HP 48GX ON key problem

[jwhidby]

I have a HP 48GX with an ON key problem. When I try to turn the
calculator on or off as normal the key does not work. When I use ON+C
the on button works perfectly. I have no way to turn the calculator
off except waiting for it to time our or remove the batteries. Any
suggestions as to repairing this are appreciated. Jon

[Avatar_e]

Type OFF to power off the calc

For sure, the ON button is broken inside

[TW]

Post by jwhidby
I have a HP 48GX with an ON key problem. When I try to turn the
calculator on or off as normal the key does not work. When I use ON+C
the on button works perfectly. I have no way to turn the calculator
off except waiting for it to time our or remove the batteries. Any
suggestions as to repairing this are appreciated. Jon

I bet you have a program assigned to the OFF key. Is USER mode on?

TW

[manjo]

Post by jwhidby
I have a HP 48GX with an ON key problem. When I try to turn the
calculator on or off as normal the key does not work. When I use ON+C
the on button works perfectly. I have no way to turn the calculator
off except waiting for it to time our or remove the batteries. Any
suggestions as to repairing this are appreciated. Jon

Hello,

(if your GX is old enough or if it was exposed to fine dust :-)
you may have the problem i had with old SX !
Just about under first row of keys there are contacts which connect your
calculator motherboard with keyboard PCB.
(that's why it seems to be working when you press ON-C you press the
keyboard PCB so it gets slightly closer to MBRD -that's why it seems to be
working in that case)

These contacts are just touching eachother making contact that's why this is
sensitive to dust.

note: if that's the case it will not get better, it will get worse and more
anoying so consider following...

possible fix :
take your GX apart, try to blow away the dust with highly compressed air,
(use high preassure so you won't move the dust around, you would rather blow
it out and away)
in case this doesn't fix the issue go further: separate keyboard PCB from
motherboard and clean properly

I don't recommend this if you're not experienced in taking things apart and
puting them back tougether (without permanent damage :-)

manjo

[Edwin Mendoza]

I had the same issue some years ago after I opened my 48g.
The reason would be in yur case that the main board is not making
contact properly with the keayboard. The signal of the keys is
introduced to the main board right below the screen

Try turning it on but pressing the metal cover just above the the "C"
key. (In fact, it worked better for my between the "B" and "C" keys)

If it works, the problem is that the main PCB might have loosen. You
can 1) Get used turning it on and off that way (althow you might
program another button for the off function) 2) Hit it hard by a side
with your hands hoping luck fix it (it worked to me in some 49Gs when
the screen became crazy) 3) Try open it and tighten the board again.

I recomend #1

Edwin

[jwhidby]

Post by Edwin Mendoza
I had the same issue some years ago after I opened my 48g.
The reason would be in yur case that the main board is not making
contact properly with the keayboard. The signal of the keys is
introduced to the main board right below the screen
Try turning it on but pressing the metal cover just above the the "C"
key. (In fact, it worked better for my between the "B" and "C" keys)
If it works, the problem is that the main PCB might have loosen. You
can 1) Get used turning it on and off that way (althow you might
program another button for the off function) 2) Hit it hard by a side
with your hands hoping luck fix it (it worked to me in some 49Gs when
the screen became crazy) 3) Try open it and tighten the board again.
I recomend #1
Edwin

Edwin, Thanks for the advice. I tried your suggestion of pressing
above the B and C keys and using the on/off button. That works
perfectly. Is there any reason to try the distilled water wash
suggested for dirty HP48's? I don't think mine has ever had anything
spilled on it but it is 10+ years old. Thanks.

[Edwin Mendoza]

Post by jwhidby

Post by Edwin Mendoza
I had the same issue some years ago after I opened my 48g.
The reason would be in yur case that the main board is not making
contact properly with the keayboard. The signal of the keys is
introduced to the main board right below the screen
Try turning it on but pressing the metal cover just above the the "C"
key. (In fact, it worked better for my between the "B" and "C" keys)
If it works, the problem is that the main PCB might have loosen. You
can 1) Get used turning it on and off that way (althow you might
program another button for the off function) 2) Hit it hard by a side
with your hands hoping luck fix it (it worked to me in some 49Gs when
the screen became crazy) 3) Try open it and tighten the board again.
I recomend #1
Edwin

Edwin, Thanks for the advice. I tried your suggestion of pressing
above the B and C keys and using the on/off button. That works
perfectly. Is there any reason to try the distilled water wash
suggested for dirty HP48's? I don't think mine has ever had anything
spilled on it but it is 10+ years old. Thanks.

Wow... I've never read anything about cleaning with distilled water...
Sounds creepy. I wouldn't try that, but maybe its better than opening
the hp... the scars never dissapear. However I don't think water could
be good for electronics... maybe try the compressed air suggested above
without opening the HP...

Edwin

[Veli-Pekka Nousiainen]

Post by Edwin Mendoza

Post by jwhidby

Post by Edwin Mendoza
I had the same issue some years ago after I opened my 48g.
The reason would be in yur case that the main board is not making
contact properly with the keayboard. The signal of the keys is
introduced to the main board right below the screen
Try turning it on but pressing the metal cover just above the the
"C" key. (In fact, it worked better for my between the "B" and "C"
keys)
If it works, the problem is that the main PCB might have loosen. You
can 1) Get used turning it on and off that way (althow you might
program another button for the off function) 2) Hit it hard by a
side with your hands hoping luck fix it (it worked to me in some
49Gs when the screen became crazy) 3) Try open it and tighten the
board again.
I recomend #1
Edwin

Edwin, Thanks for the advice. I tried your suggestion of pressing
above the B and C keys and using the on/off button. That works
perfectly. Is there any reason to try the distilled water wash
suggested for dirty HP48's? I don't think mine has ever had anything
spilled on it but it is 10+ years old. Thanks.

Wow... I've never read anything about cleaning with distilled water...
Sounds creepy. I wouldn't try that, but maybe its better than opening
the hp... the scars never dissapear. However I don't think water could
be good for electronics... maybe try the compressed air suggested
above without opening the HP...

Distilled water - which yearns fhe ions from your metal parts?
Why not sulphur acid right away?!
maybe:
Tap water rinse & dry with compressed air

[Edwin Mendoza]

Post by Veli-Pekka Nousiainen
Distilled water - which yearns fhe ions from your metal parts?
Why not sulphur acid right away?!
Tap water rinse & dry with compressed air

Tap water would leave "dust" too or worst..
Imagine you get incrustations (such as when you boil water in a
recipient)... the you have to use Acetic Acid (CH3COOH)!!! (just
fooling around)

I say No to the water *idea*, nor acid!

Edwin

[manjo]

Post by Edwin Mendoza
I say No to the water *idea*, nor acid!
Edwin

That's right Edwin,
say NO to water :-)

however if one would, and i'm not saying that one should,
take the calculator appart and wash it COMPLETELY in destiled water AND dry
it completely using
compressed air or blowdrier it should be fine.

if one considers to wash only partialy dissasembled unit one shoud be awarw
of this :
when you wash your unit with destilled water, water gets dirty from dust and
dirt from your calculator,
naturally it is no longer destilled water -it is rather like dirty rain
water.

When water is drying it would gather in very tight and hard-to-reach places
leaving there a nice cover of
dirt from the water, even more sticked to the PCB than it was before.
So you may easily end up creating more problems.

manjo

NOTE (Now for real):
Cleaning method is not critical at all, just make it clean and dry (by means
available or familiar to you), ensure good contact
between the boards. It will work like new !

the rest is mumbo-jumbo or in my case: brain-exercise :-)

[John H Meyers]

Distilled water - which yearns the ions from your metal parts?
Why not sulphuric acid!

Jonathan Edwards?

maybe: Tap water rinse & dry with compressed air

Tap water -- which deposits minerals on your PCB?
Why not iron filings :)

Or shampoo (Brother Joe's miracle cure :)
http://groups.google.com/group/comp.sys.hp48/msg/e43be0f52af1159a

Or leave well enough alone, and just press the case crown down :)

Uh-oh, that might be another instance of...

http://en.wikipedia.org/wiki/Cross_of_gold_speech
Note the "Yellow brick road" connection:
http://en.wikipedia.org/wiki/Yellow_brick_road
http://en.wikipedia.org/wiki/Political_interpretations_of_The_Wonderful_Wizard_of_Oz

The pure original speech:
http://www.h-net.msu.edu/~shgape/internet/crosgold.html
"You shall not press down upon the brow of labor this crown of thorns,
you shall not crucify mankind upon a cross of gold."
- William Jennings Bryan, July 9th 1896

[r->] [OFF]

[o***@gmail.com]

Post by Edwin Mendoza
I had the same issue some years ago after I opened my 48g.
The reason would be in yur case that the main board is not making
contact properly with the keayboard. The signal of the keys is
introduced to the main board right below the screen
Try turning it on but pressing the metal cover just above the the "C"
key. (In fact, it worked better for my between the "B" and "C" keys)
If it works, the problem is that the main PCB might have loosen. You
can 1) Get used turning it on and off that way (althow you might
program another button for the off function) 2) Hit it hard by a side
with your hands hoping luck fix it (it worked to me in some 49Gs when
the screen became crazy) 3) Try open it and tighten the board again.
I recomend #1
Edwin

Just great

a post from 6 years ago

today I was cleaning the room and found the very beautiful hp 48 with the exact same problem with the ON key...

I was looking on google for opening instructions to clean below the key but wait! this post from Edwin and Manjo appeared... I'm so thankful now... that was all what it took.. just a gentle touch over the C key and the miracle happened... the old machine came back to life.

So many thanks to google and Edwin and Manjo

long live to Hp 48 calculator

I'm really happy

[g***@gmail.com]

Post by Edwin Mendoza
I had the same issue some years ago after I opened my 48g.
The reason would be in yur case that the main board is not making
contact properly with the keayboard. The signal of the keys is
introduced to the main board right below the screen
Try turning it on but pressing the metal cover just above the the "C"
key. (In fact, it worked better for my between the "B" and "C" keys)
If it works, the problem is that the main PCB might have loosen. You
can 1) Get used turning it on and off that way (althow you might
program another button for the off function) 2) Hit it hard by a side
with your hands hoping luck fix it (it worked to me in some 49Gs when
the screen became crazy) 3) Try open it and tighten the board again.
I recomend #1
Edwin

Thanks Edwin. I love my 48s, which I've had for more than 20 years, and I still use it almost every day (reverse Polish notation has no rival). I've had this annoying problem for quite a while now, and I am very grateful to you for solution #1. I can live with the gentle pressing, and it solves the problem! I am not willing to try anything else for the moment. (By the way, I was born in Mendoza, Argentina, so your name evoked some nice memories of my hometown.)

Gabriel

[s***@gmail.com]

Genius! Your tip, save my hp48. I was about to destroy it!

[CosmicTruth]

I realize this is an extremely old post but wanted to add this pointer to http://www.hpmuseum.org/forum/thread-49.html to prevent people from cleaning there calculators in a vat of acid.

[DanK]

I have never opened up a HP48. I have revived a couple HP48 with water.

Basically I just soak the HP48 in warm water for a few minutes (take any batteries out first), then flushed with more warm water. Drain good, then let dry for a couple days.

I have done this with like 4-5 HP48 (both SX and GX). And the calcs have always worked as good or better after letting dry.

I wouldn't try this with newer calcs (get water stuck in the display maybe), but never seemed to be a problem with the HP48.

[g***@gmail.com]

Post by Edwin Mendoza
I had the same issue some years ago after I opened my 48g.
The reason would be in yur case that the main board is not making
contact properly with the keayboard. The signal of the keys is
introduced to the main board right below the screen
Try turning it on but pressing the metal cover just above the the "C"
key. (In fact, it worked better for my between the "B" and "C" keys)
If it works, the problem is that the main PCB might have loosen. You
can 1) Get used turning it on and off that way (althow you might
program another button for the off function) 2) Hit it hard by a side
with your hands hoping luck fix it (it worked to me in some 49Gs when
the screen became crazy) 3) Try open it and tighten the board again.
I recomend #1
Edwin

Wow! I've an old HP 48 SX with the same problem. I've pressed strongly the case between B and C keys and "voilà" the problem has gone" Perfect! Thank you so much.

[g***@gmail.com]

Post by Edwin Mendoza
I had the same issue some years ago after I opened my 48g.
The reason would be in yur case that the main board is not making
contact properly with the keayboard. The signal of the keys is
introduced to the main board right below the screen
Try turning it on but pressing the metal cover just above the the "C"
key. (In fact, it worked better for my between the "B" and "C" keys)
If it works, the problem is that the main PCB might have loosen. You
can 1) Get used turning it on and off that way (althow you might
program another button for the off function) 2) Hit it hard by a side
with your hands hoping luck fix it (it worked to me in some 49Gs when
the screen became crazy) 3) Try open it and tighten the board again.
I recomend #1
Edwin

Thanks, exactly the same point on my 48S.

[t***@gmx.net]

Holy cow,
My on key button did not work and your comment helped!
Holding the on key and a gentle touch on the metal housing above the b and c keys and the on function (or off) is back again.
Thank you sooo much.

[g***@gmail.com]

Hello i just found hp48gx inmy shelf. I changed battery tried all your suggestions but nothing has happened. There is no way to turn it on. Coyld you advise ne orher strategies? Than you

[elturco]

Some little pressure between the screen and the first white line of buttons while you turn on or off will do it.

[r***@gmail.com]

Post by g***@gmail.com
Hello i just found hp48gx inmy shelf. I changed battery tried all your suggestions but nothing has happened. There is no way to turn it on. Coyld you advise ne orher strategies? Than you

There is a common problem on the 48GX after changing the batteries where the unit will not power on. The solution is to reset the unit via the pinhole under the top, right rubber foot (when viewed keyboard down). Here are the full instructions:

http://www.shareyourrepair.com/2014/11/how-to-fix-hp-48gx-will-not-turn-on-after-replacing-batteries.html

[t***@gmail.com]

Post by Edwin Mendoza
I had the same issue some years ago after I opened my 48g.
The reason would be in yur case that the main board is not making
contact properly with the keayboard. The signal of the keys is
introduced to the main board right below the screen
Try turning it on but pressing the metal cover just above the the "C"
key. (In fact, it worked better for my between the "B" and "C" keys)
If it works, the problem is that the main PCB might have loosen. You
can 1) Get used turning it on and off that way (althow you might
program another button for the off function) 2) Hit it hard by a side
with your hands hoping luck fix it (it worked to me in some 49Gs when
the screen became crazy) 3) Try open it and tighten the board again.
I recomend #1
Edwin

#1 is BRILLIANT! Thanks!

[m***@gmail.com]

Post by t***@gmail.com

Post by Edwin Mendoza
I had the same issue some years ago after I opened my 48g.
The reason would be in yur case that the main board is not making
contact properly with the keayboard. The signal of the keys is
introduced to the main board right below the screen
Try turning it on but pressing the metal cover just above the the "C"
key. (In fact, it worked better for my between the "B" and "C" keys)
If it works, the problem is that the main PCB might have loosen. You
can 1) Get used turning it on and off that way (althow you might
program another button for the off function) 2) Hit it hard by a side
with your hands hoping luck fix it (it worked to me in some 49Gs when
the screen became crazy) 3) Try open it and tighten the board again.
I recomend #1
Edwin

#1 is BRILLIANT! Thanks!

# 1 worked, Thanks. I told HP about your answer with link to it.

[Edwin Mendoza]

Post by manjo

Post by jwhidby
I have a HP 48GX with an ON key problem. When I try to turn the
calculator on or off as normal the key does not work. When I use ON+C
the on button works perfectly. I have no way to turn the calculator
off except waiting for it to time our or remove the batteries. Any
suggestions as to repairing this are appreciated. Jon

Hello,
(if your GX is old enough or if it was exposed to fine dust :-)
you may have the problem i had with old SX !
Just about under first row of keys there are contacts which connect your
calculator motherboard with keyboard PCB.
(that's why it seems to be working when you press ON-C you press the
keyboard PCB so it gets slightly closer to MBRD -that's why it seems to be
working in that case)
These contacts are just touching eachother making contact that's why this is
sensitive to dust.
note: if that's the case it will not get better, it will get worse and more
anoying so consider following...
take your GX apart, try to blow away the dust with highly compressed air,
(use high preassure so you won't move the dust around, you would rather blow
it out and away)
in case this doesn't fix the issue go further: separate keyboard PCB from
motherboard and clean properly
I don't recommend this if you're not experienced in taking things apart and
puting them back tougether (without permanent damage :-)
manjo

I posted almost the same, sorry I didn't read it until I finished.

[g***@gmail.com]

Post by manjo

Post by jwhidby
I have a HP 48GX with an ON key problem. When I try to turn the
calculator on or off as normal the key does not work. When I use ON+C
the on button works perfectly. I have no way to turn the calculator
off except waiting for it to time our or remove the batteries. Any
suggestions as to repairing this are appreciated. Jon

Hello,
(if your GX is old enough or if it was exposed to fine dust :-)
you may have the problem i had with old SX !
Just about under first row of keys there are contacts which connect your
calculator motherboard with keyboard PCB.
(that's why it seems to be working when you press ON-C you press the
keyboard PCB so it gets slightly closer to MBRD -that's why it seems to be
working in that case)
These contacts are just touching eachother making contact that's why this is
sensitive to dust.
note: if that's the case it will not get better, it will get worse and more
anoying so consider following...
take your GX apart, try to blow away the dust with highly compressed air,
(use high preassure so you won't move the dust around, you would rather blow
it out and away)
in case this doesn't fix the issue go further: separate keyboard PCB from
motherboard and clean properly
I don't recommend this if you're not experienced in taking things apart and
puting them back tougether (without permanent damage :-)
manjo

this worked perfectly. thank you so much!

[niemarkt]

I had the same with my 24 year old 48GX. Was about to throw it away. Pressing above the B and C keys did the trick.
Thank you!
Christian

[niemarkt]

I had the same with my 24 year old 48GX. Was about to throw it away. Pressing above the B and C keys did the trick.
Thank you!
Christia
http://compgroups.net/comp.sys.hp48/

[t***@gmail.com]

I have the same problem.
First enter an alarm that turns on the calculator several key times a day.
To turn off the calc just type OFF and Enter

[HansPanzer]

Excellent!
I had to knock so hard on ON key that it was painful. Colleagues were thinking I do resuscitation to my HP. I had switched back to my even older HP28S.

Now it is Ok while pressing near B.

[d***@gmail.com]

I know this is an old post, but i see at least one reply for this year. There is a contact cleaner that might work for this... I'm going to try and see, but for now the light depression of the case above B/C and ON is working for now.

Here's a link to the cleaner that I'm talking about: http://www.homedepot.com/p/CRC-QD-11-oz-Contact-Cleaner-02130-6/202262505

I would recommend you follow up with a compressed air dry, even though this stuff evaporates fast. I'll post back and let you all know how this goes... Compressed air alone has not been effective. A little liquid will help to move stuff around.

[d***@gmail.com]

Thanks, pressing above b c worked.
Compressed air on the calculator face didn't fix problem. What did fix it was removing the memory card cover and blowing compressed air into the calculator from the top. Works like new now.

[Nordic Crystal]

I have a HP 48GX with an ON key problem. When I try to turn the
calculator on or off as normal the key does not work. When I use ON+C
the on button works perfectly. I have no way to turn the calculator
off except waiting for it to time our or remove the batteries. Any
suggestions as to repairing this are appreciated. Jon

I know it's been some time, but I have had same issue and got it sorted. So if anyone is reading this looking for a solution, try this.

In the older machines there brews a connection issue which will sometimes make the calculater not respond to the ON button being pressed.
Test this: Lightly press above the B & C button, just between the buttons and the LCD screen, while pressing try to switch on.

If that worked, you have this connection issue. On my calculator it deteriorated to including the entire top right quadrant of the keyboard. Annoying to say the least.
But I got that fixed too, i will paste the solution here below, sorry if some of the wording seems off - it's from a comment I made on Youtube so might ''read'' weird:

I had this issue on my HP 48GX and found a similar instruction somewhere online about a year ago - worked wonders for me. However, now (a year later) about a 1/3 of all buttons top right quadrant requires this to work at all. I didn't really like that so i looked for more videos on disassembly and found out it is a bi*** to take apart....
Figured I'd go for a more ''messy'' solution - just to try it out.

I removed the battery cover, batteries, and memory slot cover. I took a can of pressurized electro-cleaning fluid and sprayed A LOT in through the memory card slot, through the battery slot (where the connectors come through the plastic, and through the hole where the forward facing connector is (next to the IR lights). then i shook and turned the calculator to make sure it got in everywhere.
Now I want to be clear. I wrote A LOT above and I really mean A LOT. It was running out in a steady stream of the other end of the calculator as I sprayed like a madman on drugs.
Afterwards I used a vacuum cleaner on the same places, just to get a rinse through of air which helps evaporate any electro-cleaning fluid still stuck inside.

I no longer need to press above B and c at all, not even to start it up, contact/functionality is fully restored.

I got the idea after watching Right to Repair Nightmare - HP 48SX: (

) - where at 16:55 he shows a part sitting just below where we press connecting the board to a piezo element on the back metal frame itself. Figured there might just be a connecting issue there. I might be very wrong about what I figured, I might be so off you wouldn't believe - but the fact remains: I can now use my calculator as normal again.