EHX - Bad Stone

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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marshmellow
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Post by marshmellow »

Just had this here for repair so I thought I'd take a couple of pictures. The wiring was intermittent, somebody messed with the DC jack wiring, and all the dual opamps are switched out and socketed. I have a suspicion the two last issues are related :D. I also fixed the volume drop. Forgot to photograph the enclosure, just added it so there is no confusion about the versions.
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dj_shen
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marcao_cfh
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Post by marcao_cfh »

marcao_cfh wrote: 14 Sep 2020, 21:38 The closest thing to a depth mod for a Bad Stone is already on the project: the feedback pot.
From Electro-Harmonix themselves: "Feedback determines the depth of the phase effect" (source: https://www.ehx.com/products/bad-stone).

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Scruffie
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Post by Scruffie »

I provided you with a potential depth mod in another thread, you even thanked me by PM at 10:24 so why are you asking for one again at 10:26? I already told you via PM that if you want a phaser with a depth mod, this probably isn't the one to try it on but you have something to try.

I think my suspicions I'm being messed with might have been accurate...

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dj_shen
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Post by dj_shen »

I understand what you mean, sorry, i am novice and i am not a master like you guys, i also made the circuit and now i found out there is a feedback depth mode, thank you but the feedback pot does not work well and i want it to be more effective or any changes to the circuit ? So I wanted a mod

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The G
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Post by The G »

Putting here the info from the Russian page shared by dj_shen:
Update August 12, 2017 User Alexey Zhukovich (I hope he wrote it correctly) found an error on the board. Chip CD4009, 13 leg should be connected to 14 leg. This will turn on an additional phase rotation stage. Materials have been corrected, for those who have already collected on the old seal, drop a drop of tin between these tracks. Without one cascade, the pedal works, so I didn't notice, but it will work fully with it.
[...]
Device diagram.
electro-harmonix_bad-stone_sch.png
View of the board from the side of the parts. Please note that there are many jumpers on the board. Do not miss. The wire to the body can be taken from the fill next to the Bad Stone inscription. There is a lot of earth, drill a hole at any point and solder to the screen.
electro-harmonix_bad-stone_layout.png
View of the board from the side of the tracks.
electro-harmonix_bad-stone_pcb.png
Wiring the pedal inside the case.
electro-harmonix_bad-stone_wiring.png
Parts list.

resistors. power 0.25W.

82 - 1pc.
100 - 1pc.
150 - 1pc.
330 - 1pc.
470 - 2 pcs.
510 - 2 pcs.
1k - 2pcs.
2.2k - 1pc.
2.7K - 1pc.
3.3K - 1pc.
4.7K - 16pcs.
6.8K - 2pcs.
10K - 5pcs.
15K - 1pc.
27k - 10pcs.
100k - 3pcs.
510k - 1 piece or 100k at the entrance.
1M - 1pc.

Capacitors for a voltage of at least 16 volts.
Electrolytes.
1uF - 2pcs.
10uF - 1pc.
100uF - 1pc.
470uF - 1pc.

Regular.
10n - 1pc.
47n - 7 pcs.
100n - 2 pcs.

Diodes.

1n4001 or any other from this series 1n4007 for example.
1n4148 or 1n914
LED

Potentiometers.

speed C1M
feedback C100k
manual B100k

trimpot 10k

Microcircuits.

4558 - 4 pcs.
LM324 - 1pc.
CD4009 - 1pc.

Transistor.

2n5088 or 2n3904 - 1pc.

Miscellanea.

Jacks, sockets 6,3 mm - 2 pcs.
Power socket. - 1 PC.
SPDT toggle switch - 1pc.
3PDT button. - 1 PC.
Gainta g0473 case

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