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
