HP Forum Archive 06

[ Return to Index | Top of Index ]

9114A Battery component ? Message #1 Posted by Michael Meyer, M.D. on 5 Oct 2001, 12:40 a.m. I just bought an HP-9114A disc drive. Works great. Problem is: the battery pack is missing a component on the circuit board. There's a diode, a resistor, and one removed at the bottom of the board (bottom in case). Does anyone know what the missing component is? THANKS, ANYONE, for your help!

Re: 9114A Battery component ? Message #2 Posted by Michael Meyer, M.D. on 5 Oct 2001, 2:14 p.m., in response to message #1 by Michael Meyer, M.D. Never mind. I think it's a fuse. The manual mentions an internal fuse, and since nothing else in there is a fuse, I'm guessing that that's what's supposed to be there. Let me know if I'm wrong.

9114A Battery component ? Message #3 Posted by Andrés C. Rodríguez (Argentina) on 5 Oct 2001, 5:27 p.m., in response to message #2 by Michael Meyer, M.D. Sometimes fuses in small packages look like "0-ohm resistors", these can misled you. In general, don't assume that a missing component should be *anything* just from difference between reality and documentation. I suggest you can wait for a comment from knowledgeable people here (look also in the Articles Forum); or at least try to validate your deduction following the circuit layout. A fuse should be connected in series with a power supply component (battery, transformer, rectifiers, etc.), there may be clues in the board about different size fuses from different manufacturers... Just go slowly. Good luck! Of course, it may well be a fuse after all, but then you will need to know the fuse rating and type (fast, slow, etc.), if you wish to restore your unit to a reliable working condition. While "any" fuse will somehow work, safety will be compromised if the fuse is not the proper one.

Re: 9114A Battery component ? Message #4 Posted by Tony Duell (UK) on 5 Oct 2001, 9:40 p.m., in response to message #1 by Michael Meyer, M.D. There are 2 versions of battery pack used with the 9114. The older one (used on the 9114A only) has a fairly simple charger PCB containing a bridge rectifier, 150 ohm resistor, zener diode, TIP41A transistor and a fuse. This was originially 2A, but was increased to 5A later. The later battery, used on the 9114A and 9114B has a much more complicated charger PCB. It contains a bridge rectifier, LM311 comparator chip, 2N3906 transisotr, 2N6240 SCR, green LED, 79LO5 regulator, numerous R's, C's and diodes, and a 5A fuse. These fuses are wire-ended picofuses, and look a bit like resistors with no colour bands. One thing bothers me, though. The fuse is in series with the connection from the +ve battery terminal to the disk drive. If the fuse is open or missing the drive won't work at all. But this unit 'works fine'...

Re: 9114A Battery component ? Message #5 Posted by Michael Meyer, M.D. on 6 Oct 2001, 11:11 a.m., in response to message #4 by Tony Duell (UK) The unit worked fine with a 6v directly connected, not with the pack. I did end up re-wiring the pack. I couldn't find a lead-acid battery of the original type, either on the internet or at the local battery store. So.... I wired two battery packs from 6v camcorder packs. Now I have a 7.2AH battery instead of a 2.4AH battery. What the heck. It works great!!!! I'd have preferred NiCd's, but the NiMH packs I put in won't have a memory effect, can be used at any level of charge, and have multitude heat breakers and fuses also. I had to grind out the plastic guides and rearrange the circuit, but the pack is perfect from the outside. Heavy! Oh, and I'm sure it was a fuse, from what I've figured out and read here. Again, it works.... Thanks for your great comments and support!! Michael

Re: 9114A Battery component ? Message #6 Posted by Tony Duell (UK) on 6 Oct 2001, 2:32 p.m., in response to message #5 by Michael Meyer, M.D. It's a bit late now, but it is possible to make up a lead-acid battery pack that will fit in the original housing. You use 3 2.5Ah Cyclon cells (these are individual 2V cylindrical cells) in series. Fits almost perfectly into the HP battery pack. I've done that to both my 9114s (-A and -B), with no problems. Incidentally, the same cells fit the HP110 (Portable) and Portable+ computers. In the UK you can get them from RS Components (Electromail) amongst other places. I do hope you're not trying to charge NiMH batteries (or, indeed, NiCd ones) from the HP charger board in the 9114 battery pack. Such batteries like constant-current charging, while the HP board is a constant voltage unit (for lead acid batteries). If you're using a separate charger, no problem, of course.

Re: 9114A Battery component ? Message #7 Posted by Andreas Müller (GER) on 6 Oct 2001, 2:56 p.m., in response to message #6 by Tony Duell (UK) I did the same replacement with the Hawker Cyclon cells. It works great since 2 years. Even more stable (the internal resistance of the cyclons(does anyone need 400 A pulse current?) is less than the original). For those who live in Germany: you can get these cells from RS Components too. But from www.reichelt.de (Hawker D-2,5 Ah)you can get them cheaper. And Tony, your hint for the different kind of charging is very urgent. By the way ,I'm happy of having found this forum. I'm learnig each day. Great. Thanks to all.

Re: 9114A Battery - Cyclon cost? Message #8 Posted by Ellis Easley on 10 Oct 2001, 6:57 a.m., in response to message #7 by Andreas Müller (GER) I live in Texas and I found the Cyclon 2.5 A-H cells at a "batteries only" store for $8.40 US each. If I am looking at the right place in the newspaper, this would be about 17.90 German marks or 5.70 pounds or 60 francs. How does this compare to the prices you are seeing? I have a 9114B and a 3421A. Luckily, the Panasonic 2.4 A-H for the 9114B (with a new part number) is still available from DigiKey, I got one about two years ago for around $16. The 3.2 A-H for the 3421A is not available from Panasonic anymore but the same "batteries-only" store (Interstate) was able to order me a "Power Patrol SLA0895" which has identical dimensions and is 3.8 A-H. The price was $20 but they gave me a 20% discount to $16 because they were having a grand opening. In the catalogs, I have seen a multiple-source 6V 4A-H for around $10 US, apparently much used in emergency lighting. Its dimensions are 2.76 x 1.85 x 4.02 in., 70 x 47 x 102 mm. Just a tad too big for the 3421A, no go in the 9114B, too bad! When I got my 3421A, it had been modified to take an Interstate 630 (6V, 3A-H). This has terminals on the long side (so sits upright in the chassis) and is skinnier and about 1/2 inch longer than the original battery, so the threaded inserts were drilled out, the sheet metal clamp was discarded, and the battery was held in place with big nylon wire ties. I haven't looked for the Cyclons anywhere except the Interstate store and in the Mouser Electronics and DigiKey catalogs (neither had them). BTW, at the Interstate store I saw two other sizes of Cyclons, I think they were 5 and 10 A-H. I'm familiar with the Cyclon 2.5 A-H cells because my family had a flashlight which worked great for years under constant charge until finally one of the two cells inside shorted out and the excess current caused a component in the charging circuit to open up. The charging circuit was directly from the line with a capacitor in series to limit the current/drop most of the voltage (it was the part that opened up).

Re: 9114A Battery - Cyclon cost? Message #9 Posted by Tony Duell (UK) on 10 Oct 2001, 8:01 p.m., in response to message #8 by Ellis Easley Over here we pay about \pounds 5.00 for the 2.5Ah Cyclon cells, so your price is certainly comparable. As regards the 3421, I modified mine (remove one screw post, extend one of the wires) to take a 2.6Ah Yuasa battery (also lead-acid). It fits fairly well, and although it's lower capacity than the original, the machine runs long enough for what I need to do with it.

Re: 9114A Battery - Cyclon cost? Message #10 Posted by David Smith on 10 Oct 2001, 8:34 p.m., in response to message #8 by Ellis Easley If you live in the Dallas (Richardson) area EVS Supply has the Powersonic replacement battery for less than $13.00 (last time I checked). They also do mail order... see www.evssupply.com They also do an excellent job rebuilding just about any battery pack you can come across.

Re: 9114A Battery - Cyclon cost? Message #11 Posted by Andreas Müller (GER) on 12 Oct 2001, 3:55 p.m., in response to message #8 by Ellis Easley In Germany you will get one D-Size Cyclon 2.5Ah cell for 11.90 German marks from the Reichelt shop.

Re: 9114A Battery component ? Message #12 Posted by Michael Meyer, M.D. on 6 Oct 2001, 6:24 p.m., in response to message #6 by Tony Duell (UK) Tony, I WAS using the available circuit. It seems to work OK. Pardon my ignorance... what harm am I doing by charging with the existing circuit? I don't really mind if I'm just shortening the battery life, but is it going to explode or something? I can certainly make or buy a different charging circuit to place in the pack with the NiMH's. I'm assuming that the simple full-wave rectifier circuit is allowing varying current, as you said. Again, does this just shorten the battery life, or is there something more ominous....? Michael

Re: 9114A Battery component ? Message #13 Posted by Tony Duell (UK) on 7 Oct 2001, 8:37 p.m., in response to message #12 by Michael Meyer, M.D. Eeek... You have been very lucky (I will explain below). With most constant-voltage chargers, if you try to charge NiCds, the most likely result is bits of cell all round the room. They explode. OK. Lead acid batteries are charged from a constant voltage source (the charging voltage applied to the cell is constant, no matter what current is drwan). About 2.3V per cell IIRC. NiCd and NiMH cells are charged at constant current -- the charing current is the same no matter what voltage the cells are currently dropping (about C/10 A where C is the capacity in Ah). Normally if you try to charge NiCds from a constant voltage charger, the current goes sky high, the cells explode. What has saved you is the HP mains adapter which plugs into the battery pack. It simply can't supply much current. So the output of the charger circuit in the battery pack can't supply much current either -- if it tries to, then the input voltage from the adapter drops. Therefore it's no longer a true constant voltage source. The charging current is limited to something safe for the NiCd cells and you don't get an explosion (after all, the internal charging circuit of HP devices that use this adapter with NiCd cells is little more than a bridge rectifier and an 8.2 Ohm (or 4.7 Ohm, or something pretty low) resistor. Much of the current limiting is due to the properties of the adapter. Still, what you are doing is not good for the NiMH cells and will probably shorten their life....

Re: 9114A Battery component ? Message #14 Posted by Michael Meyer on 7 Oct 2001, 11:43 p.m., in response to message #13 by Tony Duell (UK) Tony, Thank you (again) for the education and detailed response. And I thought I knew something about batteries! I guess I was figuring that the adapter couldn't provide enough current into a 7.2AH pack to be dangerous, and while I was right by your explanation, my logic could have definitely gotten me into trouble! Michael

Re: 9114A Battery component ? Message #15 Posted by Tony Duell (UK) on 8 Oct 2001, 8:24 p.m., in response to message #14 by Michael Meyer In this case you're probably right. A 7.2Ah pack should be able to stand a continuous charging current of 720mA. The HP adapter might just about supply that, but it's pushing it. And with the battery pack and original circuitry the current is certain to be lower Jsut be careful randomly swapping NiCds and Lead Acid batteries in the future... I will always rebuild with the same type of battery if at all possible. I like to keep my HP stuff (and other classic computers) as original as possible. This doesn't just mean appearance, it also means the circuitry and type of components. A computer is not just a box to be looked at, after all :-)

Re: 9114A Battery component ? Message #16 Posted by Michael Meyer, M.D. on 9 Oct 2001, 8:41 p.m., in response to message #15 by Tony Duell (UK) Tony, Very true. All the rest of my HP stuff has stayed original, but I have to admit, I like the pack I built. It ran continously for 2 evenings of transfering all of my HP-71 cards to a floppy on just one overnight charge. But... I promise I will heed your lessons and warnings and not try to get too carried away with "power".... Michael

Re: 9114A Battery component ? Message #17 Posted by Tony Duell (UK) on 7 Oct 2001, 8:37 p.m., in response to message #12 by Michael Meyer, M.D. Eeek... You have been very lucky (I will explain below). With most constant-voltage chargers, if you try to charge NiCds, the most likely result is bits of cell all round the room. They explode. OK. Lead acid batteries are charged from a constant voltage source (the charging voltage applied to the cell is constant, no matter what current is drwan). About 2.3V per cell IIRC. NiCd and NiMH cells are charged at constant current -- the charing current is the same no matter what voltage the cells are currently dropping (about C/10 A where C is the capacity in Ah). Normally if you try to charge NiCds from a constant voltage charger, the current goes sky high, the cells explode. What has saved you is the HP mains adapter which plugs into the battery pack. It simply can't supply much current. So the output of the charger circuit in the battery pack can't supply much current either -- if it tries to, then the input voltage from the adapter drops. Therefore it's no longer a true constant voltage source. The charging current is limited to something safe for the NiCd cells and you don't get an explosion (after all, the internal charging circuit of HP devices that use this adapter with NiCd cells is little more than a bridge rectifier and an 8.2 Ohm (or 4.7 Ohm, or something pretty low) resistor. Much of the current limiting is due to the properties of the adapter. Still, what you are doing is not good for the NiMH cells and will probably shorten their life....

Re: 9114A Battery component ? Message #18 Posted by Michael Meyer on 7 Oct 2001, 11:43 p.m., in response to message #17 by Tony Duell (UK) Tony, Thank you (again) for the education and detailed response. And I thought I knew something about batteries! I guess I was figuring that the adapter couldn't provide enough current into a 7.2AH pack to be dangerous, and while I was right by your explanation, my logic could have definitely gotten me into trouble! Michael

Re: 9114A Battery component ? Message #19 Posted by Tony Duell (UK) on 8 Oct 2001, 8:24 p.m., in response to message #18 by Michael Meyer In this case you're probably right. A 7.2Ah pack should be able to stand a continuous charging current of 720mA. The HP adapter might just about supply that, but it's pushing it. And with the battery pack and original circuitry the current is certain to be lower Jsut be careful randomly swapping NiCds and Lead Acid batteries in the future... I will always rebuild with the same type of battery if at all possible. I like to keep my HP stuff (and other classic computers) as original as possible. This doesn't just mean appearance, it also means the circuitry and type of components. A computer is not just a box to be looked at, after all :-)

Re: 9114A Battery component ? Message #20 Posted by Michael Meyer, M.D. on 9 Oct 2001, 8:41 p.m., in response to message #19 by Tony Duell (UK) Tony, Very true. All the rest of my HP stuff has stayed original, but I have to admit, I like the pack I built. It ran continously for 2 evenings of transfering all of my HP-71 cards to a floppy on just one overnight charge. But... I promise I will heed your lessons and warnings and not try to get too carried away with "power".... Michael

[ Return to Index | Top of Index ]

Go back to the main exhibit hall