[scottwkurth]

I'm finally getting around to working on the electronics of my 40-185 after a couple months of real life getting in the way. My next step is to order new caps and start doing replacements one-by-one.

I've come up with the following inventory of paper and electrolytic caps in the set.

Qty Part Value Voltage Schematic
2 30-4469 0.003 mfd 1000 V 50, 55
2 30-4572 0.01 mfd 400 V 46, 52
3 30-4479 0.01 mfd 200 V 30, 40A, 42
1 30-4444 0.05 mfd 200 V 8 (actual part in radio is 30-4441)
3 30-4123 0.05 mfd 400 V 10, 17, 31
1 30-4519 0.05 mfd 200 V 32
1 30-4536 0.2 mfd 200 V 33
2 (3903DG) 0.01 mfd 600 V 64 (bakelite)
1 30-2406 16 mfd 200 V 58 (electrolytic)
1 30-2405 12 mfd 350 V 61 (electrolytic)


Before I get started, I've got a few questions as my circuits knowledge is basic and 15 years old at this point.

1. As I look at ordering replacement caps I'm a bit overwhelmed by the different types. Looking at my options at Just Radios, depending on the values required I see Metal-Foil Polypropylene, Metalized Polyester Film, Metalized Polypropylene Film, Metalized Polyester Film, and Polystyrene Film. Yikes!!! Can someone give me some guidance on which type I should be using to replace the paper caps in this radio? (BONUS Question: Why one type over another?)

2. For working voltages it seems that the general wisdom is to standardize on 630V for the paper cap replacements and 450V for the electrolytic. Assuming I can work out the answer to #1, I'm all set except for the two Part 30-4469 caps. I found conflicting advice in my searches - some said replacing those with 630V would be fine, others said that they need to be 1000V since they are connected to the audio output tubes. Can someone please clarify?

3. Assuming that I need 1000V caps, I can't seem to find a 0.003 or 0.0033 mfd 1000V cap at Just Radios. What should I be looking for as a replacement?

4. I thought I had seen some tips on how to replace the electrolytics, but I can't seem to locate them now when searching. Are these wet caps and do I need to do anything special to replace them?

Thank you for any help you can share!
Scott