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Dragon 32 black and white output
Posted: Mon Mar 24, 2025 3:32 pm
by brendan1495
Hi All,
I am trying to repair a Dragon 32 everything works fine but its in black and white. I have tried changing the pots but still the same, I have also resocketed and changed the LM1889 but no difference. Any ideas were to go from here would be appreciated.
Brendan
Re: Dragon 32 black and white output
Posted: Mon Mar 24, 2025 8:01 pm
by robcfg
Hi Brendan, welcome to the Dragon Archive!
Can you check your motherboard and tell us which part number it has written on it?
Cheers,
Rob
Re: Dragon 32 black and white output
Posted: Tue Mar 25, 2025 7:54 am
by brendan1495
Hi,
This is the board
- 1742885550087.jpg (3.87 MiB) Viewed 64290 times
- 1742885550066.jpg (4.11 MiB) Viewed 64290 times
- 1742885550097.jpg (4.12 MiB) Viewed 64290 times
Re: Dragon 32 black and white output
Posted: Tue Mar 25, 2025 9:15 am
by robcfg
Ok, according to the service information, this is what you could try:
C. Faulty Colour
1. Adjust RV1 (and RV2 if fitted).
2. Alter value of C7.
3. To obtain full green screen or to cure 'rainbow effect', fit a 2-22 pf capacitor trimmer instead of C7.
4. If colour fault on 22" or 27" SONY sets, then fit 15K resistor across Pin 4 of IC9 to Pin 4 of IC10.
5. Change IC9.
6. Change IC16.
7. Change IC12.
Are you connecting it to an old TV, new TV or to a capture device?
Re: Dragon 32 black and white output
Posted: Tue Mar 25, 2025 9:54 am
by sixxie
And check your voltages! Other way around, but I accidentally powered a D64 from a D32 PSU board before which led to no proper -5V and the most obvious symptom was no colour (and tbf pretty shonky video generally, but it was there).
Re: Dragon 32 black and white output
Posted: Tue Mar 25, 2025 10:12 am
by robcfg
That's a good thing to check!
Brendan, do you mind taking pictures of both sides of the power board?
Re: Dragon 32 black and white output
Posted: Tue Mar 25, 2025 10:20 am
by brendan1495
At work at the moment will do when I get home
Re: Dragon 32 black and white output
Posted: Tue Mar 25, 2025 10:36 am
by brendan1495
sixxie wrote: ↑Tue Mar 25, 2025 9:54 am
And check your voltages! Other way around, but I accidentally powered a D64 from a D32 PSU board before which led to no proper -5V and the most obvious symptom was no colour (and tbf pretty shonky video generally, but it was there).
Will check, thanks
Re: Dragon 32 black and white output
Posted: Tue Mar 25, 2025 5:27 pm
by brendan1495
robcfg wrote: ↑Tue Mar 25, 2025 9:15 am
Ok, according to the service information, this is what you could try:
C. Faulty Colour
1. Adjust RV1 (and RV2 if fitted).
2. Alter value of C7.
3. To obtain full green screen or to cure 'rainbow effect', fit a 2-22 pf capacitor trimmer instead of C7.
4. If colour fault on 22" or 27" SONY sets, then fit 15K resistor across Pin 4 of IC9 to Pin 4 of IC10.
5. Change IC9.
6. Change IC16.
7. Change IC12.
Are you connecting it to an old TV, new TV or to a capture device?
cnnecting to crt
Re: Dragon 32 black and white output
Posted: Tue Mar 25, 2025 5:28 pm
by brendan1495
robcfg wrote: ↑Tue Mar 25, 2025 10:12 am
That's a good thing to check!
Brendan, do you mind taking pictures of both sides of the power board?
I have modified the power board to use a meanwell, works fine on my other Dragon