Apparently it connects the transformer without rectification and filtering!
Of course not. I have a power supply board with 4700uf cap and a bridge rectifier
Okay, got a minute, Talledega NASCAR race was red flagged for a while. This hobby is cheaper than that one, except when race is on free TV channel like today.
You need to run the transformer from a light bulb box, 100 W light bulb in series with the primary. I use a grounded box so loose wires don't shock me or start fires. That will give you enough time to make measurements.
These transistors possibly didn't come from farnell via UPS. In some countries, if the store didn't substitute counterfeits, the postal or freight forwarders will substitute genuine parts from farnell/mouser/digikey with counterfeits. Repack, you'd never know. Some repairmen check a few from every batch shipped.
I'd check all drivers and output transistors for Iceo leakage. 22k resistor in series with ma scale of a dvm, then plus to npn C, minus to npn E, base open, how many milliamps. Opposite polarity on the pnp. Current should be less than Iceo on the datasheet. Most counterfeits will fail with 12 vdc out of a car/motorcycle battery charger, but you have 50 to play with.Use clip leads so you don't touch the voltage.
You need to run the transformer from a light bulb box, 100 W light bulb in series with the primary. I use a grounded box so loose wires don't shock me or start fires. That will give you enough time to make measurements.
These transistors possibly didn't come from farnell via UPS. In some countries, if the store didn't substitute counterfeits, the postal or freight forwarders will substitute genuine parts from farnell/mouser/digikey with counterfeits. Repack, you'd never know. Some repairmen check a few from every batch shipped.
I'd check all drivers and output transistors for Iceo leakage. 22k resistor in series with ma scale of a dvm, then plus to npn C, minus to npn E, base open, how many milliamps. Opposite polarity on the pnp. Current should be less than Iceo on the datasheet. Most counterfeits will fail with 12 vdc out of a car/motorcycle battery charger, but you have 50 to play with.Use clip leads so you don't touch the voltage.
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With the power transistors removed there is no short connection to ground. And it takes just seconds for the transistor to fail. I dont know why it happens. Maybe faulty transistor. Or maybe because i use Tip41C/Tip42C as drivers ?
I didn't think you were connecting the transistor pads of TO220 to the printed board. Those should just go to miniature aluminum heat sinks.
I use TIP41c/42c as drivers, my AX6 board is going over a year old. Mine are genuine Fairchild shipped direct from the US farnell warehouse (newark). I use 70 v rail voltage, regulated.
Some of the heat sinks I use on drivers and VAS are just pieces of aluminum window frame, with holes drilled in, bolted to the TO220 package with heat sink compound between. Gave me time to sort things out when I had a major wiring error. My boards are point to point, not PCB, and I had the function of various 220 ohm resistors confused for a long time.
The light bulb box will slow down the failures so you can make some voltage drop measurements across the 10 ohm base resistors and 220 ohm driver resistors to see where the fault lies. But as I said your supply chain may not be as rock solid reliable as farnell(US) to UPS to my door has been. Iceo test at 50v should give you some confidence in your TO220 transistors or condemn them as fake. If you don't have transistor datasheets, download them from datasheetcatalog.com in pdf format. pdf reader is a giveaway, I got mine from the US govt IRS website.
I use TIP41c/42c as drivers, my AX6 board is going over a year old. Mine are genuine Fairchild shipped direct from the US farnell warehouse (newark). I use 70 v rail voltage, regulated.
Some of the heat sinks I use on drivers and VAS are just pieces of aluminum window frame, with holes drilled in, bolted to the TO220 package with heat sink compound between. Gave me time to sort things out when I had a major wiring error. My boards are point to point, not PCB, and I had the function of various 220 ohm resistors confused for a long time.
The light bulb box will slow down the failures so you can make some voltage drop measurements across the 10 ohm base resistors and 220 ohm driver resistors to see where the fault lies. But as I said your supply chain may not be as rock solid reliable as farnell(US) to UPS to my door has been. Iceo test at 50v should give you some confidence in your TO220 transistors or condemn them as fake. If you don't have transistor datasheets, download them from datasheetcatalog.com in pdf format. pdf reader is a giveaway, I got mine from the US govt IRS website.
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Sure, why not? I had TO3 heat sinks in my single supply chassis, blown up, so I used NTE60 (white box MJ15003). If I were building from scratch I'd use MJL4281 or MJL21194, since the single hole is easier to drill and tap with a hand drill motor. Hard to get four holes to line up right with a hand drill motor.
MJE15028/29 or MJE15032/33 should work better for drivers than the TIP41C/42C I used. Just they were $4.50 each a couple of years ago, now down to $1.25 from Newark.
You can't use the PCB layout on page 1 if you are going to use TO3-P transistors. It is for TO3.
MJE15028/29 or MJE15032/33 should work better for drivers than the TIP41C/42C I used. Just they were $4.50 each a couple of years ago, now down to $1.25 from Newark.
You can't use the PCB layout on page 1 if you are going to use TO3-P transistors. It is for TO3.
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