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I need to replace the treble boost/cut pot in my SRA550, a bass Ibanez has not made in a while. This bass uses an active preamp/eq called the EQB3C. My ohmeter measures it at 56K so I'll guess it's a 50K and probably a linear taper. I've looked at ibanez.com and they sell the entire preamp assembly with all four pots. Ebay does have some pots but they're only specified as "for Ibanez", no other description. They might work but I'd rather see if anyone here can point me to the exact part. Thanks!

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These guys have everything.

https://www.mouser.com/?utm_source=...ectronics&utm_content=Brand%20Mouser

I would do a search for "Ibanez SRA550 schematic" online, somebody may have done all the heavy lifting for you. Also try adding the word "Forum", sometimes people will be discussing the same problem you have. Yes, it is probably linear but if it is audio taper then it won't adjust in the same way it used to. You could also google "test potentiameter for audo or linear taper" and see if anything simple comes up. You will have to remove the pot to test it and to replace it. You cannot get accurate readings with it being part of the circuit.

If not.

They will need every number off that pot, a sharp photo of the bottom would be helpful. If there is solder covering some of the codes, remove the pot (noting the location for all connections and putting labelled masking tape flags on the wiring) and first use a solder sucker and then a solder wick to remove the solder and get down to the numbers. You may have to gently file away the last layer of solder and the number should be discernable. The complete codes should inform as to the taper.

Yes, it is a PITA. Your other option is to pay a tech and hope they get it right. Cheers, Kuru


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Thanks, I appreciate the advice. I looked for markings but saw none (I'll try looking again, more closely this time). I'm guessing it's a linear taper as it has a center detent (it's an active eq pot that boosts and cuts, the zero position is in the middle). I'm ready with my Harbor Freight digital caliper if I need to measure the dimensions, then go to Mouser and find a match – but I thought it would be wise to ask here first in case anyone had been down this road before. I don't relish going through a ton of drawings on that site to find the exact pot. I can't imagine I'm the first guy with an Ibanez bass that's needed to replace a single pot! BTW I did look for a schematic of that preamp or bass and could not find one. Worse comes to worse I'll order a few pots and pick the one that fits best – that'll still cost a lot less than buying the entire preamp assembly or bringing the bass to a repair person. I'm no EE but soldering a potentiometer is not a problem for me.

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Originally Posted by Reezekeys
Thanks, I appreciate the advice. I looked for markings but saw none (I'll try looking again, more closely this time). I'm guessing it's a linear taper as it has a center detent (it's an active eq pot that boosts and cuts, the zero position is in the middle). I'm ready with my Harbor Freight digital caliper if I need to measure the dimensions, then go to Mouser and find a match – but I thought it would be wise to ask here first in case anyone had been down this road before. I don't relish going through a ton of drawings on that site to find the exact pot. I can't imagine I'm the first guy with an Ibanez bass that's needed to replace a single pot! BTW I did look for a schematic of that preamp or bass and could not find one. Worse comes to worse I'll order a few pots and pick the one that fits best – that'll still cost a lot less than buying the entire preamp assembly or bringing the bass to a repair person. I'm no EE but soldering a potentiometer is not a problem for me.


Yeah, easy solder job. I would still recommend you mark and remove the wires and then measure the resistance as the circuit it is attached to could change it. You will have to remove them anyway.

I searched ebay for "50k linear potentiometer center detent" and specified USA only for faster shipping. It's not a rare part at all, especially if you include other countries...

https://www.ebay.com/itm/50K-Ohm-Alps-Linear-Taper-Rotary-Potentiometer-Variable-Resistor-Center-Detent/282884742236?hash=item41dd3e9c5c:g:nBwAAOSwcSJa14DC


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OK looks like it's not 50K. There is one marking on it, "B100K", and after I took it out of the circuit I measured the end-to-end resistance – it's 86.2KΩ. I guess that's a 100K "low tolerance" pot, lol.

I also made a few measurements (all numbers are millimeters) and did a little photo editing. Thanks for checking out what was available on Ebay. Unfortunately the pots you linked to didn't have the right kind of shaft, I need it to be like this one (I think it's referred to as "split" and "serrated").

With these measurements I should be able to find something on Mouser, I think. Thanks again for your assistance!

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Yeah, 100k is "nominal".

Shaft is important so your knobs will fit. Mouser should have something now that you know what you need.
Cheers, Kuru


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Well, no luck at Mouser. The Bourns PDB181-GTR Series - 17 mm Guitar Potentiometer seems to be a match for mine, but lacks the center detent. I don't see a similar pot with one.

So far I looked at Ebay, Amazon, Allied, Arrow, guitarelectronics.com and a few others.

The basic form factor is not a rare thing. Here's a PDB181-GTR sold at reverb.com, it would be almost identical to mine... if it was 100K and had a center detent!

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Bummer on Mouser not having it. Did you shoot them a line and ask? Maybe they don't list them but can get one for you.

Is the center detent a must have or just a convenience?


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The center detent is where the EQ is flat, not boosted or cut. That's where I normally keep it. The more I think about it, the more I can see dealing without the detent. I'll just fudge the pot position somewhere in the middle. Thanks for planting that seed!

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Just wanted to tie a bow on this as after hours of clicking around multiple electronics parts sites, I think I have found the part that will work. It's a Bourns pot and it does exist, unfortunately it shows as out of stock everywhere except a site called Hamilton Americas – but I have my doubts as to whether they'll sell me one as I had to fill out my info to "request a quote." Not typical for a business that sells to end users like me.

I'm pretty well spent after spending this much time chasing this stupid part so I'm probably gonna order it from Mouser and wait 16 weeks. That's what they call "lead time" on this piece. All the other major suppliers that had this (Arrow, Digikey, Avnet, and Newark) had the same 0 stock and a minimum order of 450 units! Mouser is the only place that will sell me just one. Needless to say, the shipping is more than the part – by more than 6x! Beggars can't be choosers, I guess.

BTW the exact part number (subject to change if I screwed up on my measurements!) is PDB181-E218K-104B1.

BTW #2 - the Ibanez web site is NO HELP AT ALL. This post is already too long to go into detail, but it was pretty frustrating looking around there.

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Originally Posted by Reezekeys
The center detent is where the EQ is flat, not boosted or cut. That's where I normally keep it. The more I think about it, the more I can see dealing without the detent. I'll just fudge the pot position somewhere in the middle. Thanks for planting that seed!



I read your other post too, sorry about the bummer.

You could mark the end of travel in both directions, put another mark exactly in between those two and call it good. A dot on the knob and one on the bass and you can go "home" every time.
As the I Ching says, "Perseverence Furthers."


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Just ask Gorrie if you can have one of his old basses. Then send it to me. grin


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I tried that, for some reason he wasn't that receptive to the idea! smile

In the meantime, a good friend of mine who's a great player as well as a designer & builder of his own basses gave me an idea on how to continue using my bass with the current pot while I wait for the new one. He told me he hates the "split shaft" pots. He suggested breaking off the half that's almost gone (maybe I should mention that this is why I need to replace the pot in the first place!). Then, superglue that half to the other half and get a knob with a setscrew to keep it attached.

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Originally Posted by Reezekeys
I tried that, for some reason he wasn't that receptive to the idea! smile

In the meantime, a good friend of mine who's a great player as well as a designer & builder of his own basses gave me an idea on how to continue using my bass with the current pot while I wait for the new one. He told me he hates the "split shaft" pots. He suggested breaking off the half that's almost gone (maybe I should mention that this is why I need to replace the pot in the first place!). Then, superglue that half to the other half and get a knob with a setscrew to keep it attached.


That should work.
We have one of the best hardware stores in the known Universe here. I'd be inclined to get a longer set screw but that's just me being lazy.


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Yea, he mentioned I might need something to build up the pot's shaft so the screw has something to grab! (No, this is not a pitch for a porn movie plot, ha ha!).

A longer set screw should work too. Seeing as my next gig playing this bass is March 21, I'm sure I'll have it figured out. My new pot should be on a boat somewhere on the Pacific Ocean then, unless all of China is closed!

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"Your order from Mouser Electronics, Inc. is being processed by our warehouse and will ship out on JUN 22, 2020."

Well what a day. I just got this email from Mouser regarding the pot for my bass that I ordered on February 2 of this year – that's 4 months and 20 days ago! Seems like an eternity. You can tell from the post above this one that I had an inkling of what was to come and how it might affect when I would get this pot. Oh, that March 21 gig never happened and neither has any other since that time – so, no problem with this slight shipping delay!

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So, not exactly a Rush Shipping job. Glad it's (supposedly) on its way. I feel ya about the gigs, though. We have had to make some decisions over the last couple of months about the future of the band after losing our drummer to CV19 in mid-March. We just got together and 'porch-jammed' for the first time about a week ago and discussed our options. There may be more tunes coming or not, depending on the circumstances.

Hopefully venues will be able to start bringing acts in with limited capacity and some pretty strict rules, provided they're focused on the health of the customers, the employees and the band(s).

Snag some pix of the repair so we can all live vicariously at least for a few minutes. thu


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Wow I am so sorry to hear about your drummer, that's terrible. It's so depressing seeing what's going on now – I can see current events delaying live music's return even longer. AWB's May tour of the UK was cancelled of course – it's rescheduled for around the same time next year. Now I'm hearing the EU may not allow anyone from the USA to travel there! I also hear that once live music events start up again, they may limit attendance to keep people farther apart. So a 1500-seat club could become a 300-seat club. Even "selling out" those seats, how can a promoter make enough to support us (or any band with similar expenses) doing any touring? It's pretty depressing.

Oh yea, the pot! It shipped from China and probably by boat (just a guess there), plus they were in the thick of the virus earlier this year so I knew it was gonna take a long time. I'm not sure when I'll get around to installing it since I sure won't need my bass for gigs for a while. If you want pics, I'll be happy to oblidge. Stay well and stay safe!

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Thanks for the thoughts. It's odd - he and I played together since '74. Gonna take some getting used to but we think he'd be pissed if we stopped playing because of him. He was just that kind of good soul.

I'm sometimes wondering if you guys will ever get to do the UK/EU tour. Isn't that the one that was postponed from last fall? You guys just can't catch a break.

Pix would be cool, just because. Also, keep us up on when yoose guys hit the road again. I could really use another AWB show right about now.

Mask up - it's gonna be a bumpy ride.


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Ibanez basses don't need pot, they are already high...


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I do not know why I missed this originally but I did.

If you get tired of waiting then checkout an electronics supply company.

Here in the UK I would go to the CPC Farnell website (their outlet shop and distribution centre is 20 minutes walk away) or RS Components.

Both of these will probably have them in stock.

There must be a components company not sure if Radio Spares is still going in the USA but they would have been my first port of call, then a supply company like CB Gitty


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Thanks but I received the pot a few weeks ago. I wasn't home at the time but just got back. As detailed earlier in this thread, the pot was somewhat difficult for me to source since 1) I wanted an exact replacement, 2) most suppliers are not friendly to those needing one or two pieces and 3) I haven't had any experience doing this (sourcing an exact replacement, not soldering a potentiometer!). Maybe this is a common part that's easy to find but it did take me a while. The one place I found that had it and would sell me less than 50 pieces had none in stock, so I had to wait for it to ship from China during a pandemic. On the flip side, I haven't needed my bass for a gig in seven months! That's actually about to change since AWB has a gig in a week – our first since January and second one this year!

I will of course report back when all is said and done with my big repair job! Thanks again to everyone who helped me out.

PS - "Radio Spares"? Don't know them, perhaps you mean Radio Shack? Many of the b&m stores are gone, and their website has a very limited selection of electronic components (just like their stores had). Even in their heyday, the chances they would have this exact pot is zero.

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Hey, have a great gig!


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Thanks... it's gonna be a very unusual one for sure! I may share the deets in a KC post.


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