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Help Fixing UT61E MultiMeter continuously beeping

pharaon

Oct 28, 2014
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wonder if some one can help me with the multimeter failure, the beeping on the dc voltage is not normal also the continuously beeping on the diode test is not normal.

i'v a video link showing the problem as well as schematic and photos for the multimeter board




 

73's de Edd

Aug 21, 2015
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Sir pharaon . . . . .


Does this mean that this is being your only meter . . .or at least . . .the best one . . . .what, with it having that 5 digit readout display.
Thereby, shooting down our pending progress on the HT1500 receiver S.M. Pwr Supply ?

Since OHMS - DIODE and BEEEEEEEEEP function are shared. Is there a possibiity of having erred and placed an accidental voltage presence, while testing in any of those modes?
The first things that I would check would the overvoltage protection afforded by two sets of series arranged pairs of transistors.
Their connective function is to serve as protective zeners on that circuit path.
They are being the units Q1-Q8 and Q5-Q6 pairs.
To evaluate, lift the emittter which is being grounded . . .loose from its ground on both sets of transistors..
Then you check out the OHMS - BEEEEEP - diode function modes, to see if returned to normalacy.
Additionally check out all of the OHMS ranges for ~ accuracy using 10 Ω-100 Ω -1k -10k-100k and 1 meg test resistors.
Also see if the DC volts function is still good.

AND . . . . . . I hope that when you removed the range knob, that you kept track of the arrangement of the sets of spring connectors that complete connection between the PCB's 8 etched out circular ring segments.
Along with the spring loaded detent indexing B-B.

73's de Edd . . . . .

You can never, never, never trust a dog to watch your food.


.
 

pharaon

Oct 28, 2014
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Does this mean that this is being your only meter
for now it's my only meter yes

shooting down our pending progress on the HT1500 receiver S.M. Pwr Supply ?
well for now yes, although i still think it's the IC power that doesn't give power to the transformer to have an output of it

Is there a possibility of having erred and placed an accidental voltage presence, while testing in any of those modes?
yes accidentally connected the red prop of the meter while it was attached to the 10A max slot to the positive node of the battery with the A scale on the meter to test the battery ampere which cause that failure

The first things that I would check would the overvoltage protection afforded by two sets of series arranged pairs of transistors.
Their connective function is to serve as protective zeners on that circuit path.
They are being the units Q1-Q8 and Q5-Q6 pairs.
how to test those transistors

To evaluate, lift the emittter which is being grounded . . .loose from its ground on both sets of transistors..
only the ground or to remove the whole transistor?

AND . . . . . . I hope that when you removed the range knob, that you kept track of the arrangement of the sets of spring connectors that complete connection between the PCB's 8 etched out circular ring segments.
Along with the spring loaded detent indexing B-B.
didn't get what do you mean exactly
 

Harald Kapp

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yes accidentally connected the red prop of the meter while it was attached to the 10A max slot to the positive node of the battery with the A scale on the meter to test the battery ampere which cause that failure
That should have blown the fuse in the worst case. You cannot test a battery that way. In 10 A range the multimeter is essentially a short circuit.
how to test those transistors
Theoretically lift the emitter pin only, if possible. But: we're dealing with smd components here, so lifting only one pin is a bit tricky, not impossible.
For a complete check you would have to de-solder these and check them for a permanent short circuit. Better yet, put them in a transistor tester.

Check also varistors SG1 and SG2 for a possible short circuit - unfortunately you'll need another multimeter for that.

didn't get what do you mean exactly
Ed expresses his hope that you will be able to reassemble the multi function selector knob such that all the springy contacts are in their correct positions to make the right contacts for each switch position.
No need to worry if these contacts are fixed to the knob or their positions are clearly identifiable otherwise.
 

pharaon

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That should have blown the fuse in the worst case. You cannot test a battery that way. In 10 A range the multimeter is essentially a short circuit.
i checked the two fuses and they are alright

For a complete check you would have to de-solder these and check them for a permanent short circuit.
so i'll de sloder it complete from the board to check it, but how to check those four knots smd transistor for shot?

Check also varistors SG1 and SG2 for a possible short circuit
i don't see any component on the board for SG1,SG2

unfortunately you'll need another multimeter for that.
will get another one tomorrow i guess, although at the moment i'm using old analog meter with buzz option and ohm testing

Ed expresses his hope that you will be able to reassemble the multi function selector knob such that all the springy contacts are in their correct positions to make the right contacts for each switch position.
No need to worry if these contacts are fixed to the knob or their positions are clearly identifiable otherwise.
ah it's a fixed springy contacts to the switch , no need to worry about it

unit_ut61e_pcb_removed_small.jpg


akso it should not beep at the Voltage scale as it do in the video, if you like you can see how such multimeter supose to work on youtube videos or i can get a link for such video
 
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pharaon

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if i use 9 v with 3 amp current on the multi-meter as power source would that help me found the faulty component ?
 

Harald Kapp

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i don't see any component on the board for SG1,SG2
I was referencing the schematic. These components are obviously not populated on the pcb.
so i'll de sloder it complete from the board to check it, but how to check those four knots smd transistor for shot?
These transistors are similar to this one. Look up the respective pin function (base, emitter, collector).
- Check for the presence and correct working of the base-emitter diode.
- Check for the resistance between emitter and collector - should be non-conducting.
if i use 9 v with 3 amp current on the multi-meter as power source would that help me found the faulty component ?
No. the original battery is enough.
 

Harald Kapp

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The meter indicates OL - overload. Does that happen when you short-ciruit the inputs (volt/ohm vs. common), too?

Check U1, pin #37, labeled VRH, for the presence of the correct reference voltage (1.23 V, see datasheet).
 

pharaon

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The meter indicates OL - overload. Does that happen when you short-ciruit the inputs (volt/ohm vs. common), too?
depend on what scale the meter is
but the issue is the beeping on voltage scale and the continuously beeping on diode beside it doesn't do any reads as well
 

pharaon

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the multi-meter doesn't give any read on DC scale, ampere scale, ohm scale
i mean i tried to test some dc voltage, ampere and resistors no reads at all

i used analog multi-meter on 1x ohm scale to test the transistors




1 red,2 black = 8Ω > 1 red,3 black = 8Ω > 2,3,4 = shorted

1 black , 2 red = infinite > 1 black , 3 red = infinite

i test on the board and those were the same measurements for all Q1-Q8 and Q5-Q6
 
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Harald Kapp

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1 = base
2,4 = collector
3 = emitter
Your measurements between 1-2 and 1-3 are good.
Between 2-4 a short circuit is to be expected as this is a common connection for the collector (yes, 2 pins for the same function).
But: a short between 2-3 or 4-3 is unexpected. There should be no current flow.
 

pharaon

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i was using the RED probe on 1 it to be able to make the measurement does that mean it's the base? not the emitter or collector ?

to be clear, the issue happen when i shorted between those two circles in red i show on the schematic while the battery exist and the multi-meter on the A scale

 

pharaon

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i took Q1 transistor out of the board and i test it, also tested it's pin place on the board
and i got a video for the results

 

pharaon

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the transistor look




is there any further test i can do or any hope to fix the multimeter?
 

pharaon

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ok i guess it's the chip, i've tracked the 10 A path on the bard which go directly to the Chip , and as I've mentioned before i shorted it with the 9v+ from the battery
so do you agree with me it's the chip or is it something else? and if it's the chip is there a way maybe to reset it or it's done
 

Harald Kapp

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What you've traced is the ground connection. According to the schematic there s no direct connection between the 10A input and the chip.
Current flows from the terminal through fuse f2 and resistor R26 (0.01 Ω) to the common terminal.The common terminal (gnd) is connected to U1, pin 39.
This is the path you measured but this path does not allow 9 V to appear at the chip.

Should it be a defect of the chip, there is afaik no way to repair it apart from changing the chip.

Did you check the reference voltage (see post #8)?
 

Harald Kapp

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U1 is the big chip, see the schematic. U1, pin #37 means pin 37 of chip U1.
Of course: to check the reference voltage the multimeter has to be switched on. Measure from the chip's pin to gnd.
 
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