pcrock

Again, thanks for answering friend. About the transistors, I used BC548C and BC558B. They are original ones (not Chinese crap). I have two other consoles with other mods that work VERY WELL both in CRT and in this same led tv that I tested here on this post. One of then is a very very simple thing and works very well. The other uses a CD4050 and transistors (the best I've seen so far till now) but it takes a lot of work to build so I was very interested in this one that you did because the idea looks great. Here are the schematics of the ones that I have used successfully so far in my both CRT and LED TV. About the cables I tested, both are resistance less than 1 ohm. I even tested your mod with the original 75 ohm RF cable as video cable and also with a good AV cable but the defects are identical in both. In CRT the image is much better but still far from desirable. At CRT, the Trimmer works but does very little. The colors are correct in both Led TV and CRT but are weak, ugly and dark and have vertical interferences. This same led TV that I used in the photos works well in the mods I send attached to this post. The 75 ohm resistor is exactly 75 ohms in the digital multimeter. Any idea? Thanks friend again.

Hi friend. I did the mod and all ran ok on building the circuit but unfortunately the results was not good. About the transistors I used BC548 and BC558 instead 3904 and 3906 that are unusual ones here in Brazil. I attached pics to show you the image issues to ask if you could give me some idea. For the trimmer I tried from 0K to 10k but had no bright change. The image is dark and full of interferences and contours blurry. The console is in NTSC mode X200 (xtal) is 3.579545 MHZ I have great interest on this mod. Once more special thanks friend!

Please tell me one more thing. Is it correct 10K for R9 (audio) ??? It appears too much high value to me. thanks again

Wow!!! Thanks a lot again friend!! I will try it!!!

Hi friend!!! Great post!! I will do that!! Very thanks for sharing with us!! Please tell me. What is the way to get the BEST trimmer adjust ?? Thanks again!!!

I am asking because it would be a valued information to know if the issue appeared after or before the AV Mod. If the issue were before the av mode, the matter is in the console but If the issue appeared after the mod, the matter is in the AV mod.

Sorry for my ignorance but I will ask. Did this console use a RF modulator before AV mode ?? Did it haves this issue in RF mode?

Please. Send me a private message

Woww!!! Very very thanks for the Schematics!!! I really wanted it!!! The engeneer loved 8k2 resistors values!! Ahahahhahahah

How do you choose the game on this cartridge?

Today I made a discovery! I found out that of all these converted roms, centipede doesn't work on one of my consoles!! All roms converted by friend alex_79, work on 2 consoles that I have that use TIA C010444 (and also on another one that uses UM6526N) but the Centipede does not work on the console that I have that uses TIA UM6526N. All other roms work on all three consoles. That is no matter to me, I plan to change TIA UM6526 to KSC131 or C010444 but is a curious thing. I also found that the original ThunderGround (By Sega) (4K) game doesn't work on this console either. When I start, all lives die instantly one after the other and the game is over. Hundreds of other cartridges that I have work normally on this console.

I used the pcb below... The friend alex_79 member here in the forum, traced the schematics. I converted this circuit to use a 27C512 adding two more switches and now it is able to run eight 8K games. But the bankswitching is the same.. It was not changed..

I Found another one. It is a 4 in 1 The most interesting thing is that in this circuit, the switches are not SPDT devices as in the in MOST OF THEM! Here the switches are simple on/off ones.

Would be very interesting! I would like to see!

So the roms I sent you haves the same bankswitch scheme as that weird cart? Then The other ones I sent you might work too.. All of them works in the same board I tested here, so I think if one of them works all other must work too.

Please... test it and I will remove the chip from my cart to do the dump for you too.

Sent you a message.

Today, another Surprise to me!!!!! I found one more cart that DOES NOT HAVE any inverter!!!! The words on the CHIP is: AT&T ´85 QD27128A2 PGM @ 12,5V INTEL ´83 Tha games into the eprom: Frogger (no brand name) Box By ACTVISION Crackpots By PROOM FrostBite By PROOM It appears that exists a lot of 27XX that does not need any inverter to work on ATARI 2600

Woowww!! Very Cool idea!!!!

I have another 4 i 1 (4K each one game) board absolutely identical to this one but it uses a 27C128 instead 27C256 and it doesn't have the resistors.

As I told before, this is not the circuit with the floating pin. The board I test the roms haves the pins 4 and 5 connected together.

One More!!! That is a 4 in 1 (one of it 2k and 3 others 4K). It works perfect. They use a bigger 27C256 eprom than needed due to be the one they had it in the hands at those days I think. I attached here the rom dumped from it. The first eprom´s 16K is all BLANK (FF). How is it possible??? I plan to use that 27C256 in another cart and put a 27C128 here. My quest is: What is the reason to use that red pointed resistors connected from pins 6,7,8 to +B ?????????? A 27C128 will work here? 27C256_ 4in1 Bowling_Donkey Kong_Kunf Fu_Atlantis.BIN

Just to report. I don't know if this has to do with the problem but on this circuit, pins 4 and 5 of the LS00 are soldered together.

Once more Thanks friend! But tell me more please. Haves Each of the eproms exactely a half original rom codes ??? If yes, is possible to changes the roms with two 2732 ones that contains a half of Popeye (for example or any original 8K rom) code each one and it will work???

WOOOOOOOWW !!! alex_79 !!! O Tapper v3 que você me enviou hoje está funcionando MUITO BEM !!!!!!!!!!!!!!!!!!!! Sinto muito pelas fotos ruins, mas minha placa ATARI 2.6K está conectada a um dispositivo CRT !! Estou mandando as fotos !!! Muito obrigado aos amigos alex_79 e Thomas Jentzsch por me ajudarem na conversão de bankswitching para minha prancha brasileira !!! E obrigado a todos pela atenção em mim e nos meus problemas !!!!!