DSO 112 will not turn on

[igort0]

Hello,

I bought a DSO 112 and installed nokia BL-4U Li-ion battery. All worked well. Next I carried out some measurements with the oscilloscope, turned it off normally and left on the desk. Next day I tried to turn it on but it did not respond. I thought the battery discharged, so connected USB cable, but the LED just blinked once, as it does when no battery is installed. I disconnected the battery, measured voltage (result 3,8 V) and connected battery and USB cable again. This time LED turned on fine, but the device did not turn on anyway. Just in case I replaced the battery, but to no avail. Could anyone help with this or should I assume the unit got damaged with no particular reason just over night?

[jye1]

The cause for this could be high power supply impedance , i.e. there was too much voltage drop at power-up. Power supply impedance depends on power supply and cable. So you can try with different USB powers and different cables to see if there is any difference. Please have battery switched off first. With battery connected the situation is worse since both scope and battery charger will draw current.

[ashw]

I'm having the same problem.

I have charged the battery, tried to turn it on with the battery, with a high current USB charger, with both, and with
neither . My DSO 112 will not turn on. Total usage time, about 10 minutes.

I hope that I can get it to work, as it is a nice unit.

-ash

[jye1]

Did you get no backlight at all or having backlight but just a white screen?

[igort0]

Mine is absolutely dead - no backlight, no nothing.

I remember that when I removed battery that morning it was warm, but I don't remember whether charger was on or off.

In case the charger was off I guess it might suggest some short circuit that burned the unit and warmed up the battery. The battery contacts could not touch anything on the board, though.

Is there any chance to measure some voltages on the board that could point what is damaged?

Thank you for your help, by the way.

[ashw]

Now this is interesting.

Yesterday, Friday, there was nothing when I pushed the on button. The screen was its usual unlit black. There was no indication that the button had been pushed.

For this reply I went and tried to turn it on, just to check. It Turned on. It turned off. It didn't turn on. I plugged into a charger. Nothing. I unplugged it. It turned on.

For about 10 minutes it was working, but unstable.

Since then It has functioned perfectly.

My experience has been that it is a flaky device. It worked properly for a while, then failed, then worked when tried for 2 days.

As of Monday afternoon it is working and I am happy with it.

[igort0]

Having no better idea I just threw the unit into a freezer. After several hours in -15 deg Celsius it turned on and so far seems to work stable.

[ashw]

It seems that there is an intermittent start up problem. Maybe a slightly out of spec cap that prevents the pushed button being noticed. Let it sit for a while and it goes back to normal.

All in all, it is a nice little unit.