Wednesday, December 29, 2021

Starting To Feel A Bit Like Indiana Jones Here.....

 Only it's not snakes, it's power supplies.


I finished cleaning up, "Buffing Out", and reassembling the THD Analyzer and started the "Initial Checks" section of the manual. 


The first few steps went fine, and then Murphy popped up again. The (nominal) 24 Volt supply measured 27 VDC, while the (nominal) -24 Volt supply measured -30 VDC.

OOOPS.....WAY out of spec

Further checking and experimenting revealed the negative supply regulator was toast, and regardless of what resistor values I used on the "Adjust" pin, the output stayed stuck at -30 VDC. The circuit uses a uA78MG for the positive side, and a uA79MG for the negative side. These are obsolete parts, and on top of that, they're in an oddball package. *IF* you can find them, they go for $20~$30 each, plus shipping. Exact matching parts, in the odd package, are available from Europe for slightly less, but the shipping is $25 for each part! Considering I only paid $75 for the whole analyzer, there's no flipping way I'm putting that much into it for two little parts.

So, I'll replace the positive regulator with an LM317, and the negative regulator with an LM337, both of which should be available for the foreseeable future. I removed the two existing regulators and their adjustment resistors, and replaced all the filter capacitors on the power supply board. I'll build up a little "daughter board" and connect it to the rebuilt power supply board, which will become the "Rectifier and Filter Board".

Cleaned up power supply board:

 Parts should be here in a couple of days, and once the new power supply is up and running I'll continue on with the Initial Adjustments and Calibration.

Our Christmas Day celebration was a joy, and we had twenty people over, including seven little ones:

Pandemonium reigned, and paper flew everywhere....

And I received one of the most touching, thoughtful, memorable Christmas gifts I've ever received:

I'd mentioned to my SLW earlier this year that I wanted to get a flag flown over the Iowa. I thought it would be nice to have one to fly on certain days. Well, she started looking into it, and found out you can get one via the Gift Shop aboard the ship. She requested it be flown on my birthday, and was told "Uhhh.....well.....we don't do special requests like that". Being the O-6 on this here base, she's used to getting what she wants, so she marched it up the chain-of-command, and through the auspices of some Friends In High Places, she was able to get the flag flown on my birthday. She then ordered a stealth raid on my Iowa memorabilia, and procured one of my challenge coins, my CPO Club membership card, and one of the BOGO coupons I still have a ton of. My son then went on eBay and found two "covers" that had been canceled aboard the ship; one from 1946, and one from the very last mail run off the ship before she was decommissioned in 1990. They put them in a shadow box, and presented it to me Christmas Eve.

I'm truly touched, and for the first time in my life, I think I understand why Military People feel the way they do when given an award. Other people deserve this more than I do, and every time I see this on the wall, I'll think of those who served on the ship, and those who gave their lives in service to their Country.

Wishing you all a very Happy and Prosperous New Year!


  1. Well done to her! Sounds like the house stood up to the kids too! LOL

    1. @NFO - Yep, she definitely gets a "BZ" on this one. It's a riot when we have that many people, and now all the little ones are big enough to play and have fun. Makes this big old place come alive!

      @WSF - Thanks!

  2. Rank does have it's privilege...

    1. And being a Museum Plank Owner helps a bit, too!

  3. That shadow box made the room dusty. Strange how that works ...
    But BZ to the Thoughtful One for such a gift. And yeah, you've got the right of it, regarding military awards. The only one I ever received that felt deserved (mostly) was the Good Conduct Ribbon. (And that one was probably because I never got caught doing anything stupid.)

    1. "I Never Got Caught...."

      A key to success in many endeavors!

      We're forecast for 1~3" of snow Friday, with another 3~7" Friday night, so it looks like the Ariens will finally be getting some use.

      Fired it up again today and drove it around the sidewalks and driveway to make sure I still remembered how to use it!

  4. What a blessed holiday for you, drjim.

    I hope you are all safe and well. Not sure of your location in relation to the fires I saw on the TV earlier today. God bless you all and keep you safe.

    1. Thanks, Linda. Yes, it's amazing how having 7 little ones running around on Christmas Day can change your outlook! We don't have a lot of "wealth" money, but we're "wealthy" in many other ways.

      The fires are down by Boulder, about 40~45 miles South of here.

    2. May they stay far away. Happy and blessed New Year to you all, drjim.

  5. Beautiful gift, and 20 people! Careful in the firestorm...

    1. Thanks, Parson.

      Gee....20 people and not a mask in sight!


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