Fire Soot Covered Heathkit HR-20

 

I picked up this HR-20 on eBay. The eBay ad pictures did not indicate the chassis was covered in what appears to be soot possibly from a shack or house fire. The tube shields were missing so replacement will need to be obtained.

Soot covered chassis

Soot covered meter

I removed all the tubes, the front panel, and the S meter. I mixed up a warm water and Dawn dish soap solution in an empty coffee can. I used a soft paint brush and washed the chassis and tuning assembly. This removed a lot of the soot but the soot had produced a stain that could not be removed.

I checked the various coil and IF transformer slugs and trimmer capacitors to ensure they were not “frozen/stuck”, they all rotated. This changed any previous alignment the receiver had before the Fire soot covering.

There are 7 resistance checks to ground listed in the manual that are performed on the 11 pin connector. Pin 1 is suppose to be 30 ohms but my VTVM measured 57 ohms. Pin 1 connects to the audio transformer’s secondary winding and ground. This difference in resistance measurement needs to be looked into as to why it’s 20 ohm higher than the manual states it should be.

Cleaned chassis top, tuning assembly back panel, and meter. Although the soot is removed, it left a stain that can’t be removed. The tube labels and the coil and trimmer capacitor labels are still visible.

Unfortunately the soot destroyed most of the rotating tube dial frequency markings.

The meter cleaned up rather well. I removed it from the chassis to clean it manually. I verified the meter works as the meter deflected to mid scale and FS by quickly tapping the meter terminals with my Ohm meter.

The front panel was cleaned but left a dull finish.

I used ArmoAll Protector to clean up the front panel and the knobs. The knobs and front panel turned out rather well. The thin clear dial cover on the back of the front panel cleaned up nicely.

This HR-20 is not a lost cause, it’s going to take a lot of work to bring it back to operational condition.