Messages

Hi Scruffie,

Yeah, actually I do notice it now.  Not a super audible change, but when I do focus strictly on the speed, I can hear the change.  I think I had just been looking for the wrong thing before - like, say, a wider modulation as opposed to the faster modulation.

Thanks,

David

So if you're not hearing a change in modulation speed with the mod knob up, something's not right.

Yes, but should one hear a conspicuous change of speed?

Thank you,

David

Hi there,

Do most people hear a significant difference between the two modulation modes - chorus and vibrato?  With mine, for some reason, any difference is virtually undetectable.  Is that normal?

Thanks,

David

I just found the problem.  Somehow the track between R45 & IC7 pin 8 had been severed.  No continuity there.  Thanks so much, Thomasha, for turning me in the right direction to spot the fault!  Thanks for your help too, Jimilee.

David

Correction, looking at the layout I can see how the VD gets to R45.  I'll have to look closely at that area.  Thanks.

Hi Thomasha,

If the VD isn't getting there, it almost sounds like maybe a VD track could be messed up.  I looked at R45, and there doesn't seem to be any problem with it.  But I can't tell from the schematic exactly how VD gets to R45.  Maybe looking more closely at the tracks on the actual board would help.  I guess I'll try that.

Here is the other pic.

Hi Thomasha,

Okay, I just posted pics of the board.

I do indeed, have both bias trimmers at the halfway mark.  Re: the bias 2 trimmer, no matter where I the wiper, it is at 0 volts.  That is, all throughout the wiper's rotation, it still reads zero volts.  So, you're saying the problem is somewhere prior to the trimmer.  Where might a good place be to look?

David

Hi there, thomasha,

I checked it out - no luck there.

I should add that as I said before, pin 5 is zero voltage.  But both pin 6 and pin 7, when I initially probe them are both around -.3 volts.  But in both cases, when I leave the probe there, the voltages start counting up, as in -.3, -.29, -.28, -.27, etc.  As long as I leave the probe there, they continue counting up.

Any other idea's? 

Thanks,

David

Thanks, thomasha,

I will check that out!  It is true that even prior to biasing, the voltages on those IC4 B pins should be closer to correct, right?

Thanks,

David

Hi there, Jimilee,

Yes, I have indeed done what you asked.  Any thoughts?

David

Hi there,

First, should the 'Total Recall' be put through biasing procedure before expecting IC's to show approximately correct voltages?

I haven't done the biasing yet, but most of my voltages are good - all except pins 5, 6 and 7 on IC4.  I've got 0 on 5 and between .2 and .3 on 6 and 7.  Even without biasing I would have expected them to be higher than that, no?  And, for the life of me, I can't figure out the mistake that's led to this condition.  Any suggestions?

Thanks,

David