, but it's a MUSICAP!!!!!
Oh no. The price starts at $13. The one you need is $21.95.

Well I took the $21.95 went out and bought all of these:

Offline whoops

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Re: Help Indentifying Capacitor
« Reply #11 on: December 28, 2016, 08:22:32 am »
Sluckey do you have any idea if the red 1uf "Standard" cap is a waxed type or plastic type?
Thanks
« Last Edit: December 28, 2016, 08:37:24 am by whoops »

Offline Scsoul

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Re: Help Indentifying Capacitor
« Reply #12 on: December 28, 2016, 01:12:49 pm »
I think those are Mylar what ever that is there super hard, I have some but there white with black ring. 

Offline whoops

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Re: Help Indentifying Capacitor
« Reply #13 on: December 28, 2016, 05:32:51 pm »
I think those are Mylar what ever that is there super hard, I have some but there white with black ring.

Thank you so much Scsoul

Do your caps also have "Standard" written on them?

Offline Scsoul

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Re: Help Indentifying Capacitor
« Reply #14 on: December 29, 2016, 08:54:35 am »
 Yes

Offline whoops

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Re: Help Indentifying Capacitor
« Reply #15 on: January 10, 2017, 10:12:36 pm »
I took some other capacitors from the unit out,
all have "Standard" written on them.

One of them says Mylar the others don't

I got suspicious that these might be Paper in Wax capacitors because of the paper/card that surrounds them.



 


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