Questions/help with wiring Hammond 370BX in Classic Cornet

markmaloof · « **on:** 23 Nov 2005, 08:31 pm »

Other than waiting for some lonnnnng backordered Cardas RCAs from Welborne (will jury rig with some cheapo Ratshack until they come in, or say to hell with the Cardas, just send me some darn Vampires), I'm ready to put the finishing touches on my Cornet Classic. I just have a couple transformer wiring questions (NOTE: This is a Cornet Classic, not Cornet 2, but I am using the 370BX trannie, USA operation.)

1) on the PC board (secondary) side, it seems pretty self explanatory: reds to reds (does not matter which one correct? Also, same for the two greens???), red with yellow stripes on it to R/Y, yellow with black stripes to Y/B, etc. I know the violent is clipped and insulated (will treat with heavy duty dialectric goop, then double heatshrink) My question: there are two holes on the PC board for each wire color. Does it matter which hole I solder the wire in (and why are there two holes?)

2) on the primary/power input side, is this correct? For hot, I would wire from IEC to fuse, then connect sold black and solid blue together the fuse holder, right? For neutral, I would connect solid white and solid brown together to the neutral plug on the IEC, right? This leaves four extra wires: blue/yellow stripes, white/black stripes, brown/yellow stripes and black/red stripes (not as in the somewhat yummy Red Stripe beer, though.) Are all these wires extras that need to be clipped off and insulated?

Please pardon me for being a big of an ignoramous, but this is the first kit I've built, have done some minor repairs before. It's been fun and has got me motivated, will be upgrading (recapping) an older tube guitar amp of mine next, I've got the bug (and, yeah, I know about draining those big power caps, no need to have the grim reaper come calling yet!)

Eric H · « **Reply #1 on:** 24 Nov 2005, 07:42 am »

I won't try to answer 2), but I think I know about 1)... the double holes would be so that you can attach the transformer wires with quick release terminals (as in the cornet2 - what I built). In fact, the picture in the online manual seems to show this but I don't see them in the parts list... They're in the parts list for the cornet2, though, and I'd recommend them. If you ever need to pull your board completely out of the chassis they'll be worth it. Now that I think about it, I'm not even sure if the transformer wires would fit through the holes in the pc board...

Anyway, you're getting into a very fun hobby - I started on old guitar amps and then got into vintage hifi gear and then built some of Jim's gear... lots of fun (and great sounds)!

markmaloof · « **Reply #2 on:** 24 Nov 2005, 05:22 pm »

Zuma rules! I did not think about getting the quickconnects, but maybe I'll give that a whirl. Looks like this thing won't be up for another week at least (would probably have to order them, unless Ratshack has them.)

Still need to find out about the wiring on the primary side. I had found the info before with a search, but I'm having no luck now (should have printed out the info before.)

hagtech · « **Reply #3 on:** 24 Nov 2005, 10:32 pm »

1) Same color wires can be swapped. Doesn't really matter. I've found no real different in phasing the outputs. Originally thought there might be some parasitic coupling between the heater and B+ windings, and cause some super-minor interaction (in phase or not). Never found a difference, except in the stray magnetic fields. Slight change of waveshape. So either red will work.

2) Primary striped wires do not connect. Insulate them like the purple wire.

jh

markmaloof · « **Reply #4 on:** 25 Nov 2005, 10:58 am »

Thanks guys! I'm all set to put the finishing touches on this sucker. I was guessing that the extra primary wires were cut and insulated like the purple, Jim has confirmed this.