I am looking at refurbing my 30+ year old Atari 800 which is working. First on the list is to replace all of the old electrolytic caps an tantalums. I did not like the idea of tearing apart a working psu so I bought a spare working board, which I imagine also has 30+ year old caps.

I wanted to make a test jig with loads. Any idea on what I should use as loads?

 

I wanted to make a test jig with loads. Any idea on what I should use as loads?

Resistors would seem to be the obvious choice.

 

Resistors would seem to be the obvious choice.

Well of course.) But what value?

And any ideas for feeding that RF module? I am guessing without test equipment that might be a tall order?

 

Well of course.) But what value?

\( \small R = \frac{V}{I}\)

 

\( \small R = \frac{V}{I}\)

OK so what current should I expect an old 6502 based computer to consume. That is what I am trying to get at here.

 

Years ago, many years ago I was involved with a PC Hardware testing sight. They wanted a reliable test box and a way to record the data (Voltage and Current) at different loads applied. I used Ohmite "Stack Ohm) ceramic resistors and just manually switched in more parallel loads using simple toggle switches. Later design I went with using D Flip Flops to switch MOSFETS to change loads. I included some high power rehostats to trim my current. I measured the voltage and current using old 10 Amp and 50 Amp current shunts and a few Action Packs to amplify my shunt outputs.

Problem here is I don't know what your PSU max currents would be. You could maybe start by placing some higher value resistors across a known voltage out and slowly increase the load (reduce resistance) and place added resistance in parallel to increase the load until the voltage begins to fold over and drop. I used 120 VAC fans to cool my load banks.

This is an old idea of just looking at two rails:


Ron

 

OK so what current should I expect an old 6502 based computer to consume. That is what I am trying to get at here.

Look at the voltage regulators. The package and/or part numbers will tell you the maximum current they can provide. Then look for information regarding the transformer windings they're using. If they're using half amp windings on a 7805, then the max current would be closer to what the transformer can source.

 

Lamps make pretty good test loads for power supplies. When they are cold, their resistance is pretty low, and as they heat up, the resistance increases. So if you can get lamps rated to the voltage and current, you could try them. For example a 12V 24W lamp will be a good load for a 12V 2A supply.
Lamps give the power supplies a bit of a fright for a start so they get a stress test to see how they behave under heavy load.

 

Look at the voltage regulators. The package and/or part numbers will tell you the maximum current they can provide. Then look for information regarding the transformer windings they're using. If they're using half amp windings on a 7805, then the max current would be closer to what the transformer can source.

I was just thinking about this last night. Should be pretty straight forward.