Relay's installed, pics/layout included, HUM problem?

[Bob-I]

Now this is wierd. I have a hum with the boost engaged, but NOT when the mid is engaged with it.



I finally got around to installing the relays in the Peavey Classic VTX transplant. I used the bias supply, which is a 20-0-20 CT supply, very unusual. I used 1/2 of this, so just the 20-0 and used a bridge rectifier for both the bias and relay supply.

All the wiring on the relay boards is under the board. I epoxyed the relays to the boards with the leads sticking through and soldered the leads to the turrets underneath.

One small mistake I made, the upper of the 2 caps on the layout is listed as 1000uF 16V, but there's 24V on that cap so I swapped it with a 680uF 50V.

I'll be adding one more relay before making the footswitch, the mid boost.

[tictac]

Bob,

What relays did you use?

[Bob-I]

Bob,

What relays did you use?

I used the Omron 12V DPDT. Mouser part # 653-G6A-274P-DC12.

[Normster]

Sooo...do the relays work with that layout? Just curious because I'm gonna wire mine tonight and I'd rather learn from your mistakes than mine.

[Bob-I]

Sooo...do the relays work with that layout? Just curious because I'm gonna wire mine tonight and I'd rather learn from your mistakes than mine.

Well... not really. The PAB hums (read the edit). I just rewired according to your layout using the 22M resistor and it's slightly reduced, but it's very strange how the PAB only hums when the mid boost is OFF.

[Luthierwnc]

took this five minutes ago. I put them on the main board. These are on turrets that were Dremelled down to half size so they are easier to solder from below. Usually the component lead is long enough to go from its turret and into the relay turret on the underside of the board.

Being lazy and cheap, I use a common stereo jack and ground right to the chassis. Works fine with no noise on the first build. All other grounds are on the main buss behind the pots. The footswitch is connected with a stereo 1/4" cable.

Have fun, Skip

[Bob-I]

took this five minutes ago. I put them on the main board. These are on turrets that were Dremelled down to half size so they are easier to solder from below. Usually the component lead is long enough to go from its turret and into the relay turret on the underside of the board.

Being lazy and cheap, I use a common stereo jack and ground right to the chassis. Works fine with no noise on the first build. All other grounds are on the main buss behind the pots. The footswitch is connected with a stereo 1/4" cable.

Have fun, Skip

Nice looking board, interesting mounting for the relays. I've never been able to punch down turrets this close together. Also I've always had terrible noise issues with grounding the relay supply. In fact I tried grounding this relay supply and the noise went up 10 fold.

[Luthierwnc]

I squish the turrets down with the arbor press I use for fret jobs. The anvil is a piece of drill rod ground to a point and the punch is just a bolt with a hole drilled in the center just wide enough to fit the turret but not its base. For extra room, I put the outside turrets in and cut them off, then put in the center set. In the one pictured, I broke the "hot" throws off the boost relay and didn't use any turrets under them. In a pinch, use a clean butcher block when you drill the relay holes in the board, ream the block holes to slightly smaller than the base of the turrets, put the turrets in the holes, put the board on top and smack them with the punch.

The rectifier and regulator are grounded at the base of the buss. The hot goes to each relay hot and the relay grounds go to the jack. Both footswitches have an LED and resistor in parallel to ground. The OD switch is a DPDT stomper that also activates the boost independently of the Boost switch.

Mine is dead quiet operating and doesn't pop when switched. That said, the HRM is hardwired without a rock/jazz switch to what would be rock. Since the poles both reference ground, it didn't need any extra resistors.