View Full Version : Pot Roast Recipe


Winky Dink
09-26-2012, 01:58 AM
Ingredients:
2 .001mfd, 1KV mica capacitors
2 .001 mfd, 630V poly capacitors
1 12,000 ohm, 2 watt resistor
1 20,000 ohm, 1/2 watt rotary potentiometer.

1. In a medum-size steel chassis, remove two .001 mfd, 1KV mica capacitors, and replace with two new .001 mfd, 630V capacitors.

https://lh6.googleusercontent.com/-BKrtwyPtMPE/UGKLa4YUAjI/AAAAAAAAKFU/-BeQfQ9t3qc/s640/H01Mica%2520Caps.jpg

2. Set power to "on."

3. When wax starts to drip off the 2-watt resistor, set the power to "off."

https://lh4.googleusercontent.com/-R-krWPbTlGA/UGKLYKfJMSI/AAAAAAAAKFM/_X93iC_inPg/s640/H02%2520Pot%2520%2526%2520Resist.jpg

4. Voila! In less than two minutes you have roasted a pot!

https://lh6.googleusercontent.com/-_58sucxYKVs/UGKLWC7_5UI/AAAAAAAAKFE/tOdFdv9eFRg/s640/H03%2520Pot%2520Roast.jpg

I might try to repair it, but in the meantime I'm looking for a replacement. It's a 20K, 1/2-watt pot, and this is the most likely replacement I've found. Any other suggestions?

https://lh4.googleusercontent.com/-MVxBiS54p0Q/UGKgDhULe4I/AAAAAAAAKFs/Yfq0mF99_cA/s640/H04%2520Alpha%2520replacement.jpg

And while I'm here, I was looking for 1KV & up caps on Antique Electronic Supply, but got stymied by this:

https://lh4.googleusercontent.com/-IwhqDW452m0/UGKLbUPEkhI/AAAAAAAAKFc/xGDClWsPP88/s640/AES%2520Caps.jpg

Am I wrong, or are they mixing up uF, pF, and nF?

Thanks for your kind attention.

- Winky

snelson903
09-26-2012, 04:52 AM
pot roast ,i like that. i would just replace it heat destorts things ,it might even have changed value now depending on how hot it got.

Winky Dink
09-26-2012, 09:29 AM
It was actually 18.5Kohms before. After roasting it was linear 0-300 ohms, then a jump to 35K-47K.

Eric H
09-26-2012, 01:44 PM
Are you sure those were Mica Caps?

Micas rarely need replaced, you should also replace Mica with Mica, not Film Caps and never use a lower voltage that what was in there.

Some caps that look like Mica aren't really, there's a way to tell by the color coding but I'd have to Google to find the chart.

Pretty sure the AES chart is a misprint, a 2.2 Mf 2000 volt Ceramic would be huge, you also don't want to use Ceramics to replace Film or Paper Caps in most applications.

2200Pf would only be 0.0022 Mf

Here's a Pf to Mf converter, it works both directions actually.
http://www.convertunits.com/from/microfarad/to/picofarad

N2IXK
09-26-2012, 02:19 PM
a 2.2 Mf 2000 volt Ceramic would be huge

A 2.2 megafarad cap would be huge no matter what the dielectric was...:D

Even a 2.2 µF cap wouldn't be a ceramic disc.

Winky Dink
09-26-2012, 02:59 PM
No, I'm not sure they were mica caps, and I've never before considered replacing ceramic or mica. This was a last-gasp attempt to correct a problem with the horizontal hold by replacing every component that I couldn't verify for certain. The lower voltage rating was my mistake--I just forgot. As soon as I turned on the set I noticed that I'd lost some horizontal size, took a few seconds playing with controls before I noticed the wax melting on the resistor--that's when I remembered the original caps were rated 1 KV.
- Winky

Dude111
04-08-2024, 10:29 PM
I like easy recipes like this!!

Now to get the stuff to make it :)