[R-390] R-390A IF Module Layout

[Craig C. Heaton]

There have been discussions about capacitor on this list before, some quite heated. Members have left over this topic. So here goes anyhow. Nomex is the uniform of this moment.

Seems to be two camps: Those who don't replace caps, maybe their r-390's are on pedestals and are never plugged into an electrical outlet. So be it. Camp two replaces known trouble makers and use their receivers to listen to SW or maybe paired with a transmitter on the ham bands. 

Dick here is my list #1. This is where I start


PANEL & FRAME
	PART #	DESCRIPTION	NOTES	REPLACEMENT
PART #
QUANTITY				
1	C101	PAPER 220,000pF, 100 WVDC, 20%		715P
1	C103	ELECTROLYTIC 50uF, 50 WVDC,	(1)	
RF AMPLIFIER SUB-CHASSIS				
QUANTITY				
1	C227	PAPER
47,000pF, 100 WVDC 20%	(7)	715P
1	C256	PAPER
0.1uF, 200 WVDC, 10%		715P
1	C275	PAPER
0.033uF, 300 WVDC, 20%		715P
1	C309	PAPER
0.1Uf, 200 WVDC, 10%		
IF AMPLIFIER SUB-CHASSIS				
QUANTITY				
1	C504	PAPER
0.1uF, 200 WVDC, 10%		715P
1	C505	PAPER
0.1uF, 200 WVDC, 10%		715P
1	C517	PAPER
0.1uF, 200 WVDC, 10%		715P
1	C521	PAPER
0.1uF, 200 WVDC, 10%		715P
1	C528	PAPER
0.1uF, 200 WVDC, 10%		715P
1	C529	PAPER
0.033uF, 300 WVDC, 20%		715P
1	C531	PAPER
0.1uF, 200 WVDC, 10%		715P
1	C533	PAPER
0.033uF, 300 WVDC, 20%		715P
1	C534	PAPER
0.033uF, 300 WVDC, 20%		715P
1	C536	PAPER
0.1uF, 100 WVDC, 20%		715P
1	C538	PAPER
0.1 uF, 200 WVDC, 10%		715P
1	C541	PAPER
0.033uF, 300 WVDC, 20%		715P

 
1	C543	PAPER
0.1uF, 200 WVDC, 10%		715P
1	C545	PAPER
0.033uF, 300 WVDC, 20%		715P
1	C547	PAPER
0.1uF, 200 WVDC, 10%		715P
1	C548	PAPER
0.1uF, 200 WVDC, 10%		715P
1	C549	PAPER
10,000pF, 300 WVDC, 20%		715P
1	C551	PAPER
2uF, 500 WVDC, 10%	(2)	NTE
MLR205K630
1	C553	PAPER
10,000pF, 300 WVDC, 20%	(3)	715P
AF AMPLIFIER SUB-CHASSIS				
QUANTITY				
1	C601	PAPER
10,000pF, 300 WVDC, 20%		715P
1	C602	PAPER
0.033uF, 300 WVDC,  20%		715P
1	C603	ELECTROLYTIC
3 SECTION
30uF, 300 WVDC,	(4)	33uf @ 350V    140-XRL350V33
Xicon
1	C604	PAPER
10,000pF, 300 WVDC, 20%	(5)	0.022uF
Better Audio
715P

1	C605	PAPER
10,000pF, 300 WVDC, 20%	(5)	0.022uF
Better Audio
715P
1	C606	ELECTROLYTIC
2 SECTION
45uF, 300 WVDC	(4)	47uf @ 350V    140-XRL350V47
Xicon
1	C607	PAPER
10,000pF, 300 WVDC, 20%		715P
1	C608	PAPER
10,000pF, 300 WVDC,
20%		715P
 1	C609	ELECTROLYTIC 8uF, 30WVDC
	(6)	



(1)	This is the bathtub style capacitor mounted below the line filter on the rear panel. It is NOT an oil filled paper cap even though it looks like one. Watch the polarity.

(2)	Oil filled metal can paper capacitor mounted to topside of chassis next to chassis harness connector. The NTE part number (Mylar film) is one, which will fit inside of the metal can. 

(3)	Blocking cap for mechanical filters. Recommend working voltage of 600VDC or higher to help decrease the chance of frying the mechanical filters due to failure of C553. This is not a good location to use a cheap replacement capacitor. 

(4)	The Xicon part number is one, which will fit inside of the metal can. 

(5)	For improved audio performance, you can use 0.022uF caps at this location.

(6)	Also known as “the capacitor that rots off”. Leaks sulfuric acid when the seal fails. Watch the polarity when replacing. 

(7)	Stud mounted capacitor next to 6DC6 (V201)

RULE NUMBER ONE: “This is your radio, your money, and your time”
RULE NUMBER TWO: “Read rule number one”

The above list contains most of not all the capacitors that have been know to fail most often on the R390/A. Black Beauties of Death, Brown Beauties of Death, Aerovox, West-Cap and Vitamin Q are included in the list. There could be others! 

Use the list according to which side of the fence you stand, or if sitting on the fence. In the event you own a museum piece, will never plug the receiver into a power receptacle and it will always be kept on a pedestal, the list is for your reading amusement only. For the capacitor replacers, the list is a good place to start. The 715P polypropylene film style of orange drop capacitors has a good track record. I’ve used the NTE and Xicon caps with good results as noted. 

Yes other caps will work, read rule number one and two for all disagreements.