Neve A3431

[mobyd]

Client studio has a Neve 3431 mixer which has twice burned out one of the dual power supplies. These are 24v 5a conventional E-I transformer linear affairs and one side (half the channels) is fine but the other half (the rest of the channels + the masters) overdraws the 5 amp budget and runs far too hot (cracking insulation on the wiring etc). My suggestion is a couple stonking big Meanwell 350w 24v enclosed frame SMPSUs - will this cause the thing to lose whatever magical properties vintage Neves are supposed to possess. The Meanwells are certainly a helluva lot more economical than the boatanchor iron.
M

 

[radardoug]

Do it Moby, the magic is elsewhere.

 

[audiomsg]

Hi Moby and Doug, it's a custom 53 series console, based on the broadcast 5316 model, serial number A5831

 

[mjrippe]

I have maintained a 53 series console for ten years and we never had a problem with the original supplies. They are all custom by the way, at least to some degree.

Assuming you have tried swapping the supplies to check for trouble there, I would suggest looking for the source of excess draw. Adding a beefier supply may just give the board more energy to cook itself.

 

[audiomsg]

Regarding the power supplies, some years ago I was discussing it's legacy with Geoff Tanner, the ex Neve employee who seems to know everything, and he was shocked that it only had 2 supplies, as a quick tally up of the overall power draw is right at the upper limit of what they can provide. His successors at Neve after he left don't appear to have consistently upheld the expected high standards, and this appears to be example of penny pinching.
This console was delivered in 1978, a couple of years after he left.

 

[mjrippe]

Well, then it has been dying since it was born. In that case, yes - go big!

Just for comparison, the one at Studio G has 4 PSUs for 24 channels, 8 subgroups, and a penthouse with 2 comps and a few more input modules. I have a couple Power One HD24-4.8-A linear supplies set aside as spares, but never put them to use.

 

[audiomsg]

That's what Geoff was so surprised by. Mine is 36 channels, with 8 groups, and originally came with 6x 33264 comps too.
(unfortunately they didn't make it to me)
Seems almost like gross negligence!

 

[mjrippe]

Are you certain it left the factory with only two?

 

[audiomsg]

Pretty sure. Here's a picture of the power distribution unit, and apart from it being a beautiful thing, there's definitely only 2 sockets.

 

[blakeyboy]

Hmmm.... strangely, the A5831 block diagram shows a 31777 to run the relays and
a single 33605.

If it does have two 33605's, check that someone hasn't moved a B+ wire from one psu to the other.
Ideally, 33605's should have 3- 4 amps drawn from them to minimise noise.
Unless the poaer leads are very long, cables as thick as in your picture don't work as well as thinner ones.
Are you leads very long? Over 10 metres and you are into HF oscillation problems.

 

[audiomsg]

Hi Blake,

Oh that's quite interesting.
The first 16 channels, and possibly the group outputs, are all quite happy being powered by one 33605. I measured the current draw at about 3.5 amps. It's the remaining 16 channels and relays etc which are drawing in excess of 5. Mobyd is kindly building me a power supply with can handle that kind of current.
In terms of the cables, years ago I replaced the originals with those thicker ones, which are about 5 metres in length. I was worried about the voltage drop, but I'm guessing this was probably misguided, due to the fact it's now pretty clear that the real problems stem from a severely overworked 33605.

 

[mobyd]

Where there's a will, there's a way....

 

[mjrippe]

Very nice!