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

rbethman rbethman at comcast.net
Fri Dec 12 12:05:00 EST 2008 

Cecil HAS hit it on the head!

BBODs are bad news "bears"!  *IF* one or more "somehow" passes the 
tests, exhibiting MIRACULOUS behavior, it will bite you *IF* you use the 
radio.

If it doesn't take out a filter,, it may take out an IF can or some 
other hard to impossible to find component.

These animals, "R-390s or R-390As", can be hard enough to get back to 
proper working order depending upon the state when acquired.  Why 
needlessly suffer or spend $$$ needlessly?  I've had ONE in great 
working condition that I recapped, and am currently working on the 
restoration of a St. J's survivor.  I've already had to locate and 
procure two cans on the IF Deck.  I want to tell you it was NOT easy NOR 
cheap!  So the caps are being changed as I go!

Bob - N0DGN

Cecil Acuff wrote:
> 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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-- 
Bob - NØDGN

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