Re: Rotory Impedence switch wiring diagram


"Swack Daddy" <some***@xxxxxxx> wrote in message news:qqoIg.2487$JR5.965@xxxxxxxxxxxxx
OK, got that part down, but (there always seems to be a but...)

Ok output trans is hammond 1560F:
Primary 7.6K - has blue - to #3 on one output tube
Red - to B+
Brown - to #3 on the other output tube
Then blue\yellow & brown\yellow that I am unsure of....
seconadry - yellow, yellow/green, black/yellow, black, & green. These
are of various outputs... I'm wired green yellow/green connected, black
yellow/black to ground side of speaker connector, and yellow to the
other side of the speaker connector. This should give me 8 Ohms output
going to a 2x12 8ohm openback cabinet. The blue/yellow and brown/yellow
of the primary are taped off, and not connected to anything.
Should be all good but it seems to be giving me 1 watt of output.
BTW, the amp is a version of the Trainwreck express, that I built and
was working with an output with a 5.6K primary that was uncontrollable
overdrive. I replaced the output in hopes of get a little more control
of the overdrive, and to cool the amp off a little. it was like double
ZZtop overdrive with just a standard strat straight in. Now it seems
like maybe 8 or 10 watts.. like 1/2 wattage that it should be... Do the
blue/yellow brown/yellow have something to do with it? the top of the
output says: "ultra linear taps 40% of primary voltage"? what is that? I
figured it meant that the bl/y br/y taps were 40% of the primary...
Help

Since you know the maker of the transformer,
contact them for the colour code.

If it is truly ultra-linear, those "other primary"
leads must go to the screen grid resistors
and it's easy to assume the blu/yel goes to
the blue side and the bro/yel goes to the brown side.

For the secondary, I'm sure Hammond uses
black for common and the rest of the wires
simply have to be 2, 4, 8, 16 ohms unless
they went with a 32 secondary.

The box the transformer came in didn't have
a colour code sticker on the side of it?

If unsure, and I can't be certain, I'd contact
Hammond or the distributor referring to any
printing of codes on the transformer.

If it's been sitting around for years or decades
without its spec ***, you should boot
the butthead in the head or the butt (same
difference) for not storing the spec ***
with the unit.

BTW, what part of the country are you in, Swack?
Just curious since I'm getting into building amps too.
Got a website or is it a hobby?

Ed
Nawlins'
Earth






Elvis Kabong wrote:
"Swack Daddy" <some***@xxxxxxx> wrote in message news:VWNHg.2381$JR5.23@xxxxxxxxxxxxx

Anyone have a diagram for a marshall type impedence switch?


There's one in the Tube Amp Book and the History of Marshall Book,
HOWEVER Marshall and the after-market transformer manufacturers
don't always use the same colour code.

What you need to do is get the schematic for the particular Marshall
and observe where the secondary taps are and if you are lucky,
it will also identify what colours are for which taps. But if it they aren't
indicated, you should invest in an el cheapo LCR meter from MCM
which will give you henries measurements of coils.

More henries = more turns = more resistance. So if you are lucky
enough to find out which wire is common you can measure each
tap from there. The tap with the most amount of henries will
obviously be the 16 ohm tap and the one with the least will
be the 4 ohm tap, therefore the remaining one is the 8 ohm tap.

Good luck,

Ed
.

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