I’m trying to determine whether my HPS10 is acting properly. I can run it from batteries, and I can run it from a 9v DC, 500 mA adapter. I’m using 2100 mAh NIMH cells. However, when I plug in the adapter with batteries installed in the 'scope, the green “charge” LED never lights. This is how it has always acted since new – it’s not a sudden behavior change.
I have checked the charging current into the battery stack, and the 'scope seems to be charging the batteries at about 200 mA.
So, can anyone tell me if the LED is driven by firmware in the 'scope’s microcontroller, or is it just a “dumb” indicator that is supposed to light any time current flows into the battery stack?
Before I crack the unit open to look for a missing resistor or backwards LED, I want to make sure I understand how it’s supposed to work…
Found the culprit – the LED was loose due to very poor soldering (didn’t flow into the plated-through holes) combined with the LED pads being ripped off the PCB. When the 'scope was assembled, someone must have misaligned the LED and the upper case-half. This pushed the LED down, ripping the pads off the back side of the board. The pads on the front side, since the solder never flowed to them, were fine. An easy fix, but a little depressing to see damage inside my 'scope!
Sorry to read that you experience problems with your scope.
If you would have returned the item, we would have fixed it under warranty conditions.
Please re-check the charge current, it should now be approx 90mA, which is OK for continuous charging.
The led is not driven by the controller but acts as voltage reference for the charging circuit.