Cyrus 1 amp

[lrseries3]

Hi, anyone know how to determine the polarity of old Elna caps? They are orange electrolitics but have no indication of the negative side.

Thanks Stuart

 

[Iain McNeill]

Look at the shape of the leads bonding onto the cap. Are they different?

If the cap is perfectly symmetrical in every way then it might be bipolar.

 

[lrseries3]

Yes, as new they electrolitics have a short and long leg, but once they go into a circuit they are trimmed you have no idea using this method which is which. I doubt they are bipolar, their physical appearance shouts electrolitic.
Stuart

 

[lrseries3]

Mmmm, but they're not electrolitics it seems after consulting the schematic! What are they and how does one specify them in order to replace?

 

[richie00boy]

I thought they were marked, but it's been a few years now since. You can work it out from the schematic, it's available on here and elsewhere online if you do a quick search

 

[lohk]

All those small orange Elna elcaps on the Cyrus 1 board are in fact bipolar (ELNA CE-BP).

 

[lrseries3]

Thanks lohk, found a source to purchase replacements.

Stuart

 

[lrseries3]

Hi,
Anyone know what the big brown ones are that are hiding under the strap in the middle or the board are? The markings are 47016 (470R ??), x1 EKU, ROE (ROEDERSTEIN?).

Thanks
Stuart

 

[daccordimark]

Hi,
They are indeed Roederstein 470uF/6V bi-polar electrolytics. I'm still looking for suitable replacements for my own Cyrus 1 amp. I've replaced a bunch of the caps already with Black Gates (I now realise these probably aren't the best type to use in an amp) but I'm struggling to find anything to replace the Roedersteins.
Regards,
Mark.

 

[lrseries3]

Hi Mark,

I have contacted Farnells NZ to see what they can come up with.

Stuart

 

[jaycee]

You can, at a push, use ordinary electrolytic capacitors - the voltage at this point is so small that polarity is irrelevant. Also any 470uF bipolar would work, 16v ones would be fine as long as they fit the space.

 

[lrseries3]

Hi,

Go to this site and see what you think. They are bipolar electrolytics, Panasonic ECEA1CN471UE and may prove suitable. Next to find a source!

Type A series Bi-polar SU | Aluminum Electrolytic Capacitor | Passive & Electromechanical | Panasonic Industrial Solutions East Asia

Stuart

 

[daccordimark]

Hi Stuart,
I've done some more digging around. What we need are either Nichicon ES (aka Muse) or Black Gate N/Nx series. The BGs are expensive and may be too big but the Nichicons are well regarded apparently and are pretty cheap (compared to the BGs). I can get both types in the UK from amplifier valve kits, HIFI pre-amplifiers, speaker kits, upgrade components but I don't know about NZ. I don't know enough electronics to tell whether any old bi-polar would be a good idea at that point in the circuit. Have you seen this site which has the schematics for the Cyrus 1?
The Class-A Amplifier Site
Mark.

 

[lrseries3]

Hi Mark,

Thanks for contact! yes they have a bipolar 470uf 16v cap. I will contact them and see if they will deal with a Kiwi!

And yes have downloaded and printed off the circuits. They have been most helpful. In my deliberations with the amp I have killed one channel, but some sort of obstinate stubborn persistence pushes me on.

Thanks again,
Stuart

 

[daccordimark]

I've replaced all the power amp electrolytic caps with Nichicons as mentioned in my last post and I'm very happy with the results. I also corrected a couple of mistakes with my earlier mods and the old Cyrus 1 is back to it's old form. Combined with the earlier cap replacements in the PSU and phono sections I now have no original electrolytics left. These amps are definitely worth preserving so I hope you manage to get yours up and running again.
Mark.

 

[lrseries3]

Hi,

Thanks for the encouragement, I have been doing a bit of soul searching, but I will persist as I think you are right, they are good amps. I just hope I don't get out of my depth!

Stuart