I have put aside the 37-620 and am working on my Bell swan.
I am having trouble with the Ecaps. I was told that I have version 2 on the schematic but don't know where to ground these Ecaps.
The first 2 are in the metal box on top of the chassis. I believe they are 1 Uf each.
There are 2 wires coming out going under the chassis Is this where the positives connect to?
When I removed the tar block there was a wire connected to the metal box. Is that where I ground these?
Next are the 2 cans that each have one wire coming out but no other wires. Are the 2 wires the positives?
If so, how do I ground these?
If you are sure the version you have is at p2 then one cap is not grounded, but then it had to be insulated.
If this is a copper mershon (looks like it), coper can be soldered to.
So is tin.
Really? you have to ask... Of course I am not sure.
I think that based on the picture on page 2, tihere are (2) 1uf caps in the block that the negs are twisted together and grounded to the block/chassis and the positives connect to 1 outgoing wire each.
Then there are (2) 8uf caps grounded to the cans/chassis with the positives connecting to the wires coming out of the top.
What I don't get is those two 1uF caps in the block on the sch.
And from the sch one of the Mershons (8uF) is not grounded, but on the chassis I see no insulation.
Kirk;
The way they drew the schematic it's kind of hard to follow, but it looks like the filter capacitors are an 8 uf, a 4 uf, and a 2 uf, that is if your chassis is a first series model 62 and not a second or third series model 62. The first series Jackson Bell model 62 has an extra filter choke mounted on the chassis someplace, the second and third series do not. The B+ comes off the #80 tube, goes to the 2 uf cap first, then splits off with one going to a choke, followed by the 8 uf capacitor, the other side goes to the field coil and is followed by a 4 uf cap. Speaking of a bleeder resistor, this set has one on the end of a series of voltage dividers, unlike the Philco 18/118, it does not come right off the hot side of the B+ and go to ground.
Those caps you speak of are not in the power supply, one is between the cathode of the detector tube and ground, that is if they are both 1 uf and not a .1 uf. The second schematic shows a .25 uf in the detector cathode position, the other 1 uf is connected to the center tap of the filament winding for the #45 tube, the second schematic does not have one on the #45 winding center tap. That can may be a block condenser can with the bypass capacitors inside, this set has at least four of those, and two 1 uf caps all with one end connected to chassis.
Other then the 8 uf filter cap you could replace every capacitor in the set with non polarized film capacitors of at least 630 vdc, then you don't have to worry about polarity, but if you look closely the negative of each filter cap goes to chassis anyhow. You could with the 8 uf cap too but putting enough film caps together in parallel, and stuffing them inside the can, might be difficult.
Regards
Arran
P.S I see a note on the second schematic mentioning a dual section 1 uf block condenser being mounted on top of the chassis, at least in the second version where the filed coil is connected in the positive side of the B+ supply. This can seems to be connected in the same position as the two 1 uf caps are in the first version, one on the center tap of the #45 filament winding, and the other between the detector tube cathode and ground. Use poly film caps for this, but you will not need a pair of 630 volt caps to replace either of these as the potential is only 50 volts, so use a 150 or 250 volt, or whatever you can get that will fit in the can.
(This post was last modified: 09-11-2014, 09:33 PM by Arran.)
Quote:P.S I see a note on the second schematic mentioning a dual section 1 uf block condenser being mounted on top of the chassis, at least in the second version where the filed coil is connected in the positive side of the B+ supply. This can seems to be connected in the same position as the two 1 uf caps are in the first version, one on the center tap of the #45 filament winding, and the other between the detector tube cathode and ground. Use poly film caps for this, but you will not need a pair of 630 volt caps to replace either of these as the potential is only 50 volts, so use a 150 or 250 volt, or whatever you can get that will fit in the can.
Unfortunately I did not understand much of that Arran.
This is why I think it is version 2. There is the dual 1mfd block mounted on top on the chassis. Are you saying that I can just use 2 regular 1 mfd caps in this block?
I dont see any other filter caps in the chassis besides the dual block and the 2 cans. the schematic says that the 2 cans are 8mfd each, not 8 and 4 though.
I will have to look under the chassis to see if there are any more filter caps I may have missed.
1. Yes, you can use a regular cap rated at 400 volts or higher.
2. Surface has to be clean and an area that large might need more heat than what you're using puts out. Clean the area well and use some flux on it. An alternative is to run a ground wire out the bottom and ground it at a point under the chassis as close as possible to the cap.
3. Yes, you can use regular caps if the voltage rating is high enough.
John KK4ZLF
Lexington, KY
"illegitimis non carborundum"
