spectrum 128 with only 12 volt
Re: spectrum 128 with only 12 volt
Mark ,
The display is the same as i used yesterday to get the ill speccy tested.
Scope is on my right .
The display is the same as i used yesterday to get the ill speccy tested.
Scope is on my right .
Zx81-16k exp.- Spectrum 48 - Spectrum 128- Interface 1 - DIVide - Zx flashcard- Zx printer - Ram turbo-Velleman interface system-Currah microspeech -Ql - 512k exp.- Ql printer - Cst floppy interf.- Double 3.5 floppy- Minerva - Qimi-and much more .
- 1024MAK
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- Location: Looking forward to summer in Somerset, UK...
Re: spectrum 128 with only 12 volt
Sorry, maybe I was not clear.
How are you connecting the video output of the 128K, are you using composite video and ground (pins 1 and 2 on the 128K’s DIN socket). Or are you using the three video channels (R, G, B), bright, and combined sync. (pins 2, 3, 4, 6, 7 and 8 on the 128K’s DIN socket)?
Or have you done something different?
And where does this go, directly to a “normal” TV or to an adapter or converter?
In the photo you posted, it looks like you are using a video capture device and displaying the result in a window on a PC.
I’m just trying to get an understanding of your current set up. Then I hope to be able to help you further.
Mark
How are you connecting the video output of the 128K, are you using composite video and ground (pins 1 and 2 on the 128K’s DIN socket). Or are you using the three video channels (R, G, B), bright, and combined sync. (pins 2, 3, 4, 6, 7 and 8 on the 128K’s DIN socket)?
Or have you done something different?
And where does this go, directly to a “normal” TV or to an adapter or converter?
In the photo you posted, it looks like you are using a video capture device and displaying the result in a window on a PC.
I’m just trying to get an understanding of your current set up. Then I hope to be able to help you further.
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
Re: spectrum 128 with only 12 volt
Mark ,
composite video 2 wire to an usb converter , or composite video 2 wire to an hdmi converter .
my own 128 does work fine that way.
with the defective one i can only see "something" happening if i use the usb converter .
this "something" changes when i switch the 128 on or off.
the hdmi converter does not detect any video signal with the defective 128
btw , does both the cap or transistor video-mod not work on a 128 ??
composite video 2 wire to an usb converter , or composite video 2 wire to an hdmi converter .
my own 128 does work fine that way.
with the defective one i can only see "something" happening if i use the usb converter .
this "something" changes when i switch the 128 on or off.
the hdmi converter does not detect any video signal with the defective 128
btw , does both the cap or transistor video-mod not work on a 128 ??
Zx81-16k exp.- Spectrum 48 - Spectrum 128- Interface 1 - DIVide - Zx flashcard- Zx printer - Ram turbo-Velleman interface system-Currah microspeech -Ql - 512k exp.- Ql printer - Cst floppy interf.- Double 3.5 floppy- Minerva - Qimi-and much more .
- 1024MAK
- Posts: 5171
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: spectrum 128 with only 12 volt
Okay, now I understand.
With your ‘scope, can you test on the TEA2000 pin 6. This should be a composite video signal, but at different (higher) voltage levels compared to a standard composite video signal.
Try to use the trigger control on your ‘scope to lock to a positive to negative edge, so that it uses the line or field sync. Unless you use a more complex trigger control, the ‘scope image will keep changing. So if you have a “one shot” mode, use that.
If your ‘scope has two channels, you could trigger off of pin 16 of the same chip.
Mark
It isn’t needed, and because of the different internal circuitry, it’s not recommended.
With your ‘scope, can you test on the TEA2000 pin 6. This should be a composite video signal, but at different (higher) voltage levels compared to a standard composite video signal.
Try to use the trigger control on your ‘scope to lock to a positive to negative edge, so that it uses the line or field sync. Unless you use a more complex trigger control, the ‘scope image will keep changing. So if you have a “one shot” mode, use that.
If your ‘scope has two channels, you could trigger off of pin 16 of the same chip.
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
Re: spectrum 128 with only 12 volt
Mark ,
After a good look into the analogue and the use of the scope ( which could not find ANY signal !! ) i noticed this ;
an rgb modification , which renders the cvbs output fully useless.
replacing the correct resistor gives this ;
tomorrow i will fit the yellow-mod , and do some more testing with the test-card .
THANK YOU and all others !!
After a good look into the analogue and the use of the scope ( which could not find ANY signal !! ) i noticed this ;
an rgb modification , which renders the cvbs output fully useless.
replacing the correct resistor gives this ;
tomorrow i will fit the yellow-mod , and do some more testing with the test-card .
THANK YOU and all others !!
Zx81-16k exp.- Spectrum 48 - Spectrum 128- Interface 1 - DIVide - Zx flashcard- Zx printer - Ram turbo-Velleman interface system-Currah microspeech -Ql - 512k exp.- Ql printer - Cst floppy interf.- Double 3.5 floppy- Minerva - Qimi-and much more .
- 1024MAK
- Posts: 5171
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: spectrum 128 with only 12 volt
Ahh, you mean this RGB modification (really a SCART signalling modification).
Yeah, I’m not keen on that type of modification. And if owners do want to do that kind of thing, they really should attach a label on the bottom of the case saying what they have done.
Anyway, glad that you have found the “problem”
Mark
Yeah, I’m not keen on that type of modification. And if owners do want to do that kind of thing, they really should attach a label on the bottom of the case saying what they have done.
Anyway, glad that you have found the “problem”
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
Re: spectrum 128 with only 12 volt
the problem is that these units are not even second hand , but maybe 10th hand , so no-one really knows what has been done to them .
This one came in with a distinct burning smell ( as did the ill speccy from yesterday ) ,
so start searching ...................
Thanks for your help and advise !!
jojo
- now step over to a speccy which burns the same memory chip every time i try ..................
This one came in with a distinct burning smell ( as did the ill speccy from yesterday ) ,
so start searching ...................
Thanks for your help and advise !!
jojo
- now step over to a speccy which burns the same memory chip every time i try ..................
Zx81-16k exp.- Spectrum 48 - Spectrum 128- Interface 1 - DIVide - Zx flashcard- Zx printer - Ram turbo-Velleman interface system-Currah microspeech -Ql - 512k exp.- Ql printer - Cst floppy interf.- Double 3.5 floppy- Minerva - Qimi-and much more .
Re: spectrum 128 with only 12 volt
so , last pieces of the puzzle completed ,
with un-rainer mod ;
And the yellow-mod fitted ;
and tried some games too ;
memory test ran for 4 hours without problems , so another saved 128 .
jojo
with un-rainer mod ;
And the yellow-mod fitted ;
and tried some games too ;
memory test ran for 4 hours without problems , so another saved 128 .
jojo
Zx81-16k exp.- Spectrum 48 - Spectrum 128- Interface 1 - DIVide - Zx flashcard- Zx printer - Ram turbo-Velleman interface system-Currah microspeech -Ql - 512k exp.- Ql printer - Cst floppy interf.- Double 3.5 floppy- Minerva - Qimi-and much more .
- 1024MAK
- Posts: 5171
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: spectrum 128 with only 12 volt
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.