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HP25C repair, help needed
01-19-2019, 10:04 AM
Post: #20
RE: HP25C repair, help needed
Thanks Tony
Your tips were very helpful !!

I studied electronic at high school some thirty years ago so I recall some of them.

We have put together a bunch of useful documents about hp25 especially from Jaques Laporte website

Still the Hp25c is different in the PSU scheme

There are few less diodes and just to name a difference between the two models, below the display in the Hp25c there is no capacitor nor diode differently from the hp25 where part of the psu is located there.

Also, the big capacitor close to the transistors in the hp 25, in the Hp25c has evolved in two capacitors connected, so this is also a difference

there is an additional transistor close to the ACT which is not present in the Hp25

This makes more difficult to recover the testing points for the three voltages

We have a working hp25 and a Working hp25c so that we may open up those and try to locate those points

We will try to strip all the components following your advices and check them out

Still, if someone from the forum can tell us where are the testing points on an HP25C board it will really help us

If we will discover them will publish it here

In reality we now where to find this points once they arrive at the IC PINS as this is well documented but we would prefer to check them closer to the PSU components

Thanks again everyone!!!

Edoardo & Alberto
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Messages In This Thread
HP25C repair, help needed - albertofenini - 01-15-2019, 09:24 PM
RE: HP25C repair, help needed - teenix - 01-16-2019, 11:49 AM
RE: HP25C repair, help needed - teenix - 01-16-2019, 11:37 AM
RE: HP25C repair, help needed - teenix - 01-16-2019, 11:39 AM
RE: HP25C repair, help needed - AndiGer - 01-18-2019, 05:51 PM
RE: HP25C repair, help needed - teenix - 01-17-2019, 01:04 AM
RE: HP25C repair, help needed - hewlpac - 01-16-2019, 10:35 PM
RE: HP25C repair, help needed - jebem - 01-17-2019, 08:29 PM
RE: HP25C repair, help needed - teenix - 01-17-2019, 05:39 PM
RE: HP25C repair, help needed - teenix - 01-19-2019, 03:39 AM
RE: HP25C repair, help needed - albertofenini - 01-19-2019 10:04 AM
RE: HP25C repair, help needed - AndiGer - 01-19-2019, 06:09 PM
RE: HP25C repair, help needed - mpark - 01-24-2019, 07:50 PM
RE: HP25C repair, help needed - AndyWalter - 01-20-2019, 05:00 PM
RE: HP25C repair, help needed - AndyWalter - 01-20-2019, 05:37 PM
RE: HP25C repair, help needed - AndyWalter - 01-20-2019, 05:40 PM
RE: HP25C repair, help needed - mpark - 01-27-2019, 07:28 AM
RE: HP25C repair, help needed - AndiGer - 01-26-2019, 04:02 PM
RE: HP25C repair, help needed - burkhard - 02-18-2019, 07:04 PM
RE: HP25C repair, help needed - ijabbott - 02-19-2019, 04:59 PM
RE: HP25C repair, help needed - burkhard - 02-19-2019, 05:09 PM



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