Bogen CHB-10A Conversion, need help and advice

[Tom Bavis]

Connect C1(-) and D1 together - do not connect them to the chassis in different places. Keep the ripple current out of the chassis.

 

[moapys]

Bogan CHB10A hum-battle starts later today: Presently the heaters are not referenced to ground (either by CT nor resistors), so figured I'd start with a humdinger pot and see where that gets me. Wasn't going to raise reference midpoint above ground, unless others have "been here" on the CH10 and suggest an elevated DC midpoint <?>. Thereafter, will run-back with scope from the OT and see where other noise is found - 60Hz or 120Hz, etc. Have already done lead dress and one-side-grounded coax on input jack. ...Any other guidance on this chassis, from those that have gone before? THX!

Update, the usual mods above helped quite a bit. 'Still have a bit of "gain dependent" hum (e.g. stone silent w/vol-down, hum increases with volume pot setting). Interestingly, the proper chassis ground - 3 wire - helped as much as did the humdinger, and more than any additional filtering, wire re-routing or ground-point fiddling. ...'More to come.