Quadraverb Schematics....help please...

  • Thread starter Thread starter chazba
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chazba

terminally hip
I'm looking for a set of schematic drawings of the circuitry for the Quadraverb. I started doing an upgrade project on it a few months ago and it got out of hand. I installed some hi performance op-amps in the analog section which have about 1000 times less noise and distortion than the originals. I must have damaged the board in the process but I'm having a hard time w/o the drawings. Help please!!!


chazba
 
drag man.... alesis doesnt generaly give out schemos so that gonna be hard to find i think.... it's a PITA but ya may need to just trace all lines point to point...
 
You're right about their non-helpful attitude... I've been going point to point on it for a couple of months now...really tough for a guy with limited ability to focus.

chazba
 
front end analog??? i'ld think about working on it hot... with a sig generator see what's not getting to the chip... are all the voltages there???
 
Thanks for your interest.....

I've got a decent Tektronics scope and a generator and have traced it thru the first stage and the input gain control. V+/- are ok I think +11.7, -12.1 should be close enough, what do you think. Sig gets lost in 2nd stage where 2 stages are split into 2 pair,L and R from one set is combined in mono and sent to comparator for input level display, which is not working and there is no sig . DC side is what youd expect for a ladder. It looks like the opamps are latched to about +3 vdc where there should be an analog sig, I just can't figure out why. I used to be able to do this stuff in my sleep, but my concentration isn't what it used to be. I drew it out but a factory drawing would be a huge help. I did the upgrade mods on my 3630 and it came out GREAT sounding . Got any thoughts???
This was supposed to be fun......

chazba
 
hey chaz... those rails should be closer IMO... as is you should see an offset of @.4V... that's too much.... the opamps latching to +3v is a rel problem too... try taking out one at a time the coupling devices...(resistors or caps) and trace that portion as a single entity... then move to the next and repeat as necessary... now ya know why the biggest charge on any repair is time.... often it's a $1 part... but WHICH $1 part????
 
Thanks guys....

Thanks guys...I have ordered the schem from mrschematic for $10 and it should be here next week. Yeah DementedChord...I thought the rails were a little unbalanced. I will lift out the chips 1 atatime and see which one is dragging. Having a reliable drawing will be an enormoous help. I appreciate your taking the time and showing real willingness to be helpful...which somedays is rare on this BBS
 
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