Re: New 2465 Seimens brushless motor


Hi Greg,

I assume HP had two different designs for the fan during the run of the instrument. I've had three of them and I'm pretty sure all three have had the Siemens motor.

One of the fan assemblies for the 8640B sold recently on eBay:

Barry - N4BUQ

----- Original Message -----
From: "Greg Muir via Groups.Io" <>
Sent: Sunday, February 23, 2020 10:45:10 PM
Subject: Re: [TekScopes] New 2465 Seimens brushless motor


It appears that there is sort of a judgment call on the fan motor used in the
8640B signal generator.

Looking in the 8640A manual that I have (08640-90114) the motor is definitely
called out and illustrated in the schematic as of the brushless design.

However, there are differences seen in the 8640B documentation. I referred
to a 2-volume manual set for the 8640B number 08640-90215 dated May 91 and
also noted as a “Mark-up Copy” that applies to serials 2520A through 2923A
plus any included updates for later serials.

Referring to volume 1, there is a call-out in the parts list on page 6-117 of
2 DC style motors:

For serial numbers 2939A and below:
3160-0453 “FAN-TBAX 23-CFM 12VDC .25KV-DIEL” Mfr code 28480. Mfr part
number 3160-0453
(Mfr code 28480 is HP)

For serial numbers 2939A and above:
3160-0497 “”FAN-TBAX 23-CFM 12VDC” Mfr code 11039, Mfr part number 612
(Any reference for Mfr code 11039 cannot be found)

However, on page 8B-123 titled “Service Sheet 19” there is a description of
the -5.2V supply & fan driver assembly A18 where it describes the brushless
motor & associated driver.

However in volume 2 if you go to Service Sheet 19 you will find a DC motor
being driven by a simple DC controller.

As for the part number for a brushless motor, I could not find it in either

It’s not that I don’t believe that a brushless motor design was used in the
8640B since there is a hint of the description of one but it also appears
that HP once used a DC motor design as well. It looks like a judgment call
on this one.


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