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Removing trem circuit from a 410 hd 130


Posted on Sunday, May 29, 2005 - 10:08 am:   


new to the board...some good info here. thanks !!

got a 410 HD 130 on the bench and i`d like to remove the trem from the circuit. is it as easy as doing with a fender. seems to be sucking a lot of gain from the channel. the normal channel is quite a bit loader than the reverb/trem channel. the customer doesn`t particularly like the trem...so i`d like to remove it from the circuit.

did a complete cap job and biased the amp at .45 across the 10ohm cathode resistor. amp had the original sylvania 6ca7`s still in it. tubes test very strong and are fairly well balanced.

also, would like to know where to set the speaker load switch to..4 or 8 ohm. it`s a 4x10 config. measured ohms off the speaker plug..reads just under 16ohms. wiring looks stock.

thanks for any info in advance

Steve Kennedy (admin)
Posted on Tuesday, May 31, 2005 - 05:05 pm:   

The 410HD-130 came from the factory with 4 8-ohm speakers wired in series-parallel (two parallel pairs wired in series) for a total impedance of 8-ohms. This load should look like about 6-ohms on most digital meters. The switch is normally set in the 8-ohm position.

To isolate the Tremolo circuit:

1. Lift the end of R35 (4.7k) that connects to one wiper of the Reverb potentiometer. This removes the input signal to the Tremelo circuit. (You could also remove R47, but lifting the correct end would allow the circuit to be restored easily if internally documented.)

2. Lift the end of C25 (0.1�F) that connects to R34 (100k). This will disconnect the output of the Tremelo circuit.

3. Optionally, you could pull the Tremelo transistor (TR-2, 2N3391) or disconnect the + & - 16 volt power supplies to the Tremelo circuit (if you can isolate them) to absolutely kill it.


Posted on Tuesday, May 31, 2005 - 05:33 pm:   

thanks for the reply Steve...

found the speaker problem. had a blown speaker. what`s the wattage rating of the factory installed alnico`s ? do i need to lift the input AND the output of the trem circuit...or just do one of the 3 above.

thanks again
Steve Kennedy (admin)
Username: admin

Registered: 03-2002
Posted on Wednesday, June 01, 2005 - 05:44 pm:   

Either the input or the output could be loading the circuits they are connecting to, so disabling both connections will remove any doubt that they are effecting the rest of the amp.

The speaker rating is probably 40-60 watts each.