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Uk/PRC350

 

Hello, does anyone have a circuit or any information on the power module of the PRC350 please? It's module 16. Mine tries to start, but stops drawing any current. I have a block diagram, but nothing else. Thank you Andy G7BAV
 

If it tries to start but crowbars look for bad electrolytic or tantalum
bypasses.
--scott
 

Hello Scott
Thank you. Yes, I did think it was the soft start circuit, but don't have a circuit or layout for the module.


Thanks
Andy

----- Original Message -----
From: "Scott Dorsey" <kludge@...>
To: <[email protected]>
Sent: Thursday, October 10, 2024 12:38 PM
Subject: Re: [RacalRadio] Uk/PRC350


If it tries to start but crowbars look for bad electrolytic or tantalum
bypasses.
--scott






---
This email has been checked for viruses by AVG.
 

Andy,
Please see attached; I¡¯d test the big smoothing caps for high ESR, or other problems, especially the one on the 9V rail, that provides feedback to the custom chip? ?In recent years, I¡¯ve found bad solder joints on the bigger caps, possibly from 40 years of temperature cycling, so could be worth having a close look at the soldering?
73
?
Al
G8LIT
 

?
Hello Alan
?????? Ok, thank you. Thanks for the info, and your experinace of problems.
?
?
????????????????? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? Thank you
??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? Andy G7BAV
----- Original Message -----
Sent: Thursday, October 10, 2024 5:20 PM
Subject: Re: [RacalRadio] Uk/PRC350

Andy,
Please see attached; I¡¯d test the big smoothing caps for high ESR, or other problems, especially the one on the 9V rail, that provides feedback to the custom chip? ?In recent years, I¡¯ve found bad solder joints on the bigger caps, possibly from 40 years of temperature cycling, so could be worth having a close look at the soldering?
73
?
Al
G8LIT

Virus-free.

 

?
Hello Alan
?????? Sorry when I try to open the attched, I can't see any detail. It's just a fuzzy blur. Could you try sending each as an attachment please? Or I would be happy to pay you photo copy and post to me if you could please?
?
?
?
??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? Thank you
??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? Andy G7BAV
----- Original Message -----
Sent: Thursday, October 10, 2024 5:20 PM
Subject: Re: [RacalRadio] Uk/PRC350

Andy,
Please see attached; I¡¯d test the big smoothing caps for high ESR, or other problems, especially the one on the 9V rail, that provides feedback to the custom chip? ?In recent years, I¡¯ve found bad solder joints on the bigger caps, possibly from 40 years of temperature cycling, so could be worth having a close look at the soldering?
73
?
Al
G8LIT

Virus-free.

 

Andy,?
Sorry about that; I just realised that Groups.io helpfully resized the pics I attached enough to blur any useful detail: my local copy was as sent, but unreadable once logged in to the Groups.io interface.
I¡¯ve re-sent the pics direct to you, at full definition, so they should be as readable as possible; they¡¯re from a copy, of a copy of a Racal factory manual, so not very good in the first place, unfortunately. ?Hopefully just the big capacitors, or a bad joint, and not the tiny Unobtainium Plessey chip!
?
73,
?
Al
G8LIT?
 

?
Hello Alan
?????? Ok, thank you. I can understand the moderators not wanting to put info into public, but it's not very helpful at times.
As the 350 was a Plessey design, I did not expect to see Racal on the drawings. But the MOD did let contracts in a very odd way!
The custom chips for some of the Clansman kit was made at the Plessey semicon factory about 10 miles from me. I think the overlays etc still exisit to make the chips, but not a cheap thing to do.
?
?
???? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? Thanks again
??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? Andy G7BAV
----- Original Message -----
Sent: Friday, October 11, 2024 5:02 PM
Subject: Re: [RacalRadio] Uk/PRC350

Andy,?
Sorry about that; I just realised that Groups.io helpfully resized the pics I attached enough to blur any useful detail: my local copy was as sent, but unreadable once logged in to the Groups.io interface.
I¡¯ve re-sent the pics direct to you, at full definition, so they should be as readable as possible; they¡¯re from a copy, of a copy of a Racal factory manual, so not very good in the first place, unfortunately. ?Hopefully just the big capacitors, or a bad joint, and not the tiny Unobtainium Plessey chip!
?
73,
?
Al
G8LIT?

Virus-free.

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