I'm used to digging out resin and silicone to get to components. Repaired the CDI on my neighbor's KVF 400 4 wheeler, and the PCM on my 92 Dodge Dakota. The Bakelite tar was rather easy. Would have been worse if I had to save the capacitors.
The RCA jack and switch connection in the schematic did surprise me. Here's some number on it.
Haven't looked at the caps that I bought to go into the bakelite case yet (bought parts about 2 years ago). Hope they are very tiny or it could be real fun.
Reckon I could use flexible, insulated wire if I had to, if the caps fit like the originals. They were the size of AAA batteries.
Otherwise I'll have the empty case mounted with the caps on both sides at the bottom..
Little more work on the Bakelite. Got the old wires off with my solder sucker. Put 2 ceramic caps in, I could have better thought the routing but hey.. Will solder them in, and do the outer wire terminals about the same time. The caps should stay in place, just will have to check that the solder doesn't drip out when I do the outer stuff.
Debating whether to silicone (888) the caps in. Not like a car with moisture outside.
Don't use silicone. Some of them secrete acids as they dry and can rot things.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Right - under no circumstances should you ever use silicone in an electronic device.
A fellow I know showed me a box once that had been filled with electronics, then potted with silicone. The silicone had eaten away all the wiring. Not pretty.
Hot glue is a much safer solution. If the components can withstand the heat for a short period as the glue cools down, it will not affect the wiring at all.
As a matter of course, I pot every AC line bypass bakelite block I rebuild, to ensure the wires do not short together. I also dress the leads in such a manner that they are as far apart from one another as possible, and are also placed away from the terminal holes (unless the particular lead goes through a particular hole).
I knew about not using regular silicone since it has acid in it. I've been using this stuff which is supposed to be okay. The right number was 388, not 888.
Since I won't be exposing it to moisture or vibration, I probably won't pot it.
BUT, got another question. Since I was in the area of the 6F6G tube messing with the block, I noticed the speaker wires were in the way. They are very brittle and have broken outside the cabinet. I got off on a tangent and started checking the resistance values of the speaker.
The 400 ohm part 38 output transformer looks open. I measure between 1 & 3 (my markings) and get nothing. Am I measuring in the right place?
Between 1 & 2 I get 1177 ohms which looks correct for part 37.
The wattage would be the plate current vs plate voltage. Approximations can be taken from schematic values and characteristics for 6F6. Knowing how to do this is a learning curve, but well worth the effort.
Hammond manufactures quality output transformers but remember to look at the mounts and do not go over in wattage as they do get expensive.
Further, be aware that the schematic indicates the speaker has a hum buck coil, do not separate the connection of that coil to the voice coil. Do not exchange the field coil wires. You "may" have to swap the series combination of the hum buck and the voice coil if there is residual hum. That is the only place to make that exchange.
You "may" have to use a universal output transformer if there is no "close" match, such a transformer has taps and the correct one is used to match.
GL
Chas
Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
Sacrilege? Not really. I installed one on a Philco 90 speaker (1-47) last week and it works just fine. (I used the black and brown primary leads, and the 4 ohm secondary even though the secondary impedance is just under 1 ohm for a 90 speaker.)
$10 for a line matching transformer, or $60 (or more) for a Hammond 125BSE 5 watt universal single ended output that likely won't sound any better.
I really appreciate the info. I'll have to do some studying. Been out all day tearing out a rotten handicapped ramp at my father's place. I'm 66 yrs old. I know basic electronics but more a part exchanger. Don't have much experience/knowledge of audio systems. I do read all of the warnings about not powering up the radios without doing repairs.
I got the transformer info from the Philco library. Just need to understand the relation between the tube output and the transformer. I noticed a "pig in a poke" parts radio on Ebay. Might do that. This is my father's radio that I used to listen to in the bedroom when I was a kid. Not planning on selling it, don't mind spending money to get it working. If the transformer looked somewhat similar to the original I wouldn't mind. Some have a lot of wires.
