Re: LL PCB repair

Thanks ! I happened to still have a "high profile" 12,096 Mhz crystal in my parts boxes... I once suspected it to be defective but there was another problem on that board where it came from.

Soldered it in and sure enough the 6Mhz test point is happily pulsing now. Also no more clock complaints from the Fluke.

So, next I ran a Bus test and got the message that the Reset was stuck active. So, I grounded the watch-dog circuit.

Now when I do a Bus test I seem to simply get no response. Does that mean that the 9100A thinks the bus is OK ? The busy light is only on very shortly.

The text on the screen is :
TEST BUS AT ADDR 0
ADDR OPTION: MEMORY

OK, next I figured I'd try to test the program Ram acc. to Kevin's table: Fast test at 0000-01FF

I get:
Attempted to write at 0 read FF
Cannot modify RAM data.

Tried various addresses within the range with all the same result. I have a feeling there's no RAM at all in that address space....maybe some chips missing ? Remember I'm flying blind a bit on this board....it's a bootleg mod....

I have only two 2114 RAMs at H2 and J1

Also noticed that it looks like D2 and E2 have been removed for the mod.

Are Lunar Lander and Asteroids identical when it comes to RAM ? I do think so.

I included a pic of the board for your enjoyment.

When I run a test on RAM area 4000-47FF I get d0 and d1 as stuck high.

I'll fiddle around a bit more, forgive me my newbie style ;)

Oh, when I run UUT there's plenty stuff toggling around the board. Maybe it's worth a try in the cab or maybe I should hook up my scope but my wife is already not too happy with all the mess on the dinner table ;)

Op 22 feb. 2013, om 15:50 heeft wboucher6@cogeco.ca het volgende geschreven:

>
> Here's the low profile series cut 12.096 MHz crystal at Digikey...
> http://www.digikey.ca/product-detail/en/ECS-121-S-4/X429-ND/79335
>
> Bill Boucher
> http://www.biltronix.com
>
>
>
>>
>>
>>
>> On 2/21/2013 3:35 PM, Jess Askey wrote:
>>> Man.... I had an email all typed up saying that I bet $5 it was the crystal but then I deleted it as I didn't want
>> to seem like an pretentious ass. :-) Now Im just a groveling-wannbe-ass. :-) :-)
>>
>>
>> Funny, I did too. ;-)
>>
>> Andre, do yourself a favor and order the low profile xtals. Apparently
>> mouser no longer stocks these in the 12.096 MHz but they are
>> soooooooooooooomuch better than the standard height components and
>> really can't snag on anything and snap off.
>>
>> Picture below (not sure if it will come through on the list).
>>
>>
>> ABRACON ABL-10.000MHZ-B2
>>
>>
>>
>>
>>
>> [Attachment: Example of Low Profile Xtal (10 MHz)]
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André Huijts
andre.huijts@upcmail.nl

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Received on Fri Feb 22 18:10:01 2013