Repairing a Joyo Digital Delay - bust voltage regulator?

[jim68000]

A friend has given me his broken Joyo Digital Delay (JF-08) to fix. The symptoms are that true bypass works, but when the effect is on, there's only a very muted output and no delay.

Before attempting to trace it out properly I thought I'd check the voltages for the things I should be able to figure out - eg, the opamp Vcc should be c. 9v and the PT2399 delay chip wants 5v. It turns out the PT2399 is only getting .2v at Vcc. Tracing back from that it looks like the voltage regulator is blown - I get 9v at the input but the same 0.2v out. The voltage reg is a 78L05 in a TO-92 case, and the output pin is connected directly to pin 1 on the PT2399.

My understanding is that these things are pretty much indestructible, especially at the kind of voltages found in battery powered effects pedals -  the datasheet says 35V max.

Is this kind of failure common? What can cause a voltage regulator to fail? (If you're not running it without filtering in a car ignition system, that is. That's the only other place I've found reference to a failure of this type)

[PRR]

Look for a shorted capacitor on the regulator's output.

FWIW: that can happen if someone puts AC into a DC-power pedal.

[jim68000]

Thanks! I should probably replace the caps around it on general principles.

Jim

[Chrisfromiowa]

I know this was half a decade ago, but did you get it working? I've got a Joyo Dseed that has the same symptoms. Thanks