[Gaussmarkov / Markusw / Bernarduur] 9V Electric Mistress Debugging

[ilponiz]

Hi everyone,
i originally joined the following thread:
http://www.diystompboxes.com/smfforum/index.php?topic=44582.0

but, as my build report went on, i decided to post a new one to explain better the problem i encountered while building a 9v EM.

I used the files posted by Markusw and hosted on Gaussmarkov's site. From what i knew, the layout was obtained by tracing the pcb of an original Electric Mistress owned by Bernarduur.

I started using the layout provided, than, due to my bad soldering, i redrawn the pcd simply by reducing the ground areas. I checkd the new pcb layout and is exactly like the original one drawn by Markusw.

in the first picture you can see the old pcb board and two new ones (one populated and one without components



i soldered all the components and only substituted the following parts:
- 1n961b diode replaced with a 12V zener diode
- the 13k resistor replaced with a 12k one

then, i added the followoing modifications:
- i removed the filter matrix switch and jumpered the pads as suggested by paul at gaussmarkov's site
- i jumpered the send & return pads
- i didn't use the bypass pad

here's the layout i used with changes and substitutions highlighted:



and here's a picture of the actual populate board before boxing it. changes and modifications are noted:



then, i put everything inside a box. the enclosured was drilled by a frien of mine (i haven't my own drill yet, at that time) but few alignement mistakes were done. for that reason i had to cut a little portion of the board to fit in the power jack. new ground pads were added and the interrupted ground track was jumpered (it's the white wire close to the 9v jack). here's a pic of it;



when testing the unit i had this response:
signal passes through when the effect is not engaged. but when i switch to the effect there's still a clean sound coming out with no flanging at all. since i socketed the IC's, i tried the unit with 3 different sad1024 (the reticon chips were already tested anf fully working, as i have an original 18V electric mistress from the 1980).

moreover, the pedal can only be powered with a psu, if using a battery the led isn't even lighting.

now, my friends, i'm stuck with this problem and don't have a clue how to solve it...any help would be highly appreciated
thanks in advance

poniz

[ilponiz]

...is there anybody out there? 

please, let me know what you think, guys!

thanks

poniz

[mth5044]

Crappy switch?

[markusw]

Hey Poniz,

some questions:   
did you check voltages at the chips? have you already tested with an audio probe whether the audio signal passes through all stages? Does the LFO work?

Connecting the battery via the 2k7 btw doesn't work unless the 2k7 is shorted by the ps jack (only if no ps is plucked in). Otherwise the current via 2k7 will drop too much voltage. Basically, cou can forget about the 2k7 and wire both, the battery plug and the ps jack as usual via the ps+ pad.
I know this doesn't help too much for your main issue but it explains why not even the LED works if you're on battery. 

Regards,

Markus

[ilponiz]

Crappy switch?

unfortunately not. it's a new 3pdt, however, i'll try with another one, cause you never know! 

Hey Poniz,

some questions:   
did you check voltages at the chips? have you already tested with an audio probe whether the audio signal passes through all stages? Does the LFO work?

Connecting the battery via the 2k7 btw doesn't work unless the 2k7 is shorted by the ps jack (only if no ps is plucked in). Otherwise the current via 2k7 will drop too much voltage. Basically, cou can forget about the 2k7 and wire both, the battery plug and the ps jack as usual via the ps+ pad.
I know this doesn't help too much for your main issue but it explains why not even the LED works if you're on battery. 

Regards,

Markus

hi Markus,
thanks for your reply. well, i'll check the voltages tomorrow and let you know.
do you think that the problem could be caused by the jumpers i added to remove the filter matrix?

by the way, thanks for the info about the battery v+ pad, i'll do as you suggested.
have a glorious day

poniz

[ilponiz]

Connecting the battery via the 2k7 btw doesn't work unless the 2k7 is shorted by the ps jack (only if no ps is plucked in). Otherwise the current via 2k7 will drop too much voltage. Basically, cou can forget about the 2k7 and wire both, the battery plug and the ps jack as usual via the ps+ pad.
I know this doesn't help too much for your main issue but it explains why not even the LED works if you're on battery. 

done, i attached the red wire coming from the battery snap to the proper lug on the ps jack (as usual) and the led now works fine!

i'll try to measure the voltages tomorrow

have a nice day

poniz

[ilponiz]

i finally sorted everything out!!!!!!



after tons of hours i spent debugging it, i found the following errors:

- i forgot to put the small jumper between the 100k trimpot and the 3n3 cap (the green one in the pic)
- the lugs 1 & 3 of each pot were reversed
- one of the pot (the 1M color pot) was not working perfectly

so, after tons of hours i spent debugging it i found out i was an idiot! 

now it's fully working and...what a sound!
i think i'll post soon a complete build report with the new layout i made for this excellent project!

finally, a big, special thanks to Markusw for his support and kind words throughout this building experience!



here's a new pic of the new circuit:



have a nice day guys!
poniz