Pulsar 1970's LED repairs

[JerseyMo]

I've been messing around with a Pulsar led module 5408-2 last few hours.  the display will light up and was fully functional but after a few hours it starts to not respond.  What I had done originally was to blast it with some electronic cleaner than held it near a heat source.  That got it to work but now again the display is acting up.  Cold solder somewhere?

 

 

[LittleWatchShop]

A cold solder joint is definitely a possibility.  More likely a probability since you have shown that it is working in real time.  Could also be contacts to the battery...but I imagine you have already explored that.

If batteries were left in it and they deteriorated, the acids (or whatever) from the battery could destroy circuit traces...but that seems unlikely given that you have made it work in real time.

What does the pcb look like in the pulsar? 

[JerseyMo]

I'll take out the module tomorrow and add some pics. right now I'm calling it quits for the night. But I did lookup the original price of this watch in 1976  and it sold for $395.  That would be  $1,853.82 in 2021.  back in 1976 I was working part time and making  $2.50 an hour pumping gas.  Guess either way I would have to wait 45 before I could have one.... 

[LittleWatchShop]

31 minutes ago, JerseyMo said:

I'll take out the module tomorrow and add some pics. right now I'm calling it quits for the night. But I did lookup the original price of this watch in 1976  and it sold for $395.  That would be  $1,853.82 in 2021.  back in 1976 I was working part time and making  $2.50 an hour pumping gas.  Guess either way I would have to wait 45 before I could have one.... 

I remember my dad getting one in his shop for reasons that escape me.  I wore it for a day and felt very important!!  I have several Longines LED watches that are not working.  Have not explored the cause for their failure.

[JohnR725]

You may find the links below interesting. I was kinda hoping for a DIY repair site but didn't find that. I have a suspicion they may have had a high failure rate but I could be wrong.

 

http://pulsarledtime.com/home.php

http://www.oldpulsars.com/

 

[JerseyMo]

well it ran well overnight but the time display button is a bit odd. It takes a few presses to get the display to light up. Than it goes whacky such as the AM and PM segments stay on.  If I take the batteries out than a random digit lights up.  I guess this is why it went into the sock draw of the original owner.

[LittleWatchShop]

Well...you could try to touch up each exposed solder joint.  It's a crap shoot.  Do you have the equipment to do that?  If not, you could send it to me and I would give it a shot.

[HectorLooi]

I believe the contacts of the display switch have oxidized and are not closing the circuit properly. If the switch is replaced, I believe the circuit would work just fine.

[KOwatch]

There's at least two replacement module makers for the pulsars, they use the original LEDs  (and quartz crystals?) but modern batteries and circuit design, so I would imagine they would have better battery life. I haven't tried either, but they look interesting. At least one of them has the option of adding a few extra functions, like the month and date display with a long keypress.

https://pulsarledtime.com/Replacement-LED-Watch-Modules/

http://www.strikesandspares.eu/modpulsar.htm