[R-390] Part Replacement Comments

[Perry Sandeen via R-390]

List,


 
Very Long Post-Sorry


 
(Not selected in any order)


 
Wrote: If you do that, there won't be an original solderjoint left, leaving the set in poorer condition than it was.


 
The vast majority of us who have been soldering for years doas good as or better than the factory. Especially so if one had a NASA solder training course. 


 
If one doesn’t know how or to do it well there are manybooks showing one how.  An easy methodfor practice is to put  an inch high orso nail at each end of a two foot long 2 X 4. Then string a bare wire like a clothesline between them an inch or so abovethe surface.  


 
Then take a spool of hook-up wire upwind a foot or so  then strip around ¼ inch of the insulation offthe end. 


 
 (I should add at thispoint it is extremely helpful to have an adjustable soldering station.) 


 
Next take a needle nose pliers and make a 180 degree hook. Attachthat hook at one end of the suspended wire, then close it completely with theneedle nose pliers.


 
Good. Now take your iron and solder that joint.  When done clip off the spool wire so you leavean inch of attached wire.  Now repeat thisprocedure until the end of the wire while leaving 1/2 inch from the previouswire.


 
Repeat this process until you reach the end of the stretchedwire. 


 
Make up another board and repeat the process.  And maybe a third board.


 
On each solder joint you make, try to use a bit less solderand make a neater joint.


 
There is no substitute for practice.  That said, in a couple hours’ time you will developyour own soldering skills.


 
It doesn’t matter how many how crummy your beginning resultsare.  You just keep practicing until youcan make lots of perfect joints without a second thought.


 
You want to do this because there are many places in a *A*that if you start soldering and aren’t careful you can get into a heap oftrouble that will be enormously difficult to repair. (Think burned wireharness)


 
But you can lean to solder well. Like anything in life, somelean sooner, some later.


 
The three key words are: practice, practice and practice.


 
Wrote: Bite the bullet and prepare to find the next problem,if it happens in your lifetime.


 
If one doesn’t replace all original caps (including Mica’s)It will happen many timers in your lifetime. Not all caps short.  Many can have leakage. Refer to previouspostings about AGC problems. Also all modern major name caps are better thanwhat the originals were when they were new.


 
Wrote: Shot-gunning is like saying, "Kill them all andlet their god sort them out."


 
True it should be a last resort and not a substitute for ignorance.But there are times when what you have for test equipment doesn’t let you findthe true culprit(s).  Get two or moreshifting components and that’s when shotguning will be your best friend.


 
Wrote: No flame intended - never liked the shotgun approach.Besides, you won't have to buy mystery novels when you've got the occasionalreal mystery to solve. It's good mental exercise, right Roger?


 
There’s a point where mental exercise isn’t fun and some ofus don’t want to spend endless hours on a nagging or intermittent problem. 


 
Wrote: This is why I cringe a bit when people decide towholesale re-cap some of these radios. The parts in there have made it pastinfant mortality and various instal / damage issues. You are trading one set ofthings for another. 


 
I respectfully disagree. These parts are 50 years old.  Ifyou how to solder, gut all the carbon comp resistors and all the caps.  The replacement parts like MF resistors andnew caps are far better quality than when the OEM parts were new.  Fifty year old whisky yes. An exception tothe rule: leave the VFO alone unless it fails or can’t be adjusted properly. 


 
Wrote: Now, indeed there are some sets that simply willdrive you nuts until you find every last horrible cap in them. By now those arepretty well identified in each of the various radios. Those, yes you replace.It’s shot-gunning everything in sight that worries me.


 
You prove my point for gutting.  So you replace the “usual suspects”.  How long do you think the other 50-60 yearold caps are going to last?  Another advantageof gutting is that when you buy over 10 or 25 on up the individual piece pricedrops significantly. BTDTGTTS many times.


 
Wrote: I think we are stuck with it is a cut and tryapproach. 


 
Not so.  That is whywhen I revised the Y2K manual I added four chapters of previous info of whatothers have found and did to make their *A* better.  I drew a complete *A* schematic as a BITimage using photshop elements annotating numerous problem parts and solutionsto some tricky details. It contains info from more than 5 major *A*experts.  One can take the two files toKinko’s and they can enlarge them to any size W/O smearing.  A two by four foot print is less than $10. I’veoffered this file on the list and sent it to any who asked.


 
I’ve resurrected numerous articles on *A* upgrades andoffered them on this list and now they are going to be available on Al’s FAQsite. 


 
If anyone wants to upgrade their  OEM *A* from mild to wild, the info is readilyavailable.  This is also true for the SP600.


 
It’s fine with me if anyone wants to keep using $25 a pop26Z5 rectifier tubes, $30+ ballast tubes, shiny steel tube shields and top andbottom covers. That’s their preference, but not mine. Both positions deserverespect.


 
If anyone wants a metric boat-load of *A* or SP 600 info sendme a NEW email me at sandeenpaXatXyahoo.com and I’ll gladly respond.  Also, the R390 FAQ site has lots of good info.Also check Andy Moorer’s SP 600 site.


 

 Regards,




Perrier