+2a double vision

[prolog]

Hello

This may be a job for another forum, but I've had good adv here before.

Halloween horrors on the +2 rgb display. I've attached some pics which show any mono screen data in double vision- all the colour stuff is fine. It looks like a tiny screw twiddle should resolve it, but this may be wishful thinking!!

I've tried different scarts - no probs with toastrack or spec issue 2 48k - just the amstrad.

any ideas most welcome,
thank you!

Jeff

[RWAP]

Not something I have come across before, so I asked Ian Gledhill (who does my repairs) and he also has not come across this...

You may need to ask on the World of Spectrum forums..

However, our general advice (thanks Ian):

First thing to do is to carefully twiddle the Toko coils (very carefully!).. I'd also check the composite output.
Next thing I would check is the diodes on the TEA2000 RGB outputs as it's easy to check with a multimeter, then I'd change the TEA2000 itself.

I'd also be very wary of those RGB cables that you get which use the monitor port for RGB switching as they use the composite sync output of the ULA to drive the switching signal, which overheats the ULA (TTL outputs are *not* designed to drive 75Ohm inputs). Took me ages to track down what was happening (I foolishly thought that the RGB cables which were factory made would work without any detrimental effects).

[prolog]

Ah hello, and cheers Rich - and for showing the pics to Ian, whom I also thank.

Well, so I have an uncommon issue with my retro then. I think I twiddled a toko once before and discovered that it was a bit random in that twiddling it back to where I found it didn't necessarily bring me back to my starting output! So, hmmmm.... Your proposed steps look good and I am psyching myself up for some surgery. I also had ULA at the back of my mind but would have expected this to be more common if so.

I think I will try the WoS forum before working through the steps in that case - and if I find any successful strategy I'll posy back here

thanks again!

Jeff

[RWAP]

The only other things to do is check it on a normal TV connection if you can and also check the heatsink on the ULA is properly attached.

[prolog]

Hi again,
yes the normal rf output is fine, no issues - I'll add heatsink to the list though!

Actually, Rich, as an aside you've got me worried about scart cables now though not in connection to the 2a

On WoS there is a whole Science of Scart going on and controversy over the loading on pin 16 etc. - the more mathematical posters there (that have cranked ohm/resistance/voltage calculations) seem to think there shouldn't be significant ULA overheat problems using the rgb/scart; the man with the thermometer on his ULA says otherwise.

So, I am now going into panic mode about the appropriate scart lead to use with my toastrack - please tell me there's a safe option!! Couldn't see anything on sellmyretro

[prolog]

WOW OMG

so this is with +2a and scart (not rf) into a CRT!

[prolog]

Just to complete the picture...the Klingon alphabet above is with +2a via SCART to CRT contrasts bizarrely with the attached which the the same machine plugged into another CRT via RF which gives the alphabet I want!

????
Jeff