New Dragon64 owner

[race8086]

Hi all!,
i'm new in the forum and also a newbie D64 owner
No experience at all with this machine, so a previous user manual, some books an schematics inspected

Afther a considerable troubleshoting, i've an Eurohard D64 working ... or almost.
Actions performed:
- A depth cleaning
- A new 6809 inserted
- Some replaced keys
- Two new eproms (IC17 and IC18)

All looks well, but some colours are wrongs : green is not pure, almost yellow, red doesn't exits , instead a gray tone is displayed.
Therefore, the image is very clean, with no interferences.
Sounds works and graphics modes seems too.

Did you ever hear something similar? i'm affraid that a hard investigation on 6847 and PAL subsystem should be perfomed
Any information, manual to read more 'easy' to understand than IC's datasheets?
Thanks in advance.

[Alastair]

Welcome to the forum.

How are you connecting your Dragon to a screen, is it via the TV cable or through the composite monitor port?

[zephyr]

Welcome to the forum!

Are you in the UK?

[admin]

Yes - this is quite common - I think on the Dragon 64 C32 is the trimmer for the PAL output - try moving that a very small amount to see if it improves the output.

I find that different televisions sometimes require the trimmer to be adjusted slightly - especially those with digital RF tuners rather than the much older analogue RF tuners.

[robcfg]

Welcome to the forum!

Are you in the UK?

Nope, he's a friend of mine, we are both in Spain, the second home of the Dragon, hehe

[race8086]

Thanks all!, sorry for the late reply
I'm Spanish, best regards for all the people in this forum
The output was tested via both, RF cable and monitor cable, with the similar results, this means that RF modulator is in good condition.
I've tried VR1 with no results, also i've am UK Dragon 32, that in the same TV with the same cables outputs quite well, not clear as the 64 unit, but with the right colours.

From now i'm reading 6847 datasheet and trying to find a clear PAL diagram for this machine, i'm suspecting on intermediate components beetween Y,QA and QB outputs from the 6847, and the final composite signal.

As anybody a '64' service manual, or detalied schematics ?

i'll try to constuct a procedure to test colours levels in the whole PAL chain, but it means more time, more study and refresh a lot of video and electronics concepts.

One more time thanks for the replies, i'll update the thread with new information

rms

[tormod]

Did you find Rinconete's nice schematics of the Dragon 64 PAL video circuitry?