Elektor Formant Modular

Hi Kris, ;-) feels like I'm writing something to
myself.


Thanks for your reply. I'll try to descibe the
different steps I did. 

In the beginning everything went fine, I've build the
eingangsspannungaddierers, exponentiators and heizung.
I plugged it in and after 20 minutes I have set the
voltage at kollektor tr 4 to 1.6V with trimmer
p8. So far no problem,I then continued building the
Sawtoothoscillator without soldering Tr3 so I could
meassure the current between kollektor tr3 and pin3 of
ic2. I also made the abgleichskeyboard (I had to
replace R1 with 47K because otherwise my maximum for
switch 5 was 2.86 V instead of 4 V) and soldered the
pots for range and tune to the VCO pcb. I then tried
to messure the current that is supposed to be 0.002mA
but
nomather what switch I used on the abgleichskeyboard,
or to what position I turned the range and fine-tune
pots, I'm allways measuring 0,000mA. I thought
maybe I did not solder enough components on the pcb
because of the difference between the book and the new
design so I continued the entire pcb except for tr3.
But still no result. At the end as a last resort, I
also soldered tr3 in position but still no current.
Can you tell me what measurement I can do to track the
fault? On strange thing I allready noticed is that if
I meassure betweent the mass and before R5 (range) I
have 11.84V because I set the range pot fully open.
But after R5 (100K) I measure 0V. I suppose this is
not normal and that is the cause why turning the range
pot has no influence? So is the 100K to big? 
Also would it be a problem that after the 7812 (ic7)
there is only 11.84V instead of 12V?

I've uploaded a pic of the vco to
http://www.krinkel.be/formant/formantVCO.JPG

best regards,
Kris
 


---------------------------------
I'll reply here and on personal, as the group is here
so that people like us 
can search problems first then ask.

I'll help, but moving house so I can only promise you
an answer by Tuesday, 
when I go back to work. What is the problem mate?

Regards
Kris


>From: ganesha <goaqihai@...>
>Reply-To: ElektorFormant@yahoogroups.com
>To: ElektorFormant@yahoogroups.com
>CC: synth-diy@...
>Subject: [ElektorFormant] problem with formant pro
vco (new design)
>Date: Fri, 7 Apr 2006 23:25:54 +0100 (BST)
>
>Hi,
>
>I'm building the formant pro vco from the book of
>Hans-Joachim Helmstedt. But I'm having a problem that
>I cannot solve myself. Is there anyone who has
already
>built it and who would like to assist me?
>Please contact me off-list so I can send you a mail
>where I describe the problem.
>
>Thanks in advance!
>regards, Kris
>
>
>
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