AC outlet. Set the external voltmeter to read 10 volts AC. Connect the external voltmeter common lead to the black sine wave output binding post. Connect the other voltmeter lead to the red sine wave output binding post. Disconnect the external voltmeter.
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Trouble Log Summary Gallery of Heathkit Restoration Projects Photos are shown below of additional Heathkit test instrument restoration projects using the techniques detailed on the IM project page. The end goal of this work is to refurbish nearly all test equipment on my bench to the style developed for the IM This work is time-consuming, and expensive.
However, the end results are very nice. So, I will keep going IM Harmonic Distortion Analyzer The original front panel for this instrument is shown on the right, with the polycarbonate overlay next to it. As with the IM project, the original front panel was scanned and reproduced in Adobe Illustrator.
The finished instrument is shown below. The case panels were done in a powder coat finish. Nearly all of the front panels done so far and documented on this page were first versions. In a couple of instances, however, a second panel run was required to get it right. IO Dual Trace Oscilloscope The original front panel of the instrument is shown on the right, with the polycarbonate overlay next to it. The front panel for this instrument is somewhat complex, but manageable.
The finished results are shown below. It is quite a transformation. The photo on the right shows the instrument on a roll-around stand. As with the other restorations, the case was given a powder coat finish. I have come to prefer the look of the all-white front panel over the two-tone white and blue of the original instrument. The original front panel color and legends were contained on a plastic insert.
As such, use of the polycarbonate overlay made for a clean, uncomplicated installation. IG Audio Frequency Generator The techniques used in previous update projects were repeated here. The original front panel is shown on the left, along with the replacement polycarbonate overlay on the right. A powder coat finish was used, as before. Most of the knobs were replaced with new units. User preference comes into play when the look of an instrument is under consideration. My preference is the clean white panel with the nice contrast of the blue cabinet.
In order to match the look of the other refurbished instruments, the overlay base color selected was white. The original panel is shown on the left, and the overlay is shown on the right. The unit features a large meter and intuitive layout.
The transformation was dramatic. This instrument is a pleasure to use. The large, easy to read meter is a welcome break from LCD displays, which typically do a poor job of representing varying voltages.
While the IM 25 was loaded with features and had top-notch styling, it and other multimeters of the day required one or more batteries to operate. The IM eliminated that requirement. The original front panel, shown on the left, had a white base with blue accent. The replacement overlay, on the right, simplifies the layout by eliminating the blue accent. Installation of the overlay on this style of instrument is straightforward.
A minimum of disassembly is required. This is another case where the blue accent on the front panel was eliminated. With a number of different Heathkit instruments converted to the white base polycarbonate overlay, I have come to strongly prefer the consistent look of the white panel.
Owing to the construction of the overlay, aggressive cleaning is possible if needed at some point in the future without risk of damaging the printed legends. IG Sweep Generator The IG is a perfect candidate for replacement of the front panel with a polycarbonate overlay. This instrument, like the IO above used a plastic insert over a metal base panel.
Over the years, the insert tends to yellow. As shown in the photos on the right, the original panel was in bad shape. The replacement was an enormous improvement. The original panel insert did not have an adhesive backing or at least it disintegrated over the years. This caused the old insert to fit poorly in some cases. The new panel solved this problem.
The basic color scheme is a beige panel and brown cabinet with black trim. Following the approach taken in the other instrument refurbishment projects, a white panel was produced with black and red lettering.
The cabinet was refinished in blue to match the other instruments in this line. The new front panel and cabinet color completely remakes the look of the unit so it matches the "blue line" of instruments. IM Frequency Counter The obvious approach for the IM is to duplicate the look of the existing front panel to the extent practical.
This was the starting point for development of the overlay. The original panel, with its translucent upper half, is quite difficult to duplicate with the available tools and processes. The compromise made for this overlay involves providing a window for the LED displays, rather than having the entire upper portion of the panel open.
As in the original, the basic panel color is white, with black lettering and spot color red and blue for the legends as required. The updated instruments extend the operating frequency range from the basic MHz. The newer instruments have an input selection switch and additional BNC input jacks.
The procedure for adding a new overlay is essentially identical to the IM , except for the additional hardware.
A new overlay is, of course, required. A later version, the IG , is essentially identical, except for the color scheme, which features a white front panel and blue case. Two screw-on "Amphenol"connectors are used on the front panel of the IG During the upgrade, these were changed to the more common BNC type, which is also used on the IG A large number of these instruments are in circulation.
The remake of the IP A was straightforward. No modifications of the unit were needed. When combined with a new finish for the case and new Davies knobs to match the other refurbishment projects, this turned out very nice. The first step was to remove all components from the front panel so it could be scanned to create the polycarbonate overlay artwork. Because of the construction of the unit, however, a conventional scanner was not used.
The chassis and front panel are one piece of sheet metal, Problems relating to scanning included the size and weight of the piece. Rather than use a scanner to capture the front panel, a photograph was taken and then imported into Adobe Illustrator where the artwork was created.
The end result was quite good, as shown in the photos. Audio Load Test Set This project involved updating the front panel of a special-purpose audio load test set. It appears the unit was intended for service centers, rather than consumers.
In any event, the two channel load permits easy switching of the output of an amplifier under test between external speakers and an internal load. In addition, a switchable test port is provided. The front panel of this instrument is simple and straightforward.
Two versions are available—one with an analog meter and another with a digital readout. As with previous projects, the two-tone color scheme of the front panel was eliminated in favor of an all-white panel, which matches all of the other restoration projects documented here. Projects Completed With the completion of the IP power supply above , all of the equipment on the bench has been refurbished. The bench is shown in the photo below. The test instruments are loosely grouped as follows from top row to bottom row : RF, power supplies, signal generators, signal analysis, and test sets.
In addition to the instruments shown, there are also two IO oscilloscopes. It can be seen that there are duplicates for most instruments.
This was done by design to allow for simultaneous 2-channel measurements. Also, in recognition of the age of the Heathkit equipment, having a second known-good instrument is probably a good thing. I had previously collected many more Heathkit instruments, but sold them off over time as it became clear what instruments I would use, and those that I would likely not use.
The projects that I expected to do in the future drove those decisions. I have narrowed my focus to audio amplifiers and radio receivers. Power for all the instruments comes from a single master switch to allow for convenient shutdown of all equipment.
In addition to the instruments shown here, a computer has been dedicated to measurement applications, as described in the About the Workbench page Overlays Available As noted in the previous entry, I have collected all of the Heathkit test instruments that I plan on collecting. In the process of refurbishing the instruments I have accumulated a number of extra polycarbonate overlays.
In many cases, the cost to produce one is about the same as to produce So, some extra copies are available. If you are interested in getting an overlay for one or more of the instruments shown on this page just send me an email with the mailing information. No charge. Happy to help another Heathkit enthusiast.
Audio Generator IG-5218
Heathkit IG 5218 Manual