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[resolved] HP49G+ doesn't turn on - Printable Version

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[resolved] HP49G+ doesn't turn on - k.mart - 09-29-2009

(sorry for my bad english, I'm french..)
so, i want to fix my HP49G+, when i turn it on, there are a flash on the screen and nothing happening. I opened it to check voltage and everything is ok. I think, it's a ROM problem. I searched information about an possible RS232 pins on motherboard,to reflash the ROM in the flash (SST39VF120) but I have not found informations about that. If you have an idea how I can repair my HP49G+, I'm ready to heard.

Edited: 6 Oct 2009, 1:55 p.m. after one or more responses were posted

Have you tried.. (Re: HP49G+ doesn't turn on) - Vieira, Luiz C. (Brazil) - 09-29-2009


the HP49 has a small hole in the back of it with a RESET inscription close to it. The idea is to reset the hardware (not intended to clear memory contents) in some circumstances. If you have not tried it yet, just gently insert the tip of a paper clip in the small hole till it reaches the mainboard (you will feel it canot go any further... No need to push it harder). At this point, a small metal plate is touching a contact in the mainboard, and you can keep it for about three seconds (HP recomendations). As you have already opened the calculator, you can easily locate it and even perform the reset directly. Maybe your HP49G will wake up and work fine after that.


Luiz (Brazil)

Re: HP49G+ doesn't turn on - Reth - 09-30-2009

You need to give more details about how it stopped turning on. Did you install any

Re: HP49G+ doesn't turn on - k.mart - 09-30-2009

I have already try insert a paper clip in reset hole but nothing happening (whith [+] [-] too).

For details, the first bug a few months back, and I suppose a librairy is concerning, but which .. maybe Openfire, tgv or hp49g library... I thought after few days whithout battery, it would restart but no.

Thanks you for your help.

Re: HP49G+ doesn't turn on - Reth - 09-30-2009

If you have "bad" library try this:

Holding BackSpace during Boot Sequence will put the calculator in safe mode. User library
will be completely ignored...

That means reboot: press and hold down keys [ON]+[C] and immediately after they are released press and hold down backspace [<-] (below DEL and CLEAR). The above needs to be done very quickly so you may need to try a few times.
Hope this helps

Re: HP49G+ doesn't turn on - k.mart - 10-01-2009

I tryed to this sequence but I didn't have a success. One more thing, when I put the battery, my HP49g+ start with a flash screen and nothing, and I can't turn off (I observed the intensity because I can't know if it turn on or not..). Whith this, i can't turn on my calculator with [ON] key or [ON] + [C] , so I don't know if the i can enter in safe mode.

Re: HP49G+ doesn't turn on - Bart (UK) - 10-01-2009

OK, this may be a bit of a long shot. I once had a PC that didn't start, but just beeped and flashed on the screen. It was because the air was too dry. I had to leave a humidifier in the room for a few hours before it would work. Is it very dry in your area recently? Try leaving the calculator in a room for a few hours with a humidifier or a little steam (not close to the calculator!) - but do not make condensation.

Re: Have you tried.. (Re: HP49G+ doesn't turn on) - Pal G. - 10-01-2009

Mine is bricked too. When I press the RESET button, with a small paperclip, I see a solid line that stretches across the screen, and sometimes an individual annunciator comes on (alpha, left-shift, etc) . Then, upon release of RESET, the LCD is dimly on, but does not respond to ON+plus or ON-minus. Reth's ON+C (release) CLEAR does not work either. I don't see Metakernal splash screen or anything anymore.

I've pulled all batteries for 24 hours. Nothing. I am using good batteries.

I was just programming some userrpl two days ago when it first locked up. I rebooted once or twice, but now it seems terminal.

Re: Have you tried.. (Re: HP49G+ doesn't turn on) - Reth - 10-01-2009

I got mine old HP49G+ "bricked" too for a couple of months; I even sent it to HP dealer in Melbourne, Australia - they could do nothing. It showed exactly what yours does. Joe Horn told me about the ON+C & BS (press and HOLD) trick. I had to try about 100 times before it worked. The HP49g+ and 50 are very quick (unlike the old HP49) and a lot harder and trickier to get this done, but it works. Probably the exact moment to hit the BS is important and one needs a bit of luck. Now I can do it in 2 out of 3 attempts ;).

I don't think you can really "brick" this calculator

PS I knew the problem with mine - I installed a 48 library and then "bricking" happened. Leaving all batteries out even for weeks does absolutely nothing - the flash memory port 2 doesn't get affected.

Edited: 1 Oct 2009, 7:07 p.m.

Re: HP49G+ doesn't turn on - Ed Look - 10-01-2009

This is the first I've heard of this!

One might think that the lack of moisture would not interfere with the operation of an electric (power on) circuit.

Another shot... (in the dark?) - Vieira, Luiz C. (Brazil) - 10-01-2009

Hi, all;

a few days ago I updated the OS version for both HP50G I have. The primary steps to be taken are:

- press [+] and [-] keys and hold;

- proceed with regular RESET procedure: insert and remove metal tip into RESET hole in the back side of the calculator case;

- wait for about three second then release [+] and [-] keys;

- follow the OS updating instructions, etc.

The use of [-] and [+] keys was not known by me, and maybe it overrides regular start up sequence. Have you also tried it?



Edited: 1 Oct 2009, 11:08 p.m.

Re: HP49G+ doesn't turn on - Vieira, Luiz C. (Brazil) - 10-01-2009

Hi, Ed;

I'd give credit to ESD (electrostatic discharge), which goes harder in dried environment. The particles of water combined with atmosphere suspended particles would be a path for partial electrostatic discharge. The so common atmospheric discharges (lightnings) are commonly seen when the relative air humidity increases, so the moisture may turn the atmosphere into a path for ESD instead of enhancing this condition. I was never told about lightnings in dried environment.

Any other thoughts?


Luiz (Brazil)

Re: HP49G+ doesn't turn on - C.Ret - 10-02-2009

[...]It was because the air was too dry. [...]

How can the weather over The United Kingdom have change to a so extreme point that the ambient air is too dry for a computer to operate ?

Which part of the country ? All the Great Britain, the Scotland’s or the Wales have a solid reputation of rainy and foggy weather. Is this the end of an era?

Re: HP49G+ doesn't turn on - Bart (UK) - 10-02-2009

I lived in South Africa for 30 years, in the Highveld (Johannesburg area). It gets very dry there in the winter months, no rain for 4 or more months continuous. The humidity would be below 20% on my crude home barometer set. To get the PC working, it had to be above 40%. It was an i386 based machine.

I have never really investigated the possible mechanism of the problem, but considered that (as Luiz said) ESD is harder in dried environments, there may actually be a build-up of charges not conducted away as easily as in higher humidities.(Hence the ease at which one can get an ESD shock in dry climates - in electronic lab work grounding is a must!)

edit: as I said, it's a long shot because
a) I don't know if it gets that dry anywhere in France (where I believe k.mart is located)
b) no other electronic equipment I have owned before or since has been so severely affected this problem (most effects were due to a charged person touching the equipment, and a reboot sorted it)

Edited: 2 Oct 2009, 5:02 a.m.

Re: HP49G+ doesn't turn on - k.mart - 10-06-2009

Thank you very much!!

I try to put my calculator in my oven 5 minutes 100°C and it reboot! I will look the humidity and I will report to you.

You saved me, I have a math exam friday (matrix, trigonometry..)

Re: HP49G+ doesn't turn on - Ed Look - 10-06-2009

Actually, putting any electronics in an oven at 100° C DOES NOT sound like a good idea!

Besides the electronics, what do you think will happen to the PLASTIC case??!!!

It will either melt or burn!

Re: HP49G+ doesn't turn on - Bart (UK) - 10-06-2009

Be careful!!

I would not recommend anything higher than 40°C!!

Re: HP49G+ doesn't turn on - k.mart - 10-07-2009

I didn't preheat the oven so maybe the temperature did not reach 100°, the plastic case was hot but didn't fade (EDIT: molten ?).

Edited: 7 Oct 2009, 1:31 a.m.

Re: HP49G+ doesn't turn on - Bart (UK) - 10-07-2009

I wouldn't worry too much about the electronics, at work we regularly test plastic encapsulated electronics on FR4 to 125°C (we use enhanced packages). Most commercial parts are rated at ~80°C normally because low thermal conductivity of junction-to-ambient requires this to limit junction temp to 125°C during operation. Unpowered, this wouldn't present a problem at 100°C.

What I definitely would worry about is the LCD, batteries (if installed) and the plastic case.

Re: HP49G+ doesn't turn on - Bart (UK) - 10-07-2009

I didn't preheat the oven...

That probably saved it. A preheated oven could have damaged the LCD by thermal shock (stresses created due to uneven heating). The LCD would be my primary concern as you may be willing to put up with a warped/faded case, but when the LCD goes it's pretty much the end or an expensive repair (if HP sells such spares).

I would suggest using Geoff Quickfall's drying shoebox as an "environmental chamber". Use it as is to dry out, or just put in a small glass of water and close the vent hole to raise the humidity:

Thanks to Geoff for the photos.

Edit: Good to hear it is working again.

Edited: 7 Oct 2009, 7:24 a.m.

Re: HP49G+ doesn't turn on - Ed Look - 10-07-2009

You know, calcium sulfate (sulphate to some of you) is a commonly used drying agent. I believe that calcium chloride (perhaps a lot of us may use it to de-ice sidewalks in the winter) is also sometimes used for this purpose, of being a dessicant.

So, instead of a shoebox, perhaps a plastic box with a sealable lid, some of one of these salts on the bottom, and a small plate to put the calculator over it, and you have a pretty good drying environment.

Of course, don't open the lid more often than is necessary. And don't get any of that dust onto the calculator.

Re: HP49G+ doesn't turn on - John B. Smitherman - 10-07-2009

Hi Ed. Dried rice can be used as a desiccant.