Musical Fidelity Nu Vista M3 Amp upgrade?

[sprint]

My Musical Fidelity Nu Vista M3 Amp must be around 17 years old now.

I had to replace one of the transformers in the separate PS/transformer box a few years ago and I currently have an annoying issue with the LH channel doping out, pressing the mute on and off generally restores the channel again. Does anybody know what the likely cause is?

It's also now taking a longer time to 'clear it throat' to produce a clearer sound from switch on.

So after this length of time I am sure the electrolytic capacitors will need changing etc so I am looking to have the unit overhauled/upgraded?

Musical Fidelity used to offer such a service, but do not know if that is still available since their take over? The other option is JS Audio Repairs run by John Sampson who I believe had good reviews on his work.

Has anybody had experience of using either of these options or can suggest any other options, any of which I know will be fairly expensive and perhaps cost more that the value of the amp?

Thanks

[PeteT]

As I recall reading somewhere, didn't they come with spare set of NuVista valves..?
Have you tried swapping them out, I think they have a finite life.?

Couldn't guess at anything else, not techie enough... Swapping out valves worked on my x-cans v2 when that got tired and noisy.

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[Lawrence001]

MF said they'd hold on to one spare pair per amp at the time to enable a replacement, but whether they stuck to this for so long I don't know.

I think it turned out that they weren't so rare as MF claimed at the time and you might be able to find them on eBay. That was certainly the case with the ones in the TriVista Dac anyway. JS replaced mine and was very efficient I'd generally go with him.

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[sprint]

Thanks for the replies.

No, MF did not supply a spare set of valves with them, but as indicated they were supposed to have held a set for each unit sold should they need to be replaced at a later time. I doubt that they would have held them for some 20 years?

However, I did purchase a set from America some time ago so I have a spare set. Not sure that the problem I have is related to the valves, but it certainly could be?

As indicated the unit is now coming up to being some 20 yrs old and as such many, if not most, of the electrolytic caps will probably be well past their useful life so an overhaul/upgrade may be worth the cost?

Was hoping that there may be some members that may have had some direct personal experience, which is always helpful before embarking on such a route.

[verkion]

My Musical Fidelity Nu Vista M3 Amp must be around 17 years old now.

I had to replace one of the transformers in the separate PS/transformer box a few years ago and I currently have an annoying issue with the LH channel doping out, pressing the mute on and off generally restores the channel again. Does anybody know what the likely cause is?

It's also now taking a longer time to 'clear it throat' to produce a clearer sound from switch on.

So after this length of time I am sure the electrolytic capacitors will need changing etc so I am looking to have the unit overhauled/upgraded?

Musical Fidelity used to offer such a service, but do not know if that is still available since their take over? The other option is JS Audio Repairs run by John Sampson who I believe had good reviews on his work.

Has anybody had experience of using either of these options or can suggest any other options, any of which I know will be fairly expensive and perhaps cost more that the value of the amp?

Thanks

I've been looking for other people with this amp (hard since so few of them were made) to see what "upgrades" others have been doing. Not finding too much, I finally decided to do it myself. In any case, your Left Hand side dropping out issue is actually "easy" to fix. Long story short, replace the Omron G2R relays. They are quite cheap from online electronics suppliers like Newark, Digikey, Mouser etc.

Longer version:
I had the same issue with mine (I bought it used) and thought it was the ALPS volume potentiometer at first. Took it apart, cleaned it...didn't fix it. Replaced it...didn't fix it either. I then realized it hitting the mute button would fix the issue (I rarely if ever, used the mute button) which indicated the issue was probably along the muting circuit.

A few minutes later with the amp top open, I literally saw the problem. The contact pads on the Omron relay on the left side channel looked crooked--the centre part of the round pad was not making good contact. These relays actually appear to be "self-cleaning", and rub slightly upon contact which is supposed to clean away any tiny amounts of oxidation every time it makes contact. The trouble is if the contact nub is crooked, only a tiny portion of the pad makes contact and due to arcing etc., oxidizes fast. When you mash the mute button a bunch of times, it will "rub away" the oxide, but this is still less than ideal. Best solution is to either: a) take apart the relay and clean the contacts (which I did) and in my case, bend the metal parts until they were back in proper alignment, or b) just replace the relays. They are sub $10 parts.

I realized the DIY stuff should have been posted in the DIY section so I moved it there.

Thanks!
verkion