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Question regarding SAMS CB Photofact Parts List practices...

guitar_199

Sr. Member
Mar 8, 2011
897
1,173
153
Deer Park, TX
Calling on experience once again here......

I have attached a "snip" of an electrolytic caps list from a SAMS Cb Photofact. My current thought is.... it doesn't matter what radio.... I have seen this in a NUMBER of their listings.....

WVJOmWb.png


Hoping the formatting works!!!!

Take a look at the callout for C265....

The upper line says 0.47uF 50v, the line right under it does not have a callout, I am assuming that it is an alternate part of some kind......

The lower line says 47uF 50v.

THAT is QUITE a difference!!!!

So I guess... the kind of thing that I wonder is......

1) IS this what I said? Are these BOTH acceptable parts? (especially with a wide margin of difference!)

2) Does it matter which I put in? (yeah.... its a loaded question......but I'm throwing it out there! :) )

3) Does this just call for "checking my specific radio" to determine what I should get?

What is a reasonable way to play this?

As always, thanks for any tips/advice!

Bob
 

I see this too, especially on Uniden tuning section circuit callouts.

It's just easier to look on the schematic and then figure on using the listed OR the one they put in there.

I talked about this before - especially when using tuning caps as "dividers" for RF signal - ever notice the AN612 and the caps used there?

Especially around the Balanced Modulator like the AN612...
upload_2021-4-15_18-59-50.png

Does not use a LARGE value for presence, but the Audio input cap from the Mic amp usually is quite large.

It's the support "splitter" parts that are used in the circuits input pin 3 the one that uses the Clarifier IF to make the Audio Mix for that 10.7MHz IF Xtal trimming off the other two (Carrier and Opposite Sideband).
  • These values change by manufacture of the IC as well as by year or production.
So you're not the only one seeing this, but to help - looking over those callouts...

Pay attention to the package outline in the next column - PC1-50 versus PC50-50 that describes the package (note A63 then a J63 - a tolerance comparison inclusive in the next column) So these are a type of PC board specs for insertion (package outline).

So you have to review the parts lists, the part in your hand wins
  • As the Saying goes...
    • - The one in your hand is worth two parts listed on paper.
 
Good points all!

Thank you again HA !

I see this too, especially on Uniden tuning section circuit callouts.

It's just easier to look on the schematic and then figure on using the listed OR the one they put in there.

I talked about this before - especially when using tuning caps as "dividers" for RF signal - ever notice the AN612 and the caps used there?

Especially around the Balanced Modulator like the AN612...

Does not use a LARGE value for presence, but the Audio input cap from the Mic amp usually is quite large.

It's the support "splitter" parts that are used in the circuits input pin 3 the one that uses the Clarifier IF to make the Audio Mix for that 10.7MHz IF Xtal trimming off the other two (Carrier and Opposite Sideband).
  • These values change by manufacture of the IC as well as by year or production.
So you're not the only one seeing this, but to help - looking over those callouts...

Pay attention to the package outline in the next column - PC1-50 versus PC50-50 that describes the package (note A63 then a J63 - a tolerance comparison inclusive in the next column) So these are a type of PC board specs for insertion (package outline).

So you have to review the parts lists, the part in your hand wins
  • As the Saying goes...
    • - The one in your hand is worth two parts listed on paper.
 
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Reactions: unit_399
I agree with Andy 100% on this. If you're planning on doing a total cap replacement, experience has taught me to remove the cap, check the value, and replace it with a new one same value. I don't rely on the published parts list in SAMS. During the CB boom years of the 70s, there were so many new radios coming on the market that SAMS was hard pressed to keep up. So ... a lot of mistakes got into print.

- 399
 
Murphy's Law dictates that all schematic diagrams contain at least one error.

Parts lists, usually more.

What's IN the radio is the right part. Had a Tram D201 that had been "rebuilt". The guy replaced every carbon-comp resistor with a new carbon-film type. Installed the resistance values shown in the diagram.

Okay, but the radio had odd problems. Had to take the covers off another radio to be sure the correct value of a few parts. The published schematic is just wrong in a few critical places. Used the same value parts found in the "crib sheet" radio and it sounded just fine.

Live and learn.

73
 
Ditto..
For clarity sake I sometimes re-draft SAM's schematics that have been damaged. While working on a recap job, not only will you find numerous substitutions, but outright errors. SAM’s are good as a general guide, but don’t trust the contents, especially after # 100. Manufacture substitutions over time are to be expected, but all the errors I’ve been finding are unacceptable. About the only time I look at an electrolytic capacitor parts list anymore is to compare it with the stock I have on hand.
 
I agree that is probably the best way to go.

In a way, laziness was the "mother" of this question.
Was trying to make up the cap order list from the SAMS list "without having to tear in to the radio" because (around here) it may be boxed up waiting for "it's time to come".

I can see the value and wisdom though.....of checking ahead of time.

I agree with Andy 100% on this. If you're planning on doing a total cap replacement, experience has taught me to remove the cap, check the value, and replace it with a new one same value. I don't rely on the published parts list in SAMS. During the CB boom years of the 70s, there were so many new radios coming on the market that SAMS was hard pressed to keep up. So ... a lot of mistakes got into print.

- 399
 
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Reactions: Handy Andy

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