[time-nuts] Ebay Huawei Ublox M8T Modules Warning

[Bob kb8tq]

Hi

The “normal chips” that should be inside the module all have something like a 3.6V max 
supply rating on them. I would guess that 5V will melt a goodly number of them. 

Bob

> On Jan 9, 2021, at 5:38 PM, Nigel gm8pzr via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> During the December conversation re LEA-M8T modules on scraps of PCB from Ebay I commented that the same seller also had complete circuit boards available, and suggested this might be a worthwhile alternative.
> 
> I've dealt with this seller before, always been very happy with the results, and agreed a price on three such modules which arrived just before Christmas, for reference this particular Ebay ID was 333619130232, and finally found time to start checking them today.
> The modules themselves look very nice, but one of the auction photos is a connection diagram that shows Pin 2 of the 8 pin interface connector as "Power In 5V DC", and on this PCB that pin connects directly to the pin 6 Vcc input on the Ublox module, which has an absolute maximum rating of 3.6V .......whoops!
> This is not intended in any way to be a criticism of this seller, who I am more than happy to recommend, nor indeed of any other seller, but this is a generic diagram that several sellers are using for various Huawei/Ublox modules, some of which may have an onboard 3.3V regulator, as presumably did the one this diagram originally referenced, but some of which may not.
> 
> So that's the warning folks, don't trust that diagram without checking!
> Now a question, supposing someone did follow that diagram and applied 5 Volts to Vcc on the M8T, what is the risk of damage and would it be immediately obvious?
> And no, I didn't:-), but when modules are described as tested concern might arise as to the test conditions.
> Nigel GM8PZR
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