PC engine gt ,, only screen lights up

hello,

I bought a pc engine gt from a seller , I was fooled for the second time by this cheater, he gives fake description like last time, claiming its an as-is , however he sells all attempted to repair and failed consoles.

anyway thats not the matter, i seek help, i found that battery springs are broken so i used a 6v dc power supply for testing and all what i get is screen lights up, but no response at all, brightness doesn't work, games don't, its recapped already, battery cable was cut internally, I paid a fortune for it , so I just hope its not totally dead

attached are 2 photos of the motherboard, where do I start

note: I have a good to very good electronics skills.

thanks

 

i posted 2 additional photos as it seems the fool who worked on it did alot of crap works


is this repairable?

 

this is a tough repair without knowing more about the history of the PCB. the seller obviously did some work on IC 702 as well as the high-voltage section. the last one of these that I repaired had a similar issue, and I posted videos on YouTube about it. mine was a short on one of the pins to the main processor but I can't see anything obviously wrong with yours.

something like this would take a lot of patience and testing, and most likely you'd have to find a donor PC engine to pull parts from. fortunately a lot of the parts are shared between the systems and don't have custom ICs that are different.

the screen lighting up is a really good sign though, cuz that means you're high voltage section is probably okay. the real question now is if your LCD driver board is bad or if it's "just" one of the main NEC chips.

thanks for uploading nice pictures, people almost never do that when they ask for repair advice here. It helps a lot.

 

Connectors CN201 and CN700 look corroded.
IC702 got butchers with a cold soldering iron, check for cold solder joints. and damage.
USE FLUX !

Clean with I.P.A.
https://en.wikipedia.org/wiki/Isopropyl_alcohol

What did he do with the component between the grey goop ?
Reflow !

Optional !
Try to remove rest of the grey goop.
VERY GENTLY, bit by bit !!
Soak it in I.P.A.?
It could get a bit easier to remove ?

Acetone, very gently on top ? (clean with I.P.A. afterwards)
Just a few drops ?
ASK AROUND !

He also butchered that part with a soldering iron.

No further liquid damage ?

Good luck !

p.s.
could this help ?
https://console5.com/techwiki/index.php?title=TurboGrafx_16#Schematics
Source:
https://www.electro-tech-online.com/threads/need-schematic-for-turboexpress.145370/

 

ah yes, good eye. Those look pretty bad. definitely need a cleaning.

 

thanks alot for your reply, as you know in pe gt/express getting a doner is as as difficult as finding another console.. I will see what can be done about it.

also about the high voltage circuit it rarely fails, even in the worst conditions ever atari lynx and game gears usually you get the screen light to work... but I hope its a better case over here.

Thanks alot for the useful reply, I will go through it step by step when I get back home ..

obviously he did butchered some old parts..

the holes (I think) are for the metal shield which wasn't there even...

I will see what can be done , I also found a pic of pc engine gt motherboard with caps values, checked all replaced values, they are correct..

 

Check for trace damage near the high voltage section, I had one where cap leakage migrated to the other side and damaged Q501. I hate dealing with botched turboexpress/PCEGT units

 

i hate that even more, can't stop imagining that the previous owner might have spent forever trying to fix it, or even ruined it, I won't spend the rest of my life on it, but I will see what can be done, thanks for your reply

 

I still have 2 dead units on my repair table both turned on but would not load games. This is the only system that seems to just drop dead during a cap kit, but it’s a problem that must be done even if the unit still works. I’ve switched to using ceramic caps for these just to make it easier to test continuity when inevitably I have to patch some random trace or solder joint that fuzzed over. The 2 large caps in the hv and the matching one in the sound circuit are the worst, they leak enough to spill on stuff nearly 1/2 inch away, C901 lot of times causes massive damage too. This is the worst system to do a recap that I have had to do.

 

so those survive? I mean dead units?

 

1 became an organ donor and one is still intact but still dead.

 

lol , thats a no for me

 

A suggestion for the future, if it seems at all too good to be true on a rare console then it is. I've been burned almost every time buying something valued over $80 as a console by crap like your story where it's failed modifications/repairs/been worked on by idiots or the seller prior and then they try to dump it on you. Just stay far away from this stuff.

Hope you can get your money back at least, have no repair information to offer.

The days of finding turbografx/pc engine stuff that doesn't need more than new capacitors etc are well over and I'm sure hundreds have been destroyed by amateurs trying to make a quick flip with them, high danger zone.

 

absolutely right and I totally agree, it wasn't that I am trying my luck, but it was that I had a bigger trust in Ebay regulations than I should, the person claimed that it wont power on by batteries, as a person who is into electronics and assuming worst case scenario it would be repairable, but his wrong information (regardless either it was deliberate or not) miss lead me, giving me a console which battery housing springs are missing to start with so no way he could have tested it with batteries, and it lights up the screen with no response which I would never buy for 5 bucks given my experience with Atari lynx,

Its about how true what he says, and i bought many items as is ended up very well regardless to their original value, simply because sellers where honest and said each and every mini detail allowing me to decide freely.

he is offering a partial refund which is way below acceptance range, I will give the console one last look , if it works I will just forgive him and just avoid him in future, if not then I will continue my struggle with him, mainly that I have already bought all mods parts ..
was hoping he was honest

 

eBay's For Parts/Not Working condition is non-refundable/returnable unless it wasn't as described in the sense that something was missing from the package and even then it's an uphill battle. I've won a couple cases in the past where it was something extreme like empty shells; not even worth trying as the success rate is so low. Just like anything, buying something stated AS-IS is truly AS-IS. At this point he is likely just trying to bribe you to make you go away and not leave negative feedback and the offer he sent is probably just a bit less than what he paid for it "untested" originally and got burned on then passed it off to you.

 

most likely its as you said .. thanks for all the info, I wont give up because it was not cheap in price At All

 

Best of luck, try calling eBay.

 

thnx , I will

 

well ... a Huge Update

I tried to redo the stupid soldering on main IC 702 ,
which looks much cleaner now, and noooow Iam getting sound

I cleaned the connector, its clean now, with sand paper and alcohol,

now iam getting sound, no screen , no brightness level

i tried all stupid things possible, including removing the screen ribbon when its working, re putting it too, none worked , is it just a bad screen?