Hi,
I have a multimeter, (fluke 375, clamp meter) on PCB max4053 is used and v+ and v- to max4053, there is a 3 pin diode (cathode/anode common, pin3).
Marked CR7, unfortunately this CR7 is missing, the same PCB of meter, is used CR2,CR10= marking JY L , but this L is 90⁰ to first 2 letters.

CR7, not available.
Due to missing of this CR7, the OHM range is not functioning. At ohm range the meter is showing continuesly zero, or buzzering whole test probes are not even inserted or connected to each other. Any idea what type of duel diode will suite here to make the meter ohm range working.
Same as CR10, will be ok?
Meter power supply is 2 x AA Batteries, 3 VDC. What voltage range diode will fit here to protect max 4053 IC.

 

Hi,
I have a multimeter, (fluke 375, clamp meter) on PCB max4053 is used and v+ and v- to max4053, there is a 3 pin diode (cathode/anode common, pin3).
Marked CR7, unfortunately this CR7 is missing, the same PCB of meter, is used CR2,CR10= marking JY L , but this L is 90⁰ to first 2 letters. View attachment 309789
View attachment 309790
CR7, not available.
Due to missing of this CR7, the OHM range is not functioning. At ohm range the meter is showing continuesly zero, or buzzering whole test probes are not even inserted or connected to each other. Any idea what type of duel diode will suite here to make the meter ohm range working.
Same as CR10, will be ok?
Meter power supply is 2 x AA Batteries, 3 VDC. What voltage range diode will fit here to protect max 4053 IC.

 

Diode JY is a BAV199 dual diode often used for input protection. Data sheet attached. Its probable that was used for CR7 too.

However it isn't an active component - its presence, or lack of it, should have no impact on the operation of the ohms range. This suggests there is another fault - probably due to an overload situation which vaporised CR7!

I'd suggest the 4053 has been damaged, but it may not be limited to that device. Does every other range work as expected?

 

probably due to an overload situation which vaporised CR7!

No skid marks, no leads, and disturbed solder on the pads suggests to my eye the part was desoldered. Possibly in an aborted attempt at troubleshooting?

Since the problem manifests as a dead short on the input to the Ω range, it would seem relatively easy to trace back to its source.

 

No skid marks, no leads, and disturbed solder on the pads suggests to my eye the part was desoldered. Possibly in an aborted attempt at troubleshooting?

Since the problem manifests as a dead short on the input to the Ω range, it would seem relatively easy to trace back to its source.

Good point... maybe TS acquired this Fluke as faulty and someone else removed it previously. Anyway, its a high probability that the 4053 is damaged...

 

Diode JY is a BAV199 dual diode often used for input protection. Data sheet attached. Its probable that was used for CR7 too.

However it isn't an active component - its presence, or lack of it, should have no impact on the operation of the ohms range. This suggests there is another fault - probably due to an overload situation which vaporised CR7!

I'd suggest the 4053 has been damaged, but it may not be limited to that device. Does every other range work as expected?

Hi Irving,
Thanks for your support, I had been fixed the issue, JY (BAV199) Diode is used on CR7, and now the ohm range is working fine. Thanks.

 

You're welcome, glad it helped