When is a 330k pot not a 330k pot...

Setup, repair and restoration of Rickenbacker Instruments

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When is a 330k pot not a 330k pot...

Postby (espidog) » Sat May 23, 2020 2:09 am

I recently decided to give my 2004 4003 the 'vintage tone' treatment, so I purchased the RIC-supplied CTS 330k pot/pullswitch unit.

Before doing so, I had read and been intrigued by this blog page from 2017:

https://crawlsbackward.blogspot.com/2017/03/rickenbacker-electronic-mod-treble-cap.html

In it, the blogger describes how he purchased two of the (nominally) 330k pot/switch units, but when he measured their track resistances he found that both were clearly 500k components.

This didn't put me off buying mine - in fact I found it encouraging news, as my preference is for the treble pup to have as much top end bite as possible.

My 330k unit arrived yesterday. I popped my Fluke meter across its track and it measured out at... 457k - i.e. within 10% tolerance for a 500k pot. :lol:

So, personally, I am mighty pleased. It does seem odd, though, and can't help but make me wonder whether CTS has been supplying mis-labelled pots to RIC for quite a long time!

If any other forum members are reading this and you have one of these "330k" pots to hand, why not put a DMM across its track and tell us what it shows? It would be interesting to see what spread of results we get.
2004 4003 JetGlo
Epiphone Jack Casady
Ovation Magnum 1
Mania VTB-4BS
Dean Stylist w/ John Birch Magnum II pups
Yamaha BB414
Trace Elliot VA350/GP11 Mk1
Peavey TB-Raxx
2 BFM Omni 10.5 crossfire cabs
Roland Bass Cube 100
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Re: When is a 330k pot not a 330k pot...

Postby (espidog) » Sat May 23, 2020 6:21 am

Me again!

I'm posting again in my own thread to report another, quite unexpected, anomaly.

I've just finished doing the "vintage tone" mod to my bass. Once I'd taken the old tone pot out of circuit, I put my Fluke meter across it just out of curiosity. According to RIC, my 2004 bass should have been supplied with 330k pots in all positions.

The factory-fitted "330k" tone pot out of my bass measures 170k. :shock:

As you can imagine, I was astonished - that's almost half the value it should be! Crikey, no wonder I'd been feeling a lack of "bite" from my treble pup. It's definitely back now I've got the new pot in there. 8)

Makes me wonder, though, what the REAL values of the other 3 pots are? Don't fancy having to de-solder them all just to find out, though, so I think I'll let that sleeping dog lie.
2004 4003 JetGlo
Epiphone Jack Casady
Ovation Magnum 1
Mania VTB-4BS
Dean Stylist w/ John Birch Magnum II pups
Yamaha BB414
Trace Elliot VA350/GP11 Mk1
Peavey TB-Raxx
2 BFM Omni 10.5 crossfire cabs
Roland Bass Cube 100
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Re: When is a 330k pot not a 330k pot...

Postby (aceonbass) » Tue May 26, 2020 1:27 am

This is part of the reason I build wiring harnesses ro replace these under spec tone sucking pots. The shoddy soldering, and poorly constructed ROS output jacks are the other.
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Re: When is a 330k pot not a 330k pot...

Postby (espidog) » Wed May 27, 2020 8:04 am

UPDATE:

Looks like I couldn't let that sleeping dog lie after all. :D

Took another look inside my bass today. I've established that when it left the factory it had (nominally) 250k pots in all positions, not 330k as I'd thought - i.e. the pots in my bass are all CTS 07341 code.

I've now measured the actual values of all the original pots (I swapped out the treble tone pot, see further back up the thread for details), and the results are:

Neck Volume: 193k (23% below nominal)
Treble Volume: 195k (22% below nominal)

Neck Tone: 175k (30% below nominal)
Treble Tone (removed): 170k (32% below nominal)

...so, low values all round, with the two volume pots barely scraping the edge of their supposed 20% tolerance, and the tone pots nowhere near it.

I'm sorry to have to say this, but it would appear that - in 2004, at any rate - CTS were sending RIC some pretty out-of-spec components, and nobody at the RIC factory was checking them for consistency.
2004 4003 JetGlo
Epiphone Jack Casady
Ovation Magnum 1
Mania VTB-4BS
Dean Stylist w/ John Birch Magnum II pups
Yamaha BB414
Trace Elliot VA350/GP11 Mk1
Peavey TB-Raxx
2 BFM Omni 10.5 crossfire cabs
Roland Bass Cube 100
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Joined: Mon Jun 19, 2006 2:26 am
Location: Norwich, UK


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