Heathkit GR-900 Build Thread!

[N2IXK]

Got started on the build by putting together the "Troubleshooter", a simple VOM that Heath included in the kit to aid in testing and repairing the set as needed. Heathkit really went out of their way to make sure that just about anyone could successfully build one of their kits, without any need for specialized tools or test gear. They didn't assume that anyone building a TV kit actually knew anything about electronics, or already owned a multimeter. They didn't even assume you would have access to "exotic" tools like a 1/4" nutdriver, so one was included with the kit, as well as a small open end wrench and the famous red plastic nut starter. As you can see, they even included an Eveready zinc-carbon AA cell, which I was AMAZED to find not only hadn't leaked over the last 40 years, but still read 1.5 volts on my DMM! I didn't install it, though, opting for a modern alkaline AA cell instead. Will keep the included one around for laughs. Haven't seen one of those since I was a kid.

This is a 5 range DC voltmeter and ohmmeter, which also includes a special A-B-C-D-E scale to be used by non technical types to verify that a certain reading is within an acceptable range, such as resistance checks of power supply rails prior to applying power, etc. Function and range selection via a pair of 3 position slide switches. Ranges are 5, 50, or 500 VDC, and R x 1k or R x 10k for the resistance ranges. This meter was only sold as part of their TV kits, not available as a stand-alone kit.

The build itself was obviously pretty simple. The meter, switches, pot, and battery holder get mounted into the case, then the components are wired together point-to point. There are 3 precision resistors for the voltmeter ranges, and a few other resistors and diodes for the ohmmeter and meter overload protection. Construction took a leisurely hour or so, thoroughly enjoying the Heathkit experience again after many years. The meter tests out fine, and was set aside to await installation into the rest of the set.

Next up: The TV build itself gets underway with the Audio module...

[Findm-Keepm]

Are you replacing the electrolytics that came with the kit with new ones?

I'd be a bit wary building such a rare treasure with 40-year old caps.....


Cheers,

[N2IXK]

Originally Posted by Findm-Keepm

Are you replacing the electrolytics that came with the kit with new ones?

I'd be a bit wary building such a rare treasure with 40-year old caps.....

I am going to carefully reform the 2 multisection cans on a power supply, and see if they drop down to acceptable leakage current values.

The smaller low voltage ones will be tested for capacitance and ESR, and replaced if warranted.