MASTECH MS8226T DMM problem

[crnazvijezda]

 Hi all,

My MS8226T is about 3 months old and it was good until today.
It work on all functions except on resistance position measurement (resistor/diode/buzzer on one position).

So, problem is next
When I put it on resistance position after auto range it start to show 0 Ohm which start to blink
one time per second.
When select resistance it showing 0 and no change except blinking. ??
When select diode it measuring good.
When selected buzzer it buzz whole time but when connect probes (shortcircuit) it stop buzz. ??
Same when it is not on manual range.

Do anyone have some suggestion what to do?

Thanks in advance!
Regards,
Tomy

[dannyf]

Do anyone have some suggestion what to do?

Reading the manual?

[crnazvijezda]

Yes, I read the manual and have knowledge how to work with.

I made short video (YT unlisted) about problem


Regards

[crnazvijezda]

Short update.
Now only diode works and nothing else

[Lightages]

I am sorry to see your problems. I have a rather low opinion of Mastech and IMHO it has probably just died and isn't worth fixing. I would rather just buy a new meter than waste time trying fix something made by Mastech.

[Wytnucls]

Open it up and look for bad solder joints or shorts on the PCB.
Post a link to a high res picture of the inside and someone might be able to help you.

[deth502]

i concur with the previous 2 posts.

open it up and look for any obvious faults. bad solder joints, burnt/broken traces/components, and fix as necessary. if that dosent work, its not a very expensive meter, and is likely not worth putting more money/time into it than that.

[Wytnucls]

Have a look also at the range switch contacts and clean the PCB range switch traces.

[crnazvijezda]

Thanks to all for suggestions!

I check all traces and elements. One capacitor was bad look and too small capacity and I changed it.
Cleaned PCB and switch traces. No change.

Seems that problem is in microcontroller and this part is not accessible. Unfortunately it is not usable any more
but fortunately I'll buy new and probably much better, no more those cheap.