Fnirsi -TC3

[fredo_]

Too lazy to post pictures, but my TC3 works perfectly with any resistor value between 4k and 6k.
My firmware is V0.3.
Tested with this resistor box :
.

[hud]

Today I received a new motherboard for TC3 and installed it into my TC2. In general it works properly, however, there are several strange bugs.
1. Generator. The output frequency is exact only in Square and Pulse modes, in other modes (sine, triangle, sawtooth) it's way off, up to 2%, and changes only in large steps.
2. Oscilloscope. On high voltage ranges (1 V/div and higher) in DC mode the zero line is off by 100..300 mV in a random direction (depending on the range), usually up. Can this be adjusted?
3. Oscilloscope. Low time per division ranges (5 μs/div and less) have incorrect X scale. For example, a 500 kHz wave on the 2 μs/div range must be EXACTLY 1 large box wide, actually I see 14..15 waves per 12 boxes. A 100 kHz wave on the same range must be 5 boxes wide, actually it's 4 boxes (is it 2.5 μs/div???). The 10 μs/div range seems to work properly.
4. Voltage. There is a calibration mode with two points: 5 V and 20 V. After calibrating (using AD584 for 5 V and a step-up converter for 20 V), it displays 5 V, 7.5 V and 10 V correctly (+/- 5 counts), but 2.5 V is 1% off (high). Why?

How did you calibrate the voltmeter? I couldn't find the menu to calibrate 5V and 20V ?

[TheDefpom]

I basic video doing some tests for ESR measurements:

🔴 A Surprising Result ? - FNIRSI DSO-TC3 ESR Measurement Testing - No.1273

[CaptainBucko]

I am observing the follow in resistors between 20k and 40k:
- 20.05kOhm resistor (OWON XDM1041) measuring 22.1kOhm (TC3)
- 33.11kOhm resistor (OWON XDM1041) measuring 35.2kOhm (TC3)
- 27.58kOhm resistor (OWON XDM1041) measuring 29.35kOhm (TC3)

while
- 684Ohm resistor (OWON XDM1041) measuring 690Ohm (TC3)
- 474.9kOhm resistor (OWON XDM1041) measuring 480.4kOhm (TC3)

[Georgdew]

Hi TheDefpom.
tell me if this is real.
I bought a FNIRSI DSO-TC3 and it behaves nowhere near as well as in your video.
I reported via email to (service@fnirsi.com) it's been 16 days and I haven't received any response. So much for some serious company...
this is how the question I sent to the email read.

FNIRSI DSO-TC3 (Broken)
hello FNIRSI community.
I recently bought this product and after a few uses, the problem I'm going to describe appeared.
It's actually a Fnirsi DSO-TC3 component tester.
As for the oscilloscope and the Signal Generator works great.
I will show in the pictures what the problem is with measuring the component.

PIC 1-In this first image I ran the component tester without inserting any components and it shows this..
PIC 2-The second picture shows the Diode measurement.
PIC 3-The following picture shows the measurement of a zener diode..
PIC 4-The following figure shows the measurement of an NPN Transistor

[madires]

That's a hardware defect.

[Georgdew]

PIC 5-The following figure shows the measurement of a 100 uf 50V capacitor
PIC 6-The following picture shows the measurement of a 220 uf 35V capacitor
PIC 7-The following figure shows the measurement of a 47 uf 160V capacitor
PIC 8-And in the last picture, the calibration does not work, after the requested connection, the probe just stands as in the picture, it does not complete the calibration

Can you tell me what is wrong with this device?
or what component needs to be replaced?
Thank you for your understanding...

I know they will tell you that this product has its place even for that money.
but I paid 55 EUR for it in my country and it's not a waste of money for me.
I bought this product because it claims to work.
turns out it does NOT work.
Don't think I'm complaining to you, I'm just curious where the problem is?

[Georgdew]

Hi madires.
Do you know what the hardware failure is?

[madires]

Typically it's a toasted MCU pin or a damaged input protection (if used), caused by checking a charged cap. Rarely it's a bad PCB or a solder bridge.

[TheDefpom]

Pic 7 (I think it was) you had the cap between pin 1 and pin 1, watch for that, try doing caps across pin 1 and 2 instead, OR pin 2 and 3 instead, to try to determine if it is a particular input which is faulty.

I certainly isn't working as it should.

I would say to take it apart and check for any bad solder joints, solder splashes etc which might be shorting out one of the inputs, dont forget to check ALL pins of the socket, and take a close look at the MCU pins too, it could easily be a bridge somewhere causing your issue.

At the very least the unit should be good for transistors, diodes and capacitance, ESR is no good on it.

[Georgdew]

Hello.
Sorry for the late reply..
In Figure 7, as you can see, I intentionally connected POINTS 1 and 1, to demonstrate that the reading does not change.
As for the capacitors I used in the measurement, they were new.
so the capacitors were not charged (only if they were not charged from ETRA. :-)
I opened the device (Fnirsi-TC3) and made measurements, so that I did not come across any bridges (short circuits).
As for the MCU, I couldn't find the datasheet because the so-called Fnirsi company removed the laser tag from the micro controller.
All large companies that manufacture electronic devices and that of top quality do not remove the markings from the components.
To me, Fnirsi products seem to work like (DIY).
This is the only and last toy I bought from them.

[indman]

Georgdew, in your recent photos I see very unpleasant traces of Chinese flux near the ZIF connector.
I advise you to first rinse and clean these traces very carefully and thoroughly. This is important for the correct operation of the device. After washing off the traces, you should dry the device and after a while turn it on again and repeat the tests of the parts.
Active flux could also penetrate into the contacts of the ZIF panel itself, so it is very likely that you will have to temporarily remove this connector and wash this area thoroughly as well.

[KungFuJosh]

The easiest way to fix that is to order a new one, and return the defective one.

[indman]

The easiest way to fix that is to order a new one, and return the defective one.

This is indeed the simplest method, but it is not always possible for several reasons.
In any case, it was necessary to immediately open a dispute with the seller regarding this fault.

[hve]

Hello, I damaged my dso tc3. charged capacitor 😔 I replaced u6., it works but I don't want to calibrate. can anyone help?

Interesting this unmarked chip.

Looking at the foto the processor seems like a LQFP100 package...
My bet is one of these ultra low cost WCH mcu's...

Looking at the mcu selection with LQFP100 we have two candidates: CH32V303 or a CH32V307 

Looking at the datasheet the pins seem to match up:
https://www.wch-ic.com/downloads/file/325.html see datasheet CH32V307DS0.PDF


Pins 12 13 are connected to the XTAL...
Pin 72 SWDIO is connected to the pin header on the right...

The 307 has an extra a digital video interface and a 1000Mbit ethernet so I would guess its a CH32V303

[UniSoft]

I drew the schematic of the device.
I did it without removing the components from the PCB, so errors are possible.

PS. If you will see any errors, please let me know, I can re-check.

[indman]

I drew the schematic of the device.
I did it without removing the components from the PCB, so errors are possible.
PS. If you will see any errors, please let me know, I can re-check.

You did a great job!
So far I have only noticed this place, shown in the screenshot

[UniSoft]

So far I have only noticed this place, shown in the screenshot

Thanks,
Also, I forgot to draw the fuse F1 (PPTC)

Updated schematics, attached...

[indman]

Sorry, I forgot to add, I thought that you yourself would guess to add GND pin2 

[UniSoft]

Sorry, I forgot to add, I thought that you yourself would guess to add GND pin2 

Updated...
I am more focused on the firmware.

PS: If anyone have any questions about firmware feel free to ask.

[hve]

Updated schematics, attached...

Wow impressive! So its a Arm cortex M4F thingy, with 32 bits floating point unit, and it is even cheaper than the CH32V303 I thought initially...

 

[RAPo]

Fnirsi has updated the TC-3, it is now a TC-4.
Most important acclaimed 10MHz oscilloscope 13 max 50kHz waveform outputs.

[KungFuJosh]

That is exactly what they do. Instead of updating the firmware and improving the previous model at all, it's time to make a new version in a new case design. I'm shocked.

[tunk]

Fnirsi has updated the TC-3, it is now a TC-4.
Most important acclaimed 10MHz oscilloscope 13 max 50kHz waveform outputs.

Maybe this should be put in a new, separate thread?
US$65 seems a bit too high.

[RAPo]

Done.

Maybe this should be put in a new, separate thread?
US$65 seems a bit too high.