weird power supply start up problem

[beatnik]

i have just repaired a vintage electro harmonix electric mistress. the power supply section had a burnt ic and a dead transistor. i have replaced those and the pedal started working again

the problem is, if i disconnect power form the pedal when i reconnect it  the pedal doesn't work anymore, then if i touch 2N4354 base with the multimeter probe the pedal starts up !

i have used 2N5087 instead of 2N4354 and TL071 instead of LM741. I have read on the forum those replacements did work ok for another user.

here is the schematic for reference. any help is very appreciated

http://www.metzgerralf.de/elekt/stomp/mistress/images/1976-electric-mistress-v2-schematic.gif

[PRR]

> 2N4354 .... LM741

I do not see 2N4354 on the schematic you posted.

If you mean the power regulator shown as IC5 and its booster--- the TL07x is known to have trouble if an input goes all the way to the negative pin. It will be down there at start-up. The output "does the wrong thing". Your meter-poke forces the transistor on, and brings the circuit to a happy place.

The most obvious fix is to use something other than a TL07x part here.

LM358 should work, except it is a Dual so the pinout is very different and you will have to cobble it up.

If this is truly a Vintage pedal, just get a '741. Small Bear has a heap of stock at a half-buck each (or a variety pack of 35 opamps with three '741 for just over $15).
http://smallbear-electronics.mybigcommerce.com/ic-741/
http://smallbear-electronics.mybigcommerce.com/op-amp-ic-kit/

Mouser *still* has stock (the '741 is very old for them) but their price is higher than the Bear's.
http://www.mouser.com/Search/Refine.aspx?Keyword=LM741