9114 - battery - take 2



#5

Hi,

Ok, so after some traveling I came back to work on my 9114 with all the tips I got. The new battery arrived and full hope I went into swapping the old battery out for the new.

And, as many here have said alreday, it really indeed was very simple.

Checking all contacts, I closed the battery up, plugged it into my 9114a, plugged in the power and turned the 9114 on.

Hurra!!! it worked, the two leds were on, we heard some moving off the head and after a few seconds the 'fault' LED went off. All seemed great.

However about a minute or so later, all lights went off. and no amount of trying from my side was able to make the 9114 turn on again.

So I opened up the battery and started checking some contacts. And somehow there was no current going to the plug into the 9114! I checked the battery - 6.5V, the current went to the PCB but did not come out the other end. I was stymed!

I though, okay, maybe the charger burned it - it had 12v coming out of it and maybe that was too much (though the label on the battery department said 20V max. the charger I used, by the way, was a standard HP charger, I believe 82059b)

As I have a second battery pack, I did the same thing again. Swap out the old battery. Check the contacts. Close the battery, plug it in, turn on the 9114. Hurra! both LED on, the 'fault' one went out after a few seconds. And a minute or so later, the thing turned off again. And when I again checked the output of the battery-pack, there was no current coming out of it!

I'm quite flabbergasted how turning on the 9114 could burn out some part of the PCB in the battery!

Anyway, are there any good ideas out there on what to try next? I will let the charger be plugged into the battery over night to see if that does anything (i do not know if the battery was full or not when I got it, however it continued to show a very steady 6.5V when tested directly. )

Thanks!

Peter


#6

There is a picofuse on the PCB (it looks like a resistor, you may have to trace the connections from the plug to find it). My guess is that you've blown that.

Of course it's easy to replace (DO NOT be tempted to short it out -- that battery can supply several hundred amps into a short circuit, and you don't want to fry tracks on the main PCB!), but the big question is 'Why did it blow'.


#7

Tony,

I did order the pico-fuse and also found some related info here in the archive following your pointer about the pico-fuse (will consolidate and add to the summary!) Will not short out, your warning is much appreciated.

In the meantime I have built a direct powersupply following some directions from you and others. This worked well on my 9114b, but I still have some problems with the 9114a (see my other post with pictures of the open 9114a).

As for why it shorted out, I have a suspicion: When I have the metal cover on the drive, the 'fault' light does not go out, yes it always goes out when the metal cover is off. This is how I was able to test all the HP-IL commands as posted. This makes me believe that maybe the metal-cover is too tight or I have put it on wrongly so that the head cannot move. If the head or some other part is trying to move yet is stuck, could that not cause the motor to suck too much current and burn the fuse?

Anyway, all in time, I'd say. I hope I am not testing your patience when I ask you to maybe take a look at the pictures to check if you see anything strange.

Thanks so much in advance!

Cheers

Peter


#8

Quote:
As for why it shorted out, I have a suspicion: When I have the metal cover on the drive, the 'fault' light does not go out, yes it always goes out when the metal cover is off. This is how I was able to test all the HP-IL commands as posted. This makes me believe that maybe the metal-cover is too tight or I have put it on wrongly so that the head cannot move. If the head or some other part is trying to move yet is stuck, could that not cause the motor to suck too much current and burn the fuse?

As the head motor is a stepper, it won't draw significantly more current when jammed than when moving. But if the heads can't move, the unit will not pass the self-test (the fault light will stay on) since the unit moves the head back and forth and checks that the track 0 signal does the right thing.

Of course that cover might be shorting something to ground.


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