V-I Curve tracer / Component tester

[RAPo]

I have some experience,
The batteries come in with separate wires, but the - and + are connected.
No universal ground from the usb-c connection.
The LD117AG is a 50A81SMT2, the regulator above it is a 117m3,
the SO8 near the 330uH is a an isolated DC/DC xl sem1 xl6007e1 converter.
I don't see a regulator near the 2R2.

After some measuring, I think the indicated transistor is gone as a result of my looking around.

well, right now, the circuit is not working: pressing+keeping the on-button shows the LCD screen monetarily but with an off-scale low (in the sense of no green bars) bat. indicator. The battery themselves are full. I must have done something wrong/

Bummer, that's bad news.
Lets make some checks on the internal power supplies.

Remark #1 : As I don't know your level of knowledge in electronics, here are some guidelines. But if you're experienced, you might find the below advices as unecessary or overkill.

Remark #2 : If you want to start a repair action, consider creating a dedicated thread in the 'Repair' section of this forum.


At first glance, as I see no transformers on the PCB, I would say that all of the supplies should have the same GND.
But it seems also that each battery has its own set of wires.
So how does the PCB connect them together ? In // ? In series ? Or are they independant of each other ?
 
 I guess there are 4 regulators, but I can't read their markings :
- a) the LD1117AG you already mentionned; confirm the '50' voltage code  (meaning 5 VDC output)
- b) Just above the latter, the the part in the SOT223-4 package is likely also a linear regulator
- c) Towards the bottom, there's a SO8 part just above the '330'  (33µH) inductor
- d) Top right, there's another regulator/charger near the '2R2' (2,2µH)  inductor

Identify each part, find their datasheets and check their output voltage.

[timeandfrequency]

I don't see a regulator near the 2R2.

Indeed, it is not a regulator, it is actually a battery charger. Before knowing the chip's reference, guessing its' true functionality is only approximative.
Top right there's the USB connector.
Below, the 2R2 inductor
The square chip is a battery charger device : IP2326 for a 2S Li-ion battery configuration.

the SO8 near the 330uH is a an isolated DC/DC xl sem1 xl6007e1 converter.

Interesting to notice that there's an isolated DC/DC : this would mean that there are multiple GNDs on the board.
On the datasheet of the  xl sem1 xl6007e1, I only see application schematics where primary and secondary side have a common ground : there's no isolation. Even when a flyback transfomer is used in the 'SEPIC + inverting' mode. However, the circuit around the L1C winding in figure 7 could be modified to gain a truly isolated output.

Could you figure out that the way the xl6007e1 is used in the 'NI-210SC' TE provides an isolated secondary side ?

[Veketti]

Finally got my NI-210G V-I Curve tracker. Few questions raised.
1. with 4V and leads shorted the line is not perfectly vertical. Eg. compared to the 0.6V which is perfectly vertical. Other voltages are also straight vertical. Maybe this doesn't matter too much (please see first two pictures)?
2. Measured transistors from defective BT speaker. One of the transistors gave bit weird trace like two different lines. Is this definition of faulty transistor or maybe something else (see the last picture)?

Thank you

[timeandfrequency]

Hello Veketti,

1. with 4V and leads shorted the line is not perfectly vertical.
A not vertical trace means resistance : so for the range thats shows this behaviour, the probe/test leads resistance is not well compensated. Maybe there's a trimmer resistor inside thats needs some fiddling...

2. One of the transistors gave bit weird trace like two different line
Separated traces often means capacitante or TE output circuit is oscillating.
Not realy relevant to declare the transitior as defective : it depends also on the junction your are actually measuring...
What surprises me more is that the dual trace part is one division below the zero line, which means 'constant current' : and that's weird. Don't know if this is an artefact from the TE or if it has to do with the instrumented transistor. In the latter case, this could provide a slight evidence of defect.

[Veketti]

Ah, indeed capacitance. There was capacitor on that particular transistor base which showed those separated lines.

Should the scope be in AC or DC coupling when using this? With AC coupling it drops one division below zero line.


Edit: More info added
No trimpots on the pcb to adjust the 4V compensation. However I noticed under microscope that the legs of the 16 pin IC on the bottom right side of the presumably MCU were badly soldered, so I resoldered them and tested it and the 4V looks pretty darn good to me now.

[timeandfrequency]

Hello Veketti,

So it was just an artefact that came from the setting of the oscilloscope 
I would suggest you always select DC coupling.
Because what I saw (in AC mode) was a constant negative current (while the voltage was varying) : only constant current diodes show up such a particular behaviour. 

No trimpots on the pcb to adjust the 4V compensation. However I noticed under microscope that the legs of the 16 pin IC on the bottom right side of the presumably MCU were badly soldered, so I resoldered them and tested it and the 4V looks pretty darn good to me now.

Wow ! Kudos, you just fixed it , because the slanted trace meant the TE was defective on delivery .

[Veketti]

If I may continue little still, now that I've been playing around with it more. It seems that with the highest frequency 2kHz there is line separation even when the leads are disconnected. Does it mean that there are internal capacitance and whether it's normal to behave like this (see attached picture)? Would this be caused by bad design, inferior/bad components or something else?
In which case you'd need this high frequency that lower frequencies wouldn't work?

Too bad that the scope don't support ref when in XY mode. Is it normal for DSO's not supporting Ref in XY mode? Would be awesome on pcb to probe known good component and then press ref to get the waveform on display and then probe all similar components to see whether they match. Well there's the A/B function in curve tracer, but it's bit cumbersome as you run out of hands. 

[timeandfrequency]

Hello Veketti,

If I may continue little still, now that I've been playing around with it more. It seems that with the highest frequency 2kHz there is line separation even when the leads are disconnected. Does it mean that there are internal capacitance and whether it's normal to behave like this (see attached picture)? Would this be caused by bad design, inferior/bad components or something else?
In which case you'd need this high frequency that lower frequencies wouldn't work?

That's common on V/I trackers: at higher frequencies, the internal stray capacitances separate the trace. This is not to be considered as an issue.
Higher frequencies are mainly used to test capacitors and inductances that display an elliptic trace.
For these parts the possible values span over 9 to 12 orders of magnitude.
So in order to see a nice ellipse (and not a flat one), you need to select an adequate frequency.

Too bad that the scope don't support ref when in XY mode. Is it normal for DSO's not supporting Ref in XY mode? Would be awesome on pcb to probe known good component and then press ref to get the waveform on display and then probe all similar components to see whether they match. Well there's the A/B function in curve tracer, but it's bit cumbersome as you run out of hands. 

It probably depends on the scope model, but I guess that the reference trace feature is not that common when using XY mode.
On V/I trackers, the A/B function is dedicated to parts comparison.
If you're short on hands^^, upgrade the provided probe set with some Kleps or miniature crocodile clips.

[ME]

why is the scan so poor the result is tiny and unusable?.

[Veketti]

why is the scan so poor the result is tiny and unusable?.

You mean bad resolution? Well Siglent SDS800X HD -series don't really shine when it comes to XY mode. Or in other words, should I say that any analog scope beats DSO's in XY mode 
This is partly the reason why I resurrected old Tek CRT scope..

edit: Only disadvantage is taking a screenshot is bit more hmm old school. 

[ME]

Just be aware, I brought one of those with the 24v wall wart, It sends dc only to the dut not like a tracker,it means having to reverse the probes, I got the one with the perspex cover cheap option.

[Veketti]

Interesting. Mine was supplied with 5VDC 4A wall wart. So it must step up the voltage. It would have been easier to step-down the voltage, so I wonder why it was designed to be supplied with 5V instead of 24V?

[timeandfrequency]

Or in other words, should I say that any analog scope beats DSO's in XY mode 

That's exactely what I said earlier in this thread to @Smokey.
But, I got no answer to my last question

Just be aware, I brought one of those with the 24v wall wart, It sends dc only to the dut not like a tracker,it means having to reverse the probes, I got the one with the perspex cover cheap option.

Seriously ?
@Veketti 's unit has only one voltage range, which is pretty dispointing and the version you bought only outputs DC ?
What a scam !

When I look at @Veketti 's last (analog) screenshot on the TEK 2445, I'm quite sure that the output is AC.

Interesting. Mine was supplied with 5VDC 4A wall wart. So it must step up the voltage. It would have been easier to step-down the voltage, so I wonder why it was designed to be supplied with 5V instead of 24V?

Probably that 5V wall warts are easier to procure and cheaper, beacause it's the USB standard voltage.

[Smokey]

Or in other words, should I say that any analog scope beats DSO's in XY mode 

That's exactely what I said earlier in this thread to @Smokey.
..

sure.. a crt can display real time persistence in a way that an LCD can't (natively), which is why you digitize everything at a high bandwidth and then take your time and display it on whatever method/medium you want.  Hell, a high resolution digitizer using an etch-a-sketch as a display could be better than a CRT these days.
(sorry, I had to reply.. I think that's the first time anyone has @ mentioned me and I got a notification)

[Veketti]

...
@Veketti 's unit has only one voltage range, which is pretty dispointing and the version you bought only outputs DC ?
What a scam !

When I look at @Veketti 's last (analog) screenshot on the TEK 2445, I'm quite sure that the output is AC.
...

I think you confused to member Rapo's display unit which has only one voltage range? Mine has 0.6V, 4V, 8V and 16V

edit: Attached the no load curves of all the voltage ranges at 400Hz. 0.6V seem to be all over the place. Scope can't trigger to it for some reason, but at least on this freezed frame the frequency matches. I removed the ground lead from the scope probe to minimize interference. I don't know what's going on.

[RAPo]

Well, mine is really kaputt. I don't buy a new one have the old Hameg component tester and a real curver tracer that must be enough.
But when mine was working, it was a solid 4V.

I think you confused to member Rapo's display unit which has only one voltage range? Mine has 0.6V, 4V, 8V and 16V

edit: Attached the no load curves of all the voltage ranges at 400Hz. 0.6V seem to be all over the place. Scope can't trigger to it for some reason, but at least on this freezed frame the frequency matches. I removed the ground lead from the scope probe to minimize interference. I don't know what's going on.

[Veketti]

Does anyone know why some (ceramic) capacitors measured in circuit show dead short, but when measured by multimeter they're not short but instead have few hundred ohms of resistance? I quess this doesn't necessarily mean they're bad? Some same value capacitors does show as circle like capacitor should.

[Grandchuck]

A shunt path is the likely reason.