Motorola 555 ssb base tx issue

[DMRXPR]

 

[Retro CB Guy]

Yeah it's too bad he doesn't give away some more info for so MANY out there having this issue, but I get it at the same time.

73

 

[DMRXPR]

I have a working 555 I still need to sell off lol. Everything works. I don't plan on keeping the thing.

Did you ever sell your working CB555?

 

[doffo]

Did you ever sell your working CB555?

I havent sold it yet. I was randomly thinking about the radio last week, and the fact someone on here asked about it lol.... I should power it up to be sure it still works.

I wish I could sell it locally so I don't have to ship something like that out. I live in Kansas. But I may have no choice.

 

[doffo]

You will be the very first I notify when I sell it. Thanks for keeping up yer interest in it. I will try and get some pictures of it with it on and check for transmit/receive. Maybe not today but currently going through stuff in the Garage.

 

[vswr]

Yeah it's too bad he doesn't give away some more info for so MANY out there having this issue, but I get it at the same time.

73

He does this for money. Pretty sure its a VCO issue. Dual sided board issues. I have one that transmits fine but receive doesnt work and pins the needle. My other one is a real mess.

 

[DMRXPR]

Freeze spray - glad to know you have some...

That can help but if the "Heat" in the kitchen isn't the issue, but the Length of time it takes to recover it - I find interesting.

Ok, I mentioned heat because of what I saw here...

Foil Side

View attachment 57345

Top Component Side...

View attachment 57344​

This shows to me, heat fatigue - the flux and preservative used on the board got hot right around whatever is by that regulator.

The Semiconductors are NOT they only ones affected by heat, caps are too (in fact all parts are interrelated) - I think it was mentioned earlier about Capacitor ratings; one being temperature - that may affect how they operate and they don't quickly recover like their Resistor or semiconductor cousins do

Also saw this...

View attachment 57346
This is a Classic "forgot to address - redress"​

In the way this radio is assembled, you may have more work to do to correct such lead dress oversights - I hope that when the radio was put together - lead dress like the above didn't pinch and further damage parts from the short that it would have caused.

Bruce have you ever heard this might be the issue ?
FYI - This info came form a fellow I'd met on eBay years ago. HAM call sign: KB0UXV

The TX relay can go bad on 550 / 555, they seem to be on Ebay. Part number is NF4-12v/AE1353 made by National.

Intermittent transmit on a 555 / 550 will very likely be fixed by replacing C212 on the bottom of the board, upper left area mounted on the bottom point to point. The Sams manual has a misprint on this part, it says is electrolytic but its a tantalum. 1mf 35V but I used a 50v.