40 Year Old Telenorma Station- Clock Controller Checked. Analyzed and Documented
About a week ago my good pro watchmaker friend Charles contacted me about two unknown Station-clock controller driver boards that appeared completely defect. ‘Unknown’ because not a single piece of document existed of this device that was made by a well known German firm called Telenorma. That old factory probably no longer exists and it was years ago that my watchmaker friend was able to visit that factory that gave him a good impression at that time. Telenorma still exists but they couldn’t provide any info after all those years anymore. Two of these by Telenorma made devices that each had a mini-clock, and on top on 3 metal standers a now empty no longer used 4,5V DC battery holder are shown on next photo. And both were used to drive quartz crystal synchronized Station clocks. The mini-clock that is positioned on top of this board works on a 12V DC impulse of which the voltage changes in polarity between -12V and +12V. Which advances the minute hand on the mini-clock and slower of course the hour hand too. There is no second hand. But how it worked only became known after a long time of testing and examining all parts.
And that pulsating DC signal normally also drives the often on a wall outside placed big Station clocks.
But nothing seemed to work. And my friend already noticed that only one of both controller boards showed a powered lit up red led. The other board that was not exactly identical but had the same function and the same mini-clock was completely dead. Why I started to examine the board on which the led was working and the secondary transformer voltage was active.
Because my friend already said that both Telenorma boards never had worked I just started to measure all transistors out of the circuit by removing them one by one. And I checked in-circuit the passive resistors and diodes. And later-on all capacitors by removing one by one from the board. I used my DCA75 Pro semiconductor tester for the transistors. And my good old DMM for the diodes.
Testing diodes this way we can’t tell if they are zenerdiodes. But if the board and circuit finally does work we can establish if they are zeners by measuring the voltage over them. But for testing the CMOS logic IC’s I used my Chiptester Pro from Evie Salomon from the US of A. Because only with this perfectly designed and engineered (retro-) chip tester I was able to test the special CD4045AE 21-stage ripple counter/divider. Only new version 2 of this chiptester is automatically able to check any 14, 16 or larger chip without setting up any power wires first. But because I had the old but still fantastic V1 tester I used the normal CMOS 4045 test mode after connecting the two power supply wires manually first. And the large test (it took longer because of the 21 counter stages!) tested both 4045 chips as good! After testing all CMOS IC’s and none of them failing, all were placed back in the board on quality machine IC sockets. And I kept checking and testing but not finding any bad component! Therefore I started with the second defect board with the still not working red power led. And soon I discovered that the original 1000uF 35V e-cap was a complete very low ohmic short, shorting the secondary output of the B80 C1500 greatz rectifier bridge. After replacing that capacitor with a good 2200uF 50V cap now also that board showed a red working led.
Still both boards didn’t show any working mini-clock or a changing +12V to -12V Station clock driver signal (later I noticed it only shows correctly on an oscilloscope). So I started to draw a quick schematic of these devices to make some sense of how the boards operated and how exactly they were meant to be used. Because all info about these old devices is completely gone!
I made above photo of the solder side and also a few photos of the component side of the board that had an already working red power led. It shows that only two of the 3 metal stands that hold the battery holder (4,5V battery that no longer is used) have a copper layer connection to the – and + battery voltage connection on the clamp strip that also holds both AC ~ secondary transformer connections.
And the datasheets were searched and downloaded for the E112 JFet, and the special switching BCY79 (the DCA75 pro had some issues to detect it correctly at first) but after each good test I made snapshots as proof.
And of course also following some snaps of the ic tests on my Chiptester Pro v1 from Evie.
Below photo on the left shows the faulty automatic CMOS test if done on a (my) V1 IC tester why I first thought both chips were defect. But here it doesn’t recognize the cd4045 because we must make some power connections first on the V1 Chiptester Pro. Only newer IC tester version 2 is enhanced not having to worry about those power connections anymore.
Top photo on the right was the 4045 test start (CMOS chip 042/142) in Normal mode. Followed by the lower photo on the left that showed the “-“ wire powering instruction. And the next Ready To Test photo on the right showed after the 2 wires were connected. After a long test give-and-take less than a minute the 4045 chip was completely tested GOOD with tester message PASSED ALL TESTS!
Next photo shows the top view component side of the first board after the 3 screws with the battery holder was removed. Before any component was de-soldered and examined.
In the end all CMOS chips tested good and all were placed on good IC-sockets.
Previous photo showed the 230VAC white power input clamp strip behind the red led. With next in front of the red led the earlier mentioned 6 wire connector strip clamp for both ~ secondary AC wires, + and – battery, and +N and +R wire connections. Also two Line connection pins on the left of the slide switch in front show. Only after manually drawing a quick circuit from solder side photo and examining the top layer connections of this 2 layer board their functions became clearer. Below photo shows the on top placed mini-clock on the right from the empty battery holder. With in front 2 other slide switches both marked N-St.
Here follows the circuit that helped to explain most functions of the slide switches and how to use some of the undocumented connectors. And I finally got both mini-clocks working and was able to find the connection for the signal for the big outside placed Station clock. This circuit by no means is errorfree nor complete but is no doubt a great help for all those desperate Telenorma Station-clock device owners that also couldn’t find any useful info. This Telenorma board is marked 41.3101.1903 but that probably won’t help in search for any on-line info that all is lost in time. And these old boards were probably also bought on some auction from a previous owner who already passed away and no longer is able to give any existing user instructions.
The drawing showed that the single switch provided a 12V changing in polarity signal only if set to the drawn position. Only then both about 12V Zener diodes became active and provided the right signal to drive the mini-clock and for the LINE output to the Station clock. And when also both slide switches on the right were placed as shown in the previous photos the mini-clock advances about 37,4 times faster than just 5 minutes!
Here next a few photos of the other repaired board with the previously shorting 1000uF 35V e-cap.
You can double click the above photo to enlarge it
Above photo shows the correct position of the two slide switches on the right to make the miniclock work in fast speed when the minute-hand advances about 37,4 times faster than normal time.
But this 12V pulsating signal is also available on the LINE connection pins next to the single slide switch on the left as shown in one of the previous photos. And is most likely for driving a Station clock. But only on Station clocks that needs minute pulses. And I finally found out that the mini-clock only works in the right time speed when both N_St slideswitches are placed to that right set position.
My watchmaker friend didn’t know that these Telenorma boards were working minute pulse Station Clock controllers. And he asked me if I could make such a minute pulse Station clock controller for a friend of his.
That is quite easy for me now because I already programmed a 3 Zone radiocontrolled DCF clock receiver in 2007 that was published in Elektor December under the title: E-blocks DCF clock Ported onto Elektor PICee and supporting three time zones. And it was enhanced with a Station clock driver upgrade that was published in the Elektor 311 circuits book (if I’m not mistaken) under the title :
Pulse Clock Driver with DCF Synchronisation by another great maker. And the complete DCF Station Clock project fits in a single PIC16F648A with a single TC4427 18V 0.5A dual mosfet. (connected to a small DCF module of course).
And that DCF Station Clock device will work on a single 5V voltage and completely automatic will synchronize with summer/wintertime, and even with special added seconds. And displays all info on a standard 1602 LCD within about 2 minutes. And only needs a 12V power adapter for the TC4427 dual mosfet Station clock driver if Clocks do not work on a 5V minute pulse. And all parts are already ordered and I start building this DCF controlled Station Clock project in about 3 weeks.
After this we now know that both marked N_St slide switches work in Normal Stunde mode (German) when both are set to this position.
Here a last photo that shows the back of the mini-clocks, we here selected the 12V inputs.
To make a long story short: At first it looked as if both boards were completely useless, and my friend thought that they both were defect somehow. Which made me test almost all parts of the first board because we had no info or user instructions to go on at all.
Now we also know that it is a real minute pulse giving Station clock driver. Only when the signal on both LINE connector pins is watched on an oscilloscope we see a 0V DC signal that once in every minute very shortly becomes +12VDC then goes back to 0V and becomes very shortly -12V in the next minute etcetera. Because when measured with a slow digital lcd multimeter we only see the 0V level of the signal and never will notice the real signal.
In the end apart from the shorting 1000uF capacitor on the second board nothing was found out of order or defect after that. And at first both mini-clocks never worked. But after I drew most of the circuit of the first board it explained how to set the slide switches and suddenly the mini-clocks finally started to work, on both boards. (although both boards are not exactly the same they are infunction).
If any reader knows anything more about these Telenorma boards that was not yet written here, Please let my professional watchmaker friend and me know!
Here two links to very small Youtube videos that show both mini-clocks rotating in fast mode (about 37,4x faster) as proof of the now perfectly tested boards with working mini-clocks:
Time never stops, and this was all information about these Telenorma Station Clock boards.
Until another interesting repair!
Albert van Bemmelen, Weert, The Netherlands.
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Waleed Rishmawi
July 5, 2025 at 12:31 pm
Well written, detailed repair article but it was all beyond my understanding abilities but thanks for sharing. Have a blessed day
Albert van Bemmelen
July 5, 2025 at 2:40 pm
Understood Waleed. Most of the repair projects I got from my Watchmaker friend are specialized to the field of watchmaking. And my friend is very experienced in repair of these watches and clocks that requires a unique set of skills and knowledge. My retro electronics hobby in computers and software is my connection to these vintage electronic clock controllers.
The article at least explains why using a common DMM to measure a signal is not always a good plan! Because in this example only an oscilloscope showed the correct signal levels and confirmed how to connect the board to a big Station clock.
Paris Azis
July 5, 2025 at 4:46 pm
Hello Albert! Well presented and written article (as I expected it to be). I remember this company. It was a very famous manufacturer for industrial clocks. Unfortunately it doesn't exist any longer!
Your article reminded me those good old times of the past, when i was working for the erection of two power plants for our public electricity company. I remember that the well known difficult problem of creating very short time delays' circuits using analog circuits, how easy had become by using digital frequency division circuits. It was amazing to me at that time. I remember the calculations for the clock's metal film-high accuracy resistor (used with a high quality capacitor) in order to get the proper time after the (programmable as well) division. The circuits produced the time delay with amazingly high accuracy, simply by counting the high frequency pulses of the clock! That was an exciting experience for me, never known before! That's why I still remember the entire procedure. So, thank you once again for waking up these memories of the past (hopefully for other readers too)!
Albert van Bemmelen
July 5, 2025 at 6:01 pm
Thanks Paris, nice to hear from you again on Jestine's blog! It is strange and annoying that large firms like Telenorma (who I later found out apparently still exists but probably no longer that old Station clock board maker factory) had not saved the schematic and user manual of this old but still perfectly working minute pulse giving Clock controller board.
My watchmaker friend recently also showed me a dvd from Boscoclocks in the Netherlands that had a fantastic collection of +300 made mechanicle clock animations from all known clocks since the beginning of clockmaking. Complete with history background of clocks and their makers. He bought that dvd but sadly the dvd was partly heavily corrupted what meant that it only showed all clocks except at least 29 of the clockanimations with names that started in the list with S in their names. And those never could be opened. And likely because that dvd was copy protected and it also looked like it also was infected with a virus it could only be read upto 77% of its total capacity. And those last 29 animations only showed an error popup screen saying there was an error in the library and so never worked.
He of course mentioned this to the maker/seller of this collection but only got an efasive answer that the sold dvd was fine while it was not! So he asked me to check that dvd collection and I came to the same conclusion and recently also contacted the seller who quickly responded giving me the same nonsense answer. Telling us that we installed his program wrong and that he had no knowledge of computers and it was all our problem. I even told him that his copyprotected dvd when tested with the program Blindwrite immediately said that the TOC was missing. Which explained the missing of about 23% of the dvd animations data.
And because that collection is likely also sold on usb memory stick, and it is most likely the same problematic program from that seller I hereby warn every reader hereby NOT to buy it for that reason. Although very interesting for mechanicle clockmakers (beautifully made color animations with audio!) it is NOT complete and not error free either, and there is no after payment service whatsoever!
Yogesh Panchal
July 5, 2025 at 6:33 pm
Congratulations! Albert
It seems to be a very time consuming job, but with dedication and passion it is possible once we know the process of working of the equipment.
Albert van Bemmelen
July 5, 2025 at 8:57 pm
Indeed Yogesh, but just a user guide or more info would have saved me a lot of time and testing!
Parasuraman S
July 5, 2025 at 7:34 pm
Reading the caption itself rang some bells within my brain and I guessed who it should be from, and got ready mentally to duck! Sure enough, my head started reeling faster and faster and perhaps you could have used it for the clock by providing dampening wheels (Ha!Ha!) I read the article through but many things went off like water off from a duck's back! But the efforts you have put in and the inimitable analysis done by you to study the circuit is amazing! There cannot be anyone who can match you on these types of works and my hat's off!
Albert van Bemmelen
July 5, 2025 at 11:58 pm
Your very funny comment made me smile from ear to ear dear Parasuraman! But I think your repairs are often more difficult and require more time and patience to fix. This Telenorma repair article all in all only took about a week of my spare time.
I count myself lucky that I have collected a good deal of equipment to help me out when I have to quickly investigate all those questionable digital chips in often vintage (retro) devices.
At the moment I'm building a digital Low Voltage C-leakage tester that also can predict if a capacitor gets bad soon. It even can test the high voltage caps upto for instance 1000V. And that tester also can test diodes and zenerdiode upto 30V. If you are interested here is more information:
https://www.pcbway.com/project/shareproject/Low_Voltage_Capacitor_Leakage_Tester_Diode_Tester_to_30v_643c8f95.html
Parasuraman S
July 6, 2025 at 3:45 pm
Many thanks for your response and providing more detailed information with tips!
Albert van Bemmelen
July 6, 2025 at 12:03 am
PS: that digital C-leakage tester is based on Carlton's LV C-leakage tester. See this interesting Youtube video:
https://www.youtube.com/watch?v=LhovRIM5xAo
Parasuraman S
July 6, 2025 at 3:52 pm
Thanks! Shall watch it during my free time!
Mark J
July 6, 2025 at 2:25 am
Albert very informative and well written article. I can see from the Commodre 128 box in the background that you are into retro electronics and computers. Good to see you have a Youtube channel as well.
Albert van Bemmelen
July 6, 2025 at 2:33 pm
Yes Commodore C64,C128 and later on Amiga computers are fantastic home computers that in the past were great fun. And I still have several C64 computers that I fixed and collected long ago. Nowadays the Amiga also runs emulated in a cheap Raspberry Pi 400 keyboard in the great made by Chris Edwards (fantastic programmer!) free PiMiga4 program that runs and boots a fast Amiga from a cheap SD card and plays on any HDMi TV. And I also had much fun with playing games on the XBOX, and XBOX360. Mostly Halo that is and was a classic! And I made several articles on this blog about diskdrive interfaces and adapters for those computers. My Youtube channel shows only a few of those videos.
Albert van Bemmelen
July 9, 2025 at 11:14 pm
If you need a 400MHz fast 24 channel Logic Analyzer that works with the free Sigrok software (This new Analyzer is now also available online as affordable product) See also here for all info:
https://www.pcbway.com/project/shareproject/LogicAnalyzer_V6_0_cc383781.html
Humberto
July 10, 2025 at 8:02 pm
Congratulations Albert. You have writen an amazing and didactic information, and very well redacted with all the necassary details very well explained
Albert van Bemmelen
July 11, 2025 at 12:04 am
Thanks Humberto. Nice to hear from you again! I hope the power failures in your country are under control.
In case of power failure in my country I have a backup 2KW 230VAC 50Hz inverter with a 120Ah lifepo4 battery. Plus several portable units including quite a few 5V USB chargable battery packs with a 200Watt solar panel. And a 400Watt 230VAC handcrank power generator. So if needed my solder station or other equipment are operational when the power lines are out of 230VAC 50Hz.
Albert van Bemmelen
August 31, 2025 at 5:17 pm
Update: In July 2025 I also finished making the in the article mentioned Station pulse clock driver device for my watchmaker friend. The upgraded version that was published in Elektor the year 2009 and in the Elektor 311 circuits book under the title "Pulse Clock Driver with DCF Synchronisation" that was enhanced by another great maker.
But after completing that device it showed that it contained an annoying bug that showed the year and DCF pulse wrong on the 1602 LCD. Because of that also Elektor's previous sold PICs of that enhanced DCF station clock program and the PIC firmware were faulty. But because I had written the previous error-free main program myself in 2007, I examined the problem and managed to solved the error in that new firmware. Afterwards the complete DCF Station Clock project still fits in a single PIC16F648A and is now error free.
Another error in that enhanced firmware version was that the polarity of both the DCF and Error Leds was wrong. That also is now fixed in the new firmware version, and was also uploaded and shared with Elektor Magazine. Now free available to anyone that wants this new bugfixed version. Eventually with all information on what exactly was fixed in the previous buggy enhanced version.