Quicksilver 8417 power supply caps? - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 21st October 2004, 04:59 PM   #1
popeye4 is offline popeye4  United States
diyAudio Member
 
Join Date: Aug 2004
Location: Boulder Creek, CA
Default Quicksilver 8417 power supply caps?

One of the power supply caps in one of my Quicksilver 8417s is leaking. The caps are marked "320 MFD 450V" and "650MFD 450V" and are Mallorys. I've seen references that these were oversized for this application. I need to replace at least one (and might as well replace them all) so I have a couple of questions:

1. Does "MFD" mean microfarad, millifarad, or (highly unlikely) megafarad? I'm not an electrical type, but my understanding of prefixes on units is that a capital "M" means mega, which doesn't make sense here (I'm a chemical engineer and even I know that a megafarad would be HUGE).

2. What size replacement(s) do you recommend and where can I get them?

3. The circuit diagram posted elsewhere on this site doesn't agree with the configuration of the amps I have (it shows two 330 uF/475V caps in the power supply).

Again, thanks for your help and advice in advance.

Doug
  Reply With Quote
Old 21st October 2004, 05:52 PM   #2
diyAudio Member
 
Brett's Avatar
 
Join Date: Jan 2002
1: Microfarad.
2:a: Same as what's in there.
2:b: Dunno, sorry, I'm not in the US.
3: The different circuit could simply have been a revision. Quicksilver are a small company and can change their designs slightly, maybe because an original part is no longer available, or they found something better. Not having the two schems in front of me, it could simply be that they're using two 330u in parallel to equal the 650u. Email them and ask.
  Reply With Quote
Old 22nd October 2004, 12:17 AM   #3
diyAudio Member
 
Join Date: Nov 2002
Greetings to a fellow Quicksilver owner.

I would check Mouser 1-800-346-6873 or Digi-key 1-800-DIGI-KEY

1-800-344-4539 If they don't have what you need I will post so others to check.

Hope this helps

Joe
  Reply With Quote
Old 22nd October 2004, 12:20 AM   #4
diyAudio Member
 
Join Date: Nov 2002
It seems that another owner has replace a set of caps on your amps. The schematic shows (2) 320 MFD caps @ 450V which is what both of my sets of "Quickeys" have. The caps are in parallel on both sets that I have.

Joe
  Reply With Quote
Old 22nd October 2004, 12:30 AM   #5
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Hi,

The higher capacitance behind the choke doesn't hurt but in any case this drawing shows what they're like "factory fresh" so to speak:

Cheers,
Attached Images
File Type: jpg qs8417ps.jpg (43.2 KB, 322 views)
__________________
Frank
  Reply With Quote
Old 22nd October 2004, 12:36 AM   #6
diyAudio Member
 
Join Date: Nov 2002
Frank is correct and I am wrong, sorry

Thanks Frank for correcting my error.
  Reply With Quote
Old 22nd October 2004, 05:57 AM   #7
popeye4 is offline popeye4  United States
diyAudio Member
 
Join Date: Aug 2004
Location: Boulder Creek, CA
All,

Thanks for your replies. I also dug deeper into one of the earlier threads (a 99 message one, ugh) and found some reference to replacing the front cap with one in the 100 uF range and running up to 750 uF cap on the back side of the choke (pi circuit). Mike Sanders also just sent me a note back that I could use 300 uF in both slots (he doesn't have the higher capacitance unit any more), so it sounds like the actual values aren't that critical (as long as I don't go higher than the 320 uF on the front side and stay above the 450V rating).

So, if I replace the front cap with anything from 100 uF to 320 uF and the back cap with anything from 300 uF to 750 uF it should work fine, right? Of course I'd prefer to just leave it like it is as they sound pretty darned good as-is.

Sorry for the basic questions, but Circuit Design was PFM to me in college.....

Thanks, Doug
  Reply With Quote
Old 31st August 2005, 02:31 PM   #8
diyAudio Member
 
Join Date: Nov 2004
Location: Mount Isa, Queensland
Hi All,

I've been following any posts I could find on Quicksilver 8417 Monos. Information seems to be scarce,so the posts on diyAudio Forums is most appreciated.
I have just replaced a Mallory 320mF 450v cap that leaked, taking out one of the Phillips 8417s. It can join the other saved 8417s that I will try to match up when needed (I initially biased too high. Have since been advised 80ma).

You can get the 320mF Mallory from Mouser, catalogue number: CGS321T450V3C.
However I replaced mine with a Vishay/Sprague 380mF 450 volt, as that was all I could find at the time (measures over 400mF).
After seeing this thread I phoned a fellow who repairs Quicksilvers and he asssured me that there will not be a problem with the higher value.
My Q/S are early 6volt heater models that have been professionally modded. It has an 850mf cap on the cathode side of the choke and a 320mF on the other side in // with 200mF but separated by a 33k 2w resistor. It now uses only one 5AR4.

What do you think of the following? The repairer says the GE 8417 needs a 5.5 volt heater supply or they will have a short life, and should not be used unless the supply is dropped 1volt. I have quite a few GE 8417s standing by.

Space is short for more.

Audie.
  Reply With Quote
Old 31st August 2005, 06:03 PM   #9
diyAudio Member
 
Join Date: Nov 2004
Location: Mount Isa, Queensland
Hi All,

The Quicksilver repairer mentioned a few changes he has made to his own Q/S Monos, which may be of interest.

100mf 500volt Elna Cerafine for both caps. He prefers the sound to that of the larger caps.

0.22 mF coupling cap and 100k bias resistor. This gives good bass, speed and stability. He uses GE 8417 which he prefers to the Phillips/sylvania 8417.

He prefers the sound with 80mA bias. As a bonus, the tubes will last longer ( I already use 80/85mA ).

He advises a 1 amp ( 240volt ac ) main fuse for better protection.
( I will adopt this. I use a Variac to ramp the voltage up and down, so will not get the possible occasional blown fuse at startup).

Audie.
  Reply With Quote
Old 31st August 2005, 06:47 PM   #10
diyAudio Member
 
dsavitsk's Avatar
 
Join Date: Jan 2005
Location: Hartford
Quote:
Originally posted by billabong
What do you think of the following? The repairer says the GE 8417 needs a 5.5 volt heater supply or they will have a short life, and should not be used unless the supply is dropped 1volt. I have quite a few GE 8417s standing by.
The datasheets (http://tdsl.duncanamps.com/show.php?des=8417) seem to say 6.3V for the heaters, but maybe the reparer has some special knowledge of this tube?
  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
Quicksilver 8417 conversion Original Burnedfingers Tubes / Valves 25 18th December 2011 11:33 AM
Quicksilver 8417 question john65b Tubes / Valves 1 24th October 2008 08:40 PM
Quicksilver 8417 a class C amp? Original Burnedfingers Tubes / Valves 4 10th October 2006 02:19 PM
quicksilver 8417 hum dreaded 42 Tubes / Valves 4 11th September 2003 03:45 AM
Quicksilver 8417 dreaded 42 Tubes / Valves 4 5th September 2003 12:14 AM


New To Site? Need Help?

All times are GMT. The time now is 03:16 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