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CRT TV EEPROM & Micom hacking for RGB (+tube swap for 48cm to 51cm TV)


buttersoft

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This thread started out being about swapping a 48cm tube onto a chassis that originally had a 51cm tube, but has turned into a discussion of EEPROM and microcontroller hacking to enable RGB on old Australian (possibly NZ) SD CRT TV's on which it appears to have been disabled by the microcontroller (Micom). Discussion of the latter begins a few pages in, and it's all very much a work in progress.

 

Note that not all old sets need the above, in progress hack in order for you to RGB mod them. As a very rough guide, if the neckboard has colour pots for RGB bias/gain, you probably don't need to worry, injecting signals into the jungle IC should just work. For newer sets without neckboard pots, try inserting RGB, and see if it works.

 

Remember that the shumps thread is a better place for information on the subject of RGB hacking!

 

I've been hunting for more RGB-moddable chassis to drive 20"/48cm TV tubes - the standard 2ohm/14.8ohm ones in old cabs. They're getting harder to find though.

 

After @namastepat's just-make-it-fit suggestion I was wondering about swapping out the chassis from a 51cm TV and using it on a standard 48cm tube. Do the 51cm tubes typically have the same yoke resistances and pinout? Is the required HV going to be much different? I know I've seen chassis that will suit multiple tubes.

 

At the moment I'm looking at this job here - https://my.mixtape.moe/rnatkf.pdf.

 

That service manual says the chassis can handle 14", 20" and 21" tubes. (In this particular case I suspect the 20" and 21" tubes might be the same thing but US vs Aus names? i.e both the same 51cm tube, not a 48cm one?)

Edited by buttersoft
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I'm a little confused. Did you mean to say it's NOT multi master?

 

Oops. The spec is multi master. The removal of the Micom would be so it doesn't overwrite anything you don't want it to. My money is on the Micom in the CT-M5122H turning on and off the RGB as needed for the OSD, but I guess we'll find out. Perhaps it's even got some trick to allow the Micom to override the TTX IC. All I actually know is that the video noise was appalling and I wasn't able to isolate the cause.

 

The set I'm more interested in is the Samsung TV-4881 though, so I hope to be able to adapt the I2C technique.

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Also, on the Teac noise issue, I'm sure I saw in one of the data sheets pertains to this set mention of noise issues. I should've written it down when I saw it. Right now I'm not in a position to search the PDF's.

 

Try doing a text search through them for noise or crosstalk.

 

 

Sent from my iPhone using Aussie Arcade

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Now that I'm in the right territory I'll go back to pots to tune it from there. Might be a few nights before I can get back to it.

 

I'm at my wits end with this, have spent so much time with pots trying to fine tune but have gotten not improved things at all... what I had was the best I can get, I can dial it down and get worse or dial up and get worse...

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No reply from vendor with software yet.

 

I believe the software I have found will work. The main chip is the CH314a which is the same as the one on the EEPROM programmer I bought earlier. The device was plug and play, perhaps because I had already installed the EEPROM programmer.

 

I am still getting over jet lag so I was too tired to try it out last night.

 

 

Sent from my iPhone using Aussie Arcade

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The main chip is the CH314a which is the same as the one on the EEPROM programmer I bought earlier.

 

How did you figure out which chip you're new USB-to-I2c dongle is using? The unit looks sealed?

 

Part of me wonders now if it would be possible to wire-up/mod the programmer for i2c communication. Both devices would be sending discrete commands...right?

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How did you figure out which chip you're new USB-to-I2c dongle is using? The unit looks sealed?

 

After the device installed it showed up in the device manager with CH314A in the name. I googled from there...

 

Part of me wonders now if it would be possible to wire-up/mod the programmer for i2c communication. Both devices would be sending discrete commands...right?

 

Probably, but for $11...

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CRT TV EEPROM & Micom hacking for RGB (+tube swap for 48cm to 51cm TV)

 

I connected the el cheapo Ali Express CH314A adapter to the TV.

 

I managed to get some response from the television but no real success. Got it to pop and squeak and turn itself off and back on....

 

When I used the address 8A00 I would get a response. Mostly the repeating pattern 00 8F 83 00 00 8F 83 00 00 8F 83 00 00 8F 83 00

 

If I used other addresses I'd just get FF FF etc

 

Reading through the datasheet for the CH314A it seems to only be able to handle synchronous serial communication over SDA/SCL. I2C is asynchronous. I wonder if this is the issue?

 

I did learn a bit of stuff though. For the Jungle the addresses sent over the line should be 8A to read and 8B to write. The first 7 bits of the byte represent the address and the 8th represents whether it is a read or a write command. So address 100101 0, 8A to write and 100101 1 8B to read.

 

Not sure where I go from here, possibly a better serial device, don't know. Tired....

Edited by MarkOZLAD
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Still no progress on this guys, have been too busy working on RGB modding a couple of Trinitrons. Also, girlfriend moving in with me so very busy. Will get to this again when I can.

@buttersoft - do you still need that EEPROM read from the Teac?

 

You were gone for long enough that I was hoping nothing bad had happened ;)

 

No need for EEPROM, given later developments determined the layout of the EEPROM and Jugnle IC data tables had little to do with each other. Thank you for the offer though. I still have a low grade itch over reading from an operating jungle IC though, and hope to hear of progress soon before I just go and buy a USB-to_I2c dongle. Are you sure the one you have works properly? Have you tested it on anything else?

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