I too have suffered with numerous valve block failures though this was on
a Procise 494. The symptoms sound very familliar with solvents/reagents
being sucked back into the vacuum system.
In three years five blocks have been replaced and I am glad to say that
all but one was covered by a service contract. However, that doesn't help
as far as time and lost samples go!
As you say, this didn't happen in many years use of a 380B. I am sure this
is analagous to the many years that the 470/477's ran without such
failures.
Each failure occured with no warning, although a darkening of the vacuum
tubing at the point that it joins the valve block does occur with time.
Maybe this is the warning but at what time should one change the block as
a preventive measure?
Regards,
Rob.
****************************************
Robin J. Philp
Institute of Molecular and Cell Biology
30 Medical Drive
Singapore 117609
Phone: +65 874 3636
Email: mcbrp@imcb.nus.edu.sg
****************************************
On Wed, 21 Jan 1998, Mark Lively wrote:
> Fellow DNA synthesis labs:
>
> Our 18-month old PE/ABI 394 DNA synthesizer has experienced 5 valve
> block failures in its ever-so-short lifetime. The first four failures were
> in the 11-port reagent block at the front of the instrument but the
> failure that happened yesterday may be in the 5-port block at the back as
> well as the 11-port valve. One of the valve block diaphrams develops a
> hole such that reagents and solvents are sucked back into the
> vacuum-assist system. The vacuum ballast accumulates a lot of reagent, its
> fittings get corroded and the vacuum "pump" device also is damaged by the
> reagents. The pump and the block must then be replaced, usually.
>
> I am curious to know how many other labs are having this problem. The
> PE/ABI service engineers have been very prompt and have repaired our
> machine as quickly as they could but replacement parts are getting hard to
> find. I suspect there must be many other users with this problem. I would
> like to stimulate the company to increase its efforts to find a solution
> to this problem as quickly as possible. Additional information about other
> labs with this problem will be helpful. It is difficult enough to operate
> a DNA synthesis facility that is economical without problems with the
> instrument. Each day that we are down costs our users money! In over 8
> years of operation, our 380B never had this problem.
>
> Thanks in advance for any input you may provide.
>
> -Mark
>
> -------------------------------------------------------------------------
> Mark O. Lively, Ph.D. Voice: 910-716-2969
> Professor of Biochemistry Fax: 910-716-7200
> Wake Forest University School of Medicine email: lively@mgrp.bgsm.edu
> Medical Center Blvd.
> Winston-Salem, NC 27157
> HOME PAGE: http://www.bgsm.edu/molecular_genetics/
> --------------------------------------------------------------------------
>