Re: Timemaster H.O.

["William Garber" <willy46pa@garberstreet.com>]

"Michael J. Mahon" <mjmahon@aol.com> wrote in message yIadnZlMGtVs3f_YnZ2dnUVZ_uadnZ2d@comcast.com">news:yIadnZlMGtVs3f_YnZ2dnUVZ_uadnZ2d@comcast.com...
: William Garber wrote:
: > "William Garber" <willy46pa@garberstreet.com> wrote in message nrSdnceKpIsssv_YnZ2dnUVZ_rKdnZ2d@comcast.com">news:nrSdnceKpIsssv_YnZ2dnUVZ_rKdnZ2d@comcast.com...
: > :
: > : "Michael J. Mahon" <mjmahon@aol.com> wrote in message ZuGdnfSiX5dgvf_YnZ2dnUVZ_tWdnZ2d@comcast.com">news:ZuGdnfSiX5dgvf_YnZ2dnUVZ_tWdnZ2d@comcast.com...
: > : : William Garber wrote:
: > : : > "Michael J. Mahon" <mjmahon@aol.com> wrote in message ofOdnRXaZJMUc_zYnZ2dnUVZ_sadnZ2d@comcast.com">news:ofOdnRXaZJMUc_zYnZ2dnUVZ_sadnZ2d@comcast.com...
: > : : > :
: > : : > : The card has ROM on it, which is probably read to detect the card's
: > : : > : signature.
: > : : > :
: > : : > : If the computer can't see the ROM, then something quite unrelated
: > : : > : to the battery is wrong.  I expect the ROM is wired directly to
: > : : > : the address and data pins, so only the select logic and the ROM
: > : : > : itself can be the problem.
: > : : > :
: > : : > : You might try reading the ROM by plugging it into a slot and
: > : : > : using the monitor to L)ist some of the $Csxx space.  If it looks
: > : : > : like random video data, then the ROM is not driving the bus.
: > : : > :
: > : : > : *Something* must have happened to this card, since the parts we
: > : : > : are talking about are not usual failures.  Any chance of an
: > : : > : ESD zap while replacing the battery?
: > : : >
: > : : > I have an AE Serial Pro that I am trying to reconsititute.
: > : : > The Card is detected, and the clock can be set to a date
: > : : > and time, but it refuses to run. I've replaced the crystal,
: > : : > tested the Trim Cap (works), and the Zener diode so far.
: > : : > Nothing still. If I had more info, schematic, etc.....,
: > : : > then I might see which components are involved in the clock
: > : : > circuit. Otherwise, the only other thing I can do is to
: > : : > replace all of the discrete components, and then check the
: > : : > TTL on the whole card one by one until it functions.
: > : :
: > : : If the clock won't run after setting,
: > : : it sounds like the clock chip.
: > :
: > : None of the chips is defined as a clock chip.
: >
: >
: > Apologies necessary, Michael, as there is a clock
: > chip. MC145818 is in the center of the card. I had
: > mistaken this for a RAM IC. Sorry. However, this
: > one is probably unobtainum, but I find that I can
: > replace it with a DS12885 with vertain modifications.
:
: In pre-2000 PCs, this was a pretty standard clock chip.
: Maybe scavenging would turn one up (along with a new
: crystal).


Good Idea, thanks. If you mean the 32,768khz crystal,
I have a whole bag of them. Jameco sells them very cheaply.

William Garber
Email Address - willy46pa@garberstreet.com
Alt. Email - willy46pa@comcast.net
Web address - http://www.garberstreet.com