Large flip clock non-runner

[el marinero]

I recently acquired this flip clock as a non runner. It is a Bodet 6 series as far as my research tells me. Runs off 3 C-cell batteries, so it´s definitely not a slave clock as some of these are.





Unfortunately, sticking some batteries in failed to bring on a miracle start. I´m generally pretty handy but electricary is bottom of my list, although I do own a multi-meter. So I get 4.5 volts all the way up to the circuit board but nothing coming out the other side of the board. There is continuity through the motor, so I think that is OK. So I am going to have to fault find on the circuit board. This board is pretty small, 5x4 cms and some of the components are inkown to me, I see capacitors, resistors and the rest I don´t know. The back of the board looks OK, no burnt out points or anything.





I really hope that I can get this clock up and running, it has a real retro coolness to it.
I any one has good leccie skills and can offer advice, it would be greatly appreciated.

[markrlondon]

No specific things to suggest, other than that an oscilloscope might come in handy (although hopefully not).

You may need to desolder components to get good readings. There's a good possibility that one or more of the capacitors is bad (and many people would recommend replacing them all as a matter of course) but PCB tracks, through holes/vias, solder joints, diodes, transistors, resistors and ICs can all fail (so anything really). The biggest difficulty will be if one of the ICs has failed and you can't find a generic replacement, but take it one step at a time. Be systematic, look for continuity where it should be reasonably expected and test components individually where you can. Test continuity working outwards from where the power enters the PCB, a track, joint, via, component at a time.

You mentioned searching for continuity already so I'm very likely saying stuff you already know.

There are some channels on Youtube that specialise in electronic troubleshooting starting off with a multimeter for continuity, resistance and capacitance tests.

Some YT channels:
My Mate VINCE https://www.youtube.com/c/Mymatevince
Adrian's Digital Basement https://www.youtube.com/c/adriansdigitalbasement
Electronics repair school https://www.youtube.com/channel/UCoo...Z0PFAPc4Ymg3RA
CuriousMarc https://www.youtube.com/channel/UC3b...lKYm4sBaLs-Adw (this one is often super-advanced stuff but is nevertheless very informative and educational)

Good luck!



P.S. I was taking a look at the PCB and the components (top down) look to me like:-

Top left and top right: Two ICs. I can't work out the markings well enough to DuckDuckGo them but I reckon they are likely to be some kind of timed pulse generator(s) to flip the display panels when needed. That's just a guess though. (Google/DDG their reference numbers to find their purposes, datasheets, and availability in case faulty).

The four black plastic components labelled Q1, Q2, etc. look like transistors. Check their markings for specs.

To the right of the four transistors is a resistor.

To the right are three more resistors with a capacitor pressed flat on top of them.

Next row down on the left, there are two more resistors and then four diodes directly below them.

The blue spherical thing looks like another capacitor with (I think) two more capacitors to its right, and a diode directly below them.

To the right on this row is an IC, an Intersil ICM7213IPD. This is a timebase generator and its datasheet is available, as is the IC itself. This takes a pulse feed from the crystal and outputs something slower that can be used to tick away seconds, etc. (In this case, I'd like to know what the top two ICs do).

Onto the bottom row now, the cylindrical object with a screw on the top is probably a variable potentiometer or perhaps variable capacitor. I guess/presume that this is used to make timing adjustments.

To the bottom right of the PCB we have another two capacitors and a resistor, and finally the crystal which is the original source for timing.

Suspect all the capacitors. Especially look for faults with the capacitors and consider replacing them all no matter what.

[markrlondon]

Additionally, thinking about the electric motor. Does it really have just one motor for the whole thing?

Anyway, it occurs to me that the motor should (as you have already confirmed) have continuity through it but there should be some resistance. Not sure how much though. So might be worth checking that it's not a complete short. If so then a new motor might be indicated.

Also, worth checking that the motor can actually turn. Manually pulsing it with the 4.5V supply might be worth a try just to see if it responds with a movement.

[Kingstepper]

Have you seen this forum https://www.flipclockfans.com/?

[el marinero]

Additionally, thinking about the electric motor. Does it really have just one motor for the whole thing?

Anyway, it occurs to me that the motor should (as you have already confirmed) have continuity through it but there should be some resistance. Not sure how much though. So might be worth checking that it's not a complete short. If so then a new motor might be indicated.

Also, worth checking that the motor can actually turn. Manually pulsing it with the 4.5V supply might be worth a try just to see if it responds with a movement.

Many thanks for the detailed breakdown of the circuit board components, very much appreciated. Thankfully, the board is OK. I dismantled everything on the electrical side, cleaned connections and when put back together the thing came alive! However, the clock will only flip one time and then becomes jammed up on the next minute impulse. The motor tries to turn the stator (it is a sychronous motor) but fails to flip the tiles. So I am thinking that it is meeting some resistance in the gear train. I have ordered some graphite powder with the aim of carefully taking apart the mechanism, cleaning and applying lube. All the gears are plastic, so I´m thinking that a dry lubricant would be much better for the job.

The clock has a second motor, a smaller unit to power the date mechanism. It looks like this is mechanically activated at midight but I have yet to test this. First things first, get the minutes and hours running properly.

I have had a look at www.flipclockfans.com/ but there´s not much information there about this specific make of flip clock. Anyway, progress is being made!

[markrlondon]

Many thanks for the detailed breakdown of the circuit board components, very much appreciated. Thankfully, the board is OK. I dismantled everything on the electrical side, cleaned connections and when put back together the thing came alive! However, the clock will only flip one time and then becomes jammed up on the next minute impulse. The motor tries to turn the stator (it is a sychronous motor) but fails to flip the tiles. So I am thinking that it is meeting some resistance in the gear train. I have ordered some graphite powder with the aim of carefully taking apart the mechanism, cleaning and applying lube. All the gears are plastic, so I´m thinking that a dry lubricant would be much better for the job.

That's a relief. It's good the PCB is working ok. Well done!

Yup, I'd also have thought that dry lubricant would be suitable (although silicone oil would probably be safe too if dry graphite doesn't work).

The clock has a second motor, a smaller unit to power the date mechanism. It looks like this is mechanically activated at midight but I have yet to test this. First things first, get the minutes and hours running properly.

Ah, makes sense.

Good luck and well done so far.

[el marinero]

A progress update after i did some further investigation.

I started to dismantel some of the mechanism but got scared when I got to the works for the numerals, they are very well screwed together and look like a noghtmare to put back together.
I did manage to easily remove the first driven part, I guess the reduction gears going into the minutes. I connected the motor again to see what was going on and this revealed the same issue as before.....the motor will turn 180 degrees and then a minute later, on the next impulse, the motor will not turn.

Interestingly, this motor turn out to be a Lavet-type stepping motor.



You can see the rotor making a succesful 180 degree rotation here.
Good by duckdavewave, on Flickr

And on the next impulse, an unsuccseful rotation, a wobble!
Bad by duckdavewave, on Flickr

So every thime rotor gets stuck, if I turn it by hand 180 degrees and then wait for the next impulse, it makes a succesful turn. Subsequently a non-turn.
This had me very perplexed. I dismantled the stator of the motor and re-arranged it, to no effect. Then I got to thinking that the magnetism of the rotor had waned over time. Mad ideas of re-magentising it, putting it in the freezer etc.
The penny finally dropped when I did more research into how these single-phase stepper motors work. The coil need to receive alternate polarities on each minute in order for the rotor to turn. The multi-meter confirmed that each minute the motor is receiving the same polarity at about 2 volts.

With help from here (a very interesting site), it seems that I have a problem on the circuit board. More specifically, the four black transistors must be forming an H-bridge which is designed to switch the polarity. I suspect that one of these is a dud. I haven´t tested each of these yet, there´s not much space to get the multi-meter probes in and I´m not sure even how to test transistors.
Anyway, I´m pretty sure that this is the problem. If all fails I see some cheap solutions for replacing the electronics very cheaply with some sort of logic board to give the motor it´s signal. Hopef ully I can keep it all original, that would be best.

[markrlondon]

^^^ Fantastic, you've made some really substantive progress there. I am seriously impressed. Well done on the research you've done, too.

Thanks for the update.

it seems that I have a problem on the circuit board. More specifically, the four black transistors must be forming an H-bridge which is designed to switch the polarity. I suspect that one of these is a dud. I haven´t tested each of these yet, there´s not much space to get the multi-meter probes in and I´m not sure even how to test transistors.
Anyway, I´m pretty sure that this is the problem. If all fails I see some cheap solutions for replacing the electronics very cheaply with some sort of logic board to give the motor it´s signal. Hopef ully I can keep it all original, that would be best.

I reckon it would be best to desolder the transistors and test them out of circuit.

A lot of multimeters have transistor test sockets on them. Purely as the first example I found, this multimeter can test transistors: https://www.amazon.co.uk/Multimeter-.../dp/B07BMQ578Z. It would help to find the datasheets for the transistors you have.

I'm sure you could replace the circuit board with something like an Arduino (although you'd probably still need some support electronics, not sure) but that would be sort of cheating. ;-) It shouldn't be too difficult to go through all the components one by one and test them all.

If you find faulty components they should all be easily replaceable (although I couldn't make out the ref numbers on the top two ICs so not sure about those).