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 Post subject: General Note on Heathkit (x-kit) Restorations
PostPosted: Jan Sun 13, 2019 12:58 am 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 5018
Location: Sunbury, Ohio 43074
I just had it firmly re-hammered into my head that sometimes test equipment kit builders can miss a step. In this case, the simplest of instruments, a Heathkit IN-12 resistance substitution box. What can possibly go wrong? I dug this out of the depths of the "get to it someday" drawers because I'm currently on a kick to get some of my pile of basic VOM, VTVM etc fixed up and out into circulation. I've bought from a fellow ARF'er an HP meter calibrator for the voltage and current cal, re-capped and calibrated it, but still needed a range of resistances. So I decided this 10% tolerance resistance box would do the trick. I'm measuring each resistor, and rather than replacing those near or just out of original tolerance, I'm just re-marking the dial with exact values. It will serve it's intended purpose for me perfectly this way..... BUT ........ in checking them with my DER-EE, which is far more accurate than any of the meters I'm working on, I noticed that values were changing from the first time through to the second, and. third. Hmmmm what gives??? A quick inspection showed good soldering skills so I figured it was built by someone with experience.

To make an annoyingly long story short, the lead going from all the resistor commons buss to the output binding post, was NEVER SOLDERED to the common buss on the back of the switches. It was properly wrapped around the buss, but making, to say the least, bad and intermittent contact. Quick fix, but took a bit to notice. It's one of those things you keep overlooking.

As an aside, I did find one cracked (150 ohm) resistor that was reading about 22k, probably stressed during assembly. No sign of heating.

All's well. The reason for this post? When restoring a kit someone else built, you need to check it over with a microscope.

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 Post subject: Re: General Note on Heathkit (x-kit) Restorations
PostPosted: Jan Sun 13, 2019 4:31 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 14793
Location: Fernandina Beach, FL
My comments in another thread that relates to this!

Don Cavey wrote:
On checking the construction wiring, I can tell you that the TT-1A tube tester that I have just didn't work right. What found the problem was to start at the beginning of the construction manual (which came with it when I bought it!) and I found one wire on the wrong terminal of the Plate Switch. After that, it worked well. It can take some time but the IT-11 isn't all that big so you could start at the beginning and check everything if you feel so inclined.

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 Post subject: Re: General Note on Heathkit (x-kit) Restorations
PostPosted: Jan Sun 13, 2019 6:37 pm 
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Joined: Jun Fri 19, 2009 6:34 pm
Posts: 8766
Location: Long Island
It's not like there are no such things as cold or crystalized solder joints and faulty components in commercial gear too!

I've had Heathkit gear that was put together by really meticulous individuals and it is every bit as good as factory gear--in fact better than some. Then I've had other kits that were put together by slobs. Regardless of origin, I never assume any used piece of equipment works, or was repaired or adjusted properly before it came to me, and you can add correctly assembled if it was a kit. Inspecting, fixing what needs to be fixed, and checking/adjusting calibration are all part of the fun.

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 Post subject: Re: General Note on Heathkit (x-kit) Restorations
PostPosted: Jan Sun 13, 2019 7:17 pm 
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Joined: May Mon 18, 2009 5:55 pm
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Location: Erie, PA
I won’t forget a kit assembled Dynaco PAS-2 preamp that come to me for repairs for crackling and popping noise in both channels. Inside the workmanship looked excellent. Spent hours going through the whole thing piece by piece, couldn’t find a darn thing wrong but the problem persisted, plain as day. I turned the chassis upside down and started poking around and found it- The assembler folded them on so nicely it was really hard to tell… but they forgot to actually solder the secondary wires from the power transformer to the rectifier tube socket. Bingo.

-Mark-


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 Post subject: Re: General Note on Heathkit (x-kit) Restorations
PostPosted: Jan Sun 13, 2019 10:08 pm 
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Joined: May Wed 23, 2018 6:28 am
Posts: 486
It really isn't just a kit problem. I have a Stoddart Radio Interference and Field Intensity meter that I got back in the '60s that was discarded because it couldn't be fixed. It was an expensive item when it was made in the late '50s and complete Stoddart RIFI sets can still have a significant price. Stoddart made good equipment. I eventually found a joint with all of the wires soldered together but not soldered to the post they were to connect to in the power supply. The RIFI was creating its own interference.

John


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