Dunlop Crybaby JH1 broken

[Langedarm]

Hi,
I've got a Dunlop Crybaby JH1 from a friend. It looks brand new (can't post pictures yet), but its not working. When the bypass switch is pressed, I get sound, but when the circuit is active, all I get is a high squee regardless of playing the guitar when the pedal is in and nothing when its out. I can't see any connection that is loose or any bunrt resistor or anything and I don't know how to measure what part is broken, but maybe someone can help me with that or maybe the squeeling sound reveals the problem?

I'already ordered a replacement pcb for the standard crybaby GCB-95, version after 1990. It looks exactly the same and as I understand the only difference is a few resistor values. I found two interesting sites where a lot of info about the crybaby andh how to mod it is made available (http://stinkfoot.se/archives/546 and https://www.electrosmash.com/crybaby-gcb-95), so I'm planning to replace the pcb with the new part and start experimenting on the Old JH-1 pcb parts, but first I have to find out what is wrong with the old pcb, so any suggestion is very welcome.
Thnx

[Mick Bailey]

I always make sure the switch is working properly as they're a frequent failure. Also, the switch height sometimes needs to be raised so that the pedal fully actuates it and doesn't leave it partly connected. Sometimes a defective switch can be revived with contact cleaner squirted in the gap where the terminals emerge from the body. Maybe by now you've figured it out, but the DC voltages given in the link are a good starting point.

[MichaelNuzum]

I don't want to sound condescending, but are you sure you have it plugged in correctly? The reason I ask is that plugging into the output and sending the input to your amp will make screeching noises. In Pink Floyd Echoes, the "seagull" sounds in the middle section are actually a wah plugged in reverse. Is this the sound you re getting?

[Mick Bailey]

Good one! - I forgot all about the reverse connection thing.