Snap-On MT2261 timing light

[Franc Zabkar]

I'm relating the following experience to show how information held by
the US patent office helped me with a repair.

I recently repaired a Snap-On MT2261 timing light with an intermittent
flash problem. As expected, Snap-On were not able to provide circuit
diagrams, or a service manual. Their quoted price for a replacement
circuit board was AU$900 which was more than the cost of a new unit.

However, I noticed that on the ratings sticker there was a reference
to two US patent numbers. Sure enough, a search at the US patent
office turned up a document
(http://patimg1.uspto.gov/.piw?Docid=04713617) with a circuit diagram
and an in-depth functional description, including a detailed flowchart
for the firmware.

BTW, the fault was a 0.033uF HV ceramic cap connected to the low
voltage winding of the trigger transformer. I replaced it with a 2kV
pulse rated polypropylene cap. Because of its size, I had to relocate
the replacement cap and attach it with 300V fly leads. Incidentally,
the original ceramic cap tested OK on a cap meter. I confirmed that it
was faulty by reinstalling it and reproducing the original problem.

PS. The following site provided the document in a more convenient
format (a 20-page .pdf file), but required me to register (for free).

http://www.freepatentsonline.com/4713617.html

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

[hrho...@att.net]

GREAT IDEA!

H. R. Hofmann