01-31-2018, 12:49 AM
Next up - a couple of the hacked up bakelite blocks.
#9 capacitor block is a 3615L (middle of below pic) - should be 3615D. The taped together connection with the 70K resistor original went to the middle terminal of that block.
[Image: https://farm5.staticflickr.com/4722/3924...b0c8_z.jpg]
I had a 3615N block in my parts bin that I turned into 3615D just by rotating one of the terminals.
Philco probably could've saved some more pennies by not making so many different (but similar) blocks!
[Image: https://farm5.staticflickr.com/4744/2612...3d83_z.jpg]
#6 capacitor block is 3615W (lower left of below pic - with Zenith cap) - should be 3615J. Evidence of hackery as middle pin connections are there but floating.
[Image: https://farm5.staticflickr.com/4722/3924...b0c8_z.jpg]
This was a seemingly easy fix as I found a 3615J in my parts box. I restuffed it and installed it:
[Image: https://farm5.staticflickr.com/4622/3909...9831_z.jpg]
Done right? Well...I put the set back on the test bench and it was pretty clear that I broke it.
It turned out that I didn't pay close enough attention to that Zenith paper cap that I removed. When looking at layers of past repairs it's hard to guess exactly what's going on without tracing everything out - which is what I did next (should've done that to begin with). That Zenith cap was in fact a stand-in for 1/2 of #25 - a dual 0.25uF cap in a metal can. I didn't notice during my initial look through but one of the leads of #25 was clipped off:
[Image: https://farm5.staticflickr.com/4602/2512...f1c4_z.jpg]
That lead originally went to the middle terminal of #6.
[Image: https://farm5.staticflickr.com/4748/2512...fe6b_z.jpg]
I restuffed #25 and put it back on the test bench.
[Image: https://farm5.staticflickr.com/4763/3996...311a_z.jpg]
The 112 came back to life.
#9 capacitor block is a 3615L (middle of below pic) - should be 3615D. The taped together connection with the 70K resistor original went to the middle terminal of that block.
[Image: https://farm5.staticflickr.com/4722/3924...b0c8_z.jpg]
I had a 3615N block in my parts bin that I turned into 3615D just by rotating one of the terminals.
Philco probably could've saved some more pennies by not making so many different (but similar) blocks!
[Image: https://farm5.staticflickr.com/4744/2612...3d83_z.jpg]
#6 capacitor block is 3615W (lower left of below pic - with Zenith cap) - should be 3615J. Evidence of hackery as middle pin connections are there but floating.
[Image: https://farm5.staticflickr.com/4722/3924...b0c8_z.jpg]
This was a seemingly easy fix as I found a 3615J in my parts box. I restuffed it and installed it:
[Image: https://farm5.staticflickr.com/4622/3909...9831_z.jpg]
Done right? Well...I put the set back on the test bench and it was pretty clear that I broke it.
It turned out that I didn't pay close enough attention to that Zenith paper cap that I removed. When looking at layers of past repairs it's hard to guess exactly what's going on without tracing everything out - which is what I did next (should've done that to begin with). That Zenith cap was in fact a stand-in for 1/2 of #25 - a dual 0.25uF cap in a metal can. I didn't notice during my initial look through but one of the leads of #25 was clipped off:
[Image: https://farm5.staticflickr.com/4602/2512...f1c4_z.jpg]
That lead originally went to the middle terminal of #6.
[Image: https://farm5.staticflickr.com/4748/2512...fe6b_z.jpg]
I restuffed #25 and put it back on the test bench.
[Image: https://farm5.staticflickr.com/4763/3996...311a_z.jpg]
The 112 came back to life.
