[RTTY] Hal ST-8000 Memory Problems

[Dino Papas]

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