Smiths time clock repair

[mach2andy]

Bored with cutting and trimming interior panels, I decided to try to improve on the performance of my clock which was only right twice a day. Mine is the 12v CTE3107/01 version. I discovered elsewhere that of the 3 electronic components central to the mechanism it is often the transistor that fails. I sourced some new transistors online. 2N3904 general purpose NPN. 5 for £2. Bargain! The setting knob is screwed onto it's shaft and came off easily holding the shaft with a pair of needle nose pliers. You can then remove the glass by gently prising up the bezel tabs. DO NOT remove the face. It retains 2 small gears. The mechanism is secured by 3 screws. Once the mechanism is out you can press on the back end of the setting shaft to set the mechanism going, and mine appeared to move very freely. You can now see the transistor buried inside the chassis. It's half moon shaped and has 3 legs. I snipped the old transistor out, and soldered a new one in. I didn't try to bury it in the chassis. It sit's fine outside of the chassis and there is plenty of room along side the casing. I connected power, and started the clock but no joy. I further discovered that the modern transistor cannot be connected the same as the old Smiths one. It has 3 connections annotated CBE. I now know that this stands for Collector Base Emitter. I had connected C & E back to front. I tried again, started the clock and hey presto it worked. It's now been running for 48 hrs and keeps amazingly accurate time. I've even managed to put it all back together with no bits left over! I think you could effect a similar repair to the battery version, but you may need a different type of transistor.

[Tom W]

This is useful, gives me some confidence I might be able to get mine going again.

[mach2andy]

Hi Tom
My mate warned me that transistors are a bit sensitive to heat and suggested using a pair of pliers to each leg as a heatsink when soldering. I tinned each leg using pliers as a heat shrink, and then made the joints very quickly. It seems to have worked.

[Drive35]

Nice one Andy. Mine's the same, although it does work when the switch panel is left folded down

Was wondering whether to take it apart, but don't know if the transistor is at fault, or it's just worn out!
Geoff

[mach2andy]

Hi Geoff
I'm no expert, but if it's sensitive to attitude, it's more likely to be a mechanical issue I would have thought? I was going to buy a secondhand clock on eBay out of a Scimitar, but the seller said that his clock was sensitive to attitude as well. The Scimitar clock is slightly different in that the setting and adjustment knobs are at the bottom, not the top.
A guy in the US who has repaired a thousand of these clocks was very helpful to me. His name is Michael Eck
eckmichael@comcast.net. When I described my fault he said straight away that the transistor was bad.
Or you can have the guts replaced with a quartz mechanism? The cost is about £90 I think?
ATB
Andy

[Pianoman]

the clock in mine is a bit strange. if I have the panel tilted forward then the clock runs and keeps perfect time but when I push the panel back upright then the clock stops !!!

[Drive35]

Thanks for the link, Andy.
Mike Eck confirmed it's the coiled wire 'balance wheel' which warps over time and doesn't move freely when upright. Not easily repairable, apparently, but I'll still have a go sometime.
Have copied the email to you Pianoman

[Pianoman]

Thanks Geoff,
My other solution is that when I want to see the time, I could just jack up the front of the car

[Monkeyfinger]

Just a note with respect to the Scimitar clock. My original battery powered clock was completely broken internally and useless.Whilst the Scimitar clock appears to have the knobs at the bottom, it's just turned 180 degrees relative to the 'E'. I bought a 12v Scimitar one off Ebay and just swapped the clock face over. Just 2 small screws on the face, and the hands simply pull off. Bezels can also be swapped. Main advantage was the price difference compared to a working E type clock.

[Pianoman]

great idea, thanks