Hammond 1620 wiring...

[650brad]

I recently acquired a Hammond 1620 OT but, the wiring coming out of it doesn't match up with the wiring of the current one on Hammond's site. I'm assuming that they changed the wiring since mine was built. It has a date code of 01/05/95 on the sticker. I figured out the primary side using my DVM but, on the secondary the readings are too close to tell which tap is which. The secondary has 4 wires, white, green, blue and black(more of a dark brown, actually). I sent an e-mail to Hammond a week ago and haven't heard back, yet. I'm just getting back into fooling around with amps again after a long lay-off and am in the process of building a 5F4 Super clone for my son and would like as few problems as possible when I get it going. Any help is greatly appreciated.

[Chuck H]

Is it possible that the wires have faded in the sun or something? Could you be reading the colors incorrectly? I don't know of any Hammond 1620 from '95 that would have a four wire secondary. In fact, a couple of the secondary leads should have one color and a stripe of another. Is it possible that someone modified that tranny?

[650brad]

It doesn't seem to be modified in any way that I can see, nor does it look sun faded. It looks like new but for a little rust. The primary side is quite different from the modern Hammond wiring, as well. It has 5 wires, red, blue, yellow, brown and green. Assuming the red is CT (which it should be) I get my highest readings on the blue (81.6 ohm) and yellow(77.4 ohm) with the green and brown being UL taps, green for the blue wire and brown for the yellow. I used a 1620 back in the day and it had the same wiring but, that amp is long gone, along with any notes or info I may have had at the time.

[Chuck H]

Write Hammond an Email. Or even call them. They actually talk to people!!! They will probably transfere you to some old guy in the tech dept. that will have your answer.

[Bruce / Mission Amps]

Funny that they don't respond. Wish I could help. I don't think I've had any older ones, especially from 1995. I've used many Hammond transformers over the years and still have a few 1620s from late 1999 through early 2000. These have a dual/split, five wire secondary. The blue and brown are the hi-zed primary leads while blue/yellow on mine are the UL primary windings. Regardless, if all four low impedance secondary wires of your OT have continuity, it should be a very simple matter to determine what wires are for what loads. I think all Hammond OTs I've ever seen used black, and or, black/yellow as the common, 0 ohm point.

Here's something interesting I found: 1608-1650

[650brad]

Thanks guys, I will try calling Hammond early next week. I also have a Hammond 1637 30W OT built in '96 that I plan to use for a Tweed Twin project and it has a split secondary but, fortunately, I still have the box with the wiring diagram on it. I'm very close to firing up my Super project so hopefully I can get it all figured out before Christmas as it is a gift for my oldest son.