Hi got an old original s-38 from the estate of a ham. He had got it all messed up (filter cap and related circuit) and I'm trying to wire in new filters. I've figured out some of where the + 40,30,30, and +25 go. But I'm not sure, could someone please tell which pins to wire these up too along with the b- which I think goes to pin 6 of 35l6. Also, there is a mica cap right off the cathode of the 35z5 that he had soldered to actual chassis (cabinet ground) The schematic tells me it should be b-. If someone could straighten me out on this I'd be forever grateful...thank in advance, Alan

If this is the original S-38 ( six tube with pitch control ) This radio is a HOT chassis. One side of the line cord is directly connected to chassis ground. The cabinet is insulated with the rubber grommets at the slide switches and chassis to cabinet mountings. All of the filter capacitors negative ends go to chassis ground. And there is a 470 mica cap from cathode of 35Z5 to chassis ground. The 20 MFD @ 25 VDC is the cathode bypass capacitor that connects to the cathode of the 35L6 to chassis ground. The 40 MFD connects right after the 22 ohm resistor ( R-18 ) .. The 30 MFD connects right after the 680 ohm resistor ( R-17 ) … The next 30 MFD connects after 1000 ohm resistor ( R-16 ) All negative ends to chassis.

Here is a good link about Hallicrafters S-38 line.

http://www.the-s38-guy.com/

:If this is the original S-38 ( six tube with pitch control ) This radio is a HOT chassis. One side of the line cord is directly connected to chassis ground. The cabinet is insulated with the rubber grommets at the slide switches and chassis to cabinet mountings. All of the filter capacitors negative ends go to chassis ground. And there is a 470 mica cap from cathode of 35Z5 to chassis ground. The 20 MFD @ 25 VDC is the cathode bypass capacitor that connects to the cathode of the 35L6 to chassis ground. The 40 MFD connects right after the 22 ohm resistor ( R-18 ) .. The 30 MFD connects right after the 680 ohm resistor ( R-17 ) … The next 30 MFD connects after 1000 ohm resistor ( R-16 ) All negative ends to chassis.
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:Here is a good link about Hallicrafters S-38 line.
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:http://www.the-s38-guy.com/
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Thanks Warren, so the actual B- goes to cabinet ground? I guess I though the B- stayed isolated from the cabinet. Just to be clear here. Connect the - side of the caps to the physical ground? It's a little confusing as there is a chassis and cabinet ground...thanks...Alan

BTW, I restored a 5R10A which is similar but not identical and it works great.thanks again for straightening me out..Alan

The chassis is the B- ground. The metal cabinet in not to make contact with the hot chassis. The only conection from chassis to cabinet is a .1 capacitor ( C-36)

:The chassis is the B- ground. The metal cabinet in not to make contact with the hot chassis. The only conection from chassis to cabinet is a .1 capacitor ( C-36)
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Ok, sounds great I'll have to wire it up when I get home from work..thanks again for your help and explanation..73 Alan

Warren, thanks it works now..although gotta replace several paper caps..little motor boating and squeals but it works...Alan

While your at it check R-16-R-17-R-18. that's the voltage divider circuit. Use the tube pin numbers on the schematic to check B+ on all plates and grids. A good upgrade is to use a 12SG7 in place of the 12SK7. ( More IF gain ) An alignment of the IF and antenna trimmers will make it perform the best.

:While your at it check R-16-R-17-R-18. that's the voltage divider circuit. Use the tube pin numbers on the schematic to check B+ on all plates and grids. A good upgrade is to use a 12SG7 in place of the 12SK7. ( More IF gain ) An alignment of the IF and antenna trimmers will make it perform the best.
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Warren I did check the resistors, they are within tolerances of 20%. I replaced the 12sq7 due to lots of howls and squeals with a little hum. When I did so it all dissappeared. Cleaned switches and controls. Thanks for the tip on the 12sg7, see if I can find one somewhere. One thing when I turn in on, the lamp goes almost out, when the sound starts then it comes back. Is that normal? I thought it was supposed to get bright then dim down..thanks, Alan

The 35Z5 rectifier tube has a tap in the heater for a dial lamp. Some tubes have more or less resistance at that tap. ( bright bulb vs dimmer bulb ) You radio also has a 330 ohm resistor shunting the bulb. This takes some of the cold start surge. The operation is normal.