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It looks to me like those Dragon 32 PSU boards may have been swapped over. Have any of those Dragon 32s ever been working properly since you got them?

I know one of the 32's worked and displayed a screen that was scrambled to begin with but after that first time it has never displayed a picture since. The other dragon 32 didnt display anything at all so i thought i could at least try swap out the psu boards to see if it made any worked.

While i dont get any display from both 32's the both respond to me typing motor on motor off so it gives me hope

The PSU boards not suitable for direct swapping unless they are the same type. It shouldn't do any damage, but they need to be modified slightly for them to work properly. See the service information here.

starfrog wrote:

Alastair wrote:Regarding the Dragon 64 producing monochrome output. You state that you obtained it in 1988, if it is second-hand it could be that the previous owner modified it to produce a clearer video signal. It's a relatively simple procedure that was mentioned in an issue of Dragon User (though I cannot remember which issue) but it comes at the cost of losing colour output.

Sounds like a possible lead just need the info to make it less clear ! I have all the early dragon user mags so i'll take a look.

The good news is that I've found the article, it's a letter in the June 1988 issue of Dragon User, the bad news is that it requires the removal of the video modulator chip (LM1889) and if you don't have this chip you will have to source it from your Dragon 32 with the socketed LM1889 (it's near to the joystick ports). There may also be further bad news because on most Dragon 64s the LM1889 chip is soldered to the board (where it is labelled IC17 and is found jut below the XL2 crystal), so unless you are fortunate enough to have a 64 where this chip is (or was) socketed the swap will not be simple.

Of course, all of the above assumes that your Dragon 64 has been modified in this manner, it is entirely possible that other modifications will produce the monochrome output you describe or that there is a fault somewhere.

Before you do anything too drastic, take a small screwdriver and try adjusting the 10k variable resistor. I tweek this from time to time to adjust the color intensity on my Dragons. Obviously you need to have the machine powered up and plugged into your Monitor at the time. Just try a gradual quarter turn to left and again to the right to see whether the color appears - then adjust to suit.

Sorry for asking an obvious - possibly stupid - question, but if these dragons are "recently acquired", could it just be that these are NTSC Tano Dragons?

Philippe

there UK ones for sure.

MaestroSoftware wrote:Sorry for asking an obvious - possibly stupid - question, but if these dragons are "recently acquired", could it just be that these are NTSC Tano Dragons?

Philippe

The Tano is an NTSC Dragon 64, I don't believe there ever was a NTSC Dragon 32.