Cap question, similar values - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 26th November 2011, 06:12 PM   #1
diyAudio Member
 
Join Date: Apr 2002
Location: Salt Lake City
Default Cap question, similar values

Please forgive this question:
I broke off the cap attached to my NOS power switch, and think these are the values I read.
From the original power switch, the value
.01M
Z5U

The new NOS cap reads, (I think)
BC Z5U 1.03M 1 kV

Do these seem similar? Am I reading the second one incorrectly?

Of course, the only decent electronic shop in Utah is closed for the holidays this weekend, so it is the Radio Shack for me. What values can I go with that will work with this? I assume it is just used to block the surge and protect the speakers, right?
Thanks again.
Clueless but not solderless in Utah
  Reply With Quote
Old 26th November 2011, 06:59 PM   #2
diyAudio Member
 
thaumaturge's Avatar
 
Join Date: Aug 2011
Location: Utah
Hello also from Salt Lake. The cap on the power switch likely helps prolong the life of the switch by suppressing contact arcs. The second listed is not the same. The first is a 0.01uF and the second a 1.03 (or just over a hundred times the value.)
Unit should function fine without the cap till Monday.
Doc
__________________
Ne timeas a facie mulierum ea ignorare
  Reply With Quote
Old 26th November 2011, 07:29 PM   #3
diyAudio Member
 
Join Date: Apr 2002
Location: Salt Lake City
Thanks, Doc
Was hoping to get it all done today.
I knew they couldn't be the same value...but both toggle type power switches were original
for this Dynaco PAT-5, and then changed by Frank VanAlstine to a Transcendence Series Two preamp. Circa 1986
One board next to the trannie was a bit scorched. I asked Frank about it...

Later we found a better way of getting rid of the excess voltage and heat. We simply wired the power transformer for 240V operation. Then when used on 120V as intended, this cut the operating voltage in half and made the output of the power transformer much easier to manage without the need for huge high wattage hot running power resistors.

Which I think my electronic friend and I can figure partly, but my friend had this question for Frank:
I suspect that if you drop the power transformer output voltage, then you'll want to reduce the value of the power resistors as well. Did Frank give you new values for that?
No answer from Minnesota. The wind blows cold and empty...
Lyndon
  Reply With Quote
Old 26th November 2011, 07:49 PM   #4
diyAudio Member
 
indianajo's Avatar
 
Join Date: Jan 2010
Location: Jeffersonville, Indiana USA
Modern caps are marked with 2 significant digits and a power of 10 in picofarads. So your new cap, if it doesn't have a decimal point (it probably doesn't) is 10*10^3 picofarads, or 10000 picofarads, or 0.01 microfarad. Same value. Modern "M" is a voltage rating, pretty high one. The old "M" is microfarads, replaced since about 1980 with a "u" which is not greek to me. Modern practice is to use a UL rated "X2" cap for switch bypass, but the old way is to put a 1000 V rated cap on the switch. You can get 600 V transients on the 120 vAC line, is why the 1000V rating. I lost a 1000V rated .01 uf across my power switch probably due to lightning years ago, also bridged the switch (toasted plastic) but no damage to the PAS2 power transformer.
Z5U is the type of ceramic insulator, a budget one but stable capacitance over temperature is not required for a function like this.
__________________
Dynakit ST70, ST120, PAS2,Hammond H182(2 ea),H112,A100,10-82TC,Peavey CS800S,1.3K, SP2-XT's, T-300 HF Proj's, Steinway console, Herald RA88a mixer, Wurlitzer 4500, 4300

Last edited by indianajo; 26th November 2011 at 07:54 PM.
  Reply With Quote
Old 27th November 2011, 04:03 AM   #5
diyAudio Member
 
thaumaturge's Avatar
 
Join Date: Aug 2011
Location: Utah
I stand corrected.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
choosing cap values for aikido jayme Tubes / Valves 2 25th October 2006 02:09 AM
Coupling cap. values??? stoo Tubes / Valves 1 8th January 2006 04:39 AM
Determining cap values (old radio) Sherman Tubes / Valves 6 15th October 2004 11:44 PM
Question about Bride of Zen Cap Values Shoog Pass Labs 3 26th November 2002 10:41 PM
Cap voltage values Yoda Solid State 4 6th September 2001 12:08 AM


New To Site? Need Help?

All times are GMT. The time now is 06:08 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2