Advice on refurbishing a Mission Cyrus 2 & PSX

[ianp]

I cleaned out a cupboard over the weekend and discovered a Mission Cyrus 2 amp and PSX hidden away Always nice to find such things under a pile of old clothes!

I blew off the the dust and fired it up. After allowing it to warm up for a couple of hours I spun up some CDs. The sound is not bad at all, but it is showing it's age with the highs not as sharp as I recall and the sound is a bit muddy.

Anyone got any advice on parts to swap out or replace to help improve things ?

Anyone do such things in the US ?

Thanks

IAP

[Sonusthree]

Hi,

I would give the switches and pots a good squirt of contact cleaner and then strongly consider changing some/all of the electrolytic capacitors.

I recommend that you search the forum for the many useful posts about this subject.

[ianp]

Thanks for the reply.

I have previously searched on this forum and found a few good threads - including Geoff's very helpful schematics - and the advice on changing the caps seems to be fairly universal. I'll have to brush up on my desoldering and soldering skills before tackling the project, which is why I was wondering if anyone in the US takes on such tasks.

Some of the threads seem to indicate that the PSX may not add that much to the sound quality when used with fairly efficient speakers, which I am so I may just concentrate on thr Cyrus 2 and use the PSX case for a tube amp project

[Sonusthree]

Originally posted by ianp
........ so I may just concentrate on thr Cyrus 2 and use the PSX case for a tube amp project

That would be a waste! The PSX does add something and it wouldn't necessarily cost much extra to overhaul them both.

When the PSX is used with the Cyrus 2 ......
The main reservoir caps in the Cyrus 2 are only used for the phono section. So why not just renew the PSX caps and leave the large Cyrus 2 caps for later? Do you use the phono section?

Which Cyrus 2/PSX do you have? Plastic or metal? Push switch or toggle?

Also bear in mind that the PSX case will probably be quite brittle to work with whether it's plastic or ...... is it aluminium or magnesium alloy ?..... anyway probably not ideal for anything else.

All the best,

[ianp]

I do not use the phono section currently. It is the metal cased with push-button switch.

I have some friends over at the moment and it turns out that he used to dabble in DIY electronics a fair bit. I mentioned the project too him and given our shared disinterest in the Oscars we had soon popped the top off the amplifier and we were looking at one of Geoff's schematics.

To be honest the soldering skills needed look to be within my abilities, not sure why but I thought things were smaller. Anyways, he has volunteered to help out if I can tell him exactly what wants to be replaced and with what components. Great news indeed!

So, for component replacement I have the following posts in a single thread bookmarked.

http://www.diyaudio.com/forums/showt...30#post1177930

http://www.diyaudio.com/forums/showt...23#post1355323

In the above the 4 caps are the most obvious things to change. Any advice on the other big bang for the buck components to switch out ?

I also have a SUN Ultra 5 computer case that I plan to use as a tube amp case. Maybe the PSX will get a reprieve.

[Sonusthree]

Originally posted by ianp
I do not use the phono section currently. It is the metal cased with push-button switch. .................................................. ...........................................

............ In the above the 4 caps are the most obvious things to change. Any advice on the other big bang for the buck components to switch out ?

Personally, I would concentrate on the Cyrus Two itself first. Geoff or Chris (Anatech) are the people with much more experience and expertise.

You say the highs are not as sharp? I think that ageing caps in the PSX would perhaps cause a slight change in the bass regions only.

I'd first replace the two caps in the feedback loop on the Cyrus 2, check and clean the switches, pot and ribbon cable connection.

Also, Chris (Anatech) has mentioned an issue with the ageing caps in the phono stage causing oscillation. Maybe this is what is affecting your 'highs'? You could disconnect power to that section altogether by simply using the PSX without plugging the Cyrus 2 into the mains electricity.

You could try a step by step approach of replacing caps but I wouldn't recommend removing the transistors from the heatsink too many times. It's probably best just to do as many of the small caps as you can in one go.

Here's an old pic of my halfway renewed C2 with mostly new caps and a new Alps pot. I replaced the electrolytic input caps with polypropylene that barely fit inside the case!! I later removed the switches and pot completely!