Core Grafx II just died on me

[scanline99]

Hello all! I should probably introduce myself first. My name is scanline, I'm 26 and from the UK and a big fan of shmups - hence why I finally got myself a PC-Engine this week !! I should add, I'm also a fledgling modder.

I've been chuffed to bits with the little guy, and the seller on eBay I'd bought it from had also done an RGB mod which I thought was a bonus. However, when I got the unit I noticed it wasn't amped (and also wouldn't sync on my Sony PVM) so I figured I'd take things into my own hands and put together an amp, as per the recommended schematic which I've seen all around the web - http://www.gamesx.com/grafx/pce_rgb.jpg

Anyways, after a good couple of hour's careful soldering last night, I got the amp put together and it all seemed to work well on my LCD downstairs, but, still no sync on the PVM, shame. On the sync line of the amp, I had substituted the 300 ohm resistor connecting to the 5v line for a 330 ohm as this was the closest I had available. I figured maybe this was the problem and tried experimenting with some other resistors (75, 100, 400) to no avail.

I also tried removing the resistor altogether and that's when the system gave up giving me anything at all - no video, no sound, from any pins in the SCART lead on the multimeter even... it's a shame there's no power LED, but I'm guessing it's stone dead at this point. I obviously noticed the fuse while I was working on the system and so did the logical thing and checked it - seems perfectly intact and the multi meter registers a voltage through it when the power's plugged in (unless I'm checking it incorrectly). So, I guess my question is - can anyone suggest where I should go from here? Have I completely borked the system from simply removing that resistor connecting the transistor to the 5v line in the amp? I have at this point completely desoldered the amp and additional wiring from the EXT port and so we're back to a no-frills vanilla machine which should also eliminate any shorting concerns and still no dice - or so it would seem, I don't have a standard AV lead, but I'm still not getting a reading from the EXT pins, so that would lead me to assume it's still on the fritz.

I have to point out again that I am new to troubleshooting electronics so, please go easy on me guys, I'm still wet behind the ears :oops:!

[Necromancer]

Welcome to the forum!  I'm too dumb to help ya, but I'm sure one of the knowledgeable peeps will pop in soon to give you some leads.

[turboswimbz]

Welcome Comrade.  Sorry to hear of your troubles.  However, The normal crew should be along to help you quite soon.  most pop in sometime in the afternnon here in the US.  They are some of the best around!   

[scanline99]

Thank you very kindly for the warm welcome, chaps .

Hopefully if we can get this baby fired up again, I'd really look forward to getting down to some deep, thoughtful discussion about pixellated things that go boom with you all .

[Arkhan]

The problem is, you live in the UK.     That broke it.    That also kinda sucks since the fixer-dudes of choice live in USA and the USPS hates us all and charges like 40$ to ship things to you.


Did you try hacking together some AV cables on the appropriate pins and sticking it on some sort of screen?   







How long ago did you get this thing?  File an ebay claim and say it arrived broken, lol.  SCAM THE SYSTEMMMMMMMMMMMMMM.

Don't do that.   

[turbokon]

Check the fuse for continuity. Your meter should have a continuity setting?

[scanline99]

Arkhan, I would blame my Britishness for alot of things, but on this occasion, it was just plain and simple universal clumsiness on my part!! I shall however look into some AV cables for safety - if any of you chaps know where I could find some for under a fiver, let me know. Got the machine on Monday, won it last week - the (evil) thought flashed through my mind, but I was a bit of a bastard to the seller and really argued him down on the price anyways. No doubt he's glad to see the back of me.

Turbokon, it's extremely embarrassing that I didn't just trust the continuity setting on my meter to begin with when it didn't beep. Tried it on another fuse just to make sure I was doing it right (but come on, how hard is that) and it worked, so yes, it would seem as though I blew the fuse. Sorry for the long winded post in the first instance! Can I just solder in a regular 1A fuse (like you'd get for a wall plug) or does it have to be one of these (fast blow?) glass ones? Probably a really ridiculous question, but I just want to be totally sure.

Once I get a new one in, I'll report back, then maybe see about grilling you lot on this whole amp business and where I'm going wrong on the sync + PVM front!!

Edit: Having done a bit of research, and checked what the pcb asks for, I'm guessing the fuse has to be 125v - and here we're 240v. Looks like the only 125v I can pick up easily in this country are the Pico II fuses, much like what are used in the SEGA CD. Would one of these work the same?

[Arkhan]

aw yeah.  blowing all the fuses.

at least you aren't blowing all the guys.

 That's my job.


I'm not sure on the fuses.  I would assume yes, but you should probably find out from thesteve or BlueBMW to be sure.

[wildfruit]

i say old chap grab yourself a PAL turbografx and come and live life in the slow lane. slow but steady and being a patron of the realm you must be used to 50hz eh what?

[Arkhan]

i say old chap grab yourself a PAL turbografx and come and live life on the short bus. slow but steady and being a patron of the realm you must be used to 50hz eh what?

It's like picking to watch Metallica live in 2012 instead of 1986

[wildfruit]

i say old chap grab yourself a PAL turbografx and come and live life on the short bus. slow but steady and being a patron of the realm you must be used to 50hz eh what?

It's like picking to watch Metallica live in 2012 instead of 1986

could we have some smooth jazz instead?

[Necromancer]

could we have some smooth jazz instead?

Vasteel? 

[Arkhan]

If you play it on a PALBob, it'll be more like Assteel.

[esteban]

could we have some smooth jazz instead?

Vasteel? 

WHEN I AM LOCKED IN PIVOTAL BATTLES THAT DEFINE THE VERY SUCCESS (OR FAILURE) OF MY OVERALL WAR CAMPAIGN, I listen to smooooth jazzzz in Vasteelz.

True story.

[scanline99]

Just to update you guys, I popped in a cheeky pico 1A fuse and all seems to be well - we have life in the system again!

Still no sync on my old school PVM or 1084s though (but syncs fine on my LCD). Will start a new thread to see if we can route this out.