11.11.20

10.11.2020 New PSU for the drives and dew bands.


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Tuesday: Days of serial, heavy overcast continue.

My new Mean Well RS150-12, 12V, 12.5A, 150W PSU has arrived.

NOTE: This "industrial" PSU is designed to be encased for consumer safety. It would normally be hidden inside closed equipment requiring tools to be opened.

Things did not start well when I read the yellow notice to check the mains input voltage before switching on. With no label to suggest the voltage setting as supplied. Nor where the switch might be. The arrow actually points to it but I had no idea what I was supposed to be looking for at the time.

The online dealer would not answer queries from a private customer. Nor will I ever deal with them again. Except for possible guarantee issues.

Fortunately there were helpful souls online in the astro community who could help. There was quite a large, red, sliding switch just visible inside the perforated case. But only once I had the correct light, at the correct angle and I was wearing my strongest reading glasses. I also used a magnifying glass to help me focus through the perforated screen.

Once confirmed at 230V the first connection trial went well. My two Astrozap dew bands now worked normally via the AstroTech 4-way controller. Drawing much less current than I had expected given the short life of their recently purchased PSU. Only 1.7A with two knobs set at full on. This should not have caused premature failure of the replacement PSU with only half way settings.

Next came the AWR drives. Their original PSU had died prematurely too. The new, 5A replacement was getting warm. Now the drives worked and slewed normally once I had connected the shielded speaker plugs to the more robust PSU.

I shall have to return the month-old 5A PSU for a replacement or refund. It is always handy to have a replacement in case of further failures. They do seem to be prone to premature death. We have already had two failures of the fibre optics Internet PSU. One would assume they would choose quality over cheapness.

In the meantime I shall have to order a cooling fan and protective case for the new PSU. It is designed to be "embedded" [fully enclosed]  to protect users from shock on the bare, mains terminals. The manufacturers also ask for a metal plate mounting to act as a heat sink. I have several sizes of large, box profile aluminium sections. So I will see if anything suits the PSUs dimensions without being too bulky.

I have ordered a plastic case, with screw down lid, for the PSU and a near silent, 40mm cooling fan. I wanted basic weatherproofing and isolation from the live terminals. The aluminium box sections were so heavyweight they were total overkill. I would still need to seal the ends. 

So I searched online for properly sealed, electrical installation boxes instead. The small fan size will allow it to be mounted on the lower end of the box to avoid rainwater ingress when it is pier mounted. I should have room inside the box for an L-shaped heat sink plate for maximum area. Initial tests showed only 1°F increase over ambient on the perforated case. This was while running two dew heater bands and slewing continuously on the AWR paddle.


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