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NEC TG-16/TE/TurboDuo => TG/PCE Repair/Mod Discussion => Topic started by: Duo_R on March 29, 2016, 07:41:16 PM

Title: Supergrafx won't boot up
Post by: Duo_R on March 29, 2016, 07:41:16 PM

Update - FIXED

Was a bad trace (corroded) coming off pin 79 of a HU6270 (the chip closest to power switch). Just jumpered and all good now.


(http://uploads.tapatalk-cdn.com/20160401/155bdd6aee8e4978b9390c2ff4a16041.jpg)

Quote from: Duo_R link=topic=20751

Ok I recently posted how i obtained a Supergrafx unit. I bought it knowing it was a repair unit but I was hoping just a bad fuse. Doesn't seem to be the case. The fuse is fine, I just tested the voltage regulator and it's getting 9.5v in and outputting 4.99 on the out pin.

I replaced the 470uf cap that looked like it was going bad, cleaned up the board and everything visually looks ok no cracks. The shielding on the bottom did have blobs of solder that disconnected and I resoldered those. When I power on I get white screen then it goes all black. So appears to boot but nothing happens. Any tips on common issues? I'm a sucker for repair systems. ;-)

Title: Re: Supergrafx won't boot up
Post by: Duo_R on March 29, 2016, 09:55:45 PM

Additional info, just measure pin 40 on both HU6270 chips, getting 4.99v on both.


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Title: Re: Supergrafx won't boot up
Post by: mickcris on March 30, 2016, 02:43:31 AM

i would check closer for cracks.  look at the pics i linked to and check those areas carefully.  it took me a few tries before i found all the places on the board that had broken traces.  they can be hard to see unless you use a eye loop or some kind of magnifier.

http://www.pcenginefx.com/forums/index.php?topic=16172.msg399144#msg399144

some cracking on mine was under the hucard slot and also under the ground shield.

Title: Re: Supergrafx won't boot up
Post by: BlueBMW on March 30, 2016, 03:51:36 AM

Supergrafx are crazy prone to cracking in the middle of the board near the plastic post that supports it.  I've seen this several times now.  Repair all the broken traces from the crack and remove the post :)

Title: Re: Supergrafx won't boot up
Post by: Duo_R on March 30, 2016, 04:47:28 AM

Dang I don't see any cracks. I really don't want to remove the hucard slot if necessary but maybe I need to.


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Title: Re: Supergrafx won't boot up
Post by: Duo_R on March 30, 2016, 11:54:46 AM

Hucard slot removed, use magnifying glass and tested a bunch of traces. All seem ok.

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Title: Re: Supergrafx won't boot up
Post by: Duo_R on March 30, 2016, 04:11:10 PM

Ok so Steve was helping me troubleshoot this one. He noticed a corroded trace near the heat sink. I totally didn't see but he saw it in a photo I took. And we have a working Supergrafx! At least it's playing a PCE game! Now to test the Supergrafx mode!!!! Yeah!!!!!!!


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Title: Re: Supergrafx won't boot up
Post by: Duo_R on March 30, 2016, 04:12:02 PM

I just had to send one jumper, no cracked PCB but just a corroded trace going to Hu6270! I almost swapped in another ram chip but looks like the one I got is good!


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Title: Re: Supergrafx won't boot up
Post by: Duo_R on March 30, 2016, 04:12:20 PM

TheSteve - you rock man thanks for spot checking!


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Title: Re: Supergrafx won't boot up
Post by: BlueBMW on March 30, 2016, 04:31:14 PM

If you still have it open you may want to cut out that center mount post since one good drop of the console can crack the pcb from that thing.

Congrats on the fix though!

Title: Re: Supergrafx won't boot up
Post by: Duo_R on March 30, 2016, 04:32:56 PM

Ok so it is fine without the post?


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Title: Re: Supergrafx won't boot up
Post by: BlueBMW on March 30, 2016, 04:34:46 PM

i mean you can leave it if you want, we've just seen a lot of cracked boards right in the middle and it seems to stem from an outside impact pushing that mount post against the board and cracking it.

Title: Re: Supergrafx won't boot up
Post by: Duo_R on March 30, 2016, 04:48:45 PM

Ok just want to make sure it's stable without. Thanks man!


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Title: Re: Supergrafx won't boot up
Post by: mickcris on March 30, 2016, 04:51:02 PM

It is. Really serves no purpose. I have cut it off on mine. Thesteve recommended doing it.

Title: Re: Supergrafx won't boot up
Post by: Duo_R on March 30, 2016, 06:42:52 PM

The post near the green switch?


(http://uploads.tapatalk-cdn.com/20160331/6badb1c9883e2dc44cd623fa451aec88.jpg)


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Title: Re: Supergrafx won't boot up
Post by: mickcris on March 30, 2016, 11:14:40 PM

No. It's the one on the other side of the slot. It does not have a screw hole in it.

Title: Re: Supergrafx won't boot up
Post by: thesteve on April 01, 2016, 05:26:02 AM

bottom cover
sits between the slot screws

Title: Re: Supergrafx won't boot up
Post by: mickcris on April 01, 2016, 05:47:21 AM

I guess i cut the wrong one off.  Cutting that other one though did not make any difference in the stability of the board in the shell.

Title: Re: Supergrafx won't boot up
Post by: Duo_R on April 01, 2016, 05:54:01 AM

Ok so this guy?

(http://uploads.tapatalk-cdn.com/20160401/bbe815b86fbb302cb590cbf3e315d5d3.jpg)


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Title: Re: Supergrafx won't boot up
Post by: Necromancer on April 01, 2016, 06:03:02 AM

Remove the pencil before reassembly.  :P

Title: Supergrafx won't boot up
Post by: Duo_R on April 01, 2016, 06:04:10 AM

Why? It's a rare gold one!!!

Quote from: Necromancer on April 01, 2016, 06:03:02 AM

Remove the pencil before reassembly.  :P

Quote from: Duo_R on April 01, 2016, 05:54:01 AM

Ok so this guy?

(http://uploads.tapatalk-cdn.com/20160401/bbe815b86fbb302cb590cbf3e315d5d3.jpg)


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Title: Re: Supergrafx won't boot up
Post by: thesteve on April 01, 2016, 09:25:46 AM

yes that guy
the slot is screwed to the top cover so when the system compresses that post pushes up and the slot pushes down causing the board to snap