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Farfisa Vip 200 R problem

Marcossc

Jan 16, 2022
3
Joined
Jan 16, 2022
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I have a farfisa Vip 200 R (add schematic) where the drum machine works but the keys don't, when I rescued it from someone who was throwing it away it played for an hour and then it stopped working, when pressing the keys now it makes a ducky sound.

I have checked all the voltages coming out of my voltage regulator (ICa9) and I got

1 0 14 0
2 5v 13 6.6 v
3 5v 12 12 v
4 5v 11 12 v
5 5v 10 5v
6 7v 9 0
7 0 8 0

-I get 5 v on pin 5 of my ICa10 master oscillator, and according to my theory the output pin is 13 where I have 3.5 v but I don't see any figure on the oscillometer test it there and to ground. (first problem?)

-second problem, from the output pin 13 we get to Qa1. diagram says it is a 470 uf polystyrene capacitor. (I'm not sure, I add photo) but at the output of this guy I have 0V... is this normal?

-third problem, the tone generator ICa8 receives the power supply voltages pin 1 +12.4 v and pin 9 -15v, but the HZ measurements of each pin are irregular and I don't know how to verify if the IC is working properly. maybe because the oscillator is not working (who enters pin 2) the tone generator does not emit frequency and that's why I can't measure?

-I don't know how to check if the oscillator IC is short internally, the data sheet doesn't exist.

-my big fear, the tone generator and the oscillator are shorted, they are discontinued. i don't know how to find a replacement for them.

sincerely thanks for your attention, Marco.
 

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bertus

Moderator
Nov 8, 2019
3,304
Joined
Nov 8, 2019
Messages
3,304
Hello,

The circled capacitor is 470 pF. I never had any problems with those styroflex capacitors.
It would help if you could give us the type numbers of the chips in the citcuit.
On the output of the oscillator there will be an AC voltage, so it can not be measured with a DMM.
An oscilloscope would come into play here.

Bertus
 
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