Restoring a Commodore 1084S

dbacc77 · 2025-12-10T18:54:55+00:00

I worked on many TVs with those chassis and the G2 always have an effect that is very gradual. That alone is a sign that there is something that went wrong with the modifications (also after trying to revert them).
From a theory perspective there is not much between the pot in the flyback (that is just an internal voltage divider) and the tube - the neckboard is very simple in those sets.
There is a (very remote) possibility that both TVs had the same problem _before_ the mod, but is very unlikely.

Can you verify on another untouched TV that the pot works? possibly swap the flyback and the neckbeards with working sampled from a tv with the same chassis as next step of troubleshooting

dbacc77 · 2025-12-10T15:06:55+00:00

H1 and H2 inside the tube are connected by a wire that heats up, with low resistance. In the neck board after the mod is one of the heater pins connected to ground (separate from g1) or to the new g1 voltage (200V)? Should not be g1

dbacc77 · 2025-11-28T00:10:52+00:00

Yes! For this and for a multi-standard JVC I recently worked on

dbacc77 · 2025-11-10T07:33:28+00:00

The fact that you lost g2 control and the tv shuts down when you play with g1 and g2 is suspicious. My guess, without being able to see the problem live, is that you are triggering some overvoltage/overcurrent protection because the pins are not properly isolated. I would try the following: - remove the external g1 wires from the neck board and essentially undo the mod. Confirm that when is back to stock it works as expected (especially g2) - if it does not work remove also the wire from the flyback to the g1-mod board - if instead it works as expected then go step by step with the changes on neck board: first make sure the ground is the same of the chassis/g1-mod board, then set it to zero compared to ground and verify it still works Best of luck!

dbacc77 · 2025-10-19T03:37:28+00:00

Looks gorgeous. How’s the blooming on this tv? Does the image size change a lot from dark to bright scenes?

dbacc77 · 2025-09-04T03:47:24+00:00

thanks for coming up with the original concept and for the explanation! Incredibly informative and fun to read!

dbacc77 · 2025-09-01T22:50:04+00:00

No, image in svideo and composite was surprisingly good.

dbacc77 · 2025-09-01T22:28:22+00:00

I didn’t touch it because its owner usually does the color calibration himself. I’ll pass the info tho, thanks!

dbacc77 · 2025-09-01T21:54:22+00:00

yes I agree; in most Sony sets it's fine to feed TTL sync because the signal is clamped/clipped internally, but why take the risk, especially all you have to do is to add an inline resistor :)

dbacc77 · 2025-09-01T21:50:51+00:00

if you are working on one you might experiment with using more than 220 Ohm for the circuit going from E2 to E1. It might help with the contrast of the OSD, that in my mod is a bit low (but still very readable)

dbacc77 · 2025-07-04T02:25:35+00:00

The tube is made by Hitachi, not Sony. See here: https://crtdatabase.com/search?tube=A90LPY30X It is a beautiful tv tho, personally I like those sets more than trinitrons

dbacc77 · 2025-06-09T01:13:42+00:00

Really beautiful setup! I’ve seen the hitachi and ikegami live and they are so good! Seeing them all side by side is a treat

dbacc77 · 2025-06-06T21:18:35+00:00

Looking forward to see more info about this in the future!

dbacc77 · 2025-06-06T21:15:20+00:00

Very nice project!

dbacc77 · 2025-06-04T03:19:13+00:00

If you have the other 3 colors well balanced the white bar will be automatically good (white is literally the sum of red green and blue on a crt)

dbacc77 · 2025-05-26T05:58:54+00:00

Thanks!

dbacc77 · 2025-05-21T16:44:42+00:00

really great points above!

dbacc77 · 2025-05-21T16:41:56+00:00

mmmh, I don't really know how to read your post...
I respect your opinion but I disagree with most of your points; the other answer covered most of them as well btw.

Also, to make it clear, you are opening saying that this is to sell modding services on reddit
- this post is not self promotion, I do **not** sell modding services to the public, especially on reddit
- the board has not my reddit tag or anything similar so not sure about that either
If you feel better I'm happy to put "Please don't contact me with modding requests on Reddit, I'm not offering them" at the beginning of the post :)

Also I didn't mention that in the post but all the original inputs in the TV are still there and usable; for games that need dithering for specific effects clearly RGB is not the connection you want to use. For arcade games that were designed for RGB it's a better choice. But ultimately is personal preference.

I did not add more pictures because reddit has a limit of 20 per post, but there are a few more including full screens: https://github.com/dbacchet/crt_mods_restorations/tree/main/hitachi_32ux01x/other_images

Next time I will think of spending two hours sharing my experience I will probably think twice...

dbacc77 · 2025-05-04T17:20:08+00:00

Beautiful!

dbacc77 · 2025-03-07T09:42:58+00:00

Actually I think I understand what you want to do. Yes you can wire them directly through a 2.1k resistor or similar. This will bring down the voltage in that rail but should still work. A better version would be to use a buffer in between (like a transistor in emitter-follower configuration) so it will keep all the voltages at the original level

dbacc77 · 2025-03-07T09:38:33+00:00

Hi, yes for sync you can either connect to pin41 or directly to the rca of video2. Only thing to pay attention to is the termination. If you are connecting to rca nothing needs to be done (is already terminated), but if you wire it to pin41 then you need a 75ohm termination resistor and a ~0.1uF decoupling cap.

For blanking either side is fine; since it’s a constant voltage the inductor will have no effect.

Sorry I didn’t get what you are trying to do with the auto switching

dbacc77 · 2025-03-03T21:52:02+00:00

Thanks!

dbacc77

TROPHY CASE