Analog/Digital Trainer Pad-234A Fuse Replacement

Thread Starter

BMB280

Joined Mar 2, 2021
4
The 5V output on my digital trainer is not putting out 5V and my professor said it was a blown fuse. Does anyone know how to replace the fuse on the Analog/Digital Trainer Pad-234A? And how exactly to remove the assembly from the box?
 

dl324

Joined Mar 30, 2015
12,678

Thread Starter

BMB280

Joined Mar 2, 2021
4
The power indicator light is off when I turn on the trainer. The other two power sources (12V and -12V work as usual). How do I access the fuse? I can’t seem to take the board off.
 

dl324

Joined Mar 30, 2015
12,678
The power indicator light is off when I turn on the trainer. The other two power sources (12V and -12V work as usual).
That shouldn't be possible unless the indicator bulb is burned out.
How do I access the fuse?
The fuse is accessible from the back of the unit. It'll either be something you can turn by hand (pressing in before turning counter clockwise), or have a slot for a coin or screwdriver (still need to press in before turning). Unplug the unit before attempting to do this.

If you have all voltages except 5V, that regulator may be bad.
 

dl324

Joined Mar 30, 2015
12,678
So what would I do if the regulator was bad?
Replace any defective components. It looks like the 5V regulator is mounted on the chassis; though you still need to open the unit to remove it. Besides the regulator, there's only a bridge rectifier, filter cap, and a cap+LED+resistor on the output.

The 5V regulator uses the red secondary.
 

bertus

Joined Apr 5, 2008
21,239
Hello,

Looking at the schematic that @dl324 posted, the 5 Volts regulator is off board.
The pins 2 and 3 will measure the input voltage of the regulator.
The pins 2 and 1 will measure the output voltage of the regulator.

Bertus
 
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