You can buy leads that have fuses in them, but they are not really cheap if it is for home use. If you get the Fluke ones you still have to buy expensive fuses. My set has a ceramic 3AG fuse in them and they are ok to use, they are a bit bulky though. https://au.rs-online.com/web/p/multimeter-leads/0204583
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.
Last post by saturated - March 03, 2024, 06:35:01 PM
So I got to thinking why don't I just put a fuse in my test lead that is less than 2 amps.
It should be plenty for my little Micky 🐭 Mouse 🐁 experiments. It's not like I'm in a plant or industrial commercial setting poking around.
So I looked around my collection of glass and blade fuses to see what I could come up with. I was sure that I could scare up a few fuse holders that never got used and accumulated but couldn't find any.
So now that is the plan. I would have liked to find a 1.5 A fuse but I only found stuff like 0.5 A and much larger. And all in glass none of the blade automotive fuses were less than 5A maybe 10.
So I had always wondered about voltage ratings on capacitors and fuses and I'm guessing that a component with a lower voltage ratings will be shorted like arcing by a higher voltage.
For example if I have a 250v fuse and I apply 1500v it will short/arc/jump across it? Rather than open as intended.....idk just thinking out loud maybe I'm wrong.
I know when I had a HV probe and tried to check some HV on an oscilloscope it didn't help it arcd and sparks flew like crazy.
If they are fully encapsulated in plastic then you just need some thermal grease. A thin layer of grease and try to move the transistor around a bit against the heatsink to spread the grease evenly, clamp it and solder in. Just poke the legs through the PCB enough to solder them in, it keeps the transistors more towards the center of the heatsink.
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.
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.
Not to beat a dead horse but if the TIP 142/ 147 transistors are plastic enclosed at the collector then you do not need the mica. Just grease. As a matter of fact, it may hinder the transfer of the heat. It would be nice if you would indicate what you have as both the BDV & the TIP transistors come both ways.