Any HP25c schematics?

08312018, 01:14 PM
Post: #1




Any HP25c schematics?
Hello everyone,
I've bought a "cheap" but heavily bluewhitegreen corroded HP25c and washed and cleaned it. It was so damaged that in the wash process I almost lost a component; this the "big" black transistor on the left of the first (mid) RAM chip (thank you, Harald!): Now, I have to test it (and every component I guess) and to solder it (or a new one) on the board again. But where does it connect onto the board? I didn't find any picture or schematic neither in this site, nor on the PPC DVD of Jack Schwartz. Any help will be appreciated. 

08312018, 01:53 PM
Post: #2




RE: Any HP25c schematics?
Woodstock HP21 HP25 Schematics.pdf (Size: 1.21 MB / Downloads: 129) I've attached an ancient PDF that I had lurking around  hope that might help? I've also got a NASA HP25 program listing for calculating Loran time differences if you want to run and see if it works ok after your major trauma surgery on the calculator. Dennis Denny 

08312018, 03:08 PM
Post: #3




RE: Any HP25c schematics?
Great, many thanks!


08312018, 05:21 PM
Post: #4




RE: Any HP25c schematics?
If you want to see the last photo in whole go to the website that is shown in the pdf. So you can see the whole hardware displayed.
Andi 

08312018, 07:53 PM
Post: #5




RE: Any HP25c schematics?
(08312018 01:53 PM)Leviset Wrote: … a NASA HP25 program listing for calculating LORAN time differences … Can be downloaded from archive.org as NTRS1978002312 LORAN Time Difference. BEST! SlideRule 

09012018, 04:17 AM
Post: #6




RE: Any HP25c schematics?
(08312018 07:53 PM)SlideRule Wrote: Can be downloaded from archive.org as NTRS1978002312 LORAN Time Difference. Thanks for the link to the program. These formulas are used: \( \begin{align*} \beta_T&=\tan^{1}[C\tan(\Phi_T) ] \\ \beta_R&=\tan^{1}[C\tan(\Phi_R) ] \\ X &= \cos^{1}[\sin(\beta_R)\sin(\beta_T)+\cos(\beta_R)\cos(\beta_T)\cos(\lambda_R\lambda_T)] \end{align*} \) But we can factor out \(\cos(\beta_R)\cos(\beta_T)\) and get: \(X = \cos^{1}[\cos(\beta_R)\cos(\beta_T)(\tan(\beta_R)\tan(\beta_T)+\cos(\lambda_R\lambda_T))]\) Hence we can avoid calculating \(\sin(\beta_R)\) and \(\sin(\beta_T)\) since \(\tan(\beta_R)\) and \(\tan(\beta_T)\) have already been computed. This makes the program a bit shorter: Code: 01: 24 06 RCL 6 C Example 21282.339 π × 180 ÷ STO 5 0.99664767 STO 6 39.1930 →H STO 3 82.0615 →H STO 4 34.034604 →H STO 1 77.544676 →H STO 2 f CLEAR PRGM R/S 2317.7679 Cheers Thomas 

06172019, 06:14 PM
Post: #7




RE: Any HP25c schematics?
(08312018 01:53 PM)Leviset Wrote: I've attached an ancient PDF that I had lurking around  hope that might help? Sadly, Jaques’ site, while excellent, is on the 21 and 25, but not the 25c. While there is much relevant information, the original question seems to still be unanswered: Is there a schematic for the 25c available? Thanks.kby 

06172019, 06:40 PM
Post: #8




RE: Any HP25c schematics?
Did you look at Tony's schematics? HP25C included ...
https://www.hpmuseum.org/forum/thread13065.html 

06172019, 07:12 PM
Post: #9




RE: Any HP25c schematics?
(06172019 06:40 PM)AndiGer Wrote: Did you look at Tony's schematics? HP25C included ... Mea culpa. I had, but apparently not carefully enough. I think maybe I got an earlier version, or the name "Classic Schematics" stuck in my mind, although I did know he subsequently added the 19c and 29c.kby 

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