I imagine that you're getting a big enough voltage drop due to the bulb limiters/meter current shunt to stop the supply working properly, try measuring the voltage on the mains side when you turn the powersupply on and see if it drops. also; it's worth noting that using NOS transistors etc isn't always a good idea due to the tin whisker phenomena that plagues these devices so it's best to try and find equivalent new transistors. positive ground was very common back in that era, I still have flashbacks to when I was a kid, taking the back off a TV and getting a giant shock from the metal chassis. great video

Thanks for making these outstanding videos - this channel is under-appreciated.

I remember when I was in the college, I was baffled by the lab instruction manual in my electronics class. It always start with "1. Turn ON the power". I was thinking to my self, isn't it clear that we need to turn it on to be able to see the result? It wasn't till my mate troubleshot for hours looking for an answer as to why his reading was incorrect. When the tutor finally came to help, he immediately noticed that one part of circuits has its power in OFF position.

The rotary switch on the front is most likely a decimal point selector, often seen on 70's desktop calculators from the Eastern and Western Bloc. "B" would be the floating point mode, while the other settings would fix the decimal point at that position on the screen (e.g. the "5" setting would leave 5 digits after the decimal point).

Absolutely amazing ! Great video, great editing and production. Beautiful content

There is certainly a beauty to these devices. Such a fascinating period of technology, the aesthetic of the time and environment is so identifiable. Awesome channel!

This calculator looks a lot like the first electronic calculator I ever saw. I was amazed by the sight of it in operation.

Loving the channel and the videos you're putting out! The Soviet electronics might be a bit crude but thats what makes them fascinating & beautiful!

Your shopping trip for transistors looks very similar to the Shurick's one from "Ivan Vasylsyevich" movie 😀

Thoroughly enjoyed your video, thank you. I really appreciate the time you take to walk us through your troubleshooting along with your honesty and curiosity. I build my own analogue synthesizer modules and I learned how to create a dual power supply. When I saw you puzzled about the +ve leg of the capacitor on the ground I wished I could tell you that it was a because you'd found the actual ground between the +ve and -ve supplies. Most likely it's a full wave rectifier and the transformer secondary will have a centre tap, which becomes the relative ground. I'm inspired by your efforts and perseverance with this project and hope you manage to revisit it to complete the repair. For sure there's bound to be plenty of complex work ahead, but I hope not too much!

Wow and you’re also Russian-Eng bilingual, dang. Proper genius

That's a great piece of history! I like how you show the process and don't skip the ups and downs. And that market is awesome! :) A few observations from my own learning curve: Positive ground and negative voltages aren't uncommon in old devices. It rather appears they were the standard into the 1980s. If you encounter metal can transistors like the TO-3 package you showed it is safe to assume that none of the contacts should be grounded (to chassis). The insulating layer you showed most likely is some form of mica and ensures that the case, probably the collector, doesn't touch the metal of the case while allowing for heat transfer. Depending on the current it has to carry it may be required to add heat transfer paste between the layers without shorting the contacts. Voltages: Whenever tubes are involved voltages are going to be high. I think I've seen +110V and -110V here. They can even go beyond that in other devices. Protection against accidental contact hasn't been a thing back then. It was just assumed that service people were aware of it and prepared accordingly. Thus anything metal may have voltage on it. And that's also why I decided to get myself an isolation transformer. Probably saved me from a surprise a couple times. Mains input: This one has a decent transformer on the input side that separates the rest of the circuit from mains. It is a good idea to also check winding resistance before powering up an unknown device. If the meter shows open circuit ("O.L."): The winding may be broken or disconnected. If it shows below, say 100 Ohms: There may be a short in the winding. YMMV, though. The resistance depends on design, expected currents, and core material used for the transforner. Over time you can gather experience for reasonable values.

Great work, Thomas! Waiting for part II :)

Those pink cables and circuit boards looks delicious!

These videos are so incredibly satisfying to watch

Amazing work ! I hope to see more like this in the future !

Спасибо, что сохранятете историю электроники! У меня на канале есть Iskra-124, программируемый инженерный калькулятор в таком же корпусе, как и Iskra-121. Возможно, будет Вам интересно взглянуть :)

I'm a huge fan of this kind of stuff❤❤❤, you are a born genius.. God job... Doing awesome sir

Your broken transitory isolation sheet was probably made not from silicon but mica.

Who could resist Nixietubes or VFD's ??? Outstanding videos !

This power supply uses a "hard start" oscillator which won't start if you gradually increase the voltage. Your dim bulbs are preventing it from starting oscillating.

loved the video

That metal enclosure in the power supply is supposed to contain a line filter. They contained a capacitor (two in some models) which are known to short out eventually, causing damage upstream. One 'standard' procedure on any of these if the filter is there, is to simply remove those capacitors as a preventative measure as I was advised to by Sergei Frolov who runs the Soviet Digital Electronics Museum. I've never seen one completely missing before so it was probably ruined in this way. The dial is decimal point precision, the A1/2 buttons are memory registers. Did you get this running in the end? It can be quite a challenge to repair them - I own multiple and swap parts to at least isolate which boards have a problem. Currently 3 are fully working, one has a calculation fault but the specific bad PCB is identified, and one is a very old variant with delay-line memory, I have no idea where to start on it!

Just discovered your channel thanks to your robot video but I loved this so much. Is there any update, thank you for your incredible content

Great video, nice editing! I had non-electrolytic capacitors, film or mylar presumably, that failed and give a short. It could be a problem in case of DC-blocking capacitor for the nixies high voltage. Looking forward the next part, it is a nice piece of hardware.

the raised 5 is either the equivalent of the raised bump found on modern keyboards on the d k and 5 or F J and 5 for alignment reference. or it is where a repair has been made crudely using the wrong switch. the tray may be a junction box. all the wires terminate there the eevblog is the eevblog dave jones videos he i guess has his own store. most other youtubers get their name from some other product that they use similarly how mrs doubtfire gets her/his name from the news article "police doubt fire is suspicious" the reason that a + would be on a ground trace is because many devices have negative voltages too for things like op amps and audio amplifiers that are full wave. a good multimeter would have much better protection against mistakes like applying voltage in the wrong modes. cheap meters you may fry resistors and cause damage. the dim bulbs are to limit the current so if you have a fault you dont blow up the device testing it. if you have a shorted winding in a transformer or a bad capacitor or rectifier the bulbs will light up and hopefully you dont smoke the transformer. the power supply requires more than 200 watts or what ever the vale of the 2 bulbs are in order to work.

part 2 please 😊

A calculator the size of a breifcase, wow

You should have to say - to ИН дефис четырнадцать 😂

Интересный монстр)) у меня где-то пару штук поменьше есть. Давно хотел их подключить, да всё руки не доходят... Как поживает 23я электроника?))

People throwing bigger fuses in stuff are the biggest problem.

Alert! Deoxit Red 5 is NOT the original formulation that one can leave on connectors or pots.!!!! They changed the chemistry awhile back!!!! Red NOW, if left on, the new formula WILL continue to interact with metals, actually damaging/corroding their surfaces. As the 'new' company guy told me, they just 'decided' to change it, and 'said' they let everyone know. They did a poor job of it. For your application, I recommend their BLUE Shield Sn5. Yes, they say it's just a shield.. but it works closest to what the old RED used to. Deoxit RED has, since the 'change' to their formula, been responsible for myriad destruction of new and vintage electronics. Hope this helps. Edit: After erroneously leaving the 'new' RED in a bank of switches one time, I discovered that they were slowly being corroded by it, and additionally, that the still-present residue became slightly conductive! Had also restored a vintage HP frequency counter, using RED to clean all of the momentary push switches. Within 30 days, all of those switches had been destroyed. Gasp. That's when I reached out to CAIG, and was told I was now using their RED spray incorrectly, ahem. It is apparently designed to be used to clean, then rinsed out asap, followed by their Blue.. or something like that.

Did you get this working in the end, a follow up would be good.

Thats soooo funny to watch. A Newb is doing electronics

wheres the next video? did you leave us hanging really?

Cliffhanger!

Come on, where's the part 2?

+ capacitor to ground could be a biasing circuit

😮😁👍

4:12 arent u by any chance czech? This type of plug is from france, buts widely used in czech republic

Did you ever get this calculator working?

СОВЕТСКИЕ ТРАНЗИСТОРЫ МЕРИТЬ МУЛЬТИМЕТРОМ ЕСР КИТАИ ВРИОТ ИНОГДА~~~~~~~~

Can someone send me device with nixies as gift as well? :)

Are you sure it is Soviet? Isn't it Slovenian?

1977, surely 45 years not 35?

50 Hertz? Are you in Russia?

rc filters inductor values are not critical

Woketronics ...