Changing gears: SBE Console V is coming on to the bench!

[Bobcat]

And, good grief do I have my job cut out for me!!!!
It is, as I mentioned, an SBE Console V which I believe was manufactured in the very late 70s ... maybe 78-79 ( guess)

Right away, I think a re-cap is needed just based on the fact that it is approaching 40 years old!

However... many years ago I was doing a little work in the area of the channel displays, required soldering and, wouldn't you know it, I must have touched a wrong thing and bridged two pins together...because it started picking up an odd extra segment lit up in the lower digit display. Should have fixed it then but one thing led to another, and my focus went off of it until now.

So ... last night, I thought I'd take a quick minute to confirm WHICH extra segment lit and which it was tied to... just by looking at the patterns.

When I turn it on.... several things are different than they were years ago....

1) the meter light, LEDs, and channel displays USED to just "snap on"! I mean.... flip the switch....they were on. I noticed last night that they all sort of.... "ooze" their way on. Literally you flip the switch and they seem to "fade" on!!! Fairly quickly.... but you see the fade.

2) the meter light is not as bright as it used to be (could be my eyes...but I don't think so.

3) the channel displays.... come up to about 1/2 brightness and all segments are on BOTH displays. SO ...it is a dim '88' showing up and it WILL NOT change with the channel changer. The sound on the radio changes.... so I believe that the channel changing circuitry is doing SOMETHING... but the displays are not following. That said...... for just a moment...... they popped brightly onto Channel 4. I change to 3 ...it went. I changed to 2 it went. I changed to 1... it followed for a moment....then..... splat... beck to the dim '88' and could never get it back.

4) The audio is very very very low. I didn't have an antenna plugged in..... but it used to be louder THAN THIS.... even so!!!!

I don't know why...(after all this is a bit of learning. I am well versed in practical electronics, that was my education... I am just trying to get back to it after years of abusing my mind with software development!!! ) but I am thinking the caps are just so far gone.... that at the VERY least I have low supply voltage issues. For under $20 I can replace every electrolytic and tantalum cap in the thing.. and I am willing to invest that and my time in changing them out (42 electrolytics and 9 tantalum) to see what remaining problems exist. Then make a decision at that point. At the moment, I think the PLL assembly is most likely working, the audio chip is working... to me... that seems like a good piece of the battle.

Onward... through the fog!!!!!!!!

[Bobcat]

A question, if anybody sees it....

Is there a value in going ahead and replacing the tantalums at this point?

Some say, "if it ain't broke, don't fix it"

But I'm going into this thing so deep I'll need hip-waders... and the tantalums are only about $7 or so.... why not do it and be done with it?

What does the world think?

[sonoma]

I change the tantalums out when I do a recap. I use electrolytics of the same value or a higher voltage and they work just fine. at least I have 5 radios I have done this to and they are working great. 3 858 PLL washingtons and 2 cobra 142 radios . these are my own radios and have some customers from pre 2012 that they are working fine in.

[Bobcat]

Noted. ....
I think I'm going to stick to the tantalum though. ...
I remember seeing a recap video where the author claimed that the tantalums had better stability under temperature. .. and designers often put them where that stability was critical. At Mouser they are only 0.63 each. ... so cost isn't an issue.

But I do thank you for letting me know that it will work.

[ Post made via Android ]

[redlght]

Those radios are notorious for plate through hole issues.

To populate the smaller board they used double sided boards where the components on top cover the part number and traces run under caps and such that you can't get to easy.

They could of made the board bigger and single sided there was enough room. Also the processor board has a lot of failures that cause low modulation output.

[Bobcat]

I have the Sams for the Sidebander V. Plus I have a service manual for the Console V. Both show a good xray view of the PCB and you can see the top traces. ... and where the thru holes are. While I am recapping. ... I intend to take a look at those.

Also. .... I've never been in one of these. .... and I don't know if you know. .... but I am guessing that they created a way to hide the PLL board INSIDE the metal cage mounted OVER the up/down logic on the main board.

[ Post made via Android ]

[redlght]

I worked on a few of these not a big fan of the design and the scan feature scans for open channels not busy ones now a days most are open and it is hard to get the scan to work.

I wouldn't mind having a scan of the service manual for the Console V on hand.