WB2VSJ HP-23 Rebuild Page

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HP-23 Rebuild

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Heathkit HP-23 Rebuild

The HP-23 that I purchased was part of a SB-101 transceiver, SB-610 station monitor a

for $150!) When I got the units home, I decided to restore all of them back to near f

collection of my notes as to what I have found in terms of replacement parts and pain

and tricks I learned along the way.

Here are some photos of the power supplies initial condition. This thing looked like

didn't even try to turn it on, not even with a Variac. I decided it wasn't worth the trouble since I was going

rebuild it anyway.

The top of the transformer is a nicely coated with a good layer of rust

WB2VSJ HP-23 Rebuild Page http://www.heilsnis.com/wb2vsj/hp-23/hp-23.html

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Dust, spider webs and more dust


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At least the bottom looks a bit cleaner.


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Disassembly

Here is what the power supply looks like taken apart. Basically, I now have a Heathk

much to it once it is in pieces. The electrolytic capacitors measured ok in terms of

ESR was very high for them.


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The 100K bleeder resistors all were way out of spec. They measured:

Value Measured Value


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100K Ohm 124.66K Ohm

100K Ohm 115.824K Ohm

100K Ohm 119.180K Ohm

100K Ohm 118.496K Ohm

Capacitor Rebuild

Using a large tubing cutter, I was able to open the cans up. I didn't like the way th

"crimped" the edge of the cans. I may use a lathe on the other two as to not damage

Update - I was able to fix the "inward flare" by taking a 15/16" Sears Craftsman sock

the can and lightly tapping the edge with a rubber mallet. This smoothed out the edg

I then used a heat gun to heat the cans up a bit so the innards would slide out. I r

outside - they really reek. You know that smell of antique radio, that unique scent

radios? The scent that says "Say, there must be a antique radio in this room somewher

Well, it's the capacitors. Take one apart someday and take a small whiff. You'll k

I ordered modern caps from Mouser to put inside the old cans. I'll use some aluminum

and bottom halves together. Once the paper covers are placed back on, you'll never k

(hopefully)


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Here's a closeup of the edge after I straightened out with a 15/16" socket. These th

tar . It took many cleanings with gasoline and "Goof Off" to get it all out. (Worst p

decided to roll in my dirty rags and get it on her head. The gas had pretty much eva


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the smelly tar that she had on her head. I swear, Yellow Labs are the most loyal, lov

world, but they have a sack of potatoes for brains.)


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Now we have all the parts to make a "new" can cap.

New cap is rated 150uf/450V at 105 Deg C. Sorry that doesn't show up in the picture.


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Here is the new Cap mounted on the old base. I cut off the aluminum feeder strips, th


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holes, one near the ground lug and one near the original pos lead and then soldered t

the bottom side. I put some heat shirnk on the leads for the heck of it..


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Bottom view


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Here are the top and bottom. You can see where the leads from the cap are now wrapped


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Taped together with aluminum tape.


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With the paper sleeves on. Which one is the original and which one is the rebuilt one

clean the flux off the lugs on the right one.

Old capacitor was rated 125uF 450V at 85 Deg C

New capacitor is rated at 150uf 450V at 105 Deg C


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I was able to get my HVLP sprayer working today and was able to shoot the bottom plat

supply. Here is what I did:

Stripped the paint off with paint stripper. Two applications didn't not take it all o1.

Sanded the rest of the paint off with a palm sander.2.

Cleaned the surface off with lacquer thinner.3.

Primed the surface with 2 coats of Lowes Valspar interior/exterior primer .4.

In order to give it some texture I used some Rust-oleum texture paint. I tried the "

does not have a 3D effect, It is only 2D. It is very flat, no texture. I need to try

Traditions Stone spray. But I'm thinking that may have too much texture.

5.

Two top coats of my Home Depot Blend. 6.

Finished off with a light coat of lacquer gloss to give it some sheen.7.

Between steps 5 and 6 I wanted to try out Glen Zooks, K9STH formulas to see how they

the Heathkit colors were not very uniform and I may not have a good match.

So I went to Sherwin-Williams and asked them to scan the chassis and then compare it

K9STH (His paint formulas are here ->http://k9sth.com/uploads/Boat_Anchor_Paint_article.pdf

behind the counter seemed to think that K9STH's formula would match better than what


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it is like the guys in the movie "The Matrix" - they can see people and things in the

screens.

I came home with a quart of "Apache Green" and tried it out. It was a bit too dark.

Heathkits variants. I had a another paint sample that was made up at Home Depot and

perfectly. I finished it off with a light coat of clear lacquer gloss to give it a bit of sheen.

Here you can see the newly painted bottom plate (the one with the slots) up against t


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Another View - The bottom plate is really glossier than it looks. And the original c

photograph makes it out to be.


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The next thing I tackled was the power transformer cover. It was completely rusted. I


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fiber abrasive wheel to remove most of the rust. The inside corners required a bit o

paint job here was a bit simpler:

Sanded off the rust/paint1.

Cleaned with lacquer thinner2.

Primed3.

Painted with high gloss black lacquer4.

Here is the cover screwed down to the bench so it is easier to sand.


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The only real problem I had was removing the four bolts that held the covers and lami


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one came out fine, the next three all sheared off. Two of which I was able to hammer

one was a royal pain in the a@@. I eventually had to drill it out. The potting material had glued it so tight

never coming out. All this to paint something no one will ever see once it's assembled ...

Assembly! (finally)

Fresh paint and all the parts ready to go.


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New power plugs (from Radio Daze)


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Before you email me and ask why the color changed, let me explain. All the previous

flash on the camera. This photo below was taken with ambient room lighting. The lig

will make things look different.


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