06-23-2008, 04:03 PM
BDM Wrote:Bill, has the set been fully re-capped? Did you check the values against the schematic. I see cap #23 should be an .05/mf. Is it? I could see that cap being off or bad, effecting all the RF trimmers. It sounds like the capacitance is too high, and you're not able to trim low enough. Someone please correct if I'm wrong.
With the limited time I have had to investigate I'm not 100% sure. I have not pulled the Bakelite blocks to see if they have been re stuffed but from the top side it looks like they were. The only caps I see that have not been replaced are a few mica caps. All other caps including the electrolytic's have been replaced. I need to set a day aside to verify all component values and confirm their correct installation. This radio is such a basket case its blinding me. Cap #23 sure does look suspect after you pointed it out, thanks BTW. I will check it out for sure. Could the resistors that are in parallel with #23 cause a similar affect if they were the wrong values?
The last time I was looking it over I determined its a early model 620 because the B.C wirewound (#70 on the early diagram) resistor only has 2 sections not 3 as the later models have. I also found that the volume control was replaced with the wrong part as it has no tap for the tone control. I have the correct part so no big deal.
rghines1 thanks for your comments also. My father was a old radio guy and he claims the grid cap solder joints are problematic on 75's. I take this with a grain of salt as my father is not the god he once was. It's H**l getting old. I wish I could turn back time.
Bill
It's not what you don't know that hurts you it's what you know that's not so.