Recapping Neve V66 Channels.

[bradholland]

Hey Guys,

We keep meaning to get around to installing our meter bridge into our Neve V66.
Although its installed it's never actually worked properly, all the meters gave different levels even when running a test tone across all channels.
We went down the path of re-capping one of the meter modules and discovered that the problem remained.
Then after more testing and messing around and doing things that we really should have though of in the first place realised that when swapping channel modules around, the meter reading discrepancies would move with the modules. Clearly meaning that the issue laid within the channel modules themselves, rather than the meters.

As I started to think about re-visiting this issue again today (always have to drop it because of other tasks) we were chatting and remembered that when we first built the console, my partner went around and 'calibrated' each fader with a small screwdriver as the levels going back into our convertors were all different. (we'd forgotten about this entirely)
I think what this is telling us is that although our channels all sound equal etc the issue that we are seeing in the meters is reflecting whats really going on with the channels, but we are just compensating for it at the fader.

So, with that now understood (unless someone disagrees with me) I guess we need to start thinking about re-capping some channels, perhaps just 1 bucket first. and see if that gets us closer to a fully happy console.

My question is, there are a lot of electrolytics in these channel modules, what is the general method here, do we go about replacing every single cap on every board inside the module or is a re-cap generally just replacing a few 'key' caps?
An ideal world we'd be replacing every cap on the board, but thats going to take me some serious man hours...

Any advice here would be very graciously accepted!

Regards,
Brad

 

[PRR]

Bad caps won't be just different levels.

> my partner went around and 'calibrated' each fader with a small screwdriver

This is like a carpenter shimming studs. He may get the 1st floor straight but now the 2nd is all crooked; the attic is so far off he can only tarp the roof and get out of town. Except a carpenter usually does not swap studs after shimming.

Don't just screwdriver-poke and guess. Set up a standard tone, standard knob settings, and measure signal level at EVERY available point on EVERY channel.

 

[bradholland]

Yeah I understand that.
This was a couple of years ago when we first bought the console, we didnt know much about it and it was completely in pieces in  a lockup in LA.

As we were then really wet behind the ears with all this stuff we just thought the faders were out of whack. Of course we know now that this is not the case.

SO yeah, we'll be putting the faders back to 0 and then hopefully we can work on the channels.

Still need to know how deep I need to go on the recapping..

 

[PRR]

I do not see, from your post,  any reason to re-cap at all.

 

[squib]

Get an ESR meter. Put few channels on the bench and test the ESR of quite a selection of capacitors.  Get the vibe for where they are at.

 

[radardoug]

Put 1 k tone on your signal path. Set to zero on meter at end of chain. Change tone frequency to 30 Hz. Make sure the generator level is constant. Has the meter at the end of your chain dropped by a dB or more? If so, you need to recap. If not, you don't.
I am just refurbishing a 3M 79 recorder, the output caps are 470 uF, on test they read about 600 uF. They don't need changing.

 

[CJ]

forgot about John Klett,

might be some useful re-cap info in here>

http://www.technicalaudio.com/reading/neve1081/1081.html