MF Nu-Vista problem [Archive] - The Art of Sound Forum

sprint

30-11-2014, 21:00

My MF Nu-Vista integrated amp just suddenly stopped. On checking the separate power unit I have found that the T630mA Pre-Amp fuse has blown!

Don't have any replacements so have ordered some. However, it is a bit of a concern as to why it has blown? Could be just one of those things or something more serious downstream?

Won't know until I get some replacement fuses and see what happens. Has anybody had experience of this type of failure to enlighten what may have been the cause?

Stratmangler

30-11-2014, 21:06

It might just be a tired old fuse.
It happens.
If it reoccurs after changing the fuse then there may be something else needs looking at, but until you get some replacement fuses ....

sprint

30-11-2014, 21:35

Thanks Chris.

sprint

03-12-2014, 15:00

Received the fuses today.

The Nu Vista has a separate PSU which comprises of the two power amp toroidal transformers, the pre-amp toroidal transformer, two relays that switch to connect the power amp transformers and a relay pcb with separate fuses for the power amps and pre-amp outputs.

With nothing more than the mains lead connect the mains LED came on but as soon as the relays activated the pre-amp T630 mA fuse blew immediately.

Disconnected the power to the relays and this time the fuse did not blow immediately but still blew after a few secs. Fuse wire vaporized.

Anybody have any experience of theses power supplies and amp who can give any suggestions?

Firebottle

03-12-2014, 16:12

Definitely sounds like a fault has developed in the pre-amp section, a low ohm short if it's vapourising the fuse.

:cool: Alan

anthonyTD

03-12-2014, 16:39

It will need to be inspected before anyone here could posibly give an accurate diagnosis.
A...

sprint

03-12-2014, 16:56

Definitely sounds like a fault has developed in the pre-amp section, a low ohm short if it's vapourising the fuse.

:cool: Alan

Hi

Fuse is blowing without the pre-amp psu cable being connected to the pre-amp, just the power supply on it's own as shown in attached photos.

sprint

03-12-2014, 16:58

It will need to be inspected before anyone here could posibly give an accurate diagnosis.
A...

Hi

Appreciate that, but was hoping that somebody may have had a similar direct experience that may pin point the likely cause?

Can anybody advise a good audio engineer in the Eastbourne/East Sussex area?

Spectral Morn

03-12-2014, 17:31

Hi

Appreciate that, but was hoping that somebody may have had a similar direct experience that may pin point the likely cause?

Can anybody advise a good audio engineer in the Eastbourne/East Sussex area?

Ring MF and speak to their technical department or if still in warranty contact the dealer you bought it from.

Regards Neil

TheMooN

03-12-2014, 17:44

I would suggest that you have a chat with John, he was an in house MF tech for several years and is excellent with older MF kit...

http://jsaudiorepairs.co.uk

best of luck.

sprint

03-12-2014, 18:34

Ring MF and speak to their technical department or if still in warranty contact the dealer you bought it from.

Regards Neil

Hi Neil

Unit(s) are 14 years old now and well outside warranty.

Have spoken to MF and all they say is send it back to them. They weigh a ton, amp 65lbs and psu 30lbs, and will cost a fortune to post/courier and sending back to manufacture for repairs will not be cheap.

sprint

03-12-2014, 18:35

I would suggest that you have a chat with John, he was an in house MF tech for several years and is excellent with older MF kit...

http://jsaudiorepairs.co.uk

best of luck.

Thanks.

Will see if he can help.

DSJR

03-12-2014, 19:30

I would suggest that you have a chat with John, he was an in house MF tech for several years and is excellent with older MF kit...

http://jsaudiorepairs.co.uk

best of luck.

If he was there in the late nineties to early noughties, I can vouch for that :)

Power supplies blowing fuses with no load on them could be nothing more than a faulty rectifier bridge. Good engineers usually go further than this though as the supply caps may have been stressed too and will need to be checked.

Ali Tait

03-12-2014, 19:46

I'd suggest John Caswell, who can be contacted on the World Designs forum. He's in Wokingham. I can give him a shout for you if you want to PM your email.

Spectral Morn

04-12-2014, 00:00

Hi Neil

Unit(s) are 14 years old now and well outside warranty.

Have spoken to MF and all they say is send it back to them. They weigh a ton, amp 65lbs and psu 30lbs, and will cost a fortune to post/courier and sending back to manufacture for repairs will not be cheap.

Hi Andy

MF are doing Nu Vista amps again so it could have been the current one you were talking about.

Regards Neil

sprint

04-12-2014, 17:13

If he was there in the late nineties to early noughties, I can vouch for that :)

Power supplies blowing fuses with no load on them could be nothing more than a faulty rectifier bridge. Good engineers usually go further than this though as the supply caps may have been stressed too and will need to be checked.

Thanks for the reply.

There is a rectifier on the relay pcb, see photo.

Might be work lifting that off and checking?

Andy

sprint

04-12-2014, 17:16

Hi Andy

MF are doing Nu Vista amps again so it could have been the current one you were talking about.

Regards Neil

Hi Neil

No it is definitely the early original one. I have the original invoice from 2001.

Andy

sprint

05-12-2014, 13:07

Thanks for the reply.

There is a rectifier on the relay pcb, see photo.

Might be work lifting that off and checking?

Andy

Bridge rectifier is a W04M which checks out OK.

Floyddroid

07-12-2014, 17:20

My experience with MF isn't good when it comes to this kind of thing. I have a Tri-Vista SACD player that has been a static display for about 8 years now because they didn't have the parts for it. The advice above is your best bet, especially theex MF Engineer. Jez Arkless may be able to help too as he worked for MF for some time. Sound him out at Arkless Electronics.
Bridge rectifier is a W04M which checks out OK.

Spectral Morn

07-12-2014, 17:25

sprint

08-12-2014, 17:02

Spoke to John at JS Audio Repairs today. Very helpful person.

With the power to the relays disconnected all that is left is the pre-amp transformer and the relay pcb. Having removed and checked the pcu bridge rectifier all that is left is the pre-amp transformer.

After speaking to John he was of the same opinion. So I an trying to source a replacement. Waiting on MF to see if they can help if not John gave me link to get one made with a bit more power.

Unfortunately one of the Neutrik XLR 5 pin socket solder tags fell off so I now also need one of those.

From the photos can anybody identify the socket or know if the pins are available separately?

Barry

08-12-2014, 17:59

Andy, you should be able to obtain the 5-pin Neutrik XLR socket from either RS or Farnell, or perhaps from Maplin.

sprint

08-12-2014, 19:25

Andy, you should be able to obtain the 5-pin Neutrik XLR socket from either RS or Farnell, or perhaps from Maplin.

Thanks Barry

But from what I have been able to make out the current versions, NC5's have different mount holes positions and I am not sure if existing male plug and lead which carries the 60V and 10V supplies to the amp is interchangeable?

Andy

DSJR

08-12-2014, 21:14

The domestic arm of Farnell UK is CPC and you only need to spend a fiver at a time. Loadsof others that should be able to send you the exact part, including MF themselves I suspect ;)