Nominal voltage for a single cell can be up to 1.5 V for a nicad. 1.45 is reasonable for full charge.
[image: image.png] On Fri, Mar 13, 2020 at 12:51 PM Tom Wilson <[email protected]> wrote: > > Yes, 4.3v sounds right for the charge voltage of a 3 cellNiCd pack. > > So now I’m confused by why or how that circuit is holding 4.2-4.3v with no > AAs in the holder. Are there a lot of caps in that circuit? > > I have a hard time believing that a 1987 era battery is holding a charge, > but I hat the AAs out for a while with the memory switch on, and the > voltage in that circuit never dropped. > > Should I put a small load on that circuit, maybe an LED with a 200 ohm > resistor? > > > > On Fri, Mar 13, 2020 at 7:53 AM Stephen Adolph <[email protected]> > wrote: > >> my 2 cents, I think that 4.3V is common on the 3 cell NiCd when it is >> being charged by the system. After unplugging it, it will likely drop to >> 3.7 to 3.6 and hold well. >> If it is bad, it won't hold 3.6V. >> >> never bad to replace though. >> >> >> On Fri, Mar 13, 2020 at 10:50 AM B4 Me100 <[email protected]> wrote: >> >>> Congratulations! Welcome to the Model T102 owners club :) >>> >>> From the motherboard pic the battery looks like an original Yusa I doubt >>> it has been replaced. At 4.3V it is bad it should be around 3.7V when off >>> to allow the SRAM to drop into their lowest standby current. As Josh would >>> say it should be replaced immediately. I would also carefully check all >>> the electrolytic caps for signs of leakage or out gassing. Probably >>> replace those too while the lid is off the box they are at end of life and >>> could give trouble down the line. >>> >>> Does the battery box have signs of a battery leak? Might want to check >>> around the box to make sure it has not leaked onto the PCB sometimes they >>> have and can destroy the PCB under the battery carrier leading to RS232 >>> failure – at least on a T102 I have. >>> >>> On the ROM you might want to look at building your own. The ROM images >>> are available and with the range of available PCBs at OSH park they are >>> quite easy to build. An original ROM is quite rare and a little fragile >>> depending on how they were constructed – there seems to have been quite a >>> selection of methods used to fill that OPT ROM socket in the past :) >>> >>> From: M100 <[email protected]> on behalf of Tom Wilson < >>> [email protected]> >>> Reply-To: <[email protected]> >>> Date: Friday, March 13, 2020 at 1:46 AM >>> To: M100 Mailing List <[email protected]> >>> Subject: [M100] T-102 is here! >>> >>> My 102 has arrived, and she's in good shape! >>> >>> This is serial 807001339, manufactured in 1988.7 (I assume that's July), >>> and it appears that the RAM chips are all soldered in: It has 32K of RAM >>> and no empty sockets (just the empty option ROM socket.) >>> >>> Surprisingly, the backup battery appears to be brand new! I've had the >>> machine open for about half an hour now, and the battery still reads 4.3v, >>> with no AAs inserted. The soldering job on the battery is impeccable. >>> >>> On a side note... does anyone have a TS-DOS ROM? Or something that >>> includes DOS, like the Ultimate ROM? >>> >>> Picture time!! >>> >>> >>> <snip> >>> >> -- > Tom Wilson > [email protected] > (619)940-6311 > K6ABZ >
