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WEM Copycat.......Help!

12/22/2000 4:06 PM
WEM Copycat.......Help!
Hi All,  
Slightly urgent problem! Anyone got or know of a schem for a solid state Copycat. Failing that - any ideas what might be causing this:  
Copycat suddenly stopped echoing at rehearsal this week. The playback heads still give a signal when tapped with a screwdriver. The straight through signal works, so I know the preamp is OK. The bias oscillator gives 260 mV rms sin wave at 62.5 kHz, which seems about right to me. The record head appears to be OK (~75 ohms). But no echo on any of the record heads. The guitar signal is just not getting summed with the bias, but I can't work out why.  
A schematic would help, but maybe someones come across this problem before. I assume all I can do otherwise is chase the guitar signal through the board with a scope and find out where it stops. I've got a scope and sig. gen.  
Any help gratefully received. I've got a gig on the 26th and I don't want to spend christmas over the soldering iron:)  
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