help with 'dead' t/s 2068
11 messages · 2003-11-01 → 2003-11-21 · Yahoo Group era · View archive on archive.org
Participants: Alvin, joe schmoe, David, Jarek Adamski, James Diffendaffer, John Simpson, Jack Boatwright, Scott A. Rossell, Luis Alberto D'Ardis
Preserved from the Timex/Sinclair 2068 Yahoo Group (2001–2019), which is no longer online. Text reproduced from the archive.org archive; email addresses masked.
Messages
1. help with 'dead' t/s 2068
David · Sat, 01 Nov 2003 23:08
Well, suffise it to say, but I recently purchased a 2068 off of ebay. Unfortunately the
computer is fried (and the jerk who sold it won't refund my money).
The thought crossed my mind that this may be fixable, but I'm not sure (I'm not an
expert on the electronics of the 2068).
Here is what I know of the normal 2068 bootup sequence (Yes, I do remember this).
1 - large black and white bars across the screen.
2 - after about a second, the screen goes black (except for the border).
3 - you then get the copyright notices.
3 - the 'K' cursor appears.
So, with this in mind, what could possibly be the problem with my 2068 if it freezes
during step 1? All I get are black and white bars, and it will not go any farther?
I'm guessing this is either a RAM or ROM issue (hopefully ROM, as I may be able to
get a set of T/S ROM chips - there are two that can be popped out and replaced
easily).
Any thought on this?
Thanks
-dave
2. Re: help with 'dead' t/s 2068
Jarek Adamski · Mon, 03 Nov 2003 18:20
--- In [email], "David" <ozyr@s...> wrote:
> 1 - large black and white bars across the screen.
> So, with this in mind, what could possibly be the problem
> with my 2068 if it freezes during step 1? All I get are
> black and white bars, and it will not go any farther?
I vote for the Z80CPU. (Less possible - the 16MHz crystal,
I used to repleace one.)
Regards,
--
Jarek Adamski
ul.Sobieskiego 10A/5
99-200 Poddêbice
Poland
tel. +48603445345
mailto:[email]
Do you wish to upgrade an 8bit computer?
see http://zx.yarek.com and contact me.
3. RE: [ts2068] help with 'dead' t/s 2068
John Simpson · Mon, 3 Nov 2003 16:18:
Make sure you give negative feedback to the guy who sold you the defunct
2068 so other's are warned of his uselessness...
-----Original Message-----
From: David [mailto:[email]]
Sent: Saturday, November 01, 2003 3:09 PM
To: [email]
Subject: [ts2068] help with 'dead' t/s 2068
Well, suffise it to say, but I recently purchased a 2068 off of ebay.
Unfortunately the
computer is fried (and the jerk who sold it won't refund my money).
The thought crossed my mind that this may be fixable, but I'm not sure
(I'm not an
expert on the electronics of the 2068).
Here is what I know of the normal 2068 bootup sequence (Yes, I do
remember this).
1 - large black and white bars across the screen.
2 - after about a second, the screen goes black (except for the border).
3 - you then get the copyright notices.
3 - the 'K' cursor appears.
So, with this in mind, what could possibly be the problem with my 2068
if it freezes
during step 1? All I get are black and white bars, and it will not go
any farther?
I'm guessing this is either a RAM or ROM issue (hopefully ROM, as I may
be able to
get a set of T/S ROM chips - there are two that can be popped out and
replaced
easily).
Any thought on this?
Thanks
-dave
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4. Re: help with 'dead' t/s 2068
James Diffendaffer · Tue, 04 Nov 2003 02:04
Well... without knowing the memory map or the chips I can't say
exactly what's wrong but here is how I would go about it.
Odds are it's not a ROM, crystal or the Z80 but it's possible.
More likely, some part received a static shock. The chips most likely
to have that happen are ones that have I/O ports exposed to the
outside of the machine. That means whatever any expansion connector
or ROM port goes through. Another possibility is a statick shock from
the keyboard. I've seen those kill chips.
My guess is that it's going to be a large custom chip that's difficult
or impossible to replace. :(
Now... why do I say that?
5. Re: [ts2068] help with 'dead' t/s 2068
Alvin · Tue, 04 Nov 2003 03:51
David wrote:
>
> Well, suffise it to say, but I recently purchased a 2068 off of ebay. Unfortunately the
> computer is fried (and the jerk who sold it won't refund my money).
>
> The thought crossed my mind that this may be fixable, but I'm not sure (I'm not an
> expert on the electronics of the 2068).
>
> Here is what I know of the normal 2068 bootup sequence (Yes, I do remember this).
> 1 - large black and white bars across the screen.
> 2 - after about a second, the screen goes black (except for the border).
> 3 - you then get the copyright notices.
> 3 - the 'K' cursor appears.
>
> So, with this in mind, what could possibly be the problem with my 2068 if it freezes
> during step 1? All I get are black and white bars, and it will not go any farther?
Step 1 is the RAM test. The entire RAM is written with two
complementary bytes that look like bars in the pixel part of the display
file and when they are written to the attributes area of the display
file you'll see that red/black combination. The computer should set
RAMTOP to the last byte of physical good RAM it finds. I expect the
computer would crash as you describe if the amount of good RAM found is
less than what is needed to start up the BASIC system.
So, I would check for bad RAMs first. Use the finger test: if any of
the ram chips seem a little too hot with the computer on, it may be at
fault.
Another easy thing you can do is to try resitting the ROM chips. These
are socketed on the 2068 so could work loose during shipping or could
have built up some oxide on the pins over years of disuse. Pop them out
and then reinsert them.
I put my money on one of these two culprits.
Alvin
6. Re: [ts2068] help with 'dead' t/s 2068
Jack Boatwright · Tue, 4 Nov 2003 05:43:
MessageI think saw that auction and, as I remember, the seller stated exactly how the machine booted up. If this IS the auction I remember, I emailed the seller suggesting either the SCLD or RAM was the culprit. He emailed back saying he had no knowledge of anything internal.
Of course if it's not the same auction, then ...... go get him.
----- Original Message -----
From: John Simpson
To: [email]
Sent: Monday, November 03, 2003 4:18 PM
Subject: RE: [ts2068] help with 'dead' t/s 2068
Make sure you give negative feedback to the guy who sold you the defunct 2068 so other's are warned of his uselessness...
-----Original Message-----
From: David [mailto:[email]]
Sent: Saturday, November 01, 2003 3:09 PM
To: [email]
Subject: [ts2068] help with 'dead' t/s 2068
Well, suffise it to say, but I recently purchased a 2068 off of ebay. Unfortunately the
computer is fried (and the jerk who sold it won't refund my money).
The thought crossed my mind that this may be fixable, but I'm not sure (I'm not an
expert on the electronics of the 2068).
Here is what I know of the normal 2068 bootup sequence (Yes, I do remember this).
1 - large black and white bars across the screen.
2 - after about a second, the screen goes black (except for the border).
3 - you then get the copyright notices.
3 - the 'K' cursor appears.
So, with this in mind, what could possibly be the problem with my 2068 if it freezes
during step 1? All I get are black and white bars, and it will not go any farther?
I'm guessing this is either a RAM or ROM issue (hopefully ROM, as I may be able to
get a set of T/S ROM chips - there are two that can be popped out and replaced
easily).
Any thought on this?
Thanks
-dave
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7. RE: [ts2068] help with 'dead' t/s 2068
Scott A. Rossell · Tue, 4 Nov 2003 06:29:
If you paid for it with a credit card, you may have some recourse with
your credit card company.
Also, eBay has a protective clause for events of this nature if I recall
correctly. Check with them.
One last idea. If you have the guy's return address, mail him a
steaming bag of dog crap for his trouble!
Just trying to help!
-Scott-
-----Original Message-----
From: David [mailto:[email]]
Sent: Saturday, November 01, 2003 3:09 PM
To: [email]
Subject: [ts2068] help with 'dead' t/s 2068
Well, suffise it to say, but I recently purchased a 2068 off of ebay.
Unfortunately the
computer is fried (and the jerk who sold it won't refund my money).
The thought crossed my mind that this may be fixable, but I'm not sure
(I'm not an
expert on the electronics of the 2068).
Here is what I know of the normal 2068 bootup sequence (Yes, I do
remember this).
1 - large black and white bars across the screen.
2 - after about a second, the screen goes black (except for the border).
3 - you then get the copyright notices.
3 - the 'K' cursor appears.
So, with this in mind, what could possibly be the problem with my 2068
if it freezes
during step 1? All I get are black and white bars, and it will not go
any farther?
I'm guessing this is either a RAM or ROM issue (hopefully ROM, as I may
be able to
get a set of T/S ROM chips - there are two that can be popped out and
replaced
easily).
Any thought on this?
Thanks
-dave
To unsubscribe from this group, send an email to:
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Your use of Yahoo! Groups is subject to
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8. Re: [ts2068] help with 'dead' t/s 2068
Luis Alberto D'Ardis · Tue, 4 Nov 2003 13:29:
MessageHello David and hello to the entire list, Dear David spent the same thing to me with a zx spectrum from a www.ebay.com seller.
I live in Argentina and I entered in (Squear Trade) http://www.ebay.com/help/index_popup.html?confidence=problems-dispute-resolution.html and they gave to me a solution (seller sent me a new computer) please notede that work as a whole with e-bay www.ebay.com do not stop visiting this site IS YOUR REAL CHANCE TO GET WHAT IS YOURS!!!. entering from e-bay please follow this Path enter to www.ebay.com then go to the end of e-bay´s principal page and make click on Security Center then look at Choose A Topic and make click on Buying Safely then click on Dispute Resolution and then click on Square Trade Seal now you can read and know what to do please TRY THIS BEFORE POSTING FEEDBACKS COS THIS WAY MAY BE BOTH PARTS CAN MAKE A GOOD RESOLUTION AND KEEP POSITIVE FEEDBACKS.
My Considered Regards and Better Desires of Positive Resolution.
9. Re: [ts2068] help with 'dead' t/s 2068
joe schmoe · Wed, 5 Nov 2003 13:51:
Let me know if it is the SCLD chip that is the
culprit. I am fairly sure that Eric Johnson still has
a few in his Sinclair parts drawer. Last time I
checked he did along with good motherboards and other
Timex goodies. My thought is bad RAM though. Good luck
with it.
neil
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10. Re: [ts2068] help with 'dead' t/s 2068
Alvin · Fri, 07 Nov 2003 15:26
Since you're able to replace the ROMs, you could try
writing a small diagnostic EPROM that could test
the RAM area and i/o ports of the SCLD chip.
Output disgnostic beeps in case the video screen
is buggered.
You'll need to cut a trace or two to put an
EPROM into the HOME rom socket, but I think
it may be a better idea to construct a simple
daughterboard that could plug into the ROM
socket so that you don't have to modify the
original.
Alvin
11. Re: [ts2068] help with 'dead' t/s 2068
joe schmoe · Fri, 21 Nov 2003 10:48
I have a friend who has taken the JLO disk system
(Oliger)Eprom chip and piggybacked it to the Larken
Disk System along with a few jumpers plugged it in to
the cartridge socket...yes the door still closes...and
is able to switch from the Oliger to the Larken disk
O.S. through software. I really do not think he must
maunually throw any switch to change between the two.
This totally modified T/S 2068 has the capability to
switch between Timex and Spectrum modes also...plus
..the little RGB interface for true RGB color...and if
that aint enough....Larken RAM disk(non-volatile
battery backed-up) system on it. It is the most highly
modified 2068 that I have seen.
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