DS1 Keeley seeing eye/ultra mod turns on but no sound

[jhob]

So I stayed up too late last night modding my DS1 for the seeing eye/ultra mod as per these instructions.  Alas it has not worked.

The symptoms are:

• Pedal does turn on & off - the blue power led lights up appropriately
• Bypass works and allows a signal through so the input/output buffer circuits must be fine
• Flicking the switch between all-seeing-eye/ultra mod does nothing
• Twiddling the knobs does nothing

My main culprits for it not working is definitely centred around D4 & D5.  It was getting late when I was doing this bit and so an diode polarity error here is most likely, although I did double check everything.

One oddity was the the 47pF ceramic disc cap on the back of D4 & D5 measured as 0.08nf on my multimeter.  Is it possible that the multimeter can't read values that small?  I tested the batch of 5 that I bought and they all came out with the same reading.

I tested the capacitance of at least one individual from each batch of components to check I was putting the correct value in and they all came out with the capacitance that I would have expected so I don't think the meter is at fault.  If this capacitor was faulty, could it stop the pedal working or would it just affect the sound the produced?

Images
Solder side of the PCB
Enclosure

Visually the soldering look good, I can't see any points where two components are shorted together that shouldn't be.

Help with the capacitor question above would be most appreciated.  I'm still very much a novice at this so any help very much appreciated!

[antonis]

Such a low capacitance values are prone to DMMs miss-reading..
You can always place 2X0.08nF in series for an equivalent capacitor of about 40pF..

Anyway, according to your posted instructions, 47pF should replace C11 (22nF) used on Tone level..
https://www.electrosmash.com/boss-ds1-analysis

Despite its actuall value, it can't create issues like those you've experienced..
(not even in case of being shorted or open..)

[jhob]

Anyway, according to your posted instructions, 47pF should replace C11 (22nF) used on Tone level..
https://www.electrosmash.com/boss-ds1-analysis

From the instructions

0.047uF 50V Stack Metal Film Capacitor x 1  (C11)
47.0pF Capacitor x 1 (for bridging D4/D5)

So C11 is 47nF, not pF, unless I'm missing something!

For those I bought:

47nF (0.047uF) Polybox
47pF npo ceramic

I just did a visual check (have the pedal but no DMM with me here) and I'm pretty sure I put the correct value caps in.  There's definitely a polybox in C11 and a ceramic bridging D4/D5 anyway.

Despite its actuall value, it can't create issues like those you've experienced..
(not even in case of being shorted or open..)

Thanks for the confirming that.  I thought it might be the case but wasn't 100% sure.

[antonis]

There's definitely a polybox in C11 and a ceramic bridging D4/D5 anyway.

Then it's my bad (again..)

Ceramic cap bridging D4/D5 is refered as C10 (10nF) on original pedal schematic and it "smooths" diode pair clipping waveform corners..
Again, its value isn't critical for your issue but its state DOES..!!
(not for open cap but definately yes for shorted one..!!)

Re-check for (non) continuity between its legs..
(if it's shorted, results into signal grounding..)

[jhob]

There's definitely a polybox in C11 and a ceramic bridging D4/D5 anyway.

Then it's my bad (again..)

It's all good - makes me question and examine my understanding, which is one of the route by which I will learn better.

Ceramic cap bridging D4/D5 is refered as C10 (10nF) on original pedal schematic and it "smooths" diode pair clipping waveform corners..
Again, its value isn't critical for your issue but its state DOES..!!
(not for open cap but definately yes for shorted one..!!)

What I don't understand is that c10 exists on the schematic but it does not appear to be on the PCB (at least not that I can see).  Was the c10 cap an 'optional' component by Boss?

I can at least test if the cap is at fault by de-soldering it, don't even need to take the pedal to pieces so that's definitely my first port of call!

Re-check for (non) continuity between its legs..
(if it's shorted, results into signal grounding..)

Very good point, will check, thanks!

I was thinking earlier that it's unlikely to be a diode polarity issue as there should still be a sound regardless of how I orientated any of the components in the revised clipping circuit.  Is my understanding correct there?

Also I did spot a possible short via a stray cap leg.  Now snipped, will test later.

Thanks for your help 

[antonis]

What I don't understand is that c10 exists on the schematic but it does not appear to be on the PCB (at least not that I can see).  Was the c10 cap an 'optional' component by Boss?

Place/space/mark for "optional" items should be at least included on PCB..

I was thinking earlier that it's unlikely to be a diode polarity issue as there should still be a sound regardless of how I orientated any of the components in the revised clipping circuit.  Is my understanding correct there?

More than correct..
(actually, that would result into asymmetrical clipping for a single reversed diode.. )

[jhob]

What I don't understand is that c10 exists on the schematic but it does not appear to be on the PCB (at least not that I can see).  Was the c10 cap an 'optional' component by Boss?

Place/space/mark for "optional" items should be at least included on PCB..

I'm going blind!  Not sure how I didn't spot that.

So the 47.0pF is in addition to the C10 cap, which remains in the circuit.

I was thinking earlier that it's unlikely to be a diode polarity issue as there should still be a sound regardless of how I orientated any of the components in the revised clipping circuit.  Is my understanding correct there?

More than correct..
(actually, that would result into asymmetrical clipping for a single reversed diode.. )

thanks!

[jhob]

Got it working last night, turned out to be a simple short - a stray cap leg was shorting out on an adjacent blob of solder.

[jhob]

OK, so there's one thing that's not quite right.

In the ultra position the 'seeing eye' does not light up.  I think that it should and from looking at the circuit I can't see how it could possibly not light up.  All the switch does is switch in the second clipping red led, it does nothing to affect the 'seeing eye' clipping led.

Any ideas?

[anotherjim]

If the LED is added and the original diode is still there, the diode will prevent the LED getting enough voltage to act. I did this mod ages ago so can't remember too much, but it required adding a switch to changeover from LED to diode IIRC.

[jhob]

The seeing-eye led is in d4, replacing the original signal siode

d5 has the original signal diode in seeing-eye mode and adds another red 3mm led (internal so not seen) in series with the signal diode for ultra mode.

So I think the seeing eye led in d5 should activate in both positions.

I have tried it with a humbucker turned up to 10, gain all the way up and putting other pedals in front of it to boost the signal but there's not a flicker.

It actually sounds fine, but the fact it's not lighting up suggests to me that something's not right.

[anotherjim]

The Seeing Eye LED should light - wouldn't be much point drilling a hole for it if it didn't.
Some have reported liking the sound with only one diode and no LED at all.
Note that it is possible to kill a LED from too much soldering heat close to the body.
If the Seeing Eye LED was fitted with its polarity reversed, it would only light when the internal LED is switched in but if you haven't done the Ultra mod it would never light.

[duck_arse]

If the Seeing Eye LED was fitted with its polarity reversed, it would only light when the internal LED is switched in but if you haven't done the Ultra mod it would never light.

where did you source your leds from, and did you confirm the lead orientation matched the body markings/indicators before you soldered it in? there is a lot of leds about these days that don't conform to any or all of short leg, body flat, or internal anvil orientators.

[jhob]

If the Seeing Eye LED was fitted with its polarity reversed, it would only light when the internal LED is switched in but if you haven't done the Ultra mod it would never light.

where did you source your leds from, and did you confirm the lead orientation matched the body markings/indicators before you soldered it in? there is a lot of leds about these days that don't conform to any or all of short leg, body flat, or internal anvil orientators.

I ordered them from bitsbox.co.uk and did check and re-check the orientation with my DMM.   That's not to say I got it right, just that I checked it a lot!

This is how the circuit is wired (or at least how I intended to wire it)



I must have orientated the D4 led correctly as that activates in seeing eye mode.

What I don't get is that even if I had totally messed up the ultra mode and got one or both of the 1n4148 and additional led round the wrong way surely the seeing eye led would still operate as that isn't taken out of the circuit?

I think what I'm going to do is take that bit of the circuit out anyway and re-do it from scratch.  I must have made an error there, I just can't understand what sort of error would cause it the seeing eye led to work in one position but not the other.

[jhob]

Managed to resolve the issue - had the wrong LED mounted on the case! 

Although I did also spot a cap that didn't have a secure solder joint so resolved that at the same time.

[duck_arse]

win win?

[jhob]

win win?

I think so.

Lesson of story: Don't stay up till 2am doing projects that require a reasonable degree of alertness & concentration!

[Kipper4]

Lesson of story: Don't stay up till 2am doing projects that require a reasonable degree of alertness & concentration!

No no no.
Stay up late, burn the fires of passion and determination. Resolve to resolve.
Just don't do what I do and ask dumb questions I already know the answer too on posts?
Stay passionate.

[jhob]

Lesson of story: Don't stay up till 2am doing projects that require a reasonable degree of alertness & concentration!

No no no.
Stay up late, burn the fires of passion and determination. Resolve to resolve.

There also be where the fires of stupid mistakes burn!

Just don't do what I do and ask dumb questions I already know the answer too on posts?

I dunno, sometimes it's in the discussion of these things that we learn.  And sometimes the mere act of having to write the question down is enough for us to find the answer.

Stay passionate.

will do!

[duck_arse]

total fire ban here. but stay up as late as you like, you're allowed.