From: cctalk [mailto:cctalk-bounces at classiccmp.org
] On Behalf Of Chris
Sent: 04 December 2014 22:58
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Random DEC Questions
On Thursday (12/04/2014 at 02:34PM -0800), Ian McLaughlin wrote:
> > On Dec 4, 2014, at 2:27 PM, Robert Jarratt
> > I opened up the VT320 tonight. The PSU is set for 240V, which is
> > good. However, I noticed some corrosion around the flyback
> > transformer. I have posted a picture here: http://1drv.ms/1zqDhx5
> > This looks like corrosion of some kind of retaining clip perhaps,
anything functional. Am I right, or should I be
> The brown between the ferrite core and the white coil housing is normal
used in the flyback manufacture.
However, the rust on the metal clip holding the ferrite core together is
definitely unusual - I've never seen this before. Obviously a sign of
some point in its history. Is there any other signs
of moisture? The
clip itself is
purely mechanical (holding the two parts of the
ferrite core together) and
serves no electrical purpose. As long as it's still structurally sound,
I have actually seen a lot of this, particularly on VT220 I have restored.
By the looks of yours, I'd say the clip is toast.
It does hold the core together so if it comes apart and there's later
significance, the core might come apart and then you
don't have a flyback
I would try to clean up the particles that remain as they are conductive
they migrate into other parts of the circuit or if the
remains of the clip
off and end up somewhere else in the circuit,
you'll have a lot more to
Indeed, I intend to clean up the area as there are some rust particles
I have repaired several flybacks with this problem by removing them from
board, removing the rusted clip and all the gunk and
then threading a #12
#14 insulated copper wire through the core and around
the ferrite and then
twisting it back on itself to cinch it up.
You might also be able to accomplish similar without removing the flyback
from the board if you can get your cinch wire underneath the bottom of the
core, between it and the PCB and then wrap it over the top. I think the
splits right about where most of your clip has
disappeared-- about half
the side of the flyback in your photo.
I haven't it done it this way myself but you might also be able to save it
some epoxy or even hot melt glue if you can
encapsulate both halves of the
ferrite that way.
It looks like I can get some wire around the core halves to hold them
together, without removing the board. I will have a look at the weekend.