Graphic Sliders

[MarkBarl]

Hi,

I have an old Court Acoustics GE60 graphic eq. I am trying to replace some of the sliders where they have broken. The only markings on them are 838W-5KB There are 2 that appear to have been replaced before which are marked 834X 5KB They are 45mm Long with 30mm travel.

 

I have looked at Farnell, RS and maplin with no success. Any ideas of where I can get replacement parts?

 

Many thanks.

[Wrighty]

Hi,

I have an old Court Acoustics GE60 graphic eq. I am trying to replace some of the sliders where they have broken. The only markings on them are 838W-5KB There are 2 that appear to have been replaced before which are marked 834X 5KB They are 45mm Long with 30mm travel.

 

I have looked at Farnell, RS and maplin with no success. Any ideas of where I can get replacement parts?

 

Many thanks.

 

I'll ask Stephen (Court) if he knows of a source...

[MarkBarl]

Some more info. They are 5K Ohms Linear taper PCB mount pots with 31mm between pins. Any pointers to suppliers would be greatfully recieved.

[csg]

im unable to shed light on what the correct spare part is, but I have to say it is well worth fixing - ive owned both these and klark 360's, and I prefer the sound of the court. must be all those coils!

[boatman]

Some more info. They are 5K Ohms Linear taper PCB mount pots with 31mm between pins. Any pointers to suppliers would be greatfully recieved.

 

I used to use quite a few 30mm travel linear pots and it sounds like an Alps part (Linky). Unfortunately the only one I can find in the UK is a 10k part from Farnell.

 

Good luck with the search.

 

Edit: Ooops, that Farnell part seems to be a log pot. Sorry.

[Peter F]

I found some very useful info on these graphics recently. They have a tendency over time to develop scratchy faders and replacing them doesn't cure the problem. It turns out that it's a different components ageing that causes the scratchy noise. A very smart person at Juice Lighting & Sound has worked this out and, more importantly, knows how to cure it.

 

Details are HERE

 

They are worth fixing, they are superb graphics.

 

Cheers,

 

Peter

[Wrighty]

Ok, had an email back from Stephen... He says the slide pots were made by Alps. The EMO/Court Graphic is now handled by Canford Audio ( www.canford.co.uk ). One of their salesmen used to work for EMO, so they should be able to give you the part number and/or tell you where to get the replacement parts.

 

If you don't get anywhere, let me know.

[MarkBarl]

An update for anyone interested and thanks for the replies.

I had discovered that the sliders were by Alps. However it would appear that they no longer make a 5K 30mm one (Their RS30xxx range), the lowest they do is 10K. Assuming that it is a voltage control circuit, I could try a 10K one, and should only see any difference at the extremes of travel as the Vmax and Vmin would be different. In the end I have found a 5K one by a manufacturer called Alpha of Taiwan. The footprint and pins are the same, only the lever is different. Unfortunately, it would appear that no one in the UK stock them, so I have had to order them from the US.

 

I don't suppose that anyone knows where to find a service manual or schematic for this graphic?

 

Peter, I had found that article. However, I think that I have an early version. Although the front panel is virtually identicle, mine has a single board at the bottom of the enclosure, which is different to their picture.

[KevinE]

Taiwan Alpha pots are stocked by TW Electronics of Newbury. They have large minimum orders, though.

 

I agree with what you say about the VCA making it easier to put different values in, however if the graphic works like the one in the article, they wont be VCA since putting DC across the track is exactly what they're supposed to do!!

 

You might also try Deltron, they are Alps importers but the same goes for MOQ's as well..

[Wrighty]

Mark: Did you try Canford? If you're still having no joy, let me know - Stephen Court phoned yesterday to see if you'd had any success and said he'd try and help if not!

[MarkBarl]

Hi Wrighty,

Thanks for the support. I didn't call Canford in the end. As I briefly mentioned in one of my previous posts I came to the conclusion that Alps no longer made this exact one. From what I could make out in their product brochure clicky This is the series used. The dimensions and lever type are all correct, however they only go down to 10K. The best I could find was this one that I had to get from Mouser in the states. It ticked all the boxes except the lever type and the click at half way travel.

 

I have installed these now and am hoping to test it tonight. I would be interested in getting hold of a service manual or schematic if one is available. Also, when I tried using this graphic some time ago, I was finding that with the EQ switched out all was fine, but when I pressed the buttons to put the EQ in I got a serious attenuation in the signal gain, thus to make it unusable. I was using the XLR inputs and outputs at the time and didn't have time to faf about with it. There might be an issue with the BK Electronics amp that I was using, as although it has an XLR input, I believe that it is unbalanced. Although why the gain would suddenly go down when the graphic is put in I don't know. The guy I got it from said that he had used it fine but had only used the unbalanced inputs. I finaly got around to dragging it out of the cupboard last week, but it had somehow managed to break a couple of sliders in the mean time. I will hopefully have more insight when I have tested it. All the info I have found says that this is a great graphic and I am desperate to get it working again.

 

Mark.

[Wrighty]

Hi Mark,

 

Even if Alps have discontinued them, Canford may still have some stock. I'm not sure how 10k ones will affect it, with the filters being passive networks instead of active op-amp filters like most other units.

 

From memory of taking Stephen's one apart and what he said at the time:

 

The I/O on that graphic is unbalanced as standard, unless it has the octal base transformers fitted internally. Being the age it is and the original design background (apparently to BBC specs), it will be wired with the XLRs pin 3 hot as standard (pin 2 hot is the convention these days). I think it's printed with PIN 3 HOT on the back panel. There's an option to change this internally. This will affect connection to other equipment and should be checked or phase reversal adaptors/leads made. If it is transformer balanced, you'll need to ground the cold side at the unbalanced (amp) end. No electronic servo balancing like most modern stuff! If it doesn't have the transformers and is unbalanced, the signal will be on pin 3 of the XLRs with pin 1 ground.

 

Hope this helps! If you need any more info, I'll do my best to help you or ask if I don't know!

 

Cheers,

 

Richard

[Paul TC]

There might be an issue with the BK Electronics amp that I was using, as although it has an XLR input, I believe that it is unbalanced. .

 

Mark.

 

I have one of these, easily 15 years old (MXF 200), and it uses unbalanced connections on the XLR inputs, pin 2 signal , pin 1 earth, pin 3 not connected.

[Pytchley]

I hope this thread is still active as I have 2 of these great EQs, one has output transformers and works fine on it's XLRs, the other came from E-bay and has a problem. It does not have the transformers and the plugs that bridge their sockets are wired up wrong...can someone tell me how they should be bridged for unbalanced use? Any help much appreciated.

[Wrighty]

They'll probably be wired pin 3 hot, like a lot of stuff of that age. So you'll need to rewire the jumper plugs to make them pin 2 hot (shouldn't be hard to work out with a multimeter and 10 minutes with a soldering iron) or make up some phase reversal leads to go in and out of it, to interface with modern equipment.

 

I don't visit here often and don't have topic notifications switched on, so it's a good thing you PMed me!

 

Cheers,

 

Richard

 

I hope this thread is still active as I have 2 of these great EQs, one has output transformers and works fine on it's XLRs, the other came from E-bay and has a problem. It does not have the transformers and the plugs that bridge their sockets are wired up wrong...can someone tell me how they should be bridged for unbalanced use? Any help much appreciated.