my Cyrus 1 history

[jamal]

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

[jamal]

[jamal]

I doing some "improvement" on my Cyrus 1. I replaced the D3 & D4 with a transdiode.

[jamal]

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.

[sumaudioguy]

Yah the Cyrus is by far the best cheap amp out there "walking the dog" on amp 20 times the price. That NP 470µF 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!

[jamal]

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.

Originally Posted by sumaudioguy

Yah the Cyrus is by far the best cheap amp out there "walking the dog" on amp 20 times the price. That NP 470µF 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!

[sumaudioguy]

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.

[jamal]

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?

[Sherloq]

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!

[jaycee]

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.