Recent Posts

1

Test Equipment / Re: TinySA Ultra launched

« Last post by shapirus on Today at 03:16:09 pm »

More like a cosmetic issue, having all those random waveforms displayed between steps, especially since it's not the primary function of this device.

It would be nice if it could be fixed without compromising other functionality, but otherwise no big deal.

2

Beginners / Re: LC filtering for combined Vref/VDD of ADC

« Last post by temperance on Today at 03:14:55 pm »

Bonus: LDO at least gives [the chance for a] more accurate supply/ref, potentially reducing calibration error.

My posts suggests the use of a shunt reference instead of an LDO which is a better option if power loss is not an issue. It doesn't suffer from reduced PSSR when operating close to Vin like the LDO.

3

Computers / Format a 256GB pendrive with FAT32 using a windows 10 pc

« Last post by Karel on Today at 03:14:27 pm »

A friend bought a new usb pendrive with a capacity of 256GB.
It worked fine with his windows 10 pc but his DVB-T decoder with usb slot (used to record tv-programs)
did not recognize the pendrive.
Apparently the decoder accepts only pendrives formatted with FAT32 but our pendrive was formatted with exFAT,
so we used windows 10 to format the pendrive with FAT32.

Then we discovered that windows refuses to format a pendrive with FAT32 when the volume is more than 32GB 

I took his pendrive home and used my Linux machine to format the pendrive with FAT32. Problem solved.

Morale:

Linux is a system of possibilities.
Windows is a system of limitations.

4

Repair / Help needed identifying a Zener/TVS Diode (Toyota ECU)

« Last post by Signal Simon on Today at 03:11:18 pm »

I'm attempting to repair a Toyota engine ECU that it seems has had an over-voltage event, possibly failed alternator or loose battery terminal.
I have found two failed diodes, D401 and D402 (Shorted) marked "1E 8D" which just seem like series diodes from the main power supplies, so have fitted 1N4002s in their place.
However my mystery is D404.
From the screen print, it's a Zener and is directly across the internal supply.
One of its circuit tracks has blown open, so there was obviously more than just a bit of a transient.

The diode is marked: T S5225 8.C

The T I'm assuming signifies Toshiba.
It's in a substantial case 10mm diameter and 4mm thick, similar to a Motorola MR751 series.
Can't find any reference online, it obviously isn't a 1N5225

Logic says the Zener(TVS?) voltage should be in the region of 18 to 24Volts

Any help appreciated

Thanks,
Simon.

5

Test Equipment / Re: Siglent SSA 3021X... Ooops

« Last post by Joel_l on Today at 03:10:33 pm »

Something very strange happened.

It occurred to me that I do have a better way to check the input impedance of my SA, I can use my antenna analyzer ( at least for a limited range ).

I hooked it up and did a sweep around 20MHz, it showed me an SWR off the scale. I wanted to see what the impedance looked like so I switched it to do a Smith chart. When I did the sweep, the SA barked at me with an overload. I went and changed the attenuation did a few more sweeps and things looked good. Went back to do a SWR sweep and it looked good 1.2:1.

I disconnected the antenna analyzer and hooked my TX back up and it worked just fine, no more high SWR warning.

I need to look at this more and make sure I'm not chasing bad data.

6

Repair / Re: Precision Standards AC-DC Differential Voltmeter 360A - manual

« Last post by calin on Today at 03:09:26 pm »

Does look like working / turning on somewhat without releasing any magic smoke. But that's about it, the dial indicator just sticks to the max when I try to measure anything  and that is it.
I am a tad weary sticking my fingers too much in, when this thing is running, as it does produces internally some high tensions especially on the higher ranges.
At worst I can gather some really nice precision resistors from the innards and end up with a nice project box if nothing better comes out of it

7

Test Equipment / Re: TinySA Ultra launched

« Last post by KungFuJosh on Today at 03:08:48 pm »

For me, just curiosity.

8

Beginners / Re: Convert US standard 115V to International 230V

« Last post by Zero999 on Today at 03:08:05 pm »

If the circuitry after the capacitor has no problem with the voltage dips between refreshes from 120 V 60 Hz supply, there will be plenty of headroom for the slightly deeper dips when the supply is 230V 50Hz.

That's too bad if the capacitor and switching regulator are only rated to 200v.

9

Repair / Wimius P20 projector won't turn on

« Last post by veskom on Today at 03:07:35 pm »

Hi,
I have Wimius P20 projector given to me by friend that would not turn on. I have verified all the fuses, and voltages, and verified that 5V and 14V are going to the main board. But indicator LED is not coming on.
I have visually inspected the board and nothing suspicious cis coming out. There was some whitish deposits on the HDMI connections on the board, but after cleaning with IPA all cleaned up, and there are no signs of damage.
I have watched many repair videos on YT and kind of understand troubleshooting process, but for one, there is almost none for this Wimius P20, nor any documentation on the board or any service manuals.
I do not have thermal camera, but tried to use touch method, and only one section is getting hot, not right away, but after a minute or two, it starts feeling hot, it is Inductor labeled 4R7 (also labeled L4 on the board) and not sure what it is, but most likely some voltage regulator, labeled i206 (or 1206 with dot on top of the one and underline under 0), also labeled U102 on the board.. It is SMD component in SOT-23 with 5 pins (picture attached).
I have measured voltages... and output voltage is 0.7 volts, same voltage that goes to the controller board where "Power ON" button is and indicator LED (which does not turn on).
As You can see from the picture, there are 2 same SMD components on the board, and same Inductors, but the other oned does not get hot. And output voltage on that regulator is 1.2 V. Both have input of 5V.

If you can help me identify this component, and maybe I can make sense of the measurements, and help me find the short (which I believe it is), and point me to the right direction.

P.S. My brother was into electronics, and he was great help to me, but he recently passed, and I have no where to turn for help on this mater. And you can ask your brother stupidest questions without being judged, so sorry if I misuse this forum.

Thanks,

Vesko

10

Test Equipment / Re: TinySA Ultra launched

« Last post by erikka on Today at 03:03:47 pm »

PLL's locking after the step
I do not mute the output as this would slow down the maximum sweep speed and created larger gaps which you will hear as stronger clicks.
Any stepwise sweep will always have some form of artifacts

Can you explain why these may be a problem?
Or is this just curiosity because of what you saw on the DSO?