01-28-2018, 04:51 PM
Here's what I've found so far in my initial inspection this morning:
[Image: https://farm5.staticflickr.com/4714/3924...8237_n.jpg]
This is the 'late version' with dual 47 output tubes (above serial #174001).
Ron's annotated schematic is here.
Speaker
Measures good. No tears.
According to Ron's speakers.xlsx spec sheet this is a type H-4 speaker (3200 ohm field coil), 2635 output transformer (800 ohm primary).
Chassis - Top
[Image: https://farm5.staticflickr.com/4754/2817...b7de_z.jpg]
Even though the dial cord is broken I was fortunate in that the original cord and springs are present. I measured the original cord to be 0.065" diameter.
[Image: https://farm5.staticflickr.com/4611/3995...3eb5_z.jpg]
Even better I happened to have two 6uF mershon caps in my parts box:
[Image: https://farm5.staticflickr.com/4604/3905...1e45_z.jpg]
Chassis - Bottom
[Image: https://farm5.staticflickr.com/4760/3924...86b2_z.jpg]
Despite the mouse detritus there's not much evidence of destruction. Just one chewed wire that I could find:
[Image: https://farm5.staticflickr.com/4769/3905...ba5d_z.jpg]
The original #51 (15K resistor) likely suffered from the problem of being under-rated (described by Ron in this previous thread).
The open filter choke is a slight bummer but shouldn't be that bad to replace. According to the 1936 Philco Quality Radio Parts Catalog the specs are: 4H, 130ma (150ohm DC Resistance). Hopefully I have something on a parts chassis that will be a good replacement.
All resistors except #35 and #10 (both 99K, 1/2W) measure within spec. As usual it's these 'standard type' resistor that have the most problems. This chassis mostly has the 'metallized type' (metal end caps) which have been noted to be more reliable.
I found a 3615J block in my parts pile. I may have another one someplace - or I can use a different block with a similar physical configuration.
[Image: https://farm5.staticflickr.com/4629/3995...5583_z.jpg]
[Image: https://farm5.staticflickr.com/4714/3924...8237_n.jpg]
This is the 'late version' with dual 47 output tubes (above serial #174001).
Ron's annotated schematic is here.
Speaker
Measures good. No tears.
- Field coil: 3.1K
- Output transformer: 376.8 / 417.3 ohms
According to Ron's speakers.xlsx spec sheet this is a type H-4 speaker (3200 ohm field coil), 2635 output transformer (800 ohm primary).
Chassis - Top
[Image: https://farm5.staticflickr.com/4754/2817...b7de_z.jpg]
- 'Push-pull Input Transformer’ (#45, Part No. 5662) appears to be a contemporary replacement
- Original 6uF electrolytics (#65, #68) have been removed (later Philco branded replacements are under the chassis).
- Volume control potentiometer is a replacement
- Dial cord broken
Even though the dial cord is broken I was fortunate in that the original cord and springs are present. I measured the original cord to be 0.065" diameter.
[Image: https://farm5.staticflickr.com/4611/3995...3eb5_z.jpg]
Even better I happened to have two 6uF mershon caps in my parts box:
[Image: https://farm5.staticflickr.com/4604/3905...1e45_z.jpg]
Chassis - Bottom
[Image: https://farm5.staticflickr.com/4760/3924...86b2_z.jpg]
- Some mousy bits
- Two tacked on paper caps
- #51, 15K resistor previously replaced with wire wound
- Wire hanging from Part #2 first RF coil. Primary measures open.
- #66 filter choke open (Part No. 5643)
- #6 capacitor block is 3615W - should be 3615J. Evidence of hackery as middle pin connections are there but floating.
- #19 is 3615L - should be 3615J. Middle pin connections floating.
- One scary floating wire coming off of the filter block.
Despite the mouse detritus there's not much evidence of destruction. Just one chewed wire that I could find:
[Image: https://farm5.staticflickr.com/4769/3905...ba5d_z.jpg]
The original #51 (15K resistor) likely suffered from the problem of being under-rated (described by Ron in this previous thread).
The open filter choke is a slight bummer but shouldn't be that bad to replace. According to the 1936 Philco Quality Radio Parts Catalog the specs are: 4H, 130ma (150ohm DC Resistance). Hopefully I have something on a parts chassis that will be a good replacement.
All resistors except #35 and #10 (both 99K, 1/2W) measure within spec. As usual it's these 'standard type' resistor that have the most problems. This chassis mostly has the 'metallized type' (metal end caps) which have been noted to be more reliable.
I found a 3615J block in my parts pile. I may have another one someplace - or I can use a different block with a similar physical configuration.
[Image: https://farm5.staticflickr.com/4629/3995...5583_z.jpg]