Need help with turbo grafx 16 external rgb amp

[RgbGamer]

hi, newbe here to the forum but i have been around rgb goodness and modding for some time now. i have some electrics knowledge but at a lower level. i have just about every game system from 8 bit to recent consoles with the best video they can provide with the exception of the 3do putting out rgb. i am most proud of a nes super 8 rgb system i built. then adding rgb and amp to n64 with great results was also rewarding.

anyway, back to the subject of the external rgb amp for a tg16 with cd that i threw together. i already put a socket on my tg16 and custom made scart cable to run the rgb. what i did not do was add an amp on the inside in the earliest stages. later i ordered an rgb kit to build and using wiki site for schematics i built the amp and did not have much luck with it as it would not show any video. i gave up in fear of that i might fry the tg16 as i had some close calls trying to figure things out.

later i ordered nec rgb amp board from ebay otakus store. i decided i wanted to go external with the amp because i don't want to go inside the console anymore and plus i never needed or wanted to desolder the shielding. i used a cell phone power adapter to power the amp and im not sure if thats a good thing since most mods are internal running from console power regulators. i have had an external sync separator circuit i built running from a power adapter and seems to work fine for years. i have the ground of my tg16, rgb display ground, rgb amp ground and cell power adapter neg ground all tied together but im not sure if all should be together.

i ended up getting the amp running and it looks fantastic but some issues have come up. for one the chip on the amp board got hot to touch so i turned off and i haven't turned it on since. the board and no name chip don't seem to bring much on google so no luck there. after realizing something might fry without some sort of heat sink and emailing seller for some help with no reply (might be a language barrier with the seller or something being uk and me usa) i gave up. i am not sure its normal for the chip to get too warm to be able to keep my finger on the chip. if this heat is normal i will add a heat sink and hope to play with my image brighter. the rgb is ok without the amp but composite really looks brighter. having the amp running shows a rgb image that brightened more than the composite signal with the display adjusment and im hoping the amp isn't too strong.

when i turn off the tg16 and the amp is still getting 5 volts 300ma from the power adapter the rgb display shows distorted lines going down the screen of my 1084s and jvc. im wandering if this would be normal to see or perhaps worse may damage my display with some sort of offensive voltage or something. i could power the tg16 and amp with a power strip to avoid seeing the lines but i am still worried about offensive voltage.

i have four 15hz rgb displays i have to test things and use for gaming. the least cared about is a hospital medical LCD but has defective watchable screen and i am still working out the odd power socket and adapter that seems to work with some effort. the second is a commodore 1084s with quite a bit of hours but still nice. third is 13" crt jvc set up for gaming. fourth is a nice 26" crt viewsonic presentation monitor set up as the best display as its one that costs thousands in the 90s. my trusted game systems are played on the 26" and the tg16 will not until i work out these issues.

so to sum up the questions

1 is it normal for these chips to get warm?
2 is a cell phone power adapter safe or reliable to use?
3 should power adapter neg ground be the only thing hooked to rgb amp ground and not tied together with all other grounds? i could just try it but i am here typing instead and i fear having the amp on may be seconds away from something going bad.
4 could my displays be at risk of damage or are they robust handling things like this?

any help will be just fantastic. i feel the amp will just sit and the nec will not be played much since i hate composite.
thanks 

[RgbGamer]

ok, i figured it out and got it working with some possible useful info for other rgb modders going external. i have two external devices now for my rgb setup using power adapters. one is a sync seperator (very useful) and the other is the rgb amp for tg16. if your not into removing tg16 shielding and fear of frying the inner parts the external amp worked like a charm for for me. image now looks fantastic and not too bright looking anymore. there is very slight verticle bars but doesn't bug me a all. there is a way to help get rid of the bars in the install guide but that would mean going back into the console.

i emailed the otakus store again and the seller contacted me saying to check power with a meter on pos and neg. i tested the power supply and indeed the adapter rated 5 volts 300ma was putting out 6.1 volts and making the chip warm. i should always trust a meter and not the writing on the power supply. anyway, i found another 5 volt 500ma cell phone wall power supply and reads actual 5.0 volts. so maybe there is more volts on some cell phone power supplies for charging purposes and labeled differently only to confuse people like me. i am hoping the 500ma rating isn't an issue and not too high in milliamps. if so,  someone please let me know. so the amp works perfect now and not getting warm. i am glad i checked for chip heat instead of just running the amp and could have possibly fried the chip. i made the amp external meaning i have the rgb lines coming out of the console with no extra circuitry. i have rgb, composite(for sync)and ground going to a custom socket out of the tg16. i then made a male scart cable to go to the amp (in a small project box) and then to the monitor. on the amp project box i wired up a female scart for the rgb line in. vga cord for out as i have multiple ways to the monitor. composite video and stereo sound is already available out of the cd add on unit so i just use extra cables for the audio. this will be my final rgb mod as i have done multiple consoles and finally done.
hope this typing may come in useful for other rgb folks, but remember its all your own risk as i have learned.

[ApolloBoy]

Wait, if you went through the trouble of installing a custom connector for RGB, then why did you make the amp external? Makes no sense to do it that way.

[RgbGamer]

well, the custom socket and custom scart cable was part of the first work i did years ago. i only added rgb with strait wires to the socket inside the console back then and until recently i did the amp work in this order.

a month ago or so i built a rgb amp circuit. i opened up the system and cut the existing rgb wires in the middle so i could then just twist the existing wires back the way they originally hooked up if i had trouble with the amp and be able to see if rgb still worked. i then added rgb wires to the location of the amp and then added 5 volt and ground wires to the amp . i managed to add the extra wires without removing the shielding as i just fished it through. there was just enough space to put the amp board close to the game card slot. i then soldered all connections and tested continuity for most connections. when i tried the amp i got nothing. i then wiggled some things to see if it would work but still nothing. wiggling things made my solder connections weaker and some wires would break and i would solder again. one of the wires that came loose was the 5 volt while power was turned on and came close to touching some wrong parts of the motherboard. one should always power off before moving things but i was getting desperate and tension was building. i ended up putting it back the way it was with rgb and no amp and it worked as it was so i closed up the system, feeling glad nothing was fried.

later i got the otakus amp board and made it external with fantastic results. working with a power adapter and rgb outside of the console was way better than inside because i didn't have to double check things so much.

my other project rgb nes super8 console was actually not bad as far as ease. there was an already assembled board and i added some connections, installed the chips and made a cable. i turned on the nes and it just worked. making the shell was more of a pain but i at least knew the nes worked. if i had went the route of buying a top loader to do rgb mod it would have been maybe a bit too much for me. buying that expensive rgb chip and hoping for the best was not much of an option for me. didn't want to fry that chip, would have gave me nightmares. i also saved a couple hundred bucks as those rgb nes are going for 5 to 6 hundred these days. it ended up costing around three hundred for me to build. i am not doing a rgb mod on a 3DO console because it looks like a serious project. that is one rgb system i would just buy already modded and would be the only one i haven't done myself. i am glad all my consoles are finally done with the rgb. i will eventually get back into console repair as i still have broken stuff but that is another day.