Retro triple time relay - VL-34UKHL4 - gallery from inside

p.kaczmarek2 735 2

TL;DR

A vintage triple time relay VL-34UKHL4 from the USSR is opened for an inside look at its construction and timing mechanism.
The unit uses three separate relays and two control boards, while the timing itself is mechanical and the counting is already solid-state.
The plate marking C67.102.280 and the counter module built on K176TM1 and K176NE5 ICs are the key identifiers inside.
Large electrolytic capacitors, a rectifier bridge, characteristic resistors, and fully tinned tracks show the oversized, durable Soviet-era hardware.
Disassembly stopped after the 2024 flood, so the operating principle and the role of the component near the potentiometer remain unresolved.

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Post #1
21878933 07 Apr 2026 10:39

Here’s a little curiosity for today. This piece of kit is completely outside my field of expertise and not from my era, but it might still be worth a look – an old triple timer dating back to the days of the USSR. The whole thing is built using semiconductors. Time to take a look inside.

On the front panel, we can set three separate relay switching times. Just below, there is a diagram showing the internal connections and indicating which terminal screw is the common contact, normally open and normally closed. Let’s take a look inside:

Inside, we can see three separate relays and two control boards. On one of them is a potentiometer protected by paint, presumably for tuning.

What surprises me most, however, is the size of the components. The relays there bear no resemblance to today’s compact solutions. Overall, there is also much more mass, and consequently more raw material.

Progress with dismantling and part number from the circuit board - C67.102.280:

Dismantling of the board, on which a rectifier bridge, a large electrolytic capacitor and characteristic resistors can be seen. Although the time setting itself is mechanical, the counting is already carried out by a semiconductor.

There is no label layer on the board, and all tracks are tin-plated for durability.

Removing the front panel and separating the mechanical components:

Removing the relays:

Removing the meter module:

It is implemented using the K176TM1 and K176NE5 integrated circuits. I am curious about the component next to the potentiometer – is that a resonator from that era?

I also wanted to check how the time is set, but the dismantling was interrupted due to the flood in 2024 and I did not complete the analysis, and the circuit board was lost. From what I remember, however, there were separate contacts for each pin, rather than a single resistive track.

I found a similar device on this website: https://dzen.ru/a/X70JlQtK-AFJrFkT

I had originally planned a more detailed presentation, including a schematic diagram, but the 2024 floods thwarted those plans and the equipment did not survive the clean-up.

Therefore, I would be grateful for any additional information if anyone is able to identify the correct operating principle and the roles of the components inside?

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#2 21879217 07 Apr 2026 18:20

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Post #2
21879217 07 Apr 2026 18:20

Nothin' but nuthin' but nuthin' design

MŁT resistors and relays without a case with the windings protected by a material soaked in some kind of impregnation.
Typical Soviet rectifier diodes and red transistors in a truncated case are also visible.

You may laugh but they used integrated circuits and the whole thing looks pretty good. Some of the KXXX circuits often had counterparts in foreign CD series digital circuits.
https://www.embeddedlinks.com/chipdir/soviet/cmos.htm
They used D flip-flops presumably as /2 dividers, while the K176NE5 was often used in timers such as loaders.

Did they use a quartz resonator? Possibly, as the K176NE5 could have worked with a watch resonator.
An RC generator would probably have been too unstable, it would also have been clever to use a 50Hz mains frequency but divisions matched to 32768 could have been more troublesome.
#3 21879619 08 Apr 2026 10:15

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Post #3
21879619 08 Apr 2026 10:15

p.kaczmarek2 wrote:

It is implemented using the K176TM1 and K176NE5 integrated circuits.

There is also the K176LE5, 4xNOR. The correct name for this chip with a generator in the Latin alphabet is K176IE5 rather than "K176NE5", which makes it easier to search for.

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Retro triple time relay - VL-34UKHL4 - gallery from inside

FAQ

TL;DR: This FAQ explains a 3-section Soviet VL-34UKHL4 relay for restorers and teardown readers. One expert sums it up as "nothing but design": three relays, two control boards, mechanical time setting, and solid-state counting built around K176 chips solve the main question of what is inside and how it likely works. [#21878933]

Why it matters: It turns a photo teardown into a reusable reference for identifying parts, timing logic, contact terminals, and restoration risks in vintage USSR relay timers.

Timing reference	Practical reading from the thread	Main trade-off
Quartz/watch resonator	Best fit for stable timing with K176NE5	More parts, but better accuracy
RC generator	Usable, but less stable	Drift makes timing worse
50 Hz mains	Clever and available	Division chain to 32768 becomes awkward

Key insight: The VL-34UKHL4 is not a purely mechanical timer. Its front end sets three delay channels mechanically, but the counting stage is already semiconductor-based and drives three separate output relays.

Quick Facts

The teardown shows 3 relays, 2 control boards, and 1 paint-sealed potentiometer, which strongly suggests a multi-channel timer with at least one calibration point. [#21878933]
The counter module uses 2 Soviet ICs: K176TM1 and K176NE5. The reply identifies K176TM1 as a D flip-flop used as a /2 divider in timer logic. [#21879217]
The front panel provides 3 separate switching times and includes a printed contact diagram for locating common, normally open, and normally closed terminals on the screw block. [#21878933]
The PCB has no silkscreen layer and its copper tracks are fully tinned, a construction choice explicitly noted for durability in this unit. [#21878933]
The timing-reference debate in the thread compares a watch resonator, an RC generator, and 50 Hz mains timing; the expert favors the resonator path as the more stable option. [#21879217]

How does the VL-34UKHL4 triple time relay work internally, and what does each of its three timing sections control?

It works as a 3-channel timer with separate output relays. The teardown shows 3 relays and 2 control boards, while the front panel lets you set 3 independent switching times. Each timing section appears to control one relay output, and the printed front diagram maps that relay to its screw terminals. The post also states that timekeeping is mechanical at the setting side, while the counting stage is already semiconductor-based. [#21878933]

What is the role of the component next to the potentiometer in the K176TM1 and K176NE5 counter module of the VL-34UKHL4?

The thread treats that part as the timing-reference component, with a watch resonator as the strongest match. The reply says K176NE5 could work with a watch resonator, while an RC generator would be too unstable and 50 Hz mains division would be awkward. That makes the part next to the potentiometer the most plausible source of the counter clock for the K176TM1 and K176NE5 module. [#21879217]

How is the switching time set in this Soviet triple time relay if the front mechanism uses separate contacts instead of a single resistive track?

The relay sets time through discrete contact selection, not through one continuous resistor path. The author recalls that the front mechanism used separate contacts for each lead, which means each knob position likely selects a defined electrical state for the timing circuit. That matches the device having 3 separately adjustable switching times rather than one analog timing control. [#21878933]

What do the front-panel contact markings on the VL-34UKHL4 mean, and how can I identify the common, normally open, and normally closed terminals?

They show the relay contact function for each screw terminal. The front panel includes an internal connection diagram that indicates which terminal is common, which is normally open, and which is normally closed. To identify them, read the printed diagram first, then trace the corresponding screw terminals before removing any parts. [#21878933]

Why are the relays and passive components inside old USSR-era time relays so much larger than modern relay timer designs?

They are larger because this design uses older, heavier parts with more material and less integration. The teardown explicitly notes much more mass and raw material than modern compact solutions. The reply also points out open-frame relays, MŁT resistors, impregnated windings, classic Soviet diodes, and older transistor packages, all of which increase size compared with newer relay timers. [#21879217]

How can I safely disassemble a vintage semiconductor-based time relay like the C67.102.280 without damaging the mechanical timing section?

Disassemble it in stages and document every position first. 1. Photograph the front panel, contact diagram, and wiring before opening the case. 2. Remove the cover and front panel before separating the mechanical timing section. 3. Extract relays and the counter board only after you mark their orientation and linkage positions. This order matches the teardown sequence and reduces the risk of losing the timing setup. [#21878933]

What is a K176TM1 integrated circuit, and what function did it typically serve in Soviet timer or counter circuits?

"K176TM1" is a CMOS digital IC that stores binary states and divides incoming pulses, a key characteristic in timer and counter chains. In this thread, the expert identifies it as a D flip-flop and says such parts were used as /2 dividers. In the VL-34UKHL4, it sits in the counter module beside the K176NE5, which fits a timing-divider role. [#21879217]

What is the K176NE5 chip, and how was it commonly used in old timer, loader, or frequency-divider designs?

K176NE5 is the timer-oriented IC in this module, used in Soviet timing and loader circuits. The reply states that K176NE5 was often used in timers such as loaders and could operate with a watch resonator. In this relay, that places it in the clocking or division path that feeds the output timing logic. [#21879217]

What are MŁT resistors, and why do they appear so often in Soviet-era electronic equipment?

"MŁT resistor" is a fixed resistor that limits current or sets circuit values, a key characteristic being its rugged construction widely used in Soviet electronics. The reply identifies MŁT resistors in this relay as part of a very typical USSR-era component set. They appear often because this design style reused standard, proven passive parts across many control and timer devices. [#21879217]

Quartz resonator vs RC generator vs 50 Hz mains frequency: which timing reference is more accurate and practical for a relay timer built around K176 series CMOS chips?

A quartz or watch resonator is the best practical reference in this thread. The expert says an RC generator would be too unstable, while using 50 Hz mains would be clever but harder to divide when the chain is matched to 32768. For a K176-based timer that must hold repeatable delays, the resonator option is the most accurate and practical of the 3 choices discussed. [#21879217]

How can I find modern CD-series equivalents or replacements for Soviet K176TM1 and K176NE5 ICs?

Use a Soviet-to-Western logic cross-reference first, then verify function before replacing anything. The reply says some K-series chips had counterparts in foreign CD-series digital circuits and links a chip-directory resource for that purpose. Start with the K176 family, confirm whether the target part is a flip-flop, timer, or divider, and only then compare package and pinout. [#21879217]

What does the paint-sealed potentiometer on the control board usually adjust in an old time relay like the VL-34UKHL4?

It usually adjusts calibration of the timing or count-reference stage. The teardown notes one paint-protected potentiometer on a control board and explicitly describes it as presumably used for tuning. In a relay that combines mechanical setting with semiconductor counting, a sealed trimmer is a strong sign of factory-set timing adjustment rather than everyday user control. [#21878933]

Why were PCB tracks on this vintage relay fully tinned and left without a descriptive silkscreen layer?

They were tinned for durability, and the board simply was not given a silkscreen legend. The teardown states both facts directly: there is no descriptive layer on the PCB, and all tracks are tinned for durability. That construction suits a robust industrial timer, even though it makes reverse-engineering harder during restoration or tracing. [#21878933]

What should I check first when restoring a flooded or long-stored Soviet time relay with a rectifier bridge and large electrolytic capacitor?

Check the power section and visible corrosion first. The author specifically identifies a rectifier bridge, a large electrolytic capacitor, and tinned PCB tracks in the control board area, so those are the first parts to inspect after storage or flood exposure. This matters here because the 2024 flood interrupted the teardown and the board was later lost, showing how quickly a repair reference can disappear. [#21878933]

Where can I look for schematics, datasheets, or teardown references for the VL-34UKHL4 or the C67.102.280 assembly?

Start with the assembly marking, the forum teardown, and the linked comparison pages. The post gives the plate designation C67.102.280, shows extensive internal photos of the VL-34UKHL4, and links a similar device page for comparison. It also names the K176TM1 and K176NE5 chips, which gives you concrete search keys when schematic documents are missing. [#21878933]