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+--- Thread: HP 25 (/thread-17524.html)
HP 25 - Steve Hey - 09-27-2021 11:44 PM
Hi HP, ers,
I am new to the forum but have been using HP 25, 29C and all the 41's, great machine, use mainly for survey etc... on a regular basis.
I have HP 25 with problem of when in program mode most keys show 13 00, with f and g working fine, in run mode everything is also working fine i.e calculations are no problem.
Any assistance in solving my problem will be appreciated, I am not an expert in any way on pcb's.
Also wondering if Bernard of panamatik's repair of ACT is the way to go.
Cheers Steve
RE: HP 25 - teenix - 09-28-2021 04:58 AM
Sounds like a ROM issue rather than keyboard, so maybe the repair kit will fix it.
cheers
Tony
RE: HP 25 - Steve Hey - 09-28-2021 05:44 AM
Hi Teenix
Many thanks for your advice on possible ROM problem, are ROM parts avaliable anywhere.
I have the ACT repair kit coming for my 29C that got plugged in without a battery, so I may put that into the 25 as a trial.
Kind regards,
Steve
RE: HP 25 - ThomasF - 09-28-2021 06:40 AM
Hi Steve,
Could it be the RAM-chip that is failing?
All stack registers etc are locally in the ACT (the "cpu") but program memory and storage registers are in a separate RAM-chip.
Can you check that the storage register work? I.e. STO n (n:0..7) and RCL n works as expected.
If the RAM fails, normal calculation still works fine (since stack and internal registers are in the ACT) - but statistics (mean, sdev etc) will not since they make use of the r3-r7 registers.
Panamatik's ACT replacement will most probably help in that case, since the new ACT contains its own RAM and is not dependent of the old external RAM-chip.
And even if it would be the ROM (which I don't think), Panamatik's ACT will also work, since it also overrides the external ROM-chip.
Best regards,
Thomas
RE: HP 25 - Steve Hey - 09-28-2021 08:40 AM
Hi Thomas
Thanks for your reply
Will do the steps you recommended
I will let you know
Best regards
Steve
RE: HP 25 - Steve Hey - 09-28-2021 11:25 AM
Hi Thomas
Checked Sto 0 to 7 reading 13 00 sane for RCL nn
So I think I need ACT repair kit
Best regards
Steve
RE: HP 25 - ThomasF - 09-28-2021 01:53 PM
Hi Steve!
Sorry for being unclear - but I meant that you could check STO/RCL in RUN-mode.
In RUN-mode (normal calculation), can you store anything in the registers?
I.e. does "12345 STO 5 CLx RCL 5" result in "12345"?
Code:
Press Display shows
12345 "12345"
STO 5 "12345.00"
CLx "0.00"
RCL 5 "12345.00"Or, if you press "g EEX" (clear reg) and then repeatedly on "Sum+" (the summation-key below "g")?
If RAM is correct, then the value in the display should increase with one for every time you press "Sum+" like this:
Code:
Press Display shows
CLx "0.00"
g EEX "0.00"
Sum+ "1.00"
Sum+ "2.00"
Sum+ "3.00"If this doesn't work, my 2 cents are that the RAM-chip is broken, and yes, a ACT replacement kit is probably needed (or a RAM-chip from another HP25 which might have another fault chip).
Cheers,
Thomas
RE: HP 25 - Steve Hey - 09-28-2021 02:17 PM
Hi Thomas
In the 12345 test 0.00 at end
In the g eex test result is 1.0
So I believe you are correct RAM chip corrupted
So AMT repair kit sounds like the solution
Kit is on its way from Bernhard, will let you know result
Best regards
Steve
RE: HP 25 - Amafan - 09-30-2021 10:14 PM
@Steve
I have the same problem. Please let us know how it works including the purchasing and shipment of the repair kit.
(09-28-2021 02:17 PM)Steve Hey Wrote: Hi Thomas
In the 12345 test 0.00 at end
In the g eex test result is 1.0
So I believe you are correct RAM chip corrupted
So AMT repair kit sounds like the solution
Kit is on its way from Bernhard, will let you know result
Best regards
Steve