Do you get the blips when just holding one or more keys down?Or does it only make that sound right as you are pressing or releasing a key?
What voltage do you measure at +5MEM? (on U164 pin 24)
If you have all of the data lines for U164 isolated from the bus, then there arethree more pins you can experiment with, trying to see which one affectsthe blips. Leave the address and data pins bent out and isolated.
Chip enable (18)
Output Enable (20)
Write enable (21)
If you can figure out the exact signal that makes a difference, maybe wecan get a little further. It should be one of these three. Leave the power and
gnd pins connected. If you find the signal that makes the difference, then removeU164 and connect a 22pf, 33pf, or 47 pf cap to gnd from that signal as an experiment.You can just stick the leads into the socket temporarily.
You should get a similar effect. Of course it may take more than one of those signalsto cause the blips.
Bob
From: "richtrix@... [oberheim]" <oberheim@yahoogroups.com>
To: oberheim@yahoogroups.com
Sent: Saturday, March 21, 2015 9:09 AM
Subject: Re: [oberheim] Finding Clock frequency of my OBXa [2 Attachments]Message
Re: [oberheim] Finding Clock frequency of my OBXa [2 Attachments]
2015-03-21 by Bob Grieb