pc engine rgb mod,now console won't power on when connected to cd unit.

Started by bigsanta, December 17, 2008, 03:11:35 PM

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bigsanta

Which is just one of the problems with this white unit and my crt tv (UK)



I built the rgb amp,based off the 3 transistor version,which is fitted inside the console and wired from the expansion port to it,(RGB +5v),then this is wired to an 8 pin mini din socket,then the rest of the signals (negative/ground,l+r audio and composite video )are taken from the expansion port and wired to the remaining pins on the din and adding a 100 ohm resistor between pin 8 and 16 in the scart plug.

Now here is where i must have mucked up big time,instead of just wiring up the scart lead to the new 8 pin mini din plug,i decided to go for stereo sound output for when the pc engine is connected to the ifu-30 cd rom unit/interface,so instead of doing it this way
leaving the L+R pins in the din plug un-soldered,just attaching those cd rom L+R cables to wires 2 + 6 ,going to the scart pins(and ground to ground in the din plug), i decided to wire the cd rom interface's audio out leads directly into the scart plug,but leaving the audio from the pc engine's din socket,soldered to the pins in the din plug.

Does that make sense,it now has both L+R audio coming from the console's din end and going to the scart plug,and also L+R audio coming from the cd rom interface's L+R audio out ,and those leads go into the scart plug,through a hole in the side of the scart plug's casing,and meet/connected to the L+R wires from the din.

Now when i connect the pc engine to the interface with the cd rom ,and the L+R audio leads(as in the above photo)i can see power is supplied to this unit/interface,as the green light on the IFU-30 is lit,but when i slide the power switch to on on the pc engine,nothing,no game on tv screen,no auto switching,and if i manually switch to the av channel,there's just a black av channel,but if i remove the pc engine and use that by itself ,then the game comes on screen,but instead of the console auto switching to the av channel,it's still letting the sound from the tv channel come through ,but the games picture is all over ,like rolling diagonally as if it had to be fine tuned for a stable picture,some times the picture and sound will switch properly after a few seconds,but 99% of the time it won't,i have to manually switch to the av channel ,then turn on the console for a perfect picture

I've also disconnected the rgb lead,and connected the pc engine back to the IFU-30 interface unit,then inserted a composite and a L+R lead into the IFU-30,and this time when i switch everything on and turn to the av channel,i get a normal composite picture with sound (also when the pc engine is removed and used by itself).


Here's a list of the things i've tried;

1. Soldered to comp sync,then to comp video.

2. Fully checked all wiring from the engine expansion connector to the rgb amp going to the  din socket,and from expansion connector to the din socket.

3. Compared the expansion connector wiring  to the wiring from another pc engine(which doesn't have the internal rgb amp,it's in the scart plug)

4. Checked wiring from din plug to scart plug,and resistor value,soldered from pin 8-16 in the scart plug.

5. Removed resistor from pin 8-16 and just left 5v wire connected to scart pin 8, to check auto switching,switches to av channel as it normally should,but in composite ,as it should without rgb mode being activated.


6. Tested this pc engine with other IFU-30 interface's,without sucess,engine won't power on,but IFU-30's power led is on..

7. Tested other pc engine in this IFU-30,and everything works and powers up,auto switches etc etc.


8. Tested the pc engine by itself on a  samsung lcd tv,and it switches automatically ,sound and picture are working properly,albeit in poor lcd panel quality.

9. Tested on another crt tv,and this  also doesn't work properly.


10. Tested other console's on all tv's via rgb scart leads,and they switch and work perfectly.


11. And finally,sat and scratched my head for a good half a day,thinking that it's probably that dual L+R wiring that has botched the console up.!?  it is isn't it.

...........................................................................................

fraser



 

bigsanta

This is the pc engine trying to auto switch to the crt's av channel,while populous is inside.
(when i tried this again,the picture and sound went perfect after about 2 seconds.


This is without a game inserted,but trying to auto switch to the crt's av channel


This is without a game inserted,but i have manually switched to the crt's av channel before i switched on the console.


Same as above,but with a game inserted.


Same as above again.

bigsanta

I've also tried removing the  5 volt connection from scart pin 8,and just wired this directly to rgb mode pin 16 with the required resistor,which would prevent a tv from being able to use it's av auto switching.

But with my crt tv's ,the same thing/effect, happens as in picture 1 and 2,but on my samsung lcd panel,av auto switching is disabled,(as it should be)and i have no effects like  in pictures 1 and 2,just a normal tv channel broadcast programme that is,and then i manually switch to the av channel,i have a perfect rgb pc engine game picture.

I also checked a few of the other grounds on the consoles expansion connector,(compared to my other pc engine)and it seems 2 of them are no longer closed,open circuit.

duo_r

man, for some reason this thread is to long and over-explained for me to try and help you. Can you summarize what you think the issue is? So this is a SCART TV? Sounds like maybe the scart cable isn't hooked up properly. Have you double checked the SCART wiring? Have you seen MMonkeys website and how he hookedup his PC Engine scart cable???

Tiido Priim├Ągi

my old TV showed such image also when any RGB equipment was hooked up and running and TV was not on AV channel... my SCART cables lack the 12V signal needed to put the TV into the AV mode properly...
Mida sa loed ? Nagunii aru ei saa ;)

bigsanta

Well i found the solution to the problem,those negative/grounds that should have been linked together but weren't,were fixed by putting this back

I thought this was here just to stop interference,so i just never put the thing back on,and as my other white engine never had one,i thought this model probably doesn't really need it either,but i was wrong,and once i soldered it back on and checked those grounds again with my multi metre, proved that i did need it after all.




Drakon

Quote from: bigsanta on December 21, 2008, 10:33:18 AM
Well i found the solution to the problem,those negative/grounds that should have been linked together but weren't,were fixed by putting this back

I thought this was here just to stop interference,so i just never put the thing back on,and as my other white engine never had one,i thought this model probably doesn't really need it either,but i was wrong,and once i soldered it back on and checked those grounds again with my multi metre, proved that i did need it after all.

durrrrrrrrr

This's why it's always good to check your own work before you post the issue.  Because usually it's just something stupid that you did

NFG

QuoteI thought this was here just to stop interference,so i just never put the thing back on,and as my other white engine never had one,i thought this model probably doesn't really need it either,but i was wrong,and once i soldered it back on and checked those grounds again with my multi metre, proved that i did need it after all.

Interesting!  I wonder if that's why my SuperGrafx died on me.  I should have checked that before chucking it out.  Idiot.  =(