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previous: dave Kind and knowledgeable Ampagers, -- 12/8/2000 8:04 PM View Thread

Re: Yamaha E1005 analog delay prob

12/8/2000 9:15 PM
Mark Hammer
Re: Yamaha E1005 analog delay prob
The MN3005 will obviously be the source of the long delay, since it has 4096 stages where the MN3004 has 512. There is a very good chance it only uses one 3101 clock driver for the two delay chips, since you can only select short OR long delay, in which case the clock driver chip is fine. The fact that the chorus/flange function still works means that there is nothing unhealthy about the LFO.  
So, I suspect one potential reason for the presence of one and absence of the other is that the switch itself is near the end of its life, or just near the end of its unsprayed (with contact cleaner) life. You may want to lift the cover and try to identify the switch pin that carries the long delay signal and feed in another signal there. e.g., use some alligator clips and jumper the short delay signal to that pin, just to hear if something is coming through.  
Another potential reason, though my hunch is way down the list, is that the bias trimpot has somehow drifted and needs to be readjusted. The signal needs to ride on a bias voltage to get through the chip, and can appear to not be present when the bias is set wrong. HOWEVER, with two BBD chips on board from the same series, one would think that they would both tap their bias voltage from the same point, so if one still works, then it probably isn't a mis-set trimpot.

dave Thanx for the reply, Mark.D... -- 12/8/2000 11:07 PM
dave need help w/ Yamaha E1005 analog delay prob -- 12/9/2000 4:58 AM