Hal ST-8000 Memory Problems
 

To those of you who use the Hal ST-8000 HF modem....I recently had a
problem with one of my units retaining the pre-set Mark/Space/Baud Rate
memories. After consulting with Mark Prather WB9HFK at Hal it appeared
that U12, a NVRAM chip, on the modem board (top board when you remove
the top cover; lower left corner of the board) had gone south. The chip
is a DS1220Y manufactured by Dallas Semiconductor (now Dallas/Maxim) and
is still available. See:

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3126

The chip contains a small lithium backup battery that maintains the data
when disconnected from the +5V DC supply pin. Those backup batteries
have a useful life of about 10 years and since many of the ST-8000's in
the field are now passing that time frame I would imagine many will need
to replace that chip to continue working properly. That internal
battery does not recharge so the replacement should be immediately
operable.

For some reason (dumb one to boot) I didn't get the chip initially from
Dallas directly but instead ordered three chips from Jameco (Jameco PN
#114260 at $14.35 per chip). When I tried those chips in my ST-8000's I
got really weird results, not the least of which was not maintaining the
memory data properly. Thankfully I then found Dallas online and in
correspondence with their technical folks it appeared that the chips I
obtained from Jameco were possibly not true Dallas products, although
the tech guy at Jameco assured me that the units were in fact proper
after market units. Long story short I ordered three units direct from
Dallas and the cost from them was only $7.09 per chip!!! Those chips as
you might expect work like a champ. The Jameco chips are being returned
to them for a refund.

If you order some of these chips the 200 ms units are sufficient.
Additionally, both the ROHS compliant and old "leaded" chips are
available -- you'll get the ROHS chip much faster and the order is much
easier to process.

Finally, if you replace the DS1220Y be careful with inserting it into
the socket as the socket actually has 2 more holes than the number of
pins on the chip....check the orientation BEFORE you take the old one
out so you put the replacement chip in correctly.

So if your ST-8000 is "losing its memory" the DS1220Y chip may be your
problem. Hope this helps.

Dino KL0S