Thanks Lawrence!
On the schematic documents C49 is listed as 25uF - I was sure I was better than that to miss that big. I probably saw .2 on the cap and replaced it with a 0.22.
On one section of the R3/R4 combo I am thinking I am safe to measure R3 in-circuit as its just terminal to ground. I get 5K and the same on the other section - I only was suspect because the value on both legs was nearly exactly half the schematic value.
The C49 now concerns me more - you are comfortable with the value being 0.1uF, I may have read the value on the cap as 0.2uF, and all schematics I have is 25uF/400. If you never had problems with 0.1uF I cannot see how the other values would matter that much - except the 25uF is excessive for what I normally see a shunted ground resistor (from my valve amplifier days).
I guess I am second guessing the terminal resistor - could it be just 5K on each? They are in series and identical wear is not out of the question but after nearly 80 years maybe its the substrate of the resistor finally broken down.
I am planning on replacing this with a pair of coupled 10K Ohmites on a terminal strip and was concerned the 5K might be what was originally put in.
The 1K R39 is easily replaced: I have hundreds of them at 1 watt and its a simple job - I wanted to fix what is making it draw the current that burns it up and it is decoupled from anything significant when set to band 6 - so the other end of the R39 to look at was R3/R4+C48. If those are wrong, I need to correct them.
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Originally Posted by ms660
Quote:
Originally Posted by mrrstrat
Do these terminal power resistors go bad?
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The ones I had in my receiver's had at least one section go open circuit.
I would sort out the smoking R39 first, a short there would give the wrong resistance for R3 and R4 if measuring them in circuit.
In an annotated schematic I did years ago, a value of 0.1uF is shown next to C48.
Lawrence.
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