"tekman" wrote in
oups.com:


Jim Yanik wrote:
"James Sweet" wrote in
news:x93Oe.2976$0U6.2125@trnddc09:


"satelitko" wrote in message
lkaboutelectronice
qui pment.com...
Is there anyone who have a service manula for this oscilloscope? I
bought used one, but found that an IC on fan motor board is
missing - so fan doesn`t work at all.
Regards, Gregor


ISTR that it was a 5-transistor array.
IIRC,the same chip was used in 400 series scope fan
circuits(465?,485),they both used the same Hall-effect fan motor.Also
in some 7000 series mainframes(78xx79xx,IIRC).

In later 2445/65 series scopes,that fan assy was replaced by a simple
12v fan like used in PC power supplies.The rear chassis panel was
modified to accept the new fan. I would probably mod that 2465 myself
if the fan was bad,rather than try to find a IC and find the motor
was bad,or do without a fan;a bad idea.

--

It is as Jim said a 5 transistor array. A CA3046 or 3086 should work
well.

The letter series scopes ("A" or "B") have the PC style fan.

The non letter 24xx scopes have the Siemens Hall effect controlled
motor.
Same as 465/466/465B/475 and 7844/7834/7904A etc. The 7904 has no fan,
so it's really an ease for long hours work (less noise ,-) )

Thanks for the clarification!


If you want to modify a 2445/2465 for the PC style fan: Go and find a
different rear plastic; e.g. from a junker A or B model.

It's not just the rear plastic cover,the rear metal chassis plate must be
changed or altered;there are several holes for the PC fan's airflow instead
of the single large hole for the H-E fan's impeller,and I believe the PC
style rear plate has a depression for the PC style fan.

By not replacing the fan you will fry your hybrids sooner or later
(especialy the U800 IC for horizontal drive). Which means your scope
will be completely dead. Do NOT risk this.

DEFINITELY.



hth,
Andreas





--
Jim Yanik
jyanik
at
kua.net