[time-nuts] 5070B once more.... (actually 5370A fans)

[Bruce Griffiths]

The ECL and EECL chips are located on  A22 (arming board), A19 + A20
(interpolator boards), A18, A17 (count chain assembly) A8 (reference
buffer), A21 (multiplier assembly).
The interpolator boards are more or less directly in line with the
ducted airflow from the fan as are  the reference buffer and frequency
multiplier boards.
A22 which has most of the ECL and EECL logic is mounted at right angles
to the initial ducted fan airflow which impinges on its rear surface.
>From this point some air flows through the gap between A22 and the side
panel and flows across the font of A22, the input amplifier and schmitt
trigger boards and the front panel board.
The rear of A22 also deflects airflow back through thecard cage and the
other boards.
The crystal oscillator is screened from direct airflow by a sheet
aluminium shield.

Thus the airflow is quite complex and one would need to monitor the
temperatures of a large number of chips and other components to ensure
the cooling is appropriate.
Since the top and bottom covers also affect the airflow it would be
difficult to use a thermal camera to meaningfully monitor chip temperatures.
Even if the top and bottom covers were replaced with infrared
transparent materials, a thermal vision camera won't have a clear view
of all the EECL and ECL chips.

Bruce

Rick Karlquist wrote:
> Hal Murray wrote:
>   
>> How much ECL is used in a 5070?
>>     
>
> A bunch
>
> How tightly are they packed?
>
> You need a high cooling velocity even if just one chip.
>
>   
>> How much of
>> the heat goes directly from the chip to the air rather than from chip to
>> board to air?
>>     
>
> A substantial amount of cooling is from DIP to air, unlike tiny
> SMT packages used now.
>
>   
>> How much room is there above the chips?  Many years ago I saw some neat
>>     
>
> Probably not much extra room.
>
> Rick Karlquist N6RK
>
>
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