Caudio ra4001

[uniman]

Our 2 monitor racks consist of 2XRA3001 and 2XRA4001. All amps are quite old, and a believe used to serve as the main house PA in our two rooms, now repalced with NEXO and L'Aoustics systems. On Saturday we had a problem with the drum monitor. This was an LE400 (8ohm) in series with a drum fill (8ohm) bi-amped from one channel of a 3001 and 1 of a 4001. The mains fuse went on the 4001, the monitor engineer swapped over to a spare channel, 10 mins later he noticed a burning smell and knoked of the alternate 4001 power., Swapped again and had no problems for rest of gig.

 

On investigation this week, the HF driver on the drum fill has blown.

I replaced fuse on the first 4001, plugged in and got loads of smoke from the soft start resistor - obv. very hot to touch.

Checked the second 4001 and got same result.

 

I don't think we are going below the min impedance (4ohm) on the 4001 - all cones are complete and not showing problems. The HF driver having gone, shouldn't cause problems as it is being feed from a RA3001 and is in series with another (functioning) cab. The softstart resistor and all around appear to read OK.

 

Having 'phoned around nobody really is prepared to support the RA4001, so any ideas from anybody? We have atleast three 3001 and I think two 4001 in storage for spares, so circuit diagrams for either may be interesting, otherwise has anybody any suggestions for a reasonable replacement (2U preferably)

 

Many thanks in advance

 

Andy

 

PS any second hand purchases would have to be through a legit company and probably through purchase order, which obv limits us in our bargain options

[Girlyboy]

Hi Andy

 

We have a lot of C-Audio amps that we don't even bother sending off for repair anymore. The soft-start is a major problem with almost all C-Audio amps besides the Pulse range.

 

Anyway, I recently removed 2 RA4001s from some old amp racks, and as far as I'm aware, they both work. I think they both have a couple of LEDs pushed back into the casing, and they both need a bit of TLC (mainly a tightening of screws and a bit of spraypaint to cover rack scratches). I can find out a price for you, if you're interested?

 

Girlyboy

[Callanan Systems]

Hi Andy

 

We have a lot of C-Audio amps that we don't even bother sending off for repair anymore. The soft-start is a major problem with almost all C-Audio amps besides the Pulse range.

 

Anyway, I recently removed 2 RA4001s from some old amp racks, and as far as I'm aware, they both work. I think they both have a couple of LEDs pushed back into the casing, and they both need a bit of TLC (mainly a tightening of screws and a bit of spraypaint to cover rack scratches). I can find out a price for you, if you're interested?

 

Girlyboy

 

 

are the ra4001 still avalible?

 

 

cheers

dave

[Mixermend]

Soft start resistor getting hot - oh heck!

What should happen after a second or less - is that a relay contact should short out the soft start resistor to allow full mains current to be available to the transformer - this obviously isn't happening.

This could be due to a number of reasons - possibly contact or open circuit coil problems with the relay, but also could indicate a transformer problem.

Check whether the relay tries to operate and whether any voltages are being developed on the secondary side of the transformer. You will have to work quickly though, so the soft start resistor doesn't burn out......

[Pete Alcock]

Hi Uniman,

 

I have a set of schematics for the RA3001 (which is probably going to be very similar to the RA4001). PM me and I can send you a set.

 

I have three 3001s in my rack and whilst immensely heavy, they do seem to be very reliable and good sounding amps. It's possible the mains transformer has developed a shorted winding which would account for the soft start resistor cooking and fuses blowing. You should be able to confirm this fairly easily. If it is the case, I reckon the amp is scrap. If it measures OK there may be hope.

 

This is a job for an experienced technician mind. There are some hairy voltages and huge storage capacitors inside those amps, some of which are not well shrouded from fingers and tools once you've got the lid off!

 

Pete.