fender fm65r turns on but has no sound.

[wolivo]

Hi..thanks for accepting me in your forum..I am writing from Puerto Rico and my English is kind of bad...anyways I was given a FM65r and told that the speaker was replaced by a bigger one and when this happened the amp started lossing volume until now no sound is heard...can it have anything to do with the power supply?
Please advise.

[Jazz P Bass]

What does "a bigger speaker" mean?
What is the dc resistance of the speaker coil?

The FM 65r is a solid state amplifier.
The output power is directly linked to the load that is presented to the output jack.
The factory speaker is 8 ohms.
The amplifier will safely deliver 65 watts at full power into that speaker.

If a 4 ohm speaker was hooked up to the amplifier & the amp was run at full power, then the output transistors are probably bad.
P= VxV / R.
In other words, a 4 ohm load will task the output section with delivering 120 watts to the speaker.
Which it is not designed to do.

[52 Bill]

Try taking an extra instrument cable and plugging it into the preamp out and power amp in jacks.

[wolivo]

Thanks for your support I'll try these things for a start.