Ah okay, misunderstood your first post.

In that case, you could either wire up a DC jack and use an 18V DC pedal supply to power it or find a suitable replacement transformer to put in the enclosure.

Hmm, definitely something not right, your voltages are way off, transistor one should have ground on its emitter.

Does your meter have a continuity setting? It’ll probably be paired with the diode checker and have a little o))) symbol, if so, set the meter to that and put one lead on to the enclosure and one on to the ground point on the board to make sure it’s connected, if it is it should beep.

Are you sure you put the new battery snap on the right way round too? If you reversed the polarity that would be a problem.

You can’t just replace stuff and hope for the best, well you can, but as you just learned it doesn’t necessarily fix things, leads to frustration plus damages the resale value. You can take out the guess work by debugging it.

You need a multimeter (a cheap digital one off ebay or wherever will be fine) and to take voltages of the transistors, even if you’re just a solder guy it’ll be an invaluable tool, is easy to learn/use and allows others to suggest appropriate repair advice because without any information, your guess is as good as mine.

Contact EHX support and they should be able to help you out.

Ceramic caps (the disks) can last a life time, I wouldn’t suspect them unless they’ve started to physically dry out and fall apart.

The electrolytic certainly could be bad, they have a shelf life and it’s the first thing the battery sees, if it had turned in to a short the circuit would get no power.

First things first, you need to take the voltages of the 2 transistors.

Awesome!

Hmm… when you say grit, what do you mean exactly? Is it distorting? That may just mean you need to tweak the bias trimmer properly.

If it’s a ‘chirping’ noise that’s due to the low filtering and the BBD not running in parallel multiplex which improves the sampling, it can be cured though with some minimal high loss and an easily reversible mod by tacking an 820pF to 1n cap in parallel with the 6k8 in the feedback loop of the 4558.

A bad resistor is unlikely, there’s no electros or tantalums in the audio path either (at least when the pedal is engaged) that could have gone dry, although replacing the ones related to power might cut down on some noise and is probably worthwhile as they’ll eventually go dry and changing them wont affect the tone so it’s just one less thing to worry about going wrong down the line. The only other thing I can think of would be a loose solder joint so checking the board over and touching up any that look a bit iffy may be worth while.

Congratulations on getting it going again, hope you enjoy it.

Okay, that’s a lot to read through but I think I can narrow it down.

Yes the switch is original, it’s a DPDT slide switch, you can use another DPDT or SPDT (it doesn’t matter which) this one is fine http://smallbear-electronics.mybigcommerce.com/alpha-dpdt-slide/

If the power cord is dodgy by all means replace it, with 2 prongs you don’t have to worry about ground, the pedal gets AC and the transformer in there (the metal thing with yellow electrical tape) plus some circuitry converts it to the DC the pedal uses. However, putting a 3 prong cord on there would certainly be a good idea for safety and isn’t invasive regarding originality as it can easily be undone.

To do so, wire the power cables to the switch as normal then you can add a solderable washer (like this, check for screw size http://smallbear-electronics.mybigcommerce.com/solder-lug-angled/ ) to the earth cable and anchor it to the enclosure. I like to stick them between the transformer and enclosure, just stick the transformer screw through the washer and bolt it in tight with the existing screw and bolt, you want a good secure connection.

For the input and outputs being switched it’ll be a simple case of switching the jack tip wires around on those 2 jacks

Regarding its decay issues, could be a set up issue (there’s 2 trimmers, read the manual of the micro synth on the main site for an explanation of them) could be just your expectation of the pedal or it could be a fault.

If the pedal seems to work for the most part a simple servicing of replacing all the electrolytic and tantalum capacitors can sometimes help reduce noise and rectify issues and give the pedal a fresh bill of health, both types of capacitor have a limited life span and at this point they’re already at about 35 years old and probably drying up, just one less thing to worry about going wrong down the line, just remember they have a polarity which must be observed when replacing them.

I realise that goes against keeping the pedal totally original (something I am a proponent of) but it’s just one of those jobs that will have to be done sooner or later and wont effect if functionally other than extending its life, you can always save the original parts in a baggy and include them if you sell it on.

Edit: Oh and the reason your power cable was probably loose on the switch is that there should be a plastic bushing in that metal hole to hold the cable securely, you should be able to find a replacement once you’ve got the measurements of the hole and your new power cable.