GK MB150E-III no Chorus

[hodgy]

I've got this one on my bench and scratching my head.
If I'm not mistaken, U13-A (NE571) is acting as a mixer to bring the dry signal together with the chorused waveform. The amp passes signal just fine, but I'm not getting any chorusing effect. The waveform looks good at pin 1 of U14- it reacts to the rate and depth controls like it should, but it doesn't seem to have mixed with the dry signal at pin 6 of U13, like I think it should. What am I missing here?

Here's NE571:
http://www.ka-electronics.com/images...plications.pdf

[hodgy]

Hmmm, maybe the switch, U19 is not switching...

[nickb]

U14 does the mixing. U13 varies the amount of chorus dependent on its averaged amplitude. I don't know why they decided to do that but I guess the felt is sounded better.

You should see a DC voltage on pin 1 of U13 that varies with chorus signal amplitude.