Recent Posts

1

General Technical Chat / Re: Boeing Starliner upcoming launch, first w/crew

« Last post by Neilm on Today at 07:01:58 pm »

Scrubbed.

O2 valve not working well on 2nd stage.

For those that don't follow spaceflight that closely - that is an issue with the Atlas rocket not the Starliner

2

Beginners / Re: SP3T slide switch schematic, how to know the pins?

« Last post by Rick Law on Today at 07:01:56 pm »

You can tell on page 4 of the datasheet, upper right corner (top diagram) is the schematic diagram of the switch.  It shows which pin is connect to which other pin based on switch position.  The center pin (shown in dark bar) is the "source" and the other three are the target depending on switch position.

3

Other Equipment & Products / Re: CFW for KSGER/Quicko STM32 Soldering Stations

« Last post by oleg401169 on Today at 07:01:37 pm »

Hello, David! I am assembling a soldering station based on the ksger 3.1 topology with your firmware for an lcd display and am confused with connecting the display (I am attaching a diagram of the station and pinout of the display). The display is working - it worked perfectly on the Quicko station with an lcd display, but it used the cs pin, and in it is not used in this circuit. Thanks!

4

Metrology / Re: Is anyone into quantum technologies and quantum metrology?

« Last post by zrq on Today at 06:59:48 pm »

I think VCSELs are prevalent for the lowest end 850nm transceivers, and most O-band and C-band high-end devices are usually InP quantum well lasers, still quantum but not dots. QD lasers are mostly still in R&D.

5

Repair / Fluke 87-1 Constant beeping, stuck in V AC and no measurement possible

« Last post by Wildsau96 on Today at 06:58:44 pm »

Hi everyone,

i got a problem with my Fluke 87-1. When i turn it on, it just beeps and the meter is stuck on V AC. No matter what i select on the rotary switch. In the mA/A position the meter crashes. And there are no measurements possible.

At first i suspected the rotary switch. I cleaned it and the whole board with IPA. The ptf section seems to be in good condition (I attached some pictures of the board). There are no shorts in the banana jacks.
I also inspected the board for damaged traces or components. I couldn‘t find anything.
It fails the rotary switch test (0000 in every position and crashes at the mA/A positions) (The switch shaft is not reversed).

So i dug deeper into the whole thing. Modemheads guide on his blog already helped me understand the workings behind the mode selecting.
All my values for the power supply section of it are correct, except for AP6 (U4P87). When the meter is turned on, it reads -2.8 V.

P03 (U4P66) starts at 0V in the OFF and V AC position and then goes down to -2.8 V (AP6) in about -0.45 V increments with every switch position. Between the switch positions it blips down to -4.4 V (Vbt- is -5.35 V).
May that be a indicator of the problem?

I really hope U4 is not cooked, because otherwise the meter is in good condition.

I also checked various other aspects of it:
- The varistors RV1 and RV2 both measure OL.
- The fusible resistor R1 measures 1.011 kOhm
- The thermistor RT1 measures 1.469 kOhm
- The spark gap E1 measures OL
- The bridge rectifier U1 shows good results in a diode test
- The fuses F1 and F2 are still good
- The input impedance measures OL in the V AC position and 11.10 MOhm in the V DC position with a battery installed. Without a battery installed it measures about 22 MOhm in V DC
- The meter draws 9.3 μA from the battery, when the rotary switch is in the OFF position and 1.2 mA in the ON position
- I resoldered some pads that looked suspicious

6

Repair / Re: Foaming electronics-safe spray cleaner

« Last post by feedback.loop on Today at 06:58:20 pm »

There is something by 3M:
https://www.3m.com/3M/en_US/p/d/cbgbjw471223/

7

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by nctnico on Today at 06:55:09 pm »

<offtopic rant mode on>
Back in the old days I spend quite some effort and money to get really high quality CRT monitors which had a super sharp image. The likes of 21" Eizo models with active deflection to get the image sharp right into the corners and LG Flatron have been on my desk. And ofcourse high quality VGA cables with seperate BNCs for each color. Blessed was the day I got a TFT monitor. Such a nice sharp picture. But then UI graphics designers came in and decided text should be unsharp again like on the worst CRT monitors. FFS! 

8

General Technical Chat / Re: Silicone vs. PVC measuring leads

« Last post by Gyro on Today at 06:53:45 pm »

Note that only the Concordia ones are double insulated / damage evident. This will be important for some applications.

9

General Technical Chat / Re: Silicone vs. PVC measuring leads

« Last post by shabaz on Today at 06:46:56 pm »

What is its actual cross-section? Because the specs cannot be correct: they say it’s 24AWG (which is 0.22mm2) but they also specify it as 0.5mm2. Both cannot be true.

Hi! The 24AWG is incorrect (I compared it to 24 AWG enamelled copper wire, and the ECW is much thinner), it's 0.5 mm^2. Unfortunately CPC has no stock of the red wire of that type currently, only black wire.
While I was at it, I took a photo of various wires, attached below. The TPE wire (third in the photo) has attracted a lot of dust that sticks to it : ( It might wipe off with a wet-wipe but I didn't try that. The RS wire (last in the lineup) had some dust that wiped right off, it's very smooth and non-sticky.

10

Test Equipment / NOS Pomona Cables, gassing+split plastic how to clean?

« Last post by Vertamps on Today at 06:44:16 pm »

Hello, bought these two vintage shielded Pomona cables(model 1167-60).
 There probably from the early 80's im guessing, Well i got an extra discount as each cable has a connector end that is split. Just gonna plastic epoxy them.
The cables are gassing and SMELL, and leave the smell on my hands.

*Will Soaking in isopropyl alcohol damage the cables further and cause more gassing?
-Cleaning a few times with dish soap and water seems safe option.
 
Alternative @$55 brand new from digikey, with the extra discount from the seller i figured i could save the cables and be happy.
/*edit,  a quick google mentions baking soda scrub, ill try that on one cable and dish soap on the second cable then compare.*/