Boss phaser PH-1 switching problem

[Helmholtz]

The PH-1r uses a different LED wiring: http://www.geofex.com/FX_images/Boss%20PH-1r.pdf
and https://elektrotanya.com/boss_ph-1r_...wnload.html#dl

No, the LED does not come on at all..

With the jumper wire to ground/minus the LED should be on.
Which circuit version do you have?

[Mick Bailey]

I'd taken 'no flash' with the cathode grounded to imply the LED was working OK. My mistake.

[pontiacpete]

I’m going stop here with this pedal. I had a discussion with a friend that had an early boss DS1 (late 70’s early 80s) and his worked the same way, the LED would only flash when stomping it on or off and that changing that would or may decrease the value of the pedal. Since it doesn’t belong to me, but to a shop, I’ll leave that part of it’s weird behavior alone. It’s probably enough to have gotten rid of the diode and series resistor that prevents one from using it with their own power supply and not an ACA. Perhaps this thread will be useful as is.
Thanks for the help!
Pete

[Mick Bailey]

You got me thinking, so I dug out my early MIJ DS-1 and the check light stays on on this one.

[Helmholtz]

You got me thinking, so I dug out my early MIJ DS-1 and the check light stays on on this one.

The LED/switching circuit shown in the schematic of post 1 is used with many Boss and Ibanez pedals.
All the ones I've used kept the LED on.

But I'm not so sure about the PH-1r circuit with the missing LED driver Q9, where the LED is directly connected to one of the flipflop transistors.

And the OP's board doesn't seem to conform to any of the two circuits.

[Mick Bailey]

Here's a clip of the PH-1r showing that LED stays on at 0:28
https://www.youtube.com/watch?v=VKivT61oPEo

[Helmholtz]

Thanks.
That makes the most sense.

But there might have been more than 2 circuit versions - or the LED is simply bad .

[pontiacpete]

Yes that’s the PH-1r. This one here is just the plain old PH-1

[g1]

You got me thinking, so I dug out my early MIJ DS-1 and the check light stays on on this one.

But there might have been more than 2 circuit versions - or the LED is simply bad .

Here we go. It's the OD-1 but I'm pretty sure there will be the same '3rd variation'' for the PH-1 led circuit.
The official modification is described, but I don't think they show the original schematic. I think the LED cathode may have originally just went to the momentary switch?

[Mick Bailey]

That's the answer. Good work!

[g1]

The SP-1 service notes (attached) are more legible and show a dotted line where the original connection to the LED cathode would have been (other end of resistor coming off momentary switch).
With the crazy money some of these original 'stoplight series' Boss pedals are going for, I understand pontiacpete 's desire to keep it original. The flashing light is something that helps show it's age.

[Helmholtz]

Actually none of these explains why the LED didn't stay on with its cathode grounded.