RCA TRK-5 Restoration

 

 

The TRK-5 is my forth pre-war television, it was purchased from the relatives of the original owner who lived in a small town north of Newark, NJ. It was probably used into the late 40's as there was a repair tag dated 1946. Also the radio had extensive repairs done, the filter capacitor and most of the paper capacitors were replaced. Other than replacement tubes I didn't see any other signs of repairs done to the television chassis. More than likely when the television failed the radio was kept in playing condition, as the set is not much bigger than a comparable console radio of this period.

 

Before and after pictures of the interior of the set. Everything on this piece was covered in a thick nasty crud. The interior paint was flaking off, mainly due to moisture from being stored in a barn and that no primer was applied before the paint. There was a small amount of mouse damage to the tops of the chassis', but luckily no wiring or parts were used as food. All the wiring harnesses are hard and brittle and have to be replaced with new wires. The chassis' were cleaned with a solution of phosphoric acid, which removes the dirt and grime but leaves the chassis stamps intact.

 

The radio chassis before cleaning and restoration.

 

Radio chassis after cleaning and restoration

 

The television chassis before cleaning and restoration.

The television chassis after cleaning and restoration.

 

Before and after pictures of the speaker and radio power supply.

 

 

Before and after close ups of the radio bezel. I wasn't sure if the bezel and pushbuttons would be able to be salvaged as they are made of a material called "tennite" which is the equivalent of "pot metal" in the plastics world. The bezel has only shrunk a small amount and has a very small crack on the edge of the bottom center screw hole. The white crud was cleaned off with a combination of Fantastik and plastic polish. The pushbuttons still need the call sign inserts, I need to find some originals or try to create new ones.

I created the pushbutton inserts in MS Word, coloring is a little off but they complete the front.

The restoration of this set has had a small setback, the power transformer HV winding shorted out during testing. I will need to have a replacement made.  Before the transformer smoked, I was able to verify good video signal at the CRT and sweep signals to the CRT deflection plates.

August, 2004
The new transformer has been installed in the chassis. It wasn't a drop in replacement though. First problem was the new core mounting holes were different that the original, so I needed to re-drill the top and bottom covers. The top cover had enough area to make clean holes with no interference, but the bottom cover was a bit more of a problem. After getting the holes to match up and drill the new mounting holes on the chassis, another problem came to light. The new core was a 1/4" taller than the original, so the bottom of the transformer was below the chassis. After much head scratching the only thing that could be done was to remove 14 laminations to shorten the core the needed amount. Reassembling the transformer and it now fits like a glove, I'm home free - or so I thought.

Turning on the set I was able to get a raster and picture although only about 2" x 2", no adjustment of the size or position controls would help. Time to troubleshoot. First, check B+, all good here; next check HV, 3,100vdc on the tube, seems a bit high. Sure enough the maximum 2nd anode voltage for the 5BP4/1802P4 is 2,000v. Seems there was a miscommunication on the HV spec when the transformer was wound, instead of being specified for 2,000vdc output it was wound for 2,500vac output. The fix ended up being to add a resistor into the transformer HV lead to the rectifier, this brought the HV on the tube down to 1,900v and I have good deflection. The only drawback seems to be I lost some regulation on the HV so I have to put up with some blooming on bright scenes. I guess I could add a HV regulator......

May, 2011
A new power transformer with the correct HV winding has been ordered to replace the current unit, hope to have it installed in the next couple of months.

 

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