The power resistors are epoxies to the chassis for improved heat dissipation.  The original resistor (R19/20 Riders,  R78 Sam's)  is used as a terminal/mounting strip.

Model 8G005TZ1, chassis 8C40TZ2 with 117Z3 half wave rectifier miniature tube.

click this.

Most critical to proper B+ is R80 (or R18 on Rider's), 56 ohm (Green, Blue, Black).  A higher value put the B+ out of range.

For Model 8G005YT with the 8C40 chassis -  Calculations for R18 - 20 (Rider's) filament dropping resistors for the 8C40 chassis that use a 117Z6 octal tube. 

The calculations for  the 970 ohm "candohm" resistor applies to other chassis as well (i.e., 8C40TZ2).

Replaced filament resistors in a 8C40 chassis using a 117Z6 full wave octal rectifier tube.  The first 1K ohm resistor measured 983 ohms.   Therefore, no parallel resistor was added. 

This is the Chassis just removed from the radio case.

This is the restored chassis with all bad capacitors and resistors replaced.

UL rated safety Capacitors installed in the 8C40 chassis for C13 and C29.

Click on this above image to enlarge and see fault path in red.   Schematic snippet from http://www.nostalgiaair.org/Resources/421/M0025421.htm

It is important to maintain the relative position of all replacement components to the originals.  Alignment is affected by the components proximity to each other.

The yellow capacitor below the detector coil (right) was particularly sensitive to placement under the coil for proper alignment.  When the capacitor was against the chassis as was the much larger original, one of the SW bands was extremely weak.  Once moved the test signal came in loud and clear.

During alignment of the Broadcast Band, the oscillator adjustment at 1600k Hz, oscillator trimmer had to be opened up almost 0.25 inches with no adjustment range remaining  (too far for my liking).  It should be closer.  About 2 to 3 mm.  

Moving the lead wires that connect the trimmer (C19, ch 8C40) to the oscillator coil help considerably.  The wires shown on the right were grouped together.  Experimentation with a plastic stick determined the green striped wire (connected from the trimmer to the oscillator coil) had the greatest effect.  Once separated,  the trimmer capacitor could be closed down thus yielding more adjustment range.  Attempting the same technique for the detector coil trimmer (C12) adjustment yielded no additional benefit.

All antenna trimmer capacitors were aligned once the chassis was reinstalled into the restored case.

Capacitors in place of the old foil can cap.

Better look.

Hot melt the cardboard cap.

Push on until hard.

Cleaning the dirt off of the chassis.

Removing the worn speaker grommet

  Had to cut it off.

Replacement Grommets

Grinding rivets on old power resistor.

  Removal of the old power resistor.  It will go bad soon.  So better to replace it now while on the bench.

  Completed under chassis.  New power resistors are Epoxy(ed) to chassis.  this adds mechanical strength and good heat conduction.

The case was disassembled, surface mounted hardware removed and all parts cleaned.  

All of the brass was shined up with Brasso and a coat of Minwax Finishing Past Wax.  A replacement clear plastic dial cover was installed in place of the missing one.  Non brass metals were treated with Tarn-X.

The completed and aligned chassis displays all the new capacitors, resistors, UL safety capacitors and two additional line fuses.  The can capacitors present on the top of the chassis have been "re-stuffed".

Additionally; The black case was treated with Kiwi Black Leather dye, a coat of Kiwi Liquid wax and a buffing.    The plastic bezel was treated with Glazit.

Battery page with general TO links.

Thank you!

Please email any comments or questions.