EEVblog #1313 - Bad Luck Mailbag

[EEVblog]

Double 13 is worse than normal 13, obviously. More mailbag.



SPOILERS:
Back in the old lab!
Vintage Soviet PC.
10:42 3G modem with a funky antenna.
13:52 IOMEGA ZIP drive teardown
18:56 USB to RS485 interface
http://olegkutkov.me/
19:52 Another Byte magazine cover!
http://bytecovers.com/
21:41 Smoke alarm sensor teardowns
26:58 Reverse engineering a Cooler Master PSU
34:45 $1 ebay power adapter teardown gets Widlarized!
38:39 Stonetech smart integrated LCD module
https://www.stoneitech.com/

[DrG]

A fun video.

The computer board seems to have the German U880 Z-80 clone https://en.wikipedia.org/wiki/U880

Looks like the UB880D S1 hobbyist version (1989).

Not sure how it came to be, but according to the link it is described as an unlicensed clone and get this "Differences include not setting the CY flag for the OUTI command (when L goes zero)." ...that might catch a coder unawares 

[gjsmo]

@EEVblog Are you sure the Z80 computer took 3.3V on that power input? I ask because I didn't actually see a point in the copper, and I'm used to seeing +3V3 these days - but I'm totally aware that's a more modern convention with EDA software. Any chance it's actually 33V, for some very odd reason?

[nctnico]

I like the idea with the TV in the background. Can't help with the 72" TV though. 

[mwarren2]

Great idea with the large screen tv Dave! Here's my "lab", actually my HAM shack with a small work space. Radio stacks on the right and workspace in the center. You can see I'm no where as well equipped as you!! Lol Feel free to use it as one of your backdrops if this  idea comes to fruition.
Mike Warren
W6MEW
Pittsburg, CA, USA

[Rasz]

7:00 Mera was a Polish computer design/manufacturing company. They started with paper perforators, then calculators, later licensed terminal (this one) designs from Swedish company. They even tried their luck in microcomputers designing and manufacturing TRS-80 clone https://en.wikipedia.org/wiki/Mera-Elzab_Meritum. It failed miserably, had to compete with superior black market Spectrums, Ataris 800 and C64s and cheap Soviet Bloc Z81 clones. After fall of Iron Curtain Mera managed to stay afloat by restructuring and switching market segments to point of sale systems. They are still a local leader in this field to this day, something very rare in ex Soviet Bloc.

MERA CM 7209 (MERA 7953) is a terminal dedicated to Russian RIAD systems, direct unlicensed IBM System/360 clones.
https://prog.world/museum-dataart-inspection-of-the-mera-cm-7209-video-terminal/

documentation https://delibra.bg.polsl.pl/dlibra/show-content/publication/edition/13093?id=13093 'Dokumentacja techniczno-ruchowa MERA 7953N ; Monitor ekranowy MERA 7953N'

@EEVblog Are you sure the Z80 computer took 3.3V on that power input? I ask because I didn't actually see a point in the copper, and I'm used to seeing +3V3 these days - but I'm totally aware that's a more modern convention with EDA software. Any chance it's actually 33V, for some very odd reason?

"+ 32 V/1.6A - niestabilizowane, do zasilania bloku CRT"
CRT supply

8:00 Mostly Polish manufactured semiconductors on the PCB. Unitra CEMI UCY 74 series chips. MCY series were microprocessors. Unitra CEMI cloned Z80 as MCY7880, they even managed to clone Intel 8085 at one point, all behind Comecon (cold war) embargo. USSR didnt really like us having electronics industry. Poland was relegated to cheap labor and resources - coal and food was mostly exported east leaving the country hungry and poor. Meanwhile West Germany and Czechoslovakia got the industry and technology fields. Germany had VEB and Robotron to smuggle and clone western designs. Czechoslovakia had Skoda, Tatra, Tesla and other highly specialized manufacturers.

Edit: Ironically I went to technical trade school ran jointly with Unitra CEMI at around the same time it was sold to Siemens below fixed asset value. In my first year of school Siemens packed and send back to Germany all production lines, started demolishing manufacturing buildings and fired 6000 people. Its hard to remember Germany lost WW2 when you see what happens around you while growing up.



HMI display garbage software - and this is why everyone develops their own instead of using off the shelf.

[johnlsenchak]

Dave

You  should  put   two   TV  monitors   side my   side,  lift them up more and then  connect  them  to a   computer  with Windows  10 in   dual  monitor mode. This  would  give  you  stereo  view  behind  you

Stop  calling yourself    "dumb ass  Dave" you  are far  from being dumb   !

[thm_w]

Dave

You  should  put   two   TV  monitors   side my   side,  lift them up more and then  connect  them  to a   computer  with Windows  10 in   dual  monitor mode. This  would  give  you  stereo  view  behind  you

But then the bezel is in the middle.

[joeqsmith]

Nice idea to show peoples labs in the background.

[Nominal Animal]

Love it! 

Even the 55" one would work absolutely fine, if you lift it a bit higher, so that its top bezel was not visible.  Then, the image on it would look like a window to someones lab.

[EEVblog]

Even the 55" one would work absolutely fine, if you lift it a bit higher, so that its top bezel was not visible.  Then, the image on it would look like a window to someones lab.

No it won't work, you can't get me and the bench in the shot and have the frame filled with the TV, needs a 70", I have done the tests.
70" cheapie is on order, now I just have the figure out the best way to mount it.
As I asked on Twitter, thinking of a vertical sliding wall mount thing (there are advantages to being able to adjust the height), or just having it on a movable floor stand, might come in handy.

[Nominal Animal]

Even the 55" one would work absolutely fine, if you lift it a bit higher, so that its top bezel was not visible.  Then, the image on it would look like a window to someones lab.

No it won't work, you can't get me and the bench in the shot and have the frame filled with the TV, needs a 70", I have done the tests.

I know; I meant that if you just lifted the 55" higher, so that its top bezel would not be visible, it'd look enough like a "window".

The way it is in #1313, its top bezel is behind your head in the picture, and a bit distracting: like an oddly hanged picture behind you.

Try lifting it higher, and take a pic of yourself sitting, and you'll see what I mean.  The TV doesn't need to fill the entire frame; it is enough if its upper edge is not visible in the frame.  (Compare to a picture of yourself sitting on e.g. on your dinner table, and how a window behind you would be located in the frame.)

[EEVblog]

I know; I meant that if you just lifted the 55" higher, so that its top bezel would not be visible, it'd look enough like a "window".

I don't want a window, I want the entire background of the video frame.

[tarasv]

7:0 - board most likely is emulator for IBM 3270 compatible Soviet ES7920 mainframe terminal. Many emulators designs was produced in Soviet Union and Eastern Europe between late 80s and early 90s to replace obsolete terminals with all logic inside on SN74.
Soviet ICs on the board:
К155ЛЛ1 is SN7432, К555ЛЛ1 is SN74LS32 and К555ЛИ1 -    SN74LS08
КР580ВВ51 - i8251, КР580ВИ53 - i8253
КР537РУ10 - 2Kx8 bit SRAM, КР537РФ5 - 2Kx8 bit EPROM   

[VK3DRB]

The ATX standard requires -12V. I should say that settles it, but there is more to it... this voltage of -12V is used in PC's for RS-232 when the motherboard does not use a MAX232 with charge pump nor a Super I/O chip. Also the -12V was used for older PCI slots (not PIC-e) and some sound cards.

The power supply manufacturers have no idea what motherboard their power supply is going to be connected, hence it is often still there. But PCI is being phased out quickly, which is a pain if you are using NI DAQ cards that use PCI.

[Brumby]

.... IBM 3270 ....

You just threw me back 40 years!

[VK3DRB]

That cheapo charger... it looks like it has RCM approval. I suspect it is a approval. What was the creepage and clearance? How were the transformer windings coupled?

Not all electronic products made by non-joint venture companies in the "People's" Republic of China are crap. I bought a Chinese made Siglent SDS-1104X-E and I am delighted with it. Nope, it wasn't 91 cents with free shipping. The oscilloscope was almost 1000 times the cost purchased from Triotest in Sydney. Worth every cent.

The bottom line... you get what you pay for.