post #1876 of 2213
12/15/09 at 1:05am
Been working on a couple of CTH boards here and both seem to be having the same problem, which is, the E12 is tripping ON and OFF every few seconds. I haven't tried BOM coupling caps yet as I think I am out of those at the moment.
Did this build ever work properly? Assume you've tried a couple tubes...
Did you use new parts from the new BoM, install cleanly & wash the flux off?
Do the relay input leads show offset sufficient to trip CTH's e12?
IOW, ia this a case of the circuit doing its job & detecting build problems (or actually something w/CTH's e12)?
They are new builds actually..just had the parts lying around for ever now and so decided to finish them up. I will check on the voltages on the relay tomorrow (just got finished fixing the non working board on my EHHA..am tired now, but relieved. . Yes the flux has been cleaned off with rubbing alcohol, caught a few mistakes when i did my pre power up checkups (really should stop soldering late at night)
BTW I had a theory about why some had CTH e12 probs wwaayyy back w/old BoMs & w/large coupling caps on long leads. Maybe they were installed incorrectly. The outer foil is supposed be input (tube side) & inner foil the output. If one installed them w/outer foil on output I'd expect the cap to pick up more EMI & perhaps cause more noise & offset flux.
Hmmm, what exactly do you mean by inner and outer foil? The way i have it now is that the caps are tombstoned and the leads are exposed on the buffer side. I gather that is probably troublesome?
I mean new parts as in unused parts & by new BoM I mean the current one from 8/27/09 (the latest BoM rev. I believe).