Cyrus Pre - Unbalance volume

[MAT124]

Hi,

My Cyrus Pre got a problem of unbalance output in both channel. So I send it to Cyrus dealer for repair. However after 2 month, they told me that the ALPS motorized Volume is faulty but there is not replacement part for repair.

I try to search internet and find many kinds of ALPS volume available. Can anyone tell me which one is suitable for the Cyrus Pre especially the resistance value (10K, 20K, 50K, or 100K).

Many Thanks,
Clement

[Sonusthree]

Hi Mat, Welcome to the forum.

Have you tried contacting Cyrus in the UK? They may be able to help you directly.

service@cyrusaudio.com

Or .....
Do you have a picture of the old part?

Regards,
Martin

[lohk]

The older Cyrussus always had 50k pots - but the product number is written on the device, if you dare to make the repair yourself.
What is the real problem, what do you mean with "unbalanced"? (Constant, variating, etc.)

[MAT124]

Thanks for the replies.

I tried to contact Cyrus UK but got the same answer. The UK support guy told me that they suspect the Alps motorised volume was faulty but no part to repair.

The unbalance volume means the output in left channel is very soft while the right side is very loud. I try to adjust the balance of the amp but didn't help because the difference is so large.

I hope I can get the part from somewhere so that I can replace the component by myself. I have asked the dealer whether they will fix my Amp if I can get the part from other place but they refuse. The dealer said they will only repair the Amp with parts supplied by Cyrus UK.

Thanks,
Clement

[anatech]

Hi Clement,
You may easily have a problem with the Cyrus amplifier circuit. There is a large cap in the feedback loop nearest the diff pair. If it's open, it will cause this problem. Change both while you are there.

Did you troubleshoot or just guess at the control? I hope you haven't done anything to it.

-Chris

[MAT124]

No, I didn't do anything yet. It's the Cyrus UK support who told me that he suspect the problem was due to the ALPS motorized volume which they don't have part anymore.

I will try to open the Amp to take a look. For the CAP that you have mention, is there any easily way to check or should I just replace them?

Thanks,
Clement

[anatech]

Hi Clement,
I just realized you are talking about a preamp. Forget the capacitor advice.

Do look a the controls with the top off. See if they move by remote. You may have cracked solder joints on one control. Take a picture if you can please.

I service Cyrus under warranty in Canada, I'll try to help you.

-Chris

[MAT124]

Hi Chris,

Thanks for your help.

Attached please find the picture of the circuit board. I try to adjust the volume using the remote and seems that both volume did move. However the one near the centre do not move smoothly like the other one which near the edge. I guess this volume switch is in question.

There are some alphanumeric characters printed on the switch. Both switch got "531t 20KDB".

Thanks,
Clement

[anatech]

Hi Clement,
Turn the unit off and unplug it. Try to turn each control by hand. Does the one that turns intermittently feel rough?

It's possible that it's a mechanical problem or a lubrication issue.

-Chris

[MAT124]

Hi Chris,

Since both volumes are sitting very close, it is difficult to turn by my fingers. I use a pair of tweezers to turn them. Seem both can be turn by same amount of force.

If it is a mechanical problem or a lubrication issue, can I fix the volume switch or I need to get a replacement part?

Thanks,
Clement