UNI-T UT61E Multimeter teardown photos.

[ovidiu_vr]

I measured a DC current for a big DC battery (I thought the accumulators were dead) and both fuses were blown down and the second time I had the selector switch on Hz (%) and the testers inserted on the alternating current ammeter A(10A) and COM (the fuses didn't burn anymore but the circuit breaker tripped from my house. I hear some  noises from buzzer U1 when the multimeter is turned on, very lightly, just listening with my ear. With selector in diode mode it rings continuously, in mV mode it goes to "OL" all the time, in the (%) mode at Hz in AUTO/MAN is going into "OL", without measuring something. I haven't found any defective parts (rezistors, diodes D1,D3, D1B,D1A,D3A, D4,D5,D6, D18, transistors Q8, Q1, Q5, Q6,  with symbol Q). At % on 50Hz it switches to OL by itself. I'm going to feed it without a selector to see how is working W1 NJU7201U30-voltage regulator. UT61E measuring well (maybe).Has anyone bought from this site?
https://www.yoycart.com/Product/592327483069/

[ovidiu_vr]

Is it normal for PTC1 to heating up to 70 degrees in a 4-seconds, with the testers coonected to 230VAC, the switch connected to Hz(%) position and without being powered at 9Vdc? The rest of PTC2, PTC3 has 34C degree. If the switch is on Voltage(AC), PTC1 has 34C degree,  PTC2, PTC3 have 34C degree & the multimeter is powered by the 9V battery. By selecting % I have the OL indication on the display without  230Vac between V-Com and with 230Vca connected to V-Com, the buzzer has a sound of BRRR... 2-3 seconds. PTC1, 2, 3 has 1.2kO, R35-1MO. R37-200O. The voltage indication AC or DC it it OK, only 220Vdc has OL indication without voltage V-Com(DC). I forgot to move the switch from Hz(%) and testers from alternating current to 230VAC. I bought another UT61E(the same) and now I have spare components.

[rsjsouza]

Is it normal for PTC1 to heating up to 70 degrees in a 4-seconds, with the testers coonected to 230VAC, the switch connected to Hz(%) position and without being powered at 9Vdc?

The manual warns to not apply more than 30Vrms when this rsnge is selected, so it is indeed expected that the protection device will be acting to protect its frequency input.

If I understood your post correctly, you seem to be connecting the probes to 230V while the meter does not have a battery, is that so? If so, I wouldn't do this in any case, especially if the battery compartment panel is not in place.

Not all meters are built equal, especially with regards to safety. I would carefully read the manual in its entirety before experimenting with higher power circuits such as the outlet.

[ovidiu_vr]

Thank you for alerting me. They mention in manual for UT61E:when 10Hz-10MHz: 300mV<=a<=30Vrms, when >10MHz....40MHz:400mV<=a<=30Vrms, when >40MHz: unspecified. I expected it to be the same Hz circuit as for V= & AC, sorry, maybe it escaped(ES51922A) with blown fuses. For SG1 (no voltage mention),2,3,4 I will add varistor  07D751K.