C252/C352 Write units

[Guest]

Can anyone tell me why when one of these write units goes faulty you must change all 4 as a batch is this just KM trying to make more money or are there genuine technical reasons for having to fit all 4 at the same time?
I have replaced the 1 faulty unit in the past and I never had any issues.
Thanks for any info

[trublu]

Each lens in the write units is matched to the other in the set

Each write unit has a set of lenses with are matched at the factory.

Although, you may get lucky and find that you don't get any issues with replacing an individual write unit, you will eventually find that you will get colour registration or alignment issues.

Even if you think it has worked have a very close look at a test print, you may find it has registration issues

When a write unit lense is too different from the other write units it will be impossible to get correct colour registration.

Cheers.

[kingarthur]

I've also replaced only 1 unit & appear to have had no problems

[tech51]

The write units have a letter marked on them a,b,c,or d. We had a lot of failures last winter and were told by KM that you could fit individual units provided the letter either matched or was closest to the fitted set. In other words a B could be fiited to an A or C set but not a D set or an A could be fitted to a B set but not a C set. Its the old story though if you`re at a customer whos complaining you`ll just fit what you`ve got and hope for the best. Its quite important to do the colour registration adjustments though this can cause problems if not done properly.Details for that are in the manual. Cheers

[Si@danwood]

Never had an issue just replacing 1 unit!! Sounds like a money making venture to me!! Suppose there must something technical behind it same as the drum sensitivity setting on the old sharp machines never made a jot of difference!!! Si