Existing power supply 9V 0.6A, today I tried power supply 12V 2A. After connecting to the second source, 33 33 33 were lit, after a while the clock was running normally again and after about an hour of running again 33 33 33. I disconnected it again. Before that, it took about a week for 33 33 33 to appear. I'll try the adjustable power supply, according to the 9V manual, right?
Replace the 7805 with one from a well known brand. In the schematic you see C2 (100 nf) connected from the Vin pin of the 7805 to ground. Add a 100 nf capacitor connected to the Vout pin of the 7805 and to ground. Also add a 1000 uf electrolytic capacitor after diode D1 (check the polariy is ok). Add a heat sink to the 7805.
This will hopefully smoothen your voltage input further. I still have a feeling that the power supply is the cause of the issue, allthough I am out of options now. It could still be a soldering joint issue.
The + of the 1000 uf electrolytic capacitor to Vin of the 7805, so after the diode.
The - of the 1000 uf electrolytic capacitor to ground
So basicallly the electrolytic capacitor is parallel to capacitor C2, but watch the polarity.
Place the 100 nf capacitors as close as posible to the 7805.
Thanks for the picture. The soldering looks good to me.
I do see some "stuff" stuck to the board around the pins of the K155ID1 (74141) chip. It would be a very good idea to clean the back of the board with alcohol or flux remover.
Another power idea would be to try powering from a 12v car battery just to see if it makes any difference. At least with a battery you know there is no noise. Running on 12V is perfectly okay. I run mine on a 12V power supply all the time - no problem.
Every time you change power supplies you should be doing a Factory Reset so the HV generator can adjust itself to the new supply voltage.
Look into it later when the dust is clearing off the crater.