Rotovibe question: fried power supply filter

[nooneknows]

Hi,
as I've already posted on this forum, a friend of mine fried something inside my rotovibe, giving a wrong power supply voltage.
I didn't fix it in the past but now I want to put back the pedal on my pedalboard so this time the question will be more focused: please, I need to know the value of what-it-probably-was-a-capacitor connected between two lugs of the transistor shaped 7809 close to the power supply jack. That carbonized thing seems a ceramic (or a tantalum) cap, I don't think a high value.
The pcb is marked Rev.B
Thank you very much for your help.
Marcello

ps. The pedal works fine with battery so I could connect the supply to the battery socket but since it seems just a case of a boiled cap I'd like to fix it anyway

[R.G.]

I don't know what it really was, but the application notes for the 7800 series of regulators all say that the regulators need a 22uF local decoupling cap between the input pin and the ground pin. A 0.1uF on the output is a good idea as well. Be sure to get the polarity right.

[bryantabuteau]

pretty sure the dunlop tech told me 22uf on that one.   I had the same problem a few years back.  He also recommended replacing a particular transistor (probably the regulator) but it worked without doing that so I didn't bother.   Email dunlop tech support and they'll tell you exactly.  they won't give you a schem, but they'll tell you waht to replace.

[nooneknows]

thank you all for your help!

Marcello

(BTW, in the meantime i searched for the 78L09AWC datasheet (it's a to92 device)  and I didn't find it, but the 78L05 seems to need a 0.33 uF cap before and a 0.1 after the regulator, so I'm a bit confused, because I remember, as you pointed out, the there was a pretty large capacitor in front of a 78xx series on the application sheet I had yerars ago...)

[R.G.]

The negative regulators are different circuits from the positive ones. They may need different decouplers.

Also, the recommended value ahead of the positive regulators varies depending on whether you use tantalum or aluminum electrolytic. You can use a lower capacitance tantalum because the ESR is smaller for tantalum.