Bad stone

michael_krell · May 05, 2004, 04:16:28 PM

I have a Bad stone I am trying to get working. The output singal has no effects. It does sound filtered and the knobs give some variation to the sound but thats it. I replaced just about everthing in this thing and no difference. I replaced the 4558's with jrc4558p's. and i replaced all the electrolytic caps and poly caps with sprague caps. I also replaced the 5088 npn transistor. I replaced the 4009 with a new TI cd4049BE. i was told they work in place of the 4009. still NO DIFFERENCE. Can someone please help me.

luiyi · October 26, 2007, 12:27:53 AM

Im having the same problem

someone know what could it be causing it?

StephenGiles · October 26, 2007, 07:12:58 AM

A solder bridge perhaps, check that you have power to each IC and listen to the output of each IC in the phase shift chain. Is it a diy or EH Badstone?

lvs · October 26, 2007, 08:22:06 AM

Quote from: michael_krell on May 05, 2004, 04:16:28 PM
It does sound filtered and the knobs give some variation to the sound but thats it.

I had a similar problem with my Bad Stone if I understood your post right. The manual sweep worked, turning that knob made the sound change. I replaced the LFO opamp and then everything was okay again. The opamp must be a LM324 otherwise the LFO probably still won't work.

Gus · October 26, 2007, 08:52:22 AM

The CMOS chip change might make a difference. Look up both spec sheets and compare them and how they are used in the bad stone. Did you use a stactic strap and/or mat etc when handling the CMOS chips? Did you save the old one?

When working with effects with LFOs a scope helps. Do you know how to use a scope?

Angle Loss · October 26, 2007, 03:32:37 PM

Also check the manual switch. I had a problem with mine (and a few other old EH's) and it was the switch. They are easy to replace. You can also bypass it temporarly just to see if that is the problem.

luiyi · October 26, 2007, 03:44:28 PM

it was the first PCB i made (all the other proyects i did where on pre perfored board)
so im going to make it again, maybe i made a mistake with the other one.

soulsonic · October 26, 2007, 04:27:23 PM

Same problem here too. Bad Stones must break pretty easily!

luiyi · October 27, 2007, 02:52:57 AM

ok, now i made a new PCB
and when i turn it on i only hear a "eeeeeeeeeeeeeeeeeeeeeeeeeeeee"

thats when the problem is with the ground, right?

UPDATE: ground problem fixed.
still getting the signal "semi-bypassed" when on (it sounds kind of when it is on bypass, but worst)

StephenGiles · October 27, 2007, 08:54:33 AM

It does soundlike a pcb problem - which is why I always build on veroboard!

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Bad stone