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Timex 2068 Video Problem

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  Timex 2068 Video Problem mores.mark@gmail.com - 2013-02-21 01:57 -0800
    Re: Timex 2068 Video Problem Andrew Owen <aowen10@mail.bbk.ac.uk> - 2013-02-21 18:50 +0000
      Re: Timex 2068 Video Problem mores.mark@gmail.com - 2013-02-21 18:57 -0800
      Re: Timex 2068 Video Problem "Brian Gaff" <Briang1@blueyonder.co.uk> - 2013-02-22 07:47 +0000
    Re: Timex 2068 Video Problem hp <ferd@farkel.net> - 2013-02-21 17:04 -0500
      Re: Timex 2068 Video Problem mores.mark@gmail.com - 2013-02-21 19:03 -0800
        Re: Timex 2068 Video Problem Andrew Owen <aowen10@mail.bbk.ac.uk> - 2013-02-22 08:31 +0000
          Re: Timex 2068 Video Problem mores.mark@gmail.com - 2013-02-22 18:02 -0800
            Re: Timex 2068 Video Problem Andrew Owen <aowen10@mail.bbk.ac.uk> - 2013-02-25 15:18 +0000
              Re: Timex 2068 Video Problem mores.mark@gmail.com - 2013-03-02 22:15 -0800
                Re: Timex 2068 Video Problem mores.mark@gmail.com - 2013-03-02 22:16 -0800
                Re: Timex 2068 Video Problem hp <ferd@farkel.net> - 2013-03-04 16:32 -0500
                  Re: Timex 2068 Video Problem mores.mark@gmail.com - 2013-03-04 16:17 -0800
        Re: Timex 2068 Video Problem hp <ferd@farkel.net> - 2013-02-22 13:13 -0500
          Re: Timex 2068 Video Problem mores.mark@gmail.com - 2013-02-22 18:20 -0800
            Re: Timex 2068 Video Problem mores.mark@gmail.com - 2013-02-22 18:52 -0800
              Re: Timex 2068 Video Problem hp <ferd@farkel.net> - 2013-02-23 13:59 -0500
                Re: Timex 2068 Video Problem mores.mark@gmail.com - 2013-02-23 16:48 -0800
                  Re: Timex 2068 Video Problem hp <ferd@farkel.net> - 2013-02-23 20:34 -0500
                    Re: Timex 2068 Video Problem mores.mark@gmail.com - 2013-02-24 03:00 -0800
                  Re: Timex 2068 Video Problem "Daniel Mandic" <daniel_mandic@hotmail.com> - 2013-02-24 13:26 +0000
                    Re: Timex 2068 Video Problem "Daniel Mandic" <daniel_mandic@hotmail.com> - 2013-02-24 13:51 +0000
                    Re: Timex 2068 Video Problem mores.mark@gmail.com - 2013-02-24 13:24 -0800
                    Re: Timex 2068 Video Problem mores.mark@gmail.com - 2013-02-24 13:27 -0800
                      Re: Timex 2068 Video Problem "Daniel Mandic" <daniel_mandic@hotmail.com> - 2013-02-25 10:42 +0000
                  Re: Timex 2068 Video Problem hp <ferd@farkel.net> - 2013-02-24 16:10 -0500

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#1942 — Timex 2068 Video Problem

Hello,

I have a TS 2068 showing "no video" (black screen) from both composite and rf outputs. The machine appears functional as I typed in a short BASIC program to play a BEEP sound and it worked. Any advices for possible fixes? I am not a hardware guy. But if the fix is not too complicated, I can probably ask my friend to help. 

Thanks,
Mark

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#1944

On 21/02/2013 09:57, mores.mark@gmail.com wrote:
> Hello,
>
> I have a TS 2068 showing "no video" (black screen) from both composite

  and rf outputs. The machine appears functional as I typed in a short

  BASIC program to play a BEEP sound and it worked. Any advices for

  possible fixes? I am not a hardware guy. But if the fix is not too

  complicated, I can probably ask my friend to help.
>
> Thanks,
> Mark

Sorry I can't be of much help but, if BEEP is working then that pretty 
much rules out a faulty SCLD. I only had a TC2048 so I'm not sure what 
the NTSC video hardware looks like. However, I suspect the composite out 
may originate at the modulator, in which case that's where you should 
start looking for blown components or loose solder joints.

-Andrew

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#1949

> Sorry I can't be of much help but, if BEEP is working then that pretty 
> 
> much rules out a faulty SCLD. I only had a TC2048 so I'm not sure what 
> 
> the NTSC video hardware looks like. However, I suspect the composite out 
> 
> may originate at the modulator, in which case that's where you should 
> 
> start looking for blown components or loose solder joints.
> 
> 
> 
> -Andrew


Thank you Andrew. If time permits on this weekend, I will open up the machine to check its internal and post some pictures here.

Mark

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#1952

If this still used the colour difference  system of creating the video, then 
a scope might be a good thing to prod the circuit with to see where it is 
getting to.

brian

-- 
From the Sofa of Brian Gaff Reply address is  active
"Andrew Owen" <aowen10@mail.bbk.ac.uk> wrote in message 
news:kg5q9s$loh$2@speranza.aioe.org...
> On 21/02/2013 09:57, mores.mark@gmail.com wrote:
>> Hello,
>>
>> I have a TS 2068 showing "no video" (black screen) from both composite
>
>  and rf outputs. The machine appears functional as I typed in a short
>
>  BASIC program to play a BEEP sound and it worked. Any advices for
>
>  possible fixes? I am not a hardware guy. But if the fix is not too
>
>  complicated, I can probably ask my friend to help.
>>
>> Thanks,
>> Mark
>
> Sorry I can't be of much help but, if BEEP is working then that pretty 
> much rules out a faulty SCLD. I only had a TC2048 so I'm not sure what the 
> NTSC video hardware looks like. However, I suspect the composite out may 
> originate at the modulator, in which case that's where you should start 
> looking for blown components or loose solder joints.
>
> -Andrew 

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#1948

On 2/21/2013 4:57 AM, mores.mark@gmail.com wrote:
> Hello,

> I have a TS 2068 showing "no video" (black screen) from both
> composite and rf outputs. The machine appears functional as I typed
> in a short BASIC program to play a BEEP sound and it worked. Any
> advices for possible fixes? I am not a hardware guy. But if the fix
> is not too complicated, I can probably ask my friend to help.

> Thanks, Mark

I do happen to have a few 2068's tucked away still. They havent seen
daylight in some time.

(at one time I was known to USA TS users)

Paul Holmgren

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#1950

> I do happen to have a few 2068's tucked away still. They havent seen
> 
> daylight in some time.
> 
> 
> 
> (at one time I was known to USA TS users)
> 
> 
> 
> Paul Holmgren

Hello Paul! I am not sure if it's your intent to offer your 2068 for sale? I am not sure if I want another one (I already have one that works) but I am willing to listen. Actually, I am very interested a in Spectrum Emulator Cartridge if you happen to have an extra.

Mark

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#1955

On 22/02/2013 03:03, mores.mark@gmail.com wrote:
> Actually, I am very interested a in Spectrum Emulator Cartridge if you happen to have an extra.

If you're up to a little hardware project you can make your own. You 
just need to create a board with an edge connector and a 16K EPROM.
The Emulator ROM is available here: 
http://www.worldofspectrum.org/infoseekid.cgi?id=4000071

Alternatively you could give SE Basic a try. It's more compatible with 
Spectrum software than the TS2068 ROM, but it includes the SOUND and ON 
ERROR commands among other things: http://cheveron.github.com/sebasic4/

-Andrew

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#1966

Brian: Thanks. If it comes down to that, I think I have access to the necessary resources via my University.


> If you're up to a little hardware project you can make your own. You 
> 
> just need to create a board with an edge connector and a 16K EPROM.
> 
> The Emulator ROM is available here: 
> 
> http://www.worldofspectrum.org/infoseekid.cgi?id=4000071
> 

It sounds like a good long-term project for me (at least for learning purposes; my expertise is in software/programming). For short term, to get it done quickly, I will have to leave it to my friend who has the right expertise.

Do you think a graduate student in electrical engineering will be up to the task?

Could you point me to a reference for how such a board could be built (e.g., circuit diagram)? Are these 16K EPROM and edge connector standard components that I can still obtain easily? (Aren't they from 80's?)

> Alternatively you could give SE Basic a try. It's more compatible with 
> 
> Spectrum software than the TS2068 ROM, but it includes the SOUND and ON 
> 
> ERROR commands among other things: http://cheveron.github.com/sebasic4/
> 

Interesting, I will have to look more into it.

I checked message archive of this group. I saw some mentions of replacing 2068 ROM with ZX Spectrum ROM. How do you feel about this approach?

I also saw some mentions of "twister board" allowing interacing with Spectrum accessories. This sounds very useful considering that I have Divide interface. Together with emulator cartridge or ROM exchange, this will allow easy access to Spectrum software. But it looks like I will have to build one again. Do you have access to the build information?

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#1981

On 23/02/2013 02:02, mores.mark@gmail.com wrote:
> Brian: Thanks. If it comes down to that, I think I have access to the

  necessary resources via my University.
>
>
>> If you're up to a little hardware project you can make your own. You
>>
>> just need to create a board with an edge connector and a 16K EPROM.
>>
>> The Emulator ROM is available here:
>>
>> http://www.worldofspectrum.org/infoseekid.cgi?id=4000071
>>
>
> It sounds like a good long-term project for me (at least for learning

  purposes; my expertise is in software/programming). For short term, to get

  it done quickly, I will have to leave it to my friend who has the right

  expertise.

> Do you think a graduate student in electrical engineering will be up to

  the task?

Easily.

> Could you point me to a reference for how such a board could be built

  (e.g., circuit diagram)? Are these 16K EPROM and edge connector standard

  components that I can still obtain easily? (Aren't they from 80's?)

You really just need a 16K eprom with the right edge connector for the 
cartridge slot. The slot details are in the technical manual which has 
been scanned and can be found online by googling.

>> Alternatively you could give SE Basic a try. It's more compatible with
>>
>> Spectrum software than the TS2068 ROM, but it includes the SOUND and ON
>>
>> ERROR commands among other things: http://cheveron.github.com/sebasic4/
>>
>
> Interesting, I will have to look more into it.
>
> I checked message archive of this group. I saw some mentions of replacing

  2068 ROM with ZX Spectrum ROM. How do you feel about this approach?

The 2068 uses a 24K ROM. I'm not clear if this is on two separate chips. 
It's the HOME ROM that you want to replace with the Specturm ROM (or if 
you're burning an EPROM, optionally the SE Basic ROM).

>
> I also saw some mentions of "twister board" allowing interacing with

Spectrum accessories. This sounds very useful considering that I have

  Divide interface. Together with emulator cartridge or ROM exchange,

  this will allow easy access to Spectrum software. But it looks like

  I will have to build one again. Do you have access to the build

  information?
>
The 2068 has the same edge connector as the TS1000/ZX81. The twister 
board converts it to match the ZX Spectrum. After the conversion most ZX 
Spectrum peripherals will work with the TS2068 with the emulator ROM. 
Some of them (including divIDE) will work to some degree with the 
original ROM too. Unfortunately I don't have any details of the build, 
however you could work it out by comparing the TS2068 tech manual with 
the ZX Spectrum tech manual.

-Andrew

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#2035

Hello, I am giving an update.

I have successfully disconnected the keyboard cable from the mainboard. It's pretty easy this time, just gently pulled left-right a few times and that's it! I guess I just have more confidence from reading everyone's suggestion. 

I add a new photo to the link I posted previously. It shows the inside of the TV modulator. A few people suggested to investigate the UA78L12 voltage regulator and the LM1889 color/encoder video modulator. I will ask my friend to check them.

Please feel free to provide more suggestions.

Thanks,
Mark

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#2036

Post it again here for easy reference.

Link to photos:
https://www.dropbox.com/sh/wok7wqgcwhzjqip/HE7W0VoyE_ 

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#2047

On 3/3/2013 1:15 AM, mores.mark@gmail.com wrote:

> Hello, I am giving an update.

> I have successfully disconnected the keyboard cable from the
> mainboard. It's pretty easy this time, just gently pulled left-right
> a few times and that's it! I guess I just have more confidence from
> reading everyone's suggestion.

> I add a new photo to the link I posted previously. It shows the
> inside of the TV modulator. A few people suggested to investigate the
> UA78L12 voltage regulator and the LM1889 color/encoder video
> modulator. I will ask my friend to check them.

> Please feel free to provide more suggestions.

> Thanks, Mark

Wouldn't you know it,  Murphy's Law is in effect.
It will probably be the last box I dig thru.
I have been inside 3 different TS2068's and so far none of
them have the ROMswitch in it.   YET!!

I haven't Given Up Yet!

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#2049

> Wouldn't you know it,  Murphy's Law is in effect.
> 
> It will probably be the last box I dig thru.
> 
> I have been inside 3 different TS2068's and so far none of
> 
> them have the ROMswitch in it.   YET!!
> 
> 
> 
> I haven't Given Up Yet!


Oops, you probably have too many TS2068's!

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#1965

On 2/21/2013 10:03 PM, mores.mark@gmail.com wrote:
>> I do happen to have a few 2068's tucked away still. They havent
>> seen

>> daylight in some time.

>> (at one time I was known to USA TS users)

>> Paul Holmgren

> Hello Paul! I am not sure if it's your intent to offer your 2068 for
> sale? I am not sure if I want another one (I already have one that
> works) but I am willing to listen. Actually, I am very interested a
> in Spectrum Emulator Cartridge if you happen to have an extra.

> Mark

There is a chance that a 2068 with ROMswitch is lurking in a box. I have 
a somewhat faint recollection of such a critter.
I would have to dig deep, unless oldtimers hasn't totally set in.
If I can Find It, both the Kids and wifypoo would be happy if I sold it 
to clear out another bit of 'clutter'. Somehow we differ on defining 
'clutter' :-).
What I can't recall is having a front port plug-in that did that also.
I do know that I have/had other cards for the game slot that plugged in 
with ROM contained programming. (Think Hot-Z was one of them)
Might even have buried away a RAM card for that slot, again all 
depending on not being aflicted with 'oldtimers'  :-)
Shoot, might even have some naked cards for someone to utilize for 
whatever, RAM or ROM.  AH Now it Comes back, think there was a battery 
backed ram card too. It would have been covered in SyncWare News back in 
the day.

Should I temp you with more stuff???

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#1967

> There is a chance that a 2068 with ROMswitch is lurking in a box. I have 
> 
> a somewhat faint recollection of such a critter.
> 
> I would have to dig deep, unless oldtimers hasn't totally set in.
> 
> If I can Find It, both the Kids and wifypoo would be happy if I sold it 
> 
> to clear out another bit of 'clutter'. Somehow we differ on defining 
> 
> 'clutter' :-).
> 
> What I can't recall is having a front port plug-in that did that also.
> 
> I do know that I have/had other cards for the game slot that plugged in 
> 
> with ROM contained programming. (Think Hot-Z was one of them)
> 
> Might even have buried away a RAM card for that slot, again all 
> 
> depending on not being aflicted with 'oldtimers'  :-)
> 
> Shoot, might even have some naked cards for someone to utilize for 
> 
> whatever, RAM or ROM.  AH Now it Comes back, think there was a battery 
> 
> backed ram card too. It would have been covered in SyncWare News back in 
> 
> the day.
> 
> 
> 
> Should I temp you with more stuff???

You have succeeded in tempting me ;)

You sure have good stuffs. I remember reading here about "ROMSwitch" to allow switching between 2068 ROM and Spectrum ROM. If this is the case, then it sounds very interesting.

Please let me know if you want to sell anything allowing 2068 to emulate Spectrum. I would be happy to have if I can afford.

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#1968

I am opening up the machine. I see the flex cable connecting keyboard (top shell) to the main board. Is it safe to pull the cable out of its connector on the main board? It seems to fit in very tight to the connector.

If pulled, Will it be easy to connect the cable back to the connector? I never manage to connect a keyboard cable back for my TS 1000.

Thanks,
Mark

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#1969

On 2/22/2013 9:52 PM, mores.mark@gmail.com wrote:
> I am opening up the machine. I see the flex cable connecting keyboard
> (top shell) to the main board. Is it safe to pull the cable out of
> its connector on the main board? It seems to fit in very tight to the
> connector.
>
> If pulled, Will it be easy to connect the cable back to the
> connector? I never manage to connect a keyboard cable back for my TS
> 1000.
>
> Thanks, Mark

When ever we had to crack the case on a 2068 or 1000, we were careful
to grasp the membrane with plenty of fingers to spread out the pull
force. When putting back membrane tails hold it real close to the socket 
and sort of wiggle dance it in fingers on both side of the tail so your 
push/force energy is across the entire length thats trying to
be inserted into the socket.

(Should I also Mention I have a small pile of virgin never used 1000
membranes too??)

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#1970

> When ever we had to crack the case on a 2068 or 1000, we were careful
> 
> to grasp the membrane with plenty of fingers to spread out the pull
> 
> force. When putting back membrane tails hold it real close to the socket 
> 
> and sort of wiggle dance it in fingers on both side of the tail so your 
> 
> push/force energy is across the entire length thats trying to
> 
> be inserted into the socket.
> 
> 
> 
> (Should I also Mention I have a small pile of virgin never used 1000
> 
> membranes too??)


I made another attempt. It's *really really* tight. I stopped as I don't want to break the cable. I will have to try again. The good thing is the cable looks considerably less fragile than that of TS 1000. Meanwhile, I am posting pictures of the inside. I will have to find a way to open the modulator case after I can unplug the keyboard cable.

Link to pictures:
https://www.dropbox.com/sh/wok7wqgcwhzjqip/HE7W0VoyE_

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#1971

On 2/23/2013 7:48 PM, mores.mark@gmail.com wrote:
>> When ever we had to crack the case on a 2068 or 1000, we were
>> careful to grasp the membrane with plenty of fingers to spread out
>> the pull  force. When putting back membrane tails hold it real
>> close to the socket and sort of wiggle dance it in fingers on both
>> side of the tail so your push/force energy is across the entire
>> length thats trying to be inserted into the socket.

>> (Should I also Mention I have a small pile of virgin never used
>> 1000 membranes too??)


> I made another attempt. It's *really really* tight. I stopped as I
> don't want to break the cable. I will have to try again. The good
> thing is the cable looks considerably less fragile than that of TS
> 1000. Meanwhile, I am posting pictures of the inside. I will have to
> find a way to open the modulator case after I can unplug the
> keyboard cable.

> Link to pictures:
> https://www.dropbox.com/sh/wok7wqgcwhzjqip/HE7W0VoyE_


Yes its tight, now I remember this also,
I usually ended up doing this semi-blind
when I was ready to do the deed I used both hands (got more
fingers on the tail)  let the top rest on my hands as I used
pressure to try and force the end of the membrane tail into
the socket.
This worked enough that I can't recall doing it as your pics
show, with the lid vertical. I do recall trying to do it with
the lid vertical but it was a real drag compared with letting
the top rest on my hands.
You Might have to take a magnifying lens to the socket just
to satisfy yourself there is no foreign matter blocking you
or a badly bent contact in the socket.

Good lucks!

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#1972

> Yes its tight, now I remember this also,
> 
> I usually ended up doing this semi-blind
> 
> when I was ready to do the deed I used both hands (got more
> 
> fingers on the tail)  let the top rest on my hands as I used
> 
> pressure to try and force the end of the membrane tail into
> 
> the socket.
> 
> This worked enough that I can't recall doing it as your pics
> 
> show, with the lid vertical. I do recall trying to do it with
> 
> the lid vertical but it was a real drag compared with letting
> 
> the top rest on my hands.
> 
> You Might have to take a magnifying lens to the socket just
> 
> to satisfy yourself there is no foreign matter blocking you
> 
> or a badly bent contact in the socket.
> 
> 
> 
> Good lucks!

Thanks for the tips Paul! I will be very busy next week, so it will be several days because I can try again. When the time comes, I guess I will just have to forget about the fear of breaking and PULL!

...will let you know how it turns out.

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