SDM Motor failure Discussion - are the Capacitors the real culprit not the SDM Motors (Ref' David Storm's Post)


Link Posted 04/08/2016 - 19:31
In response to David Storms post; “Is this the reason why SDM lenses need to be used often and are prone to fail? I did seek the opinion of ASAHI PHOTO who recently replaced 4 SDM’s for me and have deep experience in this specific issue.

ASAHI Photo are dedicated Pentax lens repairers and their principal electronics engineer, has many years of experience on this work has specifically in all things to do with, control system electronics, lens design and engineering over many years.

He explained that SDM's have been problematic for all makes over the years, including Canon but many SDM's have been changed with no further problems and as the capacitors are part of a PCB (micro circuit board) and therefore cannot be changed as an individual component, are not considered as a contributor

The circuit boards "on extremely rare occasions" have been a problem but in his experience it is practically speaking always the SDM that is defective in almost all cases.

Pentax SDM's have been quite unreliable on the DA* series but again not all SDM's fail, as is my experience.

As regards the failing SDM’s: ASAHI Photo believe the specific cause relates to the integrity of manufacturing clearances between the annular components (rings) which can be badly affected by dimensional inaccuracies (out of tolerance).

Also as the clearances are minute then it must follow that any deterioration in cleanliness, surface integrity or roundness can also create problems,

ASAHI Photo is the go to place for Pentax lens repairs in my experience and are not only great to deal with but also undertake rigorous testing post repair before releasing the lens.

They guarantee their repairs in writing and from a cost point of view; “like for like SDM replacement” is around 50% less than other well known repairers.

My discussion was with Pramath see, full contact details below:

Asahi Photo Technical  
6 Albany Parade, High Street, TW8 0JW Brentford


• Principle contact for photographic equipment repairs is PRAMATH – 02082328111
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