ok, so double checked the clean one - 12v at terminal four, 12v at outboard side of diode, nothing on inboard side (closest to pin 7), nothing at pin 7.

Nasty board - better photos. Still clean with Acetone (for educational purposes of course, can't see this going anywhere but hey its already broke).

 

Great pictures showing a severe corrosion buildup from the 'rainroof'. Now it deserves the removal of the nasty board out of the metal chassis, even if for 'educational purposes' (and practice following traces !) as you say, and confirms the radio failure being from the extensive corrosion. Remove solder from the 4 bent metal catches and straigthen them to lift the mainboard.

Now to the not-nasty; the path of +12V BAT is on mainboard :

RearPowerPin4----------triplevia---------outerblueendofD807-----------hiddendoublevias------------L801coil------------Nichiconcapacitor---------circuitry-------->

and +12VACC path on vertical board :

RearPowerPin7------------Label7---------------hiddendoublevia-----------------hiddenzenerdiodeunderblackplastic*------------circuitry------------>

If I remember well. If some pictures of the nasty underneath after removed, I could point key locations I mentioned above in order to follow continuity and determine where is the path interrupted.
* do not get in there... yet.

 

Ok, here we go with the board removed

 

Hi.
My compfuser refused to show the arrow tip in the image: There is two places by left bottom area showing 'BATT' One should be a triple vias connecting bottom trace to top trace. Follow continuity from the Power4 rear pin to all that +12VBAT top and bottom paths. I use a red permanent marker to pertinent points to follow.
Give the board a good acetone+teeth brush treatment.




Again, failed to add the arrow below. The problem appears to be at the right pin via (near label AA62F) under the coil L801 = kaput: There is 4 pins in the image; up and down for mechanical support with no traces and left and right for connection. Needs resoldering and if needed, a wire from the that pin to the scraped! trace it is supposed to connect. Probe for continuity, should fail. Removing the coil is now recommended to see the damage and cleaning.




After all gets clean and scraped the white corrosion, hope is back for resurrection. To be continued...

That double via at the center of the next image is were my unit failed to conduct top to bottom traces :

 

C

Cleaned

 

zoomed

 

I see the two areas marked BATT, one does appear to be a triple via. I have continuity from Power 4 to all three labeled batt in triangle as well as the standalone one



Sorry, I don't follow?

Done!

I see four sets of pairs of pins for a total of 8. I assume the pairs correspond to the labels RV61f to RA62F?

Ok, I do see those both top and bottom of the board.



Sorry, don't follow, what pin to what trace?

Between what and what?

Ok, It looks like these three are required to be de-soldered to remove, true?




Here?

 

Preetier than new.


The arrowtip point is a coil wire end with no continuity, needs fixing/resoldering after scraping the trace on the other side of the board.

===============================================

No, lower at the center of that image, those two vias had no continuity to the other side on my unit. Check yours. Your circled red is the big black capacitor on the top side.
================================================== ========

The green marked are three; add the one above to make four. The blue cathode of the diode is bad also, by the 'K01-A-' label above nearby.
================================================

Am having horrendous difficulty to color mark images with my compfuser as you did. Cannot find how to. Sorry.

===========================================

The 4 labels like RV61F are not related to repairs. The original image showing that area was upside down, then what is right was left before.
=============================================

Just remove the coil (4 solder places) 2 connections, 2 supports.

Next to the coil, the blue cathode has corrosion problem connecting to its trace
===============================================

The triple via triangle is then good. Focus to traces around the coil, blue cathode to achieve continuity all along from Power4 terminal to the doublevia commented in this same post #28.
My number is +1 859 twozerotwo 6948 at any time, welcome.

 

Thanks Externet! I do appreciate your patience on this. As stated before my interest in this is primarily educational, as I enjoy learning and board level troubleshooting was a weak spot in my skill set. We may not be successful ultimately, but I am enjoying the journey
Ok, but I need to remove the coil right? So this will get fixed when I do that?
Here, right?

These four, correct?

This, yes? I need to acquire new one and replace this correct? clean board of corrosion once coil and cathode are replaced correct?


Quick sidebar instruction. Assuming you are on Windows computer - windows key plus the shift plus the S key pops up windows snipping tool - you can grab section of the screen and then the tool will pop open. Once the tool is open you can markup using pen tool at the top. Looks slightly different in W11 vs W10 but I use both and find it very easy. Once marked up you can save to a temp folder and then use the forum image insertion to upload the images.

Again, I appreciate your patience and willingness to work with me as do many other forum members for this instruction series.

Thanks for the offer on the call, I may yet take you up on it. For now I will continue here if that is ok with you. Many years ago there was a very knowledgeable board member named DiscoMike (r.i.p. ). He was a wealth of knowledge and was always willing to help board members, but unfortunately once the troubleshooting got complicated he would default to private messages and phone calls, leaving the rest of the members wondering what the resolution to the problem was. Many of the post he responded to ended that way. I personally have benefitted from many of the board post and believe in documented our process for others to benefit from and future generations as well!! Thanks again!

 

Hi.
From your post above : We will make it run !
The single orange circled is YES! * the double vias that feeds +12V to the whole radio after passing by the path
Power4 ---triplevias----bluecathode----coil---capacitor----doublevias ---->rest of radio

The 4orange circled are to be desoldered to fix corrosion under the coil and its 2 corroded connections to the board.

The topside trace where the blue cathode diode pin is soldered-to is corroded, needs attention to clean/resolder. NO adquire, no replacing anything, just desolder, remove, clean, resolder. That diode only purpose is to blow the fuse to protect the radio if a genius reverses the battery.


I do not know what Windows is. I run Linux since 2005. It is not about patience and willingness; am having fun and you should too in the process.

* ! ----> There is a chance am wrong for the location of the keypoint double vias that feeds the whole radio, as am doing this only from memory. My radio is installed not in front of me while typing.
It may be at the arrowtip below instead, if the other side of the board has a nearby L801 label. Apply red permanent marker dot to it.


To be continued...