On the regulator problem, what is the input voltage to the 7912? More importantly, what are you using for a ground reference? Measure right at the regulator terminals, in and out, to its ground pin. Neg 14.xx volts might be a result of a loose ground floating positive a bit when power is applied. Remove power and the positive current draw and the 'ground' makes its way back to ground..... Just a thought.
-Hugh
Hi all!
I bought a rare Crumar Composer I while ago but it has some problems. This synth has a mono synth section, a poly synth section, a organ section and a string section. All these sections can be combined. There is a separate output for every section and a main output. The separate outputs work but the volume for the main output and the main output itself do not work, could this be a problem in an amp-sircuit or something?
The problem I'm trying to look at now and ask about is an issue with the poly synth section. The problem is that the attack for the envelope is VERY slow, I can change the attack rate on the front panel pot but the fastest attack is about 15 seconds. Can anybody give me a hint where to look for the problem? Also there is a pop when I release the key on all keys it seems. The envelope of the poly-synth section is generated by a CEM3310 chip. There are also CEM3320 and 3330 chips on the poly section.
Last problem I'm having is that the release rate for the organ section is very sensitive, it seems that the effective range is about 30 degrees (1-1.5 on a scale from 1-10), if I turn the pot about 40 degrees I have a VERY long release time.
I would really like to get this synth in shape, it sounds so good and it's very rare, I think Crumar made only 500 of these.
Thanks in advance!