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I have the foot pedal plugged in, but it’s not switching functions? The LEDs on the foot pedal still light up though….
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Make certain the rear toggles for OVERDRIVE and PREAMP BOOST are in the PEDAL positions
I’ve read about something called an OD trimmer inside of the amp. Does the OTS have it, and what does it do?
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Yes, the OTS amplifier has an OD (short for overdrive) trimmer. This is part of the original design that
controls the amount of signal sent into the first stage of the overdrive circuit. Different settings on this control
can yield dramatically different results to the tone, amount of gain, and feel of the overdrive channel.
The OD trim sounds like fun to play with! Can I adjust it myself?
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Well, yes it can be fun to play with. However, adjusting it requires you to remove the chassis and adjust a
small trimpot that is near high voltages. We highly recommend the use of a non-conductive rubber
screwdriver, and only adjust the trimpot when the amplifier is not powered and disconnected from the wall
outlet. DO NOT ADJUST THE OD TRIMMER WHILE THE AMPLIFIER IS ON! Note that the power supply
capacitors in the amplifier can/will still store charge, and you can still be bitten by 450VDC even though the
amp isn’t connected to the wall! Adjust the OD TRIMMER only at your own risk!
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The picture on the following page shows a few of the inside of the chassis, facing the input jack side. The OD
trim is indicated by the green arrow. Insert the non-conductive screwdriver into the trimmer, make a small
adjustment, and relisten.
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We set the trimpot at about 10:00 to 11:00 o’clock (viewing the trimmer from the input jack side down to the
indicator LED side). You can also measure this by setting your DMM to the resistance measurement (about
100K), and plug the black probe into the black bias probe jack. Place the red probe on the center lug
(“wiper”) of the trimmer. Less resistance = less gain. More resistance = more gain.
