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Volume & Tone technical issue (Epiphone Jack Casady)


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Hi Again guys

I am lucky to have 2 Casady's but please read on as to why I'm lucky

White - 2014 owned for a while and this thing sounds amazing. I also have full control over the volume and tone so no issues here

Gold - 1998 (Just bought) And the volume & tone are pretty much on or off with no in between. I can solder real well but I don't understand electronics. I spoke with Guitars North West and purchased replacement Alpha 2.5k pots and the packet is labelled (Volume & Tone).
I've taken my time and fitted these by taking out both looms from each guitar so I could closely check the wiring but the problem is exactly the same. I am in the process of replacing both the capacitors and the one resistor to eliminate any issues with these

BUT

Whilst reading up on this side I came across an article about types of pots used on bass guitars and my scenario is mentioned. Not in a bad way but in a way that gives you an immediate drop in volume and treble tone if needed so the question
is was this older guitar possibly designed to be like this and was this a spec requested by Jack Casady when working with Epiphone?????

Your views would be very welcome before I just build it up and make adjustments on my amp.......

Many thanks

213153110_1680905122095238_5315817800355590907_n.jpg.33333c1504510a66f8cd4d28600c3ceb.jpgMike

Edited by Mike Bungo
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2.5k log pots would be the right ones to use, so I suspect as they sent you that value (which would be unusual in any other bass) it is the correct type. There is a capacitor and resistor wired directly across the terminals of the volume, I assume if you replaced the pot these are back in place?  

Edited by Woodinblack
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9 hours ago, Woodinblack said:

2.5k log pots would be the right ones to use, so I suspect as they sent you that value (which would be unusual in any other bass) it is the correct type. There is a capacitor and resistor wired directly across the terminals of the volume, I assume if you replaced the pot these are back in place?  

Hi. I'm thinking that the dealer whilst sending me 2.5k pots sent me the wrong type. I've found 2.5k Linear which I have ordered. I've also ordered new capacitors (.22uf & .15uf) but I am struggling to find a 690ohm Resistor. I kinda figured that it would make sense to replace them all whilst I'm doing the job and to eliminate any related issues. I'll update the post when I've done it

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On 10/07/2021 at 10:51, Woodinblack said:

They are not linear pots, they are log, and they have always been.

you won't find a 690 resistor, as it's not a series value, you will find a 680 though which is what you need. I almost certainly have one if you want one

Hi. Thanks for that.... I've just found a 680. The schematic said 690 so you've saved me a lot of trouble :)

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14 minutes ago, Mike Bungo said:

Hi. Thanks for that.... I've just found a 680. The schematic said 690 so you've saved me a lot of trouble :)

Well, the 6.8 is standard resistor size in the E12 & E24 resistor range, which is 'normal' values. 690 would be a specialist value, and as the resistors used in those guitars would be around 10%, it is well within the range!

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Hi. I’ve tried 250k’s A&B added new capacitors and a new resistor but the problem of on or off still persists. Can anyone draw me a dummies schematic or give basic advice on what to check for. I’m assuming and I have no way of checking both the transformer or the OHM selector switch

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The Jack casidy is a fairly unique design (or class of design, used on a few others) compared to an ordinary guitar which is much simpler thing, due to a very low impedance pickup and a switch to change the impedance of the whole guitar.

Normally I would say it is pretty hard to work out what is happening if you have no experience of working on them but you have the advantage that you have two of them, so with just a meter you can buzz it out and find out what the difference is.

Yes, you can measure the transformer with a normal meter, as long as it is accurate enough at low values, although it seems around the pot is a place to start, what the values as you turn it are.

You could send it to a guitar tech, although it would have to be the right one, because most of them are not particularly good with electronic, because there are a lot of things to do on a guitar and the electronics on 99% of all guitars / basses are very basic so they don't need to be.

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So apart from this issue of the volume control not being the same, do both basses sound and act basically the same - like do the switches and tone do the same thing and they have basically the same output volume when they are both full up?

Do both pots measure the same static resistance between the outside two terminals of the pot (with the volumes flat out)?

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24 minutes ago, Woodinblack said:

So apart from this issue of the volume control not being the same, do both basses sound and act basically the same - like do the switches and tone do the same thing and they have basically the same output volume when they are both full up?

Do both pots measure the same static resistance between the outside two terminals of the pot (with the volumes flat out)?

Hi. Yes they seem to be working the same but the issue is with the volume and tone control on the 2002 gold model. Volume = 8-10 loud, 3-7 no apparent changed and 1-2 off. Tone 1-3 tone difference then above 4 there is no difference. The 50-500ohm switch seems fine. I need to measure the resistance and will take both guitars apart again to double check everything. When I do this I will recheck the pot types 250/500 a&b ect. Once I've done this I will start again.

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