IBM IBM problem with slave clock stopping

[berntd]

Hello

I have ongoing issues with my master/ 1 slave IBM setup.

After trouble free operation for years, the slave clock has started misbehaving.

I find it stopped at 3 minutes past the hour whenever I look at it.

Next time I look, it will sit 3min past another hour and so on.

When I try to trouble shoot it with a multimeter, it works again and I am none the wiser.

What can this be?
The master clock 1min solenoid works correctly and it also follows the syncing pulses at the minute 59.

Best regards
Bernt

 

[roughbarked]

Perhaps your problem is not electronic?
Maybe you should tell us about this?

 

[berntd]

Perhaps your problem is not electronic?
Maybe you should tell us about this?

I am 99.6% sure that the problem is electrical.

 

[roughbarked]

just checking.

 

[fdew]

Tell us more about the slave, or a picture of the movement.

Authentic is nice, but when I worked for Simplex I found that most issues were caused by correction, either in the master or in the slave. I have. A master in my home and 4 slaves. I run straight minute impulse t9 all of them.

BTW. I think correction was more of a sales tool then a feature for impulse clocks. They are ultra reliable until you add switch contacts, and extra pulses.

 

[berntd]

Where is Harold on this one?

Anyway, bottom line is that I do not hear the slave solenoid doing anything when it should.

The setup is such that all pulses are issued through a transistor controlled relay. I did that years ago to prevent the contacts in the master from wearing/migrating.
This still works fine as the master and accumulator solenoids operate correctly and I measure 24V pulses.

I am not sure about the B pulses as I write this.

Now the slave clock is the earlier style with the bigger brass movement and the solenoid with the seesaw lever.
When I try and measure at it, I do not find any faults. But then the whole thing just works again for some time.
Just long enough to pack away the equipment. And then BAM. I find it stopped again.

I have also seen it sit at minute 59.
But that might be normal because it is waiting for a B pulse to switch back to the A line.

I suspect a problem in the slave clock switchover contacts but the measure ok when I put the ohmmeter onto them.

Looks like I will have to add some indicator leds with zeners so they will indicate near 24V pulses.
It is a persistent problem.

 

[Kevin W.]

Harold Bain passed away last year.

 

[berntd]

Inspired by your reply, I just measured it all again.
The problem is the slave clock switch channel B. It has a bad contact in that only 15V get to the solenoid while on B pulses.

I just disassembled it and had a look. The contacts look ok as I cleaned them not long ago.

However, there might be too little preload spring tension on the contacts to work reliably.

The actuator lever has a bit of wear where it runs on the cams. Do I need to fix that or is it not relevant?

 

[berntd]

Harold Bain passed away last year.

I did not know this. Thank you for letting me know.

 

[berntd]

Update:

It is the contact in the slave.
I jus disassembled and serviced it but I cannot fix it.
The contacts are suoer clean but if I switch them with the cams, they produce 25 to 200Ohm resistance on the B.
A is 0.7k.

How can I fix this? They neen more pressure but there is nothing there that can provide it.

 

[Edwardo]

I have seen this fault before
The contact rivet on the switch can become oxidized
solution is to solder the back of the rivet to the spring part of the switch

Cheers
Edd

 

[berntd]

I have seen this fault before
The contact rivet on the switch can become oxidized
solution is to solder the back of the rivet to the spring part of the switch

Cheers
Edd

Hi Edd, that makes a lot of sense. I 'll do that as I cannot find any other explanation.

Regards
Bernt