Cyrus 2 Resistors

[stoolpigeon]

Geoff, thanks for going to all that trouble to check your old Cyrus 1. It makes my repair easier, and thanks for the circuit too.

Can I ask how critical is the size of that big 470uf NP cap?

Just for the record my pcb is marked CEN C 86 16 and I also think the 1 sounds better than the 2. I thought that when I got the 2 but I guess back then I was swayed by testosterone.

Cheers, SP

[Geoff]

Originally posted by optimiser The issue 07 Cyrus Two has a problem with a noisy input selector switch, which I have sprayed with contact cleaner, but it will need replacing in time.

Is there a recommended replacement part for the input selector switch, and where is best place to purchase and part number?

I have had similar problems and when I searched about five years ago I was unable to find a supplier of suitable replacement switches. In my case this did not matter too much as I only used one source and so just bypassed the selector switch completely.

However, I have a vague recollection that a year or two back someone posted (I think on this forum) the part number and a supplier for these Alps switches. I will try to see if I can find this again.

[Geoff]

Originally posted by stoolpigeon
Geoff, thanks for going to all that trouble to check your old Cyrus 1. It makes my repair easier, and thanks for the circuit too.

No problem.

Can I ask how critical is the size of that big 470uf NP cap?

The value is higher than that strictly necessary to provide the required time constant for good low frequency extension but, IIRC, Doug Self has opined that using a larger than necessary capacitor in this position can help to minimise distortion.

IMO you could probably reduce the value to 220uF without noticing any difference and you could certainly increase it to 1000uF. The quality of this capacitor is important to the sonics, Cyrus used either a Nichicon Muse BP or an RDE EKU. When I wanted some replacements I was unable to find anything other than cheap (Chinese) bipolars here in the UK so ended up having some Panasonic SUs sent over from the States. Hopefully you have some better suppliers in Oz.

[Geoff]

Originally posted by optimiser Is there a recommended replacement part for the input selector switch, and where is best place to purchase and part number?

Originally posted by Geoff
However, I have a vague recollection that a year or two back someone posted (I think on this forum) the part number and a supplier for these Alps switches. I will try to see if I can find this again.

See Posts #6 and #11 in the following thread:

Mod Cyrus II power train for PSX?

[GEirin]

Hi all.
Cyrus 1 output stage is not similar at Cyrus 2 output stage. Why?
Anybody can explain cyrus 2 output stage? This arrangement will sound better?
Thanks.