Quartz clock movement issue

[dnhb]

I have a couple of the ubiquitous 'square' QCMs both of which seem to suffer from intermittent connectivity in terms of the pcb input tabs & the underlying 'spring steel' battery terminals. I've checked both sides are clean but even bending the 'springs' up doesn't get the magnetic cog rotating consistently when pressure is applied to close the contact. Is it the case that these contacts should be just touching the pcb pads rather than being pushed hard against them? I know these movements are cheap but I'd get satisfaction from being able to repair them as this involves learning!

[AndyGSi]

1 hour ago, dnhb said:

Is it the case that these contacts should be just touching the pcb pads rather than being pushed hard against them?

Can't quite make things out from your photo but I'd expect them to be soldered to the PCB.

[watchweasol]

Hi I have found that the contacts just don’t make it so coating the connection on he pcb with solder some times works , and che k the gears/ wheels are clean. If I have one fail I usually take it to bits to find out why, quite often the wheels are brittle and cracked. But as they cost pence it’s only me being curious to see if it can be fixed.

[HectorLooi]

If space within the clock allows, I would solder 2 wires to the gold contacts and run them outside to a battery holder. 

This way, I can use a C or D size battery and run the clock for years. But remember to use "super heavy duty" batteries and not alkaline batteries. Alkaline batteries produce water when the chemicals inside react to generate electricity, which leads to leakage. 

[dnhb]

1 hour ago, watchweasol said:

Hi I have found that the contacts just don’t make it so coating the connection on he pcb with solder some times works , and che k the gears/ wheels are clean. If I have one fail I usually take it to bits to find out why, quite often the wheels are brittle and cracked. But as they cost pence it’s only me being curious to see if it can be fixed.

Thanks for your interest. I'm in the process of trying the solder coating solution albeit soldering is something I've never been good at. Re gears/wheels - these aren't the issue as I'm only looking to get a good rotation on the initial (magnet-base) drive wheel.

1 hour ago, HectorLooi said:

If space within the clock allows, I would solder 2 wires to the gold contacts and run them outside to a battery holder. 

This way, I can use a C or D size battery and run the clock for years. But remember to use "super heavy duty" batteries and not alkaline batteries. Alkaline batteries produce water when the chemicals inside react to generate electricity, which leads to leakage. 

Thank you; I'll give that a go. Battery point noted.

[rjenkinsgb]

Try adding a small trace of light oil to the spring contact surfaces.

That can often cure intermittent connections. 

(eg. A small amount on a cloth or cotton bud & scrub the contact surface with it; not enough to creep and affect other parts of the device).

The oil film prevents air getting in to the critical metal-to-metal contact area & causing tarnish or corrosion).

3-in-1 oil is commonly use in electrical repair for this type of problem, also noisy volume control etc.

[dnhb]

Thanks to collegues' inputs I've now got one of the 2 problem movements going - the one that had suffered corrosion. Having added some solder to the pads the drive wheel worked but only when the 'plate' was pressed down in a certain way. And the movement stopped when I replaced the back. I employed a YT tip (adding flux to my copper braid) in wicking away most of the solder leaving only a thin coating. However, the problem remained. Checking the drive & 2nd wheels showed that the initial closure - when the solder was raising the 'plate' too much - had bent their plastic upper pivots. Trying to straighten them wasn't successful so I used one of my Temu micro drill bits to widen their upper 'seats' a fraction & this did the trick.

Maybe too much info but I am pleased to have got my friends clock going again and am grateful for you folks' help. Your interest was also a source of motivation.