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Epson HX-20 Display Flicker

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cgrape2

Experienced Member
Joined
Jun 11, 2009
Messages
285
Location
Lodi,CA
I have an HX-20 with and expansion box.It will start but after about 5 minutes the display begins to flicker and it acts like it's low on power.I did replace the battery pack with a new one and hooked it up to a 6V power supply for the required 8 hrs.It seemed to charge but....
What am I missing here?
Thanks!
cgrape2
 
I have an HX-20 with and expansion box.It will start but after about 5 minutes the display begins to flicker and it acts like it's low on power.
Click to expand...
So the flicker might just be a symptom of low power.

I did replace the battery pack with a new one
Click to expand...
Is the battery pack something you built yourself, or is new-old-stock (NOS), or what? If NOS, I'd be concerned about the possibility of the Ni-Cad cells having deteriated - the pack possibly having sat uncharged on a shelf for up to 28 years. Maybe someone who who's experienced with old Ni-Cad cells will comment.

and hooked it up to a 6V power supply for the required 8 hrs.It seemed to charge but....
Click to expand...
I can see the 8 hours charging figure in the HX-20 Operations Manual, but the same manual indicates that a 15V adapter/charger is used (info on last page).
 
Ah Ha!

Ah Ha!

That'll probably explain it.I got the idea that a 6V power supply was what was needed.I knew I got something wrong!BTW the battery pack was of new construction,not old stock.
Thanks for the clue!
cgrape2
 
Hold on

Hold on

6 volts seems too low, but in now looking to see where you got that figure from, I'm finding it quoted at different web sites.
For example, http://classway.com/hx20/faq.html includes "The power supply is a simple 6V@600mA wall brick."
The 1983 article at http://www.atarimagazines.com/creative/v9n3/101_Epson_HX20_computer.php includes "The only other external device is a 6-volt power supply that plugs into the back of the HX-20"

So what's the story? Why does Epson have 15V in their manual. I reread the manual. The text is "(1 15V + 10%,". So that must be 115V with a space inserted.

Turns out that this issue of HX-20 replacement batteries and charger was discussed in these forums last year. See http://www.vintage-computer.com/vcforum/showthread.php?t=10735
 
Ok,so I didn't get it wrong then?If not,then where could I be going wrong?
That 15V seemed to be a bit much,the battery pack heated up quickly and I disconnected it before anything could fry.
So I'm back to square one.Could I be using too low a wattage?My PS is a 6 Volt,200MA,which seems might be a bit low.(Negative center barrel conn.)I have another one that's 6V 500ma as well.
cgrape2

Ok it appears that 800ma,6V is the proper volt\amp combo.It is a Negative center,right?
 
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cgrape2 said:
Ok it appears that 800ma,6V is the proper volt\amp combo.It is a Negative center,right?
Click to expand...
An Epson document indicates that the adapter is part number H00AAA.
Web searches using that part number consistently show 600mA.
Example: http://www.computerhistory.org/collections/accession/X1666.99D

Can't see anything about the polarity, but you must have it right, because I can't see how else 5 minutes worth of charge would be getting into the battery pack.
 
cgrape2 said:
Could I be using too low a wattage?My PS is a 6 Volt,200MA,which seems might be a bit low.(Negative center barrel conn.)I have another one that's 6V 500ma as well.
Click to expand...
The adapter for the HX-20 (item part number H00AAA) is rated 6V @ 600mA.

One forum post includes:
the label at the bottom of my HX-20 says:
Rating: DC 4.8V, 400mA
Charge input: DC 6V, 200mA
Charge time: 8 hours

These AC adapters are typically unregulated. Perhaps the H00AAA is. If the charging current is regulated within the HX-20 to about 200mA, then the H00AAA (6V @ 600mA) could be supplying the charging circuitry at say, 7V to 8V, possibly a voltage requirement of the charging circuitry. If that's the case, your 6V @ 200mA adapter will be inadequate (can't supply 200mA at 7V to 8V).

So I think you should try your 6V @ 500mA adapter and see if it extends the discharge time.

Just confirming: Your adapters output DC don't they, rather than AC.
 
Yep,they are DC.I hooked up the Epson and the 500ma charger for 6 hours or so and I'm going to do a "longevity" test today.
Thanks for the help!
cgrape2
 
looks like somebody hgas already "been there - done that"

http://www.xs4all.nl/~fjkraan/comp/hx20/adapter.html

From what he/she says "the charging circuit is very simple, just a 3.9ohm resistor and a diode in series with the battery pack. it definitely needs an unregulated supply. This is one case where having a bigger one isn't better, as it kind of relies on the floppiness of the supply to limit the charge current.
Make sure you haven't burnt out the resistor with the high voltage supply.
 
I'll be checking that next!
My "power-on longevity test" was no great success.It lasted 1hr 45min. on the 6-7 hour charge.
The good news is,that it will run fine off the charger.
cgrape2

Thanks for the link!It explained a lot!
 
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cgrape2 said:
The good news is,that it will run fine off the charger.
Click to expand...
The HC-20 Operations Manual includes:
"Your HX-20 comes with a device labelled AC ADAPTER. This unit is designed to charge the batteries in your HX-20. It is not designed to run your HX-20 directly from AC current. In all cases, you should operate the HX-20 using only its internal nickel-cadmium batteries."

Web page http://classway.com/hx20/faq.html includes "NEVER use the HX-20 without batteries as this will damage the internal circuitry."
 
What can I say?.....Noob am I.(At least on these Epsons,come to think of it on lots of cool old stuff,after all that's one reason I'm here!)No more of the PS attached running for me then.
cgrape2
 
Up and Running

Up and Running

WIth a proper 800ma 6V power supply,the Epson now charges correctly and will run for DAYS!(Well,almost anyway)Yay!
I was afraid I'd fried it with the 15V PS.
Thanks folks for all the help and enlightenment.
cgrape2
 
I am looking for a used cassette player / recorder cartridge and LCD screen replacement for my used Epson HX-20. If anyone has these parts, please contact me.
My cassette player / recorder needs the rubber band for the motors. The LCD screen has no contrast. I barely see the pixels and text on the screen when I view it at an angle. Thanks for your time. DuaneA1965 - Oct. 21, 2013
 
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