MXR Phase 45 Fault - original script logo from 1975

[J M Fahey]

Absolute worst case, measure polarity.
Turn pedal ON, and measure voltage across each suspect cap legs.
Not a huge voltage, but youŽll find anything from, say, 0.5V to 5V between them; mark the more negtive one with a visible marker pen dot.
Mind you, leg to leg voltage, not leg to ground which here is irrelevant.
After you marked all of them, desolder old ones and place new electrolytics there.

As of the pot; lacking the Reverse Log one (C3 curve) , the "least worst" one is a linear pot, which to boot is easy to find, and the absolute worst one is an Audio/Log type which will be all but unusable.

As of your symptoms, all oscillators need a minimum positive feedback to work or they wonŽt even start; here parts value drift or pot destruction (or both) must have decreased down that positive feedback to the bare minimum, so oscillator is "lazy" and slow to start (if at all); now active components (Op Amps) do not degrade, so replacing worn passives will restore pedal to full glory.

[Leo_Gnardo]

As of the pot; lacking the Reverse Log one (C3 curve) , the "least worst" one is a linear pot, which to boot is easy to find, and the absolute worst one is an Audio/Log type which will be all but unusable.

FWIW Antique/CE show a 500K reverse Alpha pot offered R-V38-X-RA 500K , "full size" 24mm with solder lugs. Since Mouser also carries Alpha, maybe they have it too? Unless I'm mistaken Mouser has a UK/Europe branch.

[Audiotexan]

Unless I'm mistaken Mouser has a UK/Europe branch.

I'm pretty sure I recall that being the case with Newark/Farnell, but it would be news to me for Mouser! (Would be very cool news though, as they have great service and selection in some key areas IMO!)

[Mick Bailey]

Mouser has a UK-facing operation, but I've never ordered from them because I'm not sure where the products are shipped from, or whether there are additional taxes or import duty to pay.

[Leo_Gnardo]

Mouser has a UK-facing operation, but I've never ordered from them because I'm not sure where the products are shipped from, or whether there are additional taxes or import duty to pay.

Easy enough to find out: ask! I know, it's kind of hardly worth it, for a pot that costs a quid. In case they ship from some other site in Europe, better get crackin' before post Brexit import duty kicks in.

FWIW I've found Mouser USA to be a top flight outfit, with gazillions of parts and cheap shipping. Even with that, they certainly don't have everything, and some things like wire & cable, they charge whopping huge prices. Gotta shop carefully.

Also, funny thing if I order parts from Canada, no import duty and minimal shipping. BUT not the same by far shipping items the other way. I learned the hard way selling stuff on ebay. What a hassle!

[J M Fahey]

Also, funny thing if I order parts from Canada, no import duty and minimal shipping. BUT not the same by far shipping items the other way.

Canada, like most other Countries, tries to protect its own Industry, also own Commerce even if parts themselves are imported. (buy from local Maple Leaf Electronics instead of Mouser).

US on the contrary applies a suicidal free open to all zero Tariff policy.
Which is fine if you are the most Technologically advanced and largest Industry in the World but not otherwise.

I distinctly remember when schematics and projects specified "impossible" for us Arnolds Magnetics cores, Honeywell sensors, even TI Fets, and so on.

When to build a Guitar you had to import Gibson humbuckers or Fender single coils, with the "second source" being German made Schaller pickups , I installed dozens of them in my early youth.

Or Kluson tuners, second source being again Schaller (very good) until Japanese hardware swept both from the table.

[Serhat18]

I'm trying to build an MXR Phase 90 but using J113 as the JFETs instead of the original 2N5952. All the J113 are matched, but the output is slightly distorted. It's not as noticeable when lightly strumming some chords, but picking strings with some amount of force will produce some ugly bass-y distortion. I've also tried different FET configurations according to these designs but none of them seemed to help. I noticed on the data sheets that the J113 I'm using has a forward gate current of 50mA while the original 2N5952 has only 10mA. Would it be worth it to get another set of JFETs more in line with the 2N5952, or does that spec not matter?

[Serhat18]

Ggg mxr p90 phaser

I had the same problem with 2n5457 I set the trimpot to my favorite sweet spot phase expanded but the distorted audio mix still continued What is the problem?