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Ibanez Delay Rack Re-Cap

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    Ibanez Delay Rack Re-Cap

    Hello everyone,

    Hoping to get some insight on how best to go about overhauling this old Ibanez delay. Its from 1983 so it celebrates its 40th birthday this year, the unit still functions however i heard a high pitch oscillating whine from it a few weeks ago and decided to strip the chassis and have a look.

    It looks like the 25v and 16v caps are leaking, there have been a few replacement caps in its lifetime as it has some bi-polar caps installed that differ from the polarized ones in the unit.

    My plan was to swap out all of the electrolytic capacitors, i was planning to use 105c Nichicon HZ or similar the power side and use 85c Nichicon MUSE bipolar caps at the control/digital side.

    There's also 3 capacitors im having trouble identifying, two of them look like white tantalum capacitors and there's one with a blue plastic casing over it? They look quite tired so i thought i might as well swap them while im at it.

    I have a college degree in vehicle mechanics so i have experience with electronics repair and ive done some surface mount stuff before but this is a bit more labour intensive compared to what ive done in the past.

    Any additional input or advice would be appreciated.
    Attached Files

    Re: Ibanez Delay Rack Re-Cap

    I would troubleshoot it first before assuming it's all the caps. But if you don't have that ability, then "shotgun it" replace all electrolytic caps and see where that takes you.
    This thing has many trimpots, over 8? so it might just be out of alignment.
    But C145 top looks bulged.

    The one cap translucent blue is a polystyrene film cap and I leave those alone unless they have cracked. Mouser sells them under Xicon. They are special, affect the sound quality and are not easy to find replacements. So I'd leave them alone.
    The 104K cream coloured cap is just a mylar film cap, no need to replace it. It's the wet (electrolytic) caps that age poorly.

    I'd make a list of the caps and order new ones. The ones in it are good quality and may be OK a little low value.
    The blue/red factory markings appear to be part of the checkout/alignment, they marked the stages as they went along.

    The caps with blue markings do look weird though, corroded or what?


      Re: Ibanez Delay Rack Re-Cap

      Thanks for your reply,

      The idea behind replacing all caps is purely because they are 40 years old at this stage, the bigger ones haven't vented or bulged excessively but the red residue at the bottom of them doesn't look like a good sign.

      As you mentioned, it looks like someone has painted the tops of the smaller caps to differentiate between them, colours used are white, red and blue. The bigger cap values are as follows,

      1000uf 25v x 2
      1000uf 16v x 1
      100uf 25v x 3

      Then various smaller caps at 4.7uf 25v, 10uf 25v 2.2uf 50v 1uf 50v. Replacement caps in the past have been swapped for bi-polar Nichicon caps.

      The cap with the blue plastic casing looks as if the plastic is stressed or starting to fracture? That was my only reason for swapping it. I was unsure on the 104k caps but they just physically look quite tired. Im unfamiliar with their expected life span and there's only two of them so i was going to swap them too. If its unnecessary then i would just leave them.

      With regards to my testing abilities, i have a multi meter, an old incandescent test light, a power probe and that's it. No ability to view waveforms or any ESR testers etc. The sole reason for the cap overhaul is exclusively time based, I just think that keeping something in there that is past its sell by date is false economy, i would much prefer to change all electrolytic caps at once and be done with it, but that's just my thinking. If other problems arise il deal with them if possible.

      I also plan to change 7 pots as those are badly worn (its had 2 new pots in the past by the looks, 10k and 500k respectively) and i also need to reinstate the LED backlight for the LCD as its blown, i was hoping to try backlight the same way someone has done in this photo...

      Il just say that i have a few of these units and this is the worst of the bunch so i wanted to use it to go through the process of diagnostics and overhaul since its fairly beat up anyway. There's also no time constraint so if it takes a few months to get the right parts, testers etc then so be it.

      Thanks again.

      Edit: Cap C145 does look slightly bulged which i hadn't noticed, i don't see any corrosion on the caps marked with blue paint but i can upload more photos as i have the unit at hand and stripped down.
      Attached Files
      Last edited by MeanStreets; 05-13-2023, 10:31 AM.


        Re: Ibanez Delay Rack Re-Cap

        I managed to photograph the polystyrene film cap to try better identify it. The markings have worn off so i bumped the contrast and sharpness to try see it better.
        Attached Files


          Re: Ibanez Delay Rack Re-Cap

          Yeah the polystyrene plastic looks bubbled or crackled. It looks like marking Z102J which I take to be 1,000pF (aka 1nF or 0.001uF) 5% replacement would be a Xicon 23PW210. The 23PS210 is axial version. It's low voltage so 50V rated is fine.

          The 104J is a polyester film cap and I would use 0.1uF 50-63V 5% something from Wima MKS2 or MKS4 family. There are zillions of different offerings, just find the lead spacing and length that will fit.
          Polypropylene is another best dielectric for audio, so the MKP2 is best but short pins and different size 5mm.

          It's good to have a capacitance meter which I use to flush out which parts are aging. Or simply take a bunch of pictures and replace all the electrolytics.


            Re: Ibanez Delay Rack Re-Cap

            Thanks for that info, the marking does indeed look like a letter Z, its a bit easier to see in real life so if you can see a Z in the photo then i would agree with that.

            Would you say that replacing the power side with polarized Nichicon caps and doing the rest with bi-polar Nichicon caps would be ok? I would prefer bi-polar caps to minimize user error on my side, there's only a handful of caps on the power side so I would just keep those polarized.

            The pots are just dime sized varying between 10k and 500k, linear or log depending on its job, so im not too phased with those. Re-instating the LED for the backlight is straightforward but im trying to figure out how to backlight it like the image above.

            Il grab a capacitance meter so i can compare old cap readings with new ones, are there any other tools you would recommend for this work outside of the basics; ie solder gun, multi meter, good solder, de-solder gun?

            Thanks again.