Boss phaser PH-1 switching problem

[pontiacpete]

This pedal works when using the battery connection but the LED only flashes on but remains off. The pedal does not work when powered in the wall wart socket, it has a very weak distorted signal.

[Jazz P Bass]

Are you using the correct polarity wall wart?
Is D 5 in good shape?
Doesn't make sense otherwise.

[Helmholtz]

Did you use a fresh battery for the test?

Note that D2 is actually a 5.1V zener. Adding maybe 2V for LED and transistor means that loaded (!) battery voltage must be at least 7V to 7.5V to keep the LED on.

[pontiacpete]

I’m still trying to find D5.
I’m using a 1spot neg tip. I’m connecting the 1spot to the battery clip and then to the 9v socket. The LED just flashes on then off but effect works when connected to the battery connector

[Mick Bailey]

If yours is the early circuit as per the schematic it has the diode D5 and series resistor (R45?) for use with a 9v unregulated ACA adaptor. The voltage of these is around 13v. Later pedals don't have the diode/resistor and use a regulated 9v adaptor. Using this with an older pedal won't illuminate the LED very much at all, and the sound can be weak. To use an early ACA pedal with 9v you need to bypass the diode and resistor with a piece of hookup wire - I leave them in place.

[g1]

Further explanation of the ACA adapter issue and modification here: https://stinkfoot.se/archives/1019

[pontiacpete]

I thought I would have to shamefully admit that I had done about a half a dozed mods from the sinkfoot page to solve the LED and power supply issue, but this isn’t the case, I believe. First of all this pedal is not the PH-1r that sinkfoot has on it’s list. It’s a bit different. So when i jump D5 and the series resistor, which is 470R, it does nothing to solve this problem. To make sure, I’m jumping from the switch on the input jack and the series resistor. Light still flashes on bright and off.
When I’ve done these mods to make regular power supplies work with these older pedal, there is not a flash on then off, but rather no light at all when plugging into the 9v supply.
Here’s a picture.
Thanks and happy holidays!

[Helmholtz]

What is the internal supply voltage measured between the ends of D1 when powered from the adapter?

[pontiacpete]

5.8vdc when plugging in the power supply. 9.4 coming through the battery connector.

[Helmholtz]

5.8vdc when plugging in the power supply.

So here's your problem.

9.4 coming through the battery connector

Not clear what you mean, please elaborate.

What is the voltage across D1 when powered from battery?

[pontiacpete]

9.4v across D1. Isn’t that weird. Should i jump D5 and R45? Probably should just try that

[Helmholtz]

Should i jump D5 and R45? Probably should just try that

Sure, D5 and R45 eat al least 3V and only make sense with a 12V supply.

[pontiacpete]

Of course, now the voltages are equal at the battery and the power in jack. But it still has only a flash of the LED.

[Mick Bailey]

If you short the LED cathode to ground, does it stay lit?

[pontiacpete]

With the LED cathode grounded there is no flash of theLED