Assuming that the T12 collector voltage TV mentioned is just a typo, T4 voltages do not seem right.  E-B voltage indicates it should be turned on, but collector voltage is not pulling down.

Check that T7 and T8 and their diodes are ok. Check all 4 of the 0R33 5W resistors.
Power up on the bulb with no load connected.
Measure DC volts at e,b,c, of T4, T6, T9, T12.

Service manual attached.
Sounds like 'Lo' input is the higher gain circuit (meant for lower output pickups) which is opposite to the usual arrangement.

What is the wattage of your bulb?
I doubt that the 33VDC at the output was when speaker connected as that would be over 130 watts and your speaker would surely be toast.

Never try to power anything up on a limiter bulb while a load is connected to the amp.
Power up with no load.  Then, if no DC is present on the output, connect load while unit turned on.
Many amps will not power up properly on a bulb with a load connected.

HT stands for High Tension, the fuse will be in line with the highest B+ supply line.  Usually there is a turn on surge of current so they use slow-blow fuses.  As they are marked S.B., a fast blow will likely not handle the turn on surge.
Check that fuse you took out of the HT spot, if it is really a 0.5A, I don't think it would power up the amp like it did.

Looks like it's from here:  https://savageamps.com/the-amps

schematic attached.
Disconnect your load.  Check for DC voltage at the output.  Do not connect a load until you get the amp to the point where there is no longer any DC at the output.

Acoustasonic 100 & 150.

Quote from: markorock37 on March 04, 2024, 01:18:36 PMThere is some metal exposed on the back of these newer transistors. I think it will be best to use the insulators.

Thanks for the update.  Yes, you need the insulators.  I was mistaken as far as the datasheet goes.  I found pictures of other transistors with the same package (TO-247) and they are not insulated on the back either.

PR2432 can be Champion 20,40, 100. 
One side of the power amp with extra speaker is shown in a dotted line.  The 2 versions are AC100 and AC150 (mono or stereo).

No offence intended, but if you can't tell whether your unit matches up to this schematic, a different schematic won't get you anywhere.
TDA8950 power module is obsolete, maybe the new unit has a different module.  You would not be able to modify anything in the power amp, so that would not matter.
But just to speculate, the preamp might be the same.
Fender has really tightened up on any of their schematics getting out in public, so we have to work with what we can get.

This is the schematic for a Champion 40.  Not sure which PR, but it has DSP and the output IC is TDA7294.
PR number is 'production release' and does not necessarily mean it uses a different schematic.  Schematics go by model name and revision number.
Check if this schematic matches your unit.  If not, what is the output IC in yours?

When the fuse voltage rating is less than the circuit requires, the possible arcing is more likely after the fuse has blown.
Your probes have a voltage safety rating as well, and that would be lost with any modification of the probes, no matter how high the fuse rating.

Lots of modern electronic equipment has standby circuitry that is always running unless you unplug it from the wall.

The metal tab type has not been made for over 10 years, if you found some they are old stock or possibly fake.
Like Jazz said, you don't need the spacers for the plastic backed type.
Attached datasheet shows both types.
*EDIT TO-247 package does not have the back insulated and requires insulator.


If you do happen to have found some old style metal tab types, you not only need the mica spacers, but also special plastic washers for the screws.

Quote from: Tassieviking on February 26, 2024, 10:31:55 AMI have seen multimeters that physically block the holes when you turn the knob so it is only possible to use the volt probe when volt is selected

I think if you forget you were in current mode, you will likely to forget to turn the knob as well.  So then you would still do damage with the probes, which are acting as a straight piece of wire in current ranges.
My current range require switching ports, and there is a beeper that goes off if I choose any other range while plugged into the 10A port.
Still doesn't help me if I forget to switch range.