my Cyrus 1 history - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 20th September 2010, 02:35 PM   #1
jamal is offline jamal  Singapore
diyAudio Member
 
Join Date: Sep 2010
Default my Cyrus 1 history

hi, I bought a Cyrus 1 in the 80's. just after the warranty the transformer when bad and I bought a replacement. in the 2nd year the selector switch got problem. actually alot of dirt have went into the selector switch. so I take it out and soak in a cleaning solution. After soldering it back, I cover it with some electric tape also the volume and balance control. take note, till today the problem did'nt show up again.

after 10 years of service the output transistor when bad. I repair it. it work fine till today. last week I change all the electolytic capacitor and the diodes. the rectifier diode were upgrade to 6A type. but I can't get the 470uf non polarise capacitor. still looking a around for it.
also upgrade the reservoir capacitor to 10000uf. I change all the RCA or so call phone socket to gold plated version. I drill a bigger holes so that all the RCA can fit in. The speaker output were also upgrade to gold plate version.
now I am enjoying the fruit of my labour
  Reply With Quote
Old 21st September 2010, 02:26 AM   #2
jamal is offline jamal  Singapore
diyAudio Member
 
Join Date: Sep 2010
Click the image to open in full size.
  Reply With Quote
Old 23rd September 2010, 08:44 AM   #3
jamal is offline jamal  Singapore
diyAudio Member
 
Join Date: Sep 2010
I doing some "improvement" on my Cyrus 1. I replaced the D3 & D4 with a transdiode.
  Reply With Quote
Old 29th October 2010, 04:27 PM   #4
jamal is offline jamal  Singapore
diyAudio Member
 
Join Date: Sep 2010
with the Marantz CD 6300 player, plus some mod on the CD player. the Cyrus 1 sing a great song. incredible indeed the Cyrus 1. and I am turning up my chipamp ,it is coming closer to the Cyrus 1.
  Reply With Quote
Old 29th October 2010, 09:29 PM   #5
diyAudio Member
 
sumaudioguy's Avatar
 
Join Date: Jan 2010
Location: Midwest U.S.A.
Yah the Cyrus is by far the best cheap amp out there "walking the dog" on amp 20 times the price. That NP 470F you are looking for... you could use a Nichicon Muse or I just used a regular Panasonic FM because the DC there is only about 120mV. All aluminum electrolytic capacitors are non-polar up to something just over a volt. Would have to look up the exact voltage but with the low DC found there a polar works fine..

Best of luck!
__________________
What the other guy said----Standing on the shoulders of giants.
New avatar- no more little array
  Reply With Quote
Old 30th October 2010, 12:32 PM   #6
jamal is offline jamal  Singapore
diyAudio Member
 
Join Date: Sep 2010
hi thanks, the cyrus 2 with basically the same circuit ,did not have the 470uf 6v capacitor as the Cyrus 1. that drawing is issue 2006. but some friends did reported here in this forum that their Cyrus 2 indeed was install with 470uf 6v non polar capacitor. now I am bit confuse. I think it will work fine without the capacitor. as reported in this forum, putting a polar cap ,will cause the cap to go hot, coincidentally ,I have gone thru many amplifier circuits. none of them utilize such a high value of 470uf in their feedback path. May be this is the reason Cyrus remove the cap on issue 2006 onward. just a guess.

Quote:
Originally Posted by sumaudioguy View Post
Yah the Cyrus is by far the best cheap amp out there "walking the dog" on amp 20 times the price. That NP 470F you are looking for... you could use a Nichicon Muse or I just used a regular Panasonic FM because the DC there is only about 120mV. All aluminum electrolytic capacitors are non-polar up to something just over a volt. Would have to look up the exact voltage but with the low DC found there a polar works fine..

Best of luck!
  Reply With Quote
Old 31st October 2010, 02:38 AM   #7
diyAudio Member
 
sumaudioguy's Avatar
 
Join Date: Jan 2010
Location: Midwest U.S.A.
I fixed one and replaced the NP with the one mentioned and no the cap did not get hot or show any other problem and worked and sounded fine. If the cap gets hot then there is something else wrong with the amp. Hot cap means more than the 120mV there (or oscillation) which means there is a balance problem in the amp which also needs fixed. Seems to me if the cap gets hot then blaming the cap for the problem still does not fix the real problem with the amp.
__________________
What the other guy said----Standing on the shoulders of giants.
New avatar- no more little array

Last edited by sumaudioguy; 31st October 2010 at 02:46 AM.
  Reply With Quote
Old 31st October 2010, 01:51 PM   #8
jamal is offline jamal  Singapore
diyAudio Member
 
Join Date: Sep 2010
I have no problem with the cap. I just wanna change cos it is old. it were reported by a guy here in this forum that the cap get hot. btw if polar cap work fine, why do Cyrus take the trouble to put a expensive non-polar cap in the first pace?
  Reply With Quote
Old 1st November 2010, 11:57 AM   #9
Sherloq is offline Sherloq  United Kingdom
diyAudio Member
 
Join Date: Oct 2009
Hi guys, this seems to be the most up to date Cyrus One post around so thought I'd ask a quick one here:

Basically my quick blow fuses went a couple of weeks ago, and after identifying the dead transistors I worked back to find that pretty much everything past the Q31/Q33 drivers was pretty much gone. So i'm now in the process of replacing the transistors and the resistors inbetween. I've came to a bit of a confusing section in the user manual: The schematic shows R93, R95 and R97 as being 100ohm resistors - but the parts list shows them as 120R. The ones currently installed are 100 ohm from the color bands and doing some tests on the working ones. So what should I replace them with 100R or 120R?

Thanks for the help!
  Reply With Quote
Old 1st November 2010, 06:54 PM   #10
jaycee is offline jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
100 ohm. although i wouldn't say theres much in it. Do you know why the transistors failed? They usually dont "just fail"... its either due to a short on the output, or being run too hard and overheating.
  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
Cyrus 3 / Cyrus III amp help contax Solid State 12 23rd October 2010 01:53 AM
History of JBL jackinnj Everything Else 0 24th August 2010 02:38 AM
WTB Cyrus 1 or Cyrus 2 amplifier monstertrucker Swap Meet 0 20th November 2008 01:04 AM
Warfedale history anyone? Pbassred Multi-Way 1 13th January 2007 12:05 AM


New To Site? Need Help?

All times are GMT. The time now is 06:51 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