Transformer problem

[mike60510]

I garbage picked an amplifier and speaker from a Hammond M-2 organ. I have been reading about converting these to guitar amps and was somewhat excited about the potential project; however when I connect power to the input side I don't get any power from any of the output taps. I suspect the transformer is bad. Correct assumption?

[mozz]

Yes,but put it on a meter (resistance scale,transformer unplugged)to verify the windings are open.

Also,those M2 parts may be worth more On eBay and you can buy a tube amp or a kit.

[Jazz P Bass]

Here is the schematic of the 'Hammondator'.

There are multiple windings on the secondary.

If the primary shows winding resistance, make sure that you are measuring the correct secondaries. (Volts/ac)

Hammonator1r3.pdf

[Richard]

Am I reading this right? The multiple primaries are for different input voltages? I'm confused about the labeling 105, 115, 120, and 5 volts ac.

[mike60510]

Am I reading this right? The multiple primaries are for different input voltages? I'm confused about the labeling 105, 115, 120, and 5 volts ac.

Sorry, if I didn't write my post correctly. I powered the amp up. According to the schematic, the T-4 power transformer should have three output voltages from the secondary windings. 5- , 6.3- and 340-volts. I don't get power from any of the secondary taps.

[J M Fahey]

I don't get power from any of the secondary taps.

Maybe you mean "voltage" ?

1) do all windings show continuity? Specially primary.
Even better post resistance values.

2) does mains voltage actually reach primary?

3) after rechecking 1 and 2, do you now have secondary voltages?

[Jazz P Bass]

A real down & dirty check of the primary circuit:
(the power cord, the fuse, the switch & the transformer).
Unplug power cord from the outlet.
Turn the power switch to the ON position.
Set your meter to read resistance & go across the power plug.
A reading will be the primary of the transformer.

A lack of a reading must be narrowed down to which component(s). are at fault.
(the power cord, the fuse, the switch & the transformer).

[Enzo]

Where are you connecting your meter between? Those 5v wires for example will have 5v between them,, but not to ground.

MAke sure your meter is on AC volts, not DC.

[mike60510]

Where are you connecting your meter between? Those 5v wires for example will have 5v between them,, but not to ground.

MAke sure your meter is on AC volts, not DC.

Thanks for all the suggestions. I unsoldered the connections and took the transformer out. I get the following resistances:

109.6 ohms at the 340 volt secondaries going to V8 the 5U4 tube, pins 4 and 6
0.3 ohms at the 5 volt secondaries going to V8 the 5U4 tube, pins 6 and 8
0.3 ohms at the 280 volt secondaries going to V5 and V6 the 6V6 tubes, pins 3 pin both tubes

Thanks again, its a great learning experience.

[mike60510]

Thanks for all the suggestions. I unsoldered the connections and took the transformer out. I get the following resistances:

109.6 ohms at the 340 volt secondaries going to V8 the 5U4 tube, pins 4 and 6
0.3 ohms at the 5 volt secondaries going to V8 the 5U4 tube, pins 6 and 8
0.3 ohms at the 280 volt secondaries going to V5 and V6 the 6V6 tubes, pins 3 pin both tubes

Thanks again, its a great learning experience.

Actually, I initially did that make the mistakes you listed with the AC not DC and between and not to ground. But I looked at the schematic and corrected my errors.

[g1]

How about resistance on the primary side of transformer?

[mike60510]

How about resistance on the primary side of transformer?

3.8 ohms

[g1]

So apply the AC voltage to the primary again, and verify that the voltage is getting to the primary by measuring AC volts on the primary with your meter.
Then put your meter across a secondary winding that showed resistance, like the 5V secondary, do you get the 5VAC ?

[mike60510]

So apply the AC voltage to the primary again, and verify that the voltage is getting to the primary by measuring AC volts on the primary with your meter.
Then put your meter across a secondary winding that showed resistance, like the 5V secondary, do you get the 5VAC ?

I measured and got 7.4 volts, so those windings show voltage, but the higher (340 volt) showed nothing

[g1]

So the 340V winding measures 109.6 ohm when non-powered but no voltage when powered?