Synchronar MK2 Top and Bottom circuit board views

[J Thomas]

[charger105]

Nice pictures Jeff.
I had noticed on a couple of MkII boards that no surface mount caps were present in the oscillator circuit, but wasn't sure if they'd been ratted previously, or they weren't there in the first place. Yours is like this too, so they must be intergrated into the chip on the MkII. It must be the same deal with the light sensor resistors too.

It really is quite an evolution of the MkI !

Whilst on the subject, the MkI has SMD resistors (and sometimes normal resistors) in parallel with the time, date and seconds command inputs of the IC. Any idea what these are for ? These must also be integrated into the MkII chip.

Rgds,
Andrew.

[charger105]

.......btw, I've probably got one or two MkII chips you can have.

Rgds.

[J Thomas]

[charger105]

Yep, AFAIK, MkIIs have a frequency synthesizer (no idea how this is achieved....it's all in the magic chip!). I find it amazing that in the mid 70s this was developed, and today I don't know of any watches with this same feature (there probably are, but they're not common). Also only 4 reeds, and obviously no trimmer.

I've never come across a 5 reed Synchronar, but clockace has some. I've also seen MkIs with both display types, and MkIIs with both display types (from the factory, still covered in gel).

Thanks for the explanation of the components. I was thinking after posting that the resistors on the activation inputs might stop spurious activations (like a switch de-bouncer). I've never seen any resistors on the digit transistors.

Rgds,
Andrew.

[clockace]

hi andrew, i think some while back there was a discussion of whether or not there were 5 reed synchs. all i have ever seen are the 4 and 6 reed modules. at least on the working modules. the 4's have 3 on top and 1 rear. the 6's have 4 on top and 2 rear. that is all i have. jeff's photos are really an asset to the forum. now if we could just have someone post a decent schematic of the other side of the pcb. [the side with the qc] would be nice to know where the traces and resistors go with their values. i have been experimenting with rebuilding the corner where the 2 resistors and diode have been ripped out. so far i have the corner filled in and 1 of the traces completed. the easy one. the others have the pads and holes for the resistors and diode. has anyone done that yet with success? regards, peter

[J Thomas]

[clockace]

[url]this is a photo of a pcb i have recently acquired. i think it is unused. one i wanted to show you jeff. peter[/url]

[clockace]

yeah, that photo is way to big. need to work on that. peter

[J Thomas]

[bruce wegmann]

You know, those transistors look awfully similar [as in, IDENTICAL], to the surface-mount transistors used on the Pulsar P2 and P3 circuit boards. If so, you may have a vast new pool of spares to revive your Synchronars. Just an observation...

[charger105]

.....I never expected Bruce to chime in on a Synchronar post. I bet he's a closet Synchronar fan with a whole pile of them in his collection .

Well, I've never seen these variations on MkI PCBs before. Very interesting. I agree, those transistors do look like Pulsar equivalents.

Sometimes those pull down resistors are on the other side of the board....I've seen surface mount and axial varieties.

Since we're showing interesting MkI synch boards, I've got a MkI with a strange Monsanto display. It looks the same as normal, but there is a big gap between each segment on each digit. Much bigger than normal. I'll try to get a shot and post it. I'll have to use my mobile though, the camera's failed.

Rgds,
Andrew.

[charger105]

....as promised, here's the interesting display:

[IMG=http://img33.imageshack.us/img33/6455/imgp0018.gif][/IMG]

The digits on the left have big gaps between each segment. It would have been a better comparison if the one on the right wasn't in it's case, but I didn't feel like opening it up.

I hope you can see what I mean. This is the only one like this that I've seen.

Rgds,
Andrew.

[J Thomas]

[charger105]

No problem Jeff.
It could be some sort of experimental board. All of the reed switches have curved ends where they attach to the board (i.e. no posts). The midle posts for each pair of switches are there, but not at the other end, on all 6 switches. Looks original too.
I think you can just make it out in the image for the front switches.

Interesting stuff!
Rgds.