MT2400 DC Voltage multimeter issue

[Prezauto]

Recently discovered that my old vantage is showing skewed dc voltage readings. Example: both leads on vehicle battery shows 45 vdc. Compared with a friends who runs another shop, his is fine, we even swapped memory cards between units with no change. So problem is definitely in my unit. Running 7.0 in mine, friends has 2.0... Not that it makes any difference.

Anyone ever able to obtain a schematic for these tools, or repair a similar problem. I know a guy who could repair, if I can obtain a schematic.

[smithnostic]

Hi maybe I can help if if it's possible for you to also help me.


Could you please do an AC measurement using the graph function?

see if you can plot AC amplitude against time.

As for your MT2400 if you are willing to open it maybe we can compare circuits and expected voltages.

Thanks

[MonzaRacer]

Ok for the record

DO NOT SWAP THE CARDS FROM DEVICES!!!!!!!!!. Each card registers to the device and you might "brick"one or both units.
Dang people, if you ever upgraded these units it says " do not try swapping in different cards "as this new card installed will be registered to this machine and also installed updates and upgrades in firmware.
If it's failing to read voltage properly it sounds like it has some possible damage internal. But first also check the fuse as a partially blown fuse can cause issues.
Dang its xa wonder either of your u its work now.
See the cards , while updating the data base, also reconfigured/updated the bios chip on the board. SOME people have gotten away with swapping cards BUT I have seen more units bricked( and me wishing owners would sell me them for parts) by this practice.
I have mt2400 with kv modules and all but the primary wire clip, which is still available from snap on , bu also just had to send my vantage pro in for work.
Since I owe cash on V pro I would consider selling my mt 2400 , it works perfectly but has some small bleeds on screen, if you has Seiko screen module with no bleeds it would fit mine possibly.
My email,is Monza283@gmail.com or text me about it at 812-709-1006. I know how much people over these units as do i, but I like my V pro also as its easier cfor me to read.
My unit has V7.0(V8.0 was database upgrades only as it came out same time Vpro was being introduced).
So V7.0 had last of board bios reconfigurations. Just for your information.
Lee Abel

[Prezauto]

Hi maybe I can help if if it's possible for you to also help me.


Could you please do an AC measurement using the graph function?

see if you can plot AC amplitude against time.

As for your MT2400 if you are willing to open it maybe we can compare circuits and expected voltages.

Thanks

Work has been nuts the last few days, but I'd be glad to help if possible. My unit is a EETM300C, I believe one of the last models with the lighter screen.

[Prezauto]

DO NOT SWAP THE CARDS FROM DEVICES!!!!!!!!!. Each card registers to the device and you might "brick"one or both units.
Dang people, if you ever upgraded these units it says " do not try swapping in different cards "as this new card installed will be registered to this machine and also installed updates and upgrades in firmware.
If it's failing to read voltage properly it sounds like it has some possible damage internal. But first also check the fuse as a partially blown fuse can cause issues.
Dang its xa wonder either of your u its work now.
See the cards , while updating the data base, also reconfigured/updated the bios chip on the board. SOME people have gotten away with swapping cards BUT I have seen more units bricked( and me wishing owners would sell me them for parts) by this practice.
I have mt2400 with kv modules and all but the primary wire clip, which is still available from snap on , bu also just had to send my vantage pro in for work.
Since I owe cash on V pro I would consider selling my mt 2400 , it works perfectly but has some small bleeds on screen, if you has Seiko screen module with no bleeds it would fit mine possibly.
My email,is Monza283@gmail.com or text me about it at 812-709-1006. I know how much people over these units as do i, but I like my V pro also as its easier cfor me to read.
My unit has V7.0(V8.0 was database upgrades only as it came out same time Vpro was being introduced).
So V7.0 had last of board bios reconfigurations. Just for your information.
Lee Abel

Thanks for the insight Lee. I've swapped cards between 4 or so different units over the years with no issues, and thought nothing of it. I do see how it could brick a unit, since it rewrites the main BIOS. I'll refrain from doing it in the future. I have a MODIS and a VERUS, but the old Vantage was a go to because of it's quick boot and portability compared to the others. Plus it's easier to read than the MODIS which has a weak backlight.

[smithnostic]

My version a european version 2.2 firmware 2001.

The signals on both AC and DC are getting to the analogue to digital converter.

The only problem is when trying to read AC voltage and plot AC amplitude over time all other AC functions work.

strange fault?

The circuit uses analogue circuits to do peak detection which is fed to the ADC. If i remember there are 5 or 6 op amps OPA330. Also a sample and hold IC. e.g Analogue switch.

It also uses a diodes to chopped the incoming signal before its fed to a comparator to change this rectified signal into a square wave.

This signal is fed into an hex inverter 74hc cmos chip squared up and buffered and fed into a custom ASIC which is used to count this frequency. This frequency measurement is sent to the 8-bit processor and then to the display.

[JessJack]

If it's failing to read voltage properly it sounds like it has some possible damage internal. But first also check the fuse as a partially blown fuse can cause issues.
Dang its xa wonder either of your u its work now.
See the cards , while updating the data base, also reconfigured/updated the bios chip on the board. SOME people have gotten away with swapping cards BUT I have seen more units bricked by this practice.

https://www.7pcb.com