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

Fri Dec 12 08:51:30 EST 2008

Actually there are three camps.

Those that replace all BBOD caps regardless because if they are not bad now 
(that's rare), they will be.  This has little to do with whether the radio 
has been out in the weather as part of the SJC pile or not.  I've seen 
probably 80% split and the remainder exceed leakage specifications.  (I keep 
all removed components of radio restorations in large empty Biscotti 
containers for conversation pieces....)

It's a personal thing and I don't think anybody should be beat up for 
residing in any one of the three camps.  I do believe camp 2 should be the 
minimum one should do because of the issue with potential damage to the 
mechanical filters.

Cecil...
----- Original Message ----- 
From: "Craig C. Heaton" <wd8kdg at worldnet.att.net>
To: "'Richard W. Solomon'" <w1ksz at earthlink.net>; <r-390 at mailman.qth.net>
Sent: Thursday, December 11, 2008 10:11 PM
Subject: RE: [R-390] R-390A IF Module Layout

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.

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