Hi all,
I have an old Seiko A638-5000. This range uses the A638A movement with a lamp [Seiko Item Reference Number: 4530 010] soldered onto the circuit block [Seiko Item Reference Number: 4001 241].
For many years the lamp would not work but now I’ve fixed it - hooray.
I purchased a NOS A638 circuit block to replace the old one, thinking it was the onboard lamp that had failed only to find that the lamp would still not work. Here’s why, for all those with the same problem.
Firstly I cleaned the contacts on the circuit board - there are only four of these. That still did not solve the problem.
Secondly I dismantled the push buttons - this is very simple to do but one has to be extremely careful when removing the small circlips on the buttons - the point of a good quality pair of tweezers does the job. I then examined the hole for each push button to fine that over the years they were quite dirty. The dirt had buit up thus preventing the push button from being pushed all the way in, which in turn prevented the contact switch on the circuit block from efficiently making contact.
Voila! problem solved - the lamp works.
So now I have a very rare A638-5000 which is gong up for sale soon because I’ve just purchased another one in almost mint condition.
