MXR Analog Delay Repair Cont'd

[michael_krell]

I posted a topic previously about repairing an MXR analog delay. Its the version with the R5101 Reticon. Here is the last that I made to give you an idea of the problem.

Ok so i got the schematic, thanks again. And in about 3 seconds I seem to have diagnosed the problem. Looks like it is the first CD4016 chip. It is labeled A-6 on the schematic.

The signal goes through there and never reaches the next stage. So I already ordered some, because of mark's advice. So i will replace it and see what happens.

thanks, ill keep you updated.

I replaced that CD4016, and it did pretty much nothing. The strange thing is the signal seems to be stopping there. The IC gets power so I am pretty sure it is not a power issue.  Please let me know what you think.

[guitar_199]

While I don't have the schematic to your unit in question.... I was able to "Google up" a data sheet on the CD4016.  It appears to just be a quad switch. 

A)   1 in/out , 2 out/in, 13 control
B)   3          , 4         ,   5
C)   9         , 8          ,   6
D)   11       ,  10        ,  12

Each gate, it seems, will conduct in either direction so it doesnt matter which direction you feed the signal as long as the control  is activated which, it would seem, is high, or the +voltage.

With only this to go on....I would check things like....

1)  is the control voltage active?

2) is the input to whatever the 4016 feeds loading it down? (i.e. internally shorted to ground thus making it look like the signal isn't there.  If you put the new one in a socket it might be interesting to lift the output leg of the 4016, press it back into the socket, and see if something shows up on the output.

Also....what are you using to see that the signal is not there?

Bob

[michael_krell]

I am using a scope. I will check to see if the output is being loaded down or shorted or something.