exxos's Atari, Amiga & retro forum

Just got an ATARI 1040 STE, before power up I re-capped all, then I am in phase of checking-up.

With only the motherboard, nothing connected on any port, not even power supply, between +5V and GND (pin 1 and 3 on power connector) I got 115 ohms (looks like a capacitor, start at 90 ohm then raise to 115), I cannot find any data on the Web about it, what should be "normal".

If anyone with a working 1040 STE can test and tell me if is same ?

NOTE: between 12v and GND it is open loop.

I don't have an STE I can test easily, but an ST does a similar thing on the 5V input and clicks up to 158R. 12v settles at 15K but needs a while for the multimeter to get there so does read 0R for a moment.

Given there are many components involved, capacitors included, you are going to get some sort of reading, and looking at the schematic will help you understand to a degree, but unless you have a dead short, it's not going to really be a useful reading IMHO.

My personal preference is to hook up a bench PSU to the 5v input (12v is not needed to boot an ST/F/M or STE) and set the power level to something really low, so not enough to boot, and make sure there are no components that are getting warm. I slowly increase the power checking each time for evidence of overheating, and eventually take it to the power needed to boot. I usually set the overcurrent protection at about 3A @ 5v, which is the rated amperage for 5v on the ST type PSU.

For the PSU I use some of the resistors exxos has in the store to power on with a load and be sure the voltages are good before I plug it into the ST. Be aware that the load resistors do get pretty warm during testing if all is well.

Agreed, schematic and all component involve is not easy to track any hard or soft shorts, I ordered a thermal camera and will do the power injector test.


Thanks for your reply. ;)