Mike:

Graham has explained how to remove the front panel: my comments which
follow are the result of dismantling a 730/4 with my friend John,
G3UJZ.
Firstly, always note carefully where there are any spacer washers and
put them back as found otherwise thing may catch and graunch.
Secondly, try and loosen the front panel switches by a thin spanner
from the back rather than graunching the front round knurled nuts and
the finger plate.
John and I proceeded with taking the front off the 730/4 by having to
cut off and stud extract the countersunk screws which were seemingly
welded to the aly bosses. I examined the drive free from the
receiver, and noted that the logging wheel was catching. I carefully
dismantled the friction pinch mechanism, removed the three attachment
screws from the triangular brass plate which houses the antibacklash
gears (which I did NOT want to disturb!), noted the spacing washers,
and saw that the logging wheel had made rub marks on the back of the
main dial. After cleaning things up and removing unnecessary 3-in-1
lubricant, I reassembled the mechanism and replaced the drive knob so
that I could spin the flywheel to try and find the problem. I then
noticed that the drive was free running with the dial resting
downwards (supported on blocks) but on its back with the dial up it
was binding badly. With it again face down, I discovered that lifting
the knob upwards on its play seemed to cure the problem. I gently
held the flywheel forward, and re-locked the knob with a few thou of
play: and it was cured! Free spinning, no catching. And it worked on
my 750 and 888A as well. Find the flywheel access hole under the
front below the tuning knob, rotate the flywheel to the locking screw
hole: work it round with a screwdriver if the flywheel is loose,
tighten the flywheel grubscrew, pull the flywheel gently forward
using a screwdriver in the grubscrew hole, and adjust back the tuning
know so that it has a few thou play rather than the 0.15" or so. And
it worked! Both drives spin freely and the 750 tight spots have gone.
The 888A drive seems to be about 2.5 times less geared than the 750
with the 730/4 between the two. The flywheel is still loose on the
730/4, so I need to take the case off to see what is happening.

Now then, why was an access hole provided to the flywheel? Was it
because of a recurring problem such as mine? More worryingly, is mine
a good solution? Does it place unintended strain on any part of the
mechanism such as the pinch drive? It seems OK, but is it?
It would really help if we had access to someone who worked on these
dials at the factory!

Regards, Chris Harmer, M0HMR, moderator


--- In eddystone_radio_users@..., "daly8888"
<mike@e...> wrote:
>
> I have just taken delivery of my first Eddystone, a 730/4. The name
> plate on the front has the following additional information:-
ZA51262,
> Serial No. 627, Manufacturer STR/QJ. It's in fairly good condition
but
> has a problem - the tuning drive is slipping. When I turn the
tuning
> knob sometimes the tuning moves but most times it does not.
>
> I've had a quick look at the set but cannot see how to remove the
> front panel to gain access to the drive mechanism. I remember, in
my
> youth, servicing Marconi signal generators and how difficult they
> could be if a manual was not available.
>
> So, can anyone give me a hint on how to remove the front panel
please?
>
> Regards
>
> Mike
>