The Big Bad Stone Thread

[beatnik]

Hi guys,

I've finished building my first Bad Stone, using topopiccione project

http://topopiccione.atspace.com/pjimages/EHBadStone.sch.gif

http://topopiccione.atspace.com/pjimages/EHBadStone.lay.gif

I can't get it working, I get no phasing sound and a little bit of distortion.

Here are my voltages, I hope someone can give help, because I'm totally stuck with it.



ICA 4558

1  1.95
2  1.95
3  0
4  0
5  0
6  1.97
7  2.00
8  7.56

ICB 4558

1  6.44
2  6.44
3  0.02
4  0
5  0.77
6  1.66
7  2.60
8  7.56

ICC 4558

1  6.73
2  4.38
3  0
4  0
5  0
6  6.16
7  5.59
8  7.56

ICD 4558

1  1.98
2  1.97
3  0
4  0
5  0.43
6  1.96
7  1.96
8  7.56

ICE 4049

1  7.06
2  0
3  7.06
4  0
5  7.06
6  0
7  7.06
8  0
9  7.06
10 0
11  7.06
12  0
13  7.06
14  7.06
15  0
16  7.06

ICF 324

1  6.42
2  0
3  0
4  7.65
5  0.63
6  0.63
7  0.03
8  0.63
9  0.03
10  0
11  0
12  2.70
13  0
14  6.32

[beatnik]

I did some additional check on my build and I just realized I had a short between ground and one of the supply rails!

This was the main problem because now all the voltages seem correct (compared to the ones posted earlier in this topic) and the pedal is phasing.

However, I compared the sound to my other phasers and to the samples of original bad stone.

Something isn't right, because the phasing sound has not that smooth sine-wave like shape, but more like a stepped one (triangle??)

I try to post a sound sample soon so you can evaluate the problem. I've replaced all the ICs with fresh ones but nothing happened.

Then, I used a linear pote for the rate control, and I notice it's useless in the first 3/4 of the rotation. Are you guys using anti-log pots for rate or is a wrong behavior of my unit?

Here is the sound sample

http://soundcloud.com/mxxp_labs/bad-stone-lfo-sample

[beatnik]

bump... anyone?

[Scruffie]

Use anti-log.

And no clue what's going on with your LFO, seems to be jumping, check all your values, orientations etc. in that area.

[ORK]

You used the UNbuffered version of the HEX-inverter? (4049UBE) The buffered one doesn`t do smooth resistance-sweeps but rather jumps from high to low.

[beatnik]

You used the UNbuffered version of the HEX-inverter? (4049UBE) The buffered one doesn`t do smooth resistance-sweeps but rather jumps from high to low.

I've used both with same results. Tried replacing one more time all the ICs with fresh ones, but problem is still here.

I've triple checked all the connections and they seem good. Will try to replace all the diodes and polarized caps and see if something happens.

Thanks for the support, please stay tuned

[beatnik]

I've tried to replace C10 (1uF el) C13 (1uF tant) and D1 (1N4148) with no results. Checked all components values one more time and everything is correct.

I had the unit wired permanently in auto mode (ie the manual shift pot was bypassed) so today I've decided to add the manual switch and pot.

Then, I noticed a strange behavior: when going from manual mode back to auto mode, the lfo isn't working anymore and I have to power-cycle the supply. After that, I have phasing back in auto mode.

This thing is really driving me crazy and I have no clue where to look at next... Please give some thoughts and if additional measurements need to be taken, just ask me.

Thanks again

[beatnik]

still no ideas... please help

[Scruffie]

Ah! Some people did have problems with the Power line input resistor, (100R or whatever value it is) and jumpering that helped fix builds.

Is your 2N5088 orientated correctly too? Perhaps try a 2N5089 too for more hFe.

[beatnik]

thanks scruffie, tonight i'll try and report back

[puretube]

could be the old: "Fairchild vs. Texas vs. Phillips"- Hex-Inverter-chip threshold/Bias thing...

[beatnik]

I tried to leave out the 100R resistor, and swap to a BC549C with hFe around 570 which was the highest I could get (is that enough?) I even swapped the 4049 for a 4009UBE which it's the same as in the original pedal

Yet no change, lfo still has wrong shape and has that "latch-up"? problem...

could be the old: "Fairchild vs. Texas vs. Phillips"- Hex-Inverter-chip threshold/Bias thing...

please can you expand on this?

[beatnik]

BUMP I'm still struggling with this

[bluesdevil]

I had a problem with the LFO too. Here's some info that might help:
http://www.diystompboxes.com/smfforum/index.php?topic=42189.0

[The Groke]

I am also trying to resolve an "LFO won't oscillate" issue with my Bad Stone. I've tried different transistors, I am using an LF324, and I have tried 4009 as well as 4049 all to no avail.

Could anyone elaborate on what Sir HC meant in this post http://www.diystompboxes.com/smfforum/index.php?topic=42189.msg304951#msg304951

What sort of cap is he suggesting that we should add, a small ceramic in parallel with the 100uF, or another electrolytic somewhere?

Also, in my original Bad Stone, there was a 1uF tantalum, but I see that everyone (and the schematic) is using a 1.5uF.  Is this a critical part? Has anyone had theirs working with a 1uF? Easy enough to change, but I'm just curious, since 1uF seems to be the original component (in practice if not on paper).

Thanks - D

[Scruffie]

I am also trying to resolve an "LFO won't oscillate" issue with my Bad Stone. I've tried different transistors, I am using an LF324, and I have tried 4009 as well as 4049 all to no avail.

Could anyone elaborate on what Sir HC meant in this post http://www.diystompboxes.com/smfforum/index.php?topic=42189.msg304951#msg304951

What sort of cap is he suggesting that we should add, a small ceramic in parallel with the 100uF, or another electrolytic somewhere?

Also, in my original Bad Stone, there was a 1uF tantalum, but I see that everyone (and the schematic) is using a 1.5uF.  Is this a critical part? Has anyone had theirs working with a 1uF? Easy enough to change, but I'm just curious, since 1uF seems to be the original component (in practice if not on paper).

Thanks - D

I think he means add another 100uF Elec, positive to the 9V rail, negative to the V.Ref (or any point with the 'fork' on the schematic) or in parallel with the first 10k resistor coming from the 9V input on the schematic if that makes better sense.

Don't fret that tant cap, I used a 1uF Electrolytic, if the original used 1uF tant that's fine, you can't trust the original EHX schematics too much and nor can you trust EHX didn't run out of a part and substitute another so it really makes little difference.

[ORK]

maybe another helpful thread: http://www.diystompboxes.com/smfforum/index.php?topic=66768.0