Non working Gotek

[ijor]

I have a non-working Gotek. It was working fine last time I used, a few months ago.

Seems to be a powering issue. The 7-segment display shows the correct HxC setting at power up, but some flickering is perceived.

I measured voltages and indeed the 3.3V rail is a bit too low, 2.9V. The input voltage is ok, above 5V. When turned off I measure low resistance, about 200 ohms, between the 5V and the 3.3V rails.

The regulator gone bad? Or it could be another component? Checking the Gotek schematics I can't see any other component, besides the regulator itself, that can produce low resistance between 5V and 3.3V. No other component seems to be connected to both power rails, as far as I can see.

Goteks are affordable and widely available. I wouldn't bother if it wasn't that this is the old STM32 based model that is not available anymore

[exxos]

I'd assume something is overloading the regulator causing the voltage drop. Is it getting hot ?

The resistance would have to be measured both polarities with your meter as some regulators have a protection diode from input and output.

[ijor]

I'd assume something is overloading the regulator causing the voltage drop.

That's also what I thought. But if the low resistance can only by provoked by the regulator, then isn't the regulator itself what is causing this?

I mean, disregard the overloading, when turned off and disconnected there is a very low resistance between the input and the output. Something must be creating this, and unless I miss something (which is perfectly possible), I don't see how it could be something else other than the regulator itself.

Is it getting hot ?

No. At least not immediately. Didn't try leaving it like that for a long time.

The resistance would have to be measured both polarities with your meter as some regulators have a protection diode from input and output.

I see. It measures the same low resistance with both polarities.

Thanks,

[exxos]

I would assume if there is a resistance from 5V to 3.3V that it would be pulling the 3.3V higher, not lower. Though a regulator behaving like that would be a first for me. When they fail, they generally go totally shortcircuit. Though modern regulators are generally thermally protected so they will enter current limit on fault conditions.

The only way to really know is to isolate the 3.3V output of the regulator (it could be any pin so may be tricky if its the tab) then measure the voltage, and try a load resistor of like 100mA and see if it regulates correctly or not.

[ijor]

I would assume if there is a resistance from 5V to 3.3V that it would be pulling the 3.3V higher, not lower.

You are right, that makes sense. But take in mind that the low resistance was measured, of course, when the device was turned off. I assume the impedance characteristic is probably quite different with current flowing when the device is powered.

The only way to really know is to isolate the 3.3V output of the regulator (it could be any pin so may be tricky if its the tab) then measure the voltage, and try a load resistor of like 100mA and see if it regulates correctly or not.

I see. Thanks.