Hi.

Anyone have any hard won experience as to how best to tackle the removal of the cooling fan from a HP8620C sweeper mainframe?

The fan in mine, is running slow (so the instrument, and especially the plug ins, "run rather warm.") It is also making "grumbling bearing" sounds, so I'd like to remove it for overhaul (clean and lube, as I've done for many others) or replace it with a more modern alternative.

I am aware it is an early DC driven device, with external motor position sensor and drivers, plus it's speed is governed by a temperature sensor somewhere.
By the sound of it, non unlike some of the early Tek 465 'scope fans, but probably physically very different.

I've a "user" manual so far, but that just talks about removing/cleaning/replacing the mesh air filter.

Any advice at this stage welcome.

Regards to All.

Dave B

On Thu, Oct 28, 2021 at 06:42 PM, Dave_G0WBX wrote:

By the sound of it, non unlike some of the early Tek 465 'scope fans, but probably physically very different.

As it happens, some HP 8620 series were equipped with the very same Siemens fan motor that Tek used in their 465-family of 'scopes.
A lot has been written about their behaviour and overhaul, see Tekscopes groups.io.

Raymond

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As it happens, some HP 8620 series were equipped with the very same Siemens fan motor that Tek used in their 465-family of 'scopes.
A lot has been written about their behaviour and overhaul, see Tekscopes groups.io.

Raymond

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Ah!..? Interesting, as I have a scavenged Tek fan motor assembly from that era...? Somewhere...

Having worked at Tek during that time for some 3 years, I'm well aware of some of the odd behaviour they could show.? Usually down to the transistor array chip, or the thermistor partially failing.

I'll report back when I've dived in, but lots of other non tech' priorities first, sadly.

Thanks Raymond.

Dave B.

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