What brand/series of electrolytic capacitors for a Wurli 200A?

[JamieOxford]

I'm finally getting round to restoring my Wurli and wondering what models/series of electrolytic capacitors would be best for the pre & power amps? It's a bit of a minefield with things like ESR so any help would be greatly appreciated. (I usually end up using Panasonic, Vishay or Nichicons for synths & outboard equipment)

I've already bought replacement transistors and I'm working off this Vintage Vibe schematic.

Below is a list of parts I've put together that may need replacing in future. The caps are noticeably worn so I'll start with those and the preamp transistors to reduce the noise. If there's anything else worth looking at whilst I'm in there, please let me know.
Thanks !


Electrolytic Caps:
5, 6, 8, 26 - 4.7uF
7, 10 - 22uF
12 - 100uF
23 - 1uF
27 - 47uF
28, 29 - 2200uF

Film Caps:
30, 31, 34 - 0.33uF (Panasonic ECW-F2334JAQ)

Metal Film Resistors:
1 - 22k
2 - 1M
3 - 470k
4 - 150k
5 - 33k
6 - 1.8k
7 - 270
8 - 820
9 - 6.8k
10 - 56k

Transistors (spec sheet here)
TR1, TR2, TR15 - 2N5089
TR3, TR4 - 2N5088
TR7, TR8 - 2N5087
TR12 -  MPSA56
TR9, TR10, TR14, TR16 - MPSA06
TR16 -  KSP13BU (later serial # pianos - post #102905)
TR11/TR13 - TIP35C & TIP36C (power output transistors)

[velo-hobo]

Maybe sacrilege, but I'm not sure how much the choice of electrolytics brand/series matters much for this application, as long as the specs are appropriate. The Wurlizter EP amplifier is not a hi-fi or pro audio device, so IMO it's not worth sweating over audiophile type considerations, if that's part of the question at all. Forgive me for assuming so if it isn't.

In terms of quality, any of the brands you name should be totally fine. I've even used some NTE stuff when I needed to, but I tend to prefer Nichi or Vishay. Where I work we have a boatload of assorted new and NOS film caps, it's unclear even what brand some are but they've all worked for me.

Might find it difficult to source some specific cap values in the optimal lead configuration - for example you might only be able to easily source a radial cap when the PCB is meant for axial leads. In my experience it doesn't matter, since caps are now less than half the size they were when these were first made. There's plenty of room to operate. I just add a little adhesive to help support any radial cap installed in this manner.

You may also need to replace the resistors R12,13,14 and .12mfd film caps C16,17,18 in the twin-t vibrato oscillator, if you've got thumping or other issues with the function of that circuit. After replacing those caps, it may require tuning the resistor values to produce a stable and thump-free signal at the desired frequency. Would leave R13/14 at stock value and adjust R12 to taste.

[JamieOxford]

Thanks! I'll have a listen to the vibrato circuit once I've finished the acoustic set up and transistor/cap swaps, but I think it's pretty clean at the moment.

One thing I do have is noise when powering off (an audible thump on the speakers and possibly on the DI). Not sure if the recap will fix this, or if something in line with the speakers or a resistor/cap to ground on the speaker line will eliminate this?

[velo-hobo]

Hard for me to say, but maybe others have more insight to offer. You'll do the recap anyway so if the excessive thump on power-off is still there after, that's something else to look into