ciao a tutti,
I have purchased an HP65, mainly because I needed a card reader block, since one of mine has a damaged head.
However, when it has arrived, it looked better than described, and before using it as a donor, I wanted to try a restoration.
It has been cleaned inside out from the oxidation,nothing too bad, but presents anyway.
All I get is a very faint "0" with some missing segments.
If battery is attached directly to the card reader engine, this runs.
The two power supply transistors get burning hot after few seconds that the unit is powered on.
Where should I start from ?
Pictures have been taken before any operation was done, the contact plate that is misplaced in picture 1 has been put in the right place ...
Thank you very much for any help and any hints provided !!
Alberto
Restoring an HP65 (trying to .... few pics)
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06-18-2012, 06:59 AM
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06-18-2012, 09:44 AM
hello alberto, i would recommend to start the repair WITHOUT the card reader board connected ... check at first the voltages generated on the logic board and in case you have a scope you should inspect the PHI signal ... these are VERY essential testings before oing on ... look in the HP-forum there are several postings concerning the generating of the operating votlages and the according circuitry ... in case the you are able you get the calc to work WITH DISCONNECTED card reader, i can let you know some hints for the card reader ...
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06-18-2012, 10:07 AM
Hello Peter, ▼
06-18-2012, 10:47 AM
Ciao Alberto and thank-you for sharing this repearing job of the 65. This is the first time I see such a calculator opened and it's quite different if compared to the HP67, so that I will follow this post with pleasure.... A presto and compliments for your new machine. Aurelio ▼
06-19-2012, 04:25 AM
ciao Aurelio, ciao a tutti, ▼
06-19-2012, 02:35 PM
Quote: I have bought a 25 ml bottle of DeOxit D100L for 25,70 euro in The Netherlands, last April. I tried cleaning a corroded HP-21 pcb with it, but unfortunately it did nothing. I am sure it is a quality product and maybe it works well for cleaning contacts etc., but in my experience it is no good for cleaning corroded pcb's.
06-18-2012, 07:43 PM
Hi Alberto, If the two transistors on the logic board are getting hot, then you most likely have problems with the dc-dc converter. As Peter says, check the three voltages Vcc, Vss and Vgg. I would recomment you replace both transistors, the 2nF capacitor and all diodes in the dc-dc converter. Check all the "Kemet" tantalum capacitors as well, although they are apparently good quality components, they can fail.
Cheers,
Edited: 18 June 2012, 7:44 p.m. ▼
06-19-2012, 04:27 AM
I'll certainly do so, over the weekend, and post the results ... ▼
06-19-2012, 05:54 AM
hello alberto, i want to confirm the statements of John, he is a great specialist on the hp-65 and has a lot of experience ... concerning the replacement parts John described it in an expertise and stated
Q1 - 1854-0094 -> PN3646 ... be careful in using a battery pack with the original charging unit - i think it is better to use an external power-supply ... ... attention in cleaning CORRODED parts especially the hybrid unit -> because the corrosion diffundes to the inside of the hybrid and generates faults to the 6 discrete chips inside !!! ... as i mentioned before - in case the dc-dc unit is operating okay supply voltages are okay - the PHI signals are generated by the led driver and are fed to the hybrid IN pins - in case you have NO okay signals on the OUT pins -> the hybrid will be faulty and you can stop further actions OR you have a hybrid in spare !? ... Tony Duells description of the chips is very helpful and a good base for error tracing ... ... conclusion over all: for trying to repair the card reader it is ESSENTIAL that you have a working logic board/display/keyboard ... good luck from Austria peter ▼
06-19-2012, 06:17 AM
Please,can anyone post a picture of the hybrid components ? ▼
06-19-2012, 12:50 PM
here i am again ... i have attached a picture of a CORRODED hybrid ... the green arrows show them ...
it should ONLY demonstrate, what happens with corrosion ... in this case the hybrid wasn't working anymore and I opened it for demonstration ... peter from Austria ▼
06-19-2012, 02:37 PM
Thank you for uploading this picture! I have always wondered what was inside, now I know :-) ▼
06-19-2012, 05:19 PM
Dear All,here is what I did : ▼
06-20-2012, 03:46 AM
Alberto, oki doki ... step3 don't look fine ... take the steps John recommended ... change transistors ... peter ▼
06-20-2012, 07:42 AM
Dear Peter, dear All, ▼
06-20-2012, 08:02 AM
Dear All, ▼
06-20-2012, 10:00 AM
Please, ignore this last post, Ignazio (thank you so much) as ▼
06-20-2012, 12:13 PM
Alfredo,
... the link is very GOOD ...
hope this helps ... peter ▼
06-20-2012, 12:28 PM
Dear Peter, ▼
06-20-2012, 02:32 PM
Dear All,
06-22-2012, 10:58 AM
Alfredo, ... concerning wrong voltages on Vss + Vgg and Vcc=6,76V ... in think that oscillator works, because the rectification on CR2 gives right value, BUT NOT on CR1, 3 + 5 ... may be diodes are faulty or appropriate capacitors CR3, 6 + 7 ... you should use 1N34A or equivalent and be sure that the tantals are okay ... concerning the diodes look for "farnell" MICROSEMI 1N34A (€ 1,51)... CR5/C7 deliver Vss and C2/C6/CR1/CR3 voltage doubler assembly Vgg ... make sure that these components are okay ... peter ▼
06-22-2012, 11:14 AM
ciao Peter, ▼
06-22-2012, 11:18 AM
Peter, one more thing ... ▼
06-22-2012, 12:49 PM
Alberto,
First off all please excuse the wrong prename, thanks
Vgg <-- C2/C4/CR1/CR3 ... tantal -> check the polarity and that they are not damaged C2/C4 - 3,3uF and C7 - 22uF ... okay peter ▼
06-22-2012, 06:41 PM
This Message was deleted. This empty message preserves the threading when a post with followup(s) is deleted. If all followups have been removed, the original poster may delete this post again to make this placeholder disappear. ▼
06-24-2012, 10:44 AM
ciao a tutti, ▼
06-28-2012, 06:33 PM
ciao a tutti,one more update on this project. ▼
06-29-2012, 09:21 AM
Alberto, Look for the PHI 1/2 signals IN + OUT with a scope ... look the picture I posted before ... on the left side, where the test pins are located, you see PHI 1/2 OUT and on the lower side of the board there are the PHI 1/2 inputs pins, leading from the display drivers, where the PHI is generated ... in case you have NO PHI 1/2 OUT - as a function of the hybrid - may be that the hybrid is faulty ??? ... these PHI signals are very essential !!! peter ▼
06-29-2012, 09:45 AM
ciao Peter, |