Reverb Tank tranny resistance

[Dan Lawrence]

I'm trying to deduce why there's no verb coming out of an amp. I suspect the input side of the tank is the problem cuz you can hear the reverb springs respond through the speaker when you give it a little tap, but no instrument signal gets to the tank, (or no sound of instrument reverb)

The overall circuitry is beyond me, but I did measure the resistance across the input and output tranny's , (open, or disconnected from amp circuit, and I measured each one individually).

Can anyone tell me is getting just 1.2 ohms across the input transformer is reasonable, or a sign of a short or failure?

The output transformer is something like 192ohms

Sorry I don't have better specs. I'm not a tech and can't read schem's very well.

Thanks for your help

Dan

[Dan Lawrence]

Nevermind!

The positive post of the RCA connector on the input just wasn't making enough contact. Until I crushed it closed and re-opened it a bit with a prong. Now reverb is fine (as it ever was)

[52 Bill]

The positive post of the RCA connector on the input just wasn't making enough contact. Until I crushed it closed and re-opened it a bit with a prong. Now reverb is fine (as it ever was)

Bad connections are always the first thing to look for when you have reverb problems. The little wires that connect the RCA jack to the transducer coils are also a big problem

To answer your original question, yes a 1 ohm reading is normal on a tank that has a low impedance input, like an typical transformer driven Fender circuit with an 8 ohm impedance.

If the tank input impedance is higher than 8 ohms, then the resistance of the coil will increase as well. If you go to the Accutronics site there will be a chart that lists the different input coils and the resistance values that are typical for each type.

And remember that it is a transducer coil not a real "transformer".

[Phostenix]

The Accutronics values are impedence values, not DC resistance. If you measure the inductance of the transducers with an inductance meter (set to 1kHz), you can get a value of inductance in Henries. Then, you can use the formula 2Pi X F X L to calculate the impedence. F = Frequency (1000 in this case) and L equals the value measured in Henries. So, if the input transducer measures 24mH, 2*3.14*1000*.024=150 ohms.

[Mick Bailey]

This gives the approximate DC resistance for the coils;

reverb_tank.pdf