Traynor YBA-1 Odd Output

[Helmholtz]

The primary connections are blue, red, brown. With the primary disconnected:
bu-bn = 54 ohms
bn-rd = 54 ohms
rd-bu = 780 ohms!!!
How is this even possible? Has Ohm's law been repealed?
I measured and remeasured several times, both polarities. Same result. What the heck is going on?

Many DMMs have problems to correctly measure DCR if it hides behind a large inductor like an unloaded transformer.
Short the secondary while measuring primary DCR for a reliable reading.

[mhuss]

Ah - interesting and good to know. Thanks!

[drewl]

Yeah, mine the auto ranging can't figure out what range to use.

If I manually select the 2k ohm range it reads the trans resistance.

[Helmholtz]

Yeah, mine the auto ranging can't figure out what range to use.

If I manually select the 2k ohm range it reads the trans resistance.

Inductors don't like switching/pulsing signals, so they react with counter-EMF, thwarting the measuring current. This in turn may drive the meter crazy.
Shorting the coupled secondary essentially shorts the inductive part of the primary impedance.

[Mick Bailey]

My electric fence energisers show a pulse on my DMM when measuring DCR of larger inductors.

[g1]

Why would they do that!?!

Ok, but they put it in the literature. But why would they do that!?! What could possibly have been wrong with "red = B+"???

I've run into this with other Hammonds as well. Also the secondary side colours. And other manufacturers. Bottom line is verify before trusting 'conventional' wiring colour schemes. Doesn't help that much when someone gets their own scheme wrong though (commonly seen in single ended OT primary side colours).

[Chuck H]

I've run into this with other Hammonds as well. Also the secondary side colours. And other manufacturers. Bottom line is verify before trusting 'conventional' wiring colour schemes. Doesn't help that much when someone gets their own scheme wrong though (commonly seen in single ended OT primary side colours).

Ok, yeah. Completely agree. So... Hammond now manufactures clones for guitar amps from all major brands. Surely they know the old Fender standard of red (ct) brown and blue (either end) for the OT primary winding. It seems really dumb to use the same colors for another OT primary they manufacture, but allocate the colors differently.

Like a deli that makes peanut butter/jelly sandwiches, but also egg salad/tuna salad sandwiches suddenly deciding to make peanut butter/tuna salad sandwiches and egg salad/jelly sandwiches. One shouldn't mix the ingredients together in dangerous ways.

I said "it seems really dumb" earlier because I don't even know if Traynor ever used the red, blue, brown color scheme allocated as Hammond provided. If they ever did then I guess it's just an unfortunate misunderstanding.

[Chuck H]

Ok... I just went and looked at a bunch of YBA-1's and they all seem to use red as B+ for the the OT primary. And usually brown and some cool color (blue, aqua, green, etc.) for either end. It's hard to tell what the end colors actually are because of variable photo quality and lighting. My own Bassmaster is currently hard to get to at the bottom of a stack of back burner projects (no flames please, it's a later 2x2 input model ). I'm not sure that would be an accurate witness anyhow. But for the old YBA-1's, yeah, it's red (ct), brown and some cool color for either end. So... Not a smart move under any circumstances to make red one of the winding ends on that transformer. I can't think of a single good reason to do it, but I can think of a few very good reasons not to. Just my humble opinion.

[mhuss]

Epilogue: I contacted Hammond, they said "you're correct, it's wrong, we'll make an engineering change and fix it in future batches." Also, they said they couldn't believe no one had said anything about it before, it's been that way for 15 years. lol.

[The Dude]

It makes you wonder how many are out there installed incorrectly or if anyone just gave up on an amp because they couldn't get it to work with OT wires as they thought they should be.

[mhuss]

Right?