Recent Posts

51

Repair / Re: FIX - Parkside Cordless Soldering Station 20V PLSA 20 Li B2

« Last post by Kurets on Today at 01:28:05 am »

The temperature sensor in the iron is an RTD at least. I tested it by heating it with another soldering iron and it behaves as expected. I modified mine with 33R extra and got 370C when the LED goes green.

Now I think that in practice it would be nicer to replace the whole circuit. I suspect that the brushless motor controller they are using is only "just" managing to control the temperature and any unexpected behaviours causes it to freak out.

i attempted adding 15R and for some reason this increased the temperature. Similarly, changing  the 499R surface mount resistors to different values also upsets the circuit.

52

EEVblog Specific / Re: EEVblog 1634 - 15kWh AERL LFP Home Storage Battery Install!

« Last post by Brumby on Today at 01:27:03 am »

I see a gap.   

53

Repair / Re: miller dynasty what is precharge relay

« Last post by floobydust on Today at 01:23:28 am »

There's no PCB pics or repair info, but which model #?
I would guess it's an inrush limiting relay for the DC bus capacitors, so they get a pre-charge. Some soft-start circuits are dumb - a timer or voltage sense, others "smart" using MCU control.
The pre-charge resistors will cook and burn if they see mains for more than a few seconds. It might use a NTC or PTC (bank) as well.

When it switches in full mains it might reboot if there is a short? It is drawing high current from mains when the relay clicks in?
Worst case you might have a bagged IGBT preventing the bus voltage from coming up. Take it apart and a pic will tell how they did it (pre-charge).

54

Beginners / Re: Electronic welding machine in short circuit

« Last post by DisasterNow on Today at 01:23:21 am »

I preferred not to unsolder the hybrid board, in addition to the normal soldering on the back side, all the pins had the soldering cone also on the board side, and being in the part that faces the voltage regulator heatsink, it was impossible to work. I then unsoldered both the TDA1060 (which came off immediately), and also the LM324 (more difficult, it was completely drowned in the protective lacquer that prevented the heat). No damage to the pads, let's say that I then cleaned lightly with the braid but not much, and scraped the pads from the lacquer. I protected the other areas, but I see that in the lower part of the small chip there was a lot of lacquer that has taken on a brown color, but I don't think it's a problem.
I only have lead solder wire at home, I would try with that maybe.

Looking at the photo I have a doubt (the board is in the lab and I'll see it tomorrow): has the base of the small electrolytic SMD capacitor melted?
But I don't think so, I was at 370°, but it was all covered by a protective aluminum layer.

55

Buy/Sell/Wanted / Re: F/S Lecroy, Tektronix, Advantest, R&S, Bruel&Kjaer. Huge price drop!

« Last post by smaultre on Today at 01:09:45 am »

Some new old equip arrives!

56

RF, Microwave, Ham Radio / Re: Mini-Circuits KARN-50-18+ as the Reference Termination for a VSWR-Bridge

« Last post by joeqsmith on Today at 01:08:32 am »

Hello all,

I contacted Mini-Circuits sales and asked them about the DC resistances of KARN-50-18+  terminations. Here is their response:

"Our KARN-50-18+ and BTRM-50+ terminations designed to use for commercial – testing application, they are cost effective options, and they are not precise terminations. Due to internally built structure for KARN-50-18+, as this contains more resistors due to higher power handling, so more variations occur."

Were you expecting something else? Keysight has a similar note for some of their terminators, for example:

The model 11593A is not intended to be used as a precise termination.

After that I asked them to suggest me a suitable precise termination from their portfolio. Again, here is their response:

"Unfortunately, we do not have any precise terminations available in our standard catalogue."

By the way, does someone can provide me description or specification for the "Precision RF Connectors and Terminations"?  Are these specifications for mechanical or electrical or deployment characteristics of RF connectors/terminations?

Thanks, Tim

I'm sure it came as no surprise that Mini-circuits does not produce standards.  If you want some data for actual standard, the best thing would be for you to look up something that meets your requirements (something I am still not sure of).   

***
If your looking for something low cost:
https://www.ebay.com/itm/266817014023

LOAD
DC-resistance: 50 Ω ± 0.5 Ω
Return loss, min.: 42 dB @ DC to 6 GHz
Power rating, max.: 0.5 W

57

Beginners / Re: I need help creating a toggle with a type D flip flop.

« Last post by MarkS on Today at 01:05:51 am »

Compare the 74HC74 datasheet's function table (page 11 of your link: Table 8-1) with that of the CMOS 4013 (page 10: Table 1).  The 4013 matches your observed Logisism D flipflop behaviour because it has active high Set and Clear inputs.  TTL D flipflops historically had active low Set and Clear therefore the 74HC74 has also (for 7474 functional compatibility), so unless Logisism has a specific 'x74 type D flipflop model, which would have active low Set and Clear inputs,  you will need to add inverters in front of its generic D type's S and R inputs (for simulation only).

Thank you! That was it. They do have a x74 chip and that worked.

58

Test Equipment / Cami Research CableEye M3U Cable Tester Unboxing and Tests.

« Last post by KG7AMV on Today at 01:00:00 am »

I Got an Older Cami Research Cable M2 Cable Tester in July.. Thing was so Cool I ended up getting an CableEye M3U Really Want the M4. As a Bonus the V5.3 software works with the Serial M2.



Here is the Unboxing and Initial Tests... Teardown will be Soon.

59

Buy/Sell/Wanted / Free: Datalab DL905 Transient Recorder (AU)

« Last post by Chris Jones on Today at 12:52:39 am »

On offer is a Datalab DL905 Transient Recorder. Basically it turns an analogue oscilloscope into a very low performance DSO. I'm attaching a description of it from 1972 when it was released. This one did work last time I tried to use it, but that was probably 30 years ago. Any modern DSO, even a pocket one from aliexpress, would outperform it, so it is probably only of interest for historical or parts value.

It is heavy, so ideally you would pick it up in Canberra, Australia. Otherwise you would have to figure out how to get it to you and pay any costs.

Here is one in a museum:
https://collection.sciencemuseumgroup.org.uk/objects/co423984/datalab-transient-recorder-transient-recorder

Chris

60

Test Equipment / Re: CAMI Research Model M3U Research

« Last post by KG7AMV on Today at 12:44:50 am »

If you own a CAMI CableEye call them rep will have you e-mail them with the serial # and proof you bought it they will transfer ownership. Allow you to download the software but only the version the unit shipped with or last upgrade that was paid for i got mixed answers. MY Serial M2 came with V4.3 my M3U is V5.3 but the M2 works with the V5.2 Software.