White PCE only giving a screen.

[mmmonkey]

Hi folks, I thought I'd pop on here to seek some help to rescue a poor PCE.

I offered to try and do a freebie fix a PCE for another chap who said he's getting nothing from it, and so far I'm not getting far either.  I opened it up to check the fuse and found it's blown but has also been bypassed 

I removed the bridge and the fuse, to make life easier I removed the voltage regulator and the heatsink.  So, I didn't have a 1.5a fuse to pop in there but figured I'd get away with a 1.5a to use as testing and fit the proper one if I get it working.  Whilst I had the voltage regulator off, I thought I may as well pop a known good one in there.  I checked for short circuits on the input and output of the voltage regulator and it was good.

I measured some voltages and all seemed good before and after the fuse and going in and out of the voltage regulator, so I risked it and powered it on with no card in it and received a white screen, TV shows it's receiving a signal though and this is what my working PCE does with also.  I pop a known good game in it and I still only get a white screen.  Googling shows that it could be dirty contacts for the hucard slot.

I cleaned the card slot (it was filthy), I also inserted the card and pull it back a bit to try that, still white screen.  I noticed if I pull the card out ever so slightly I can check connectivity between the contacts on the card and the pins coming out of the back of the card slot, they all tested fine.

I also reflowed the solder on the connections for the flat ribbon cables for the hucard daughter board.  I checked connectivity for the ribbon cables and they were good, still get a white screen though.

I don't have a logic probe, so am a bit limited on what I can test.  I did read that some people have to replace H6270, so I reflowed the solder on it, then thought I may as well reflow the solder on the other chips in there at the same time.

It looks like an RGB mod had been attempted at some point to this cute little guy, the solder points for the pins on the Exp port for RGB look a bit worse for wear, I reflowed the solder on them.  The RF unit had also been removed at some point I think.

There was some thick black gunk over some of the traces on the underside of the board near the RF unit, I cleaned it off hoping to see some badly repaired traces there, but nope, they are good.

I replace the Cap that's on the hucard board (I found one the right spec and figured it may help with the problem being hucard related), I visually inspect the other caps and can't see anything wrong.  I don't know how to test caps though and I don't have spares to replace all of them.

I could take the H6270 off and check for dodgy traces under it, and the other chips.  I guess I could swap them out with ones from my PCE to check each of them.

Can anyone offer any advice?  This guys already done a cracking job on de-yellowing it, it would be ace to get it up and running again!

Thanks
Pete

[Keith Courage]

How are the connections for the Ribbon cable that goes in between the card slot and the motherboard? The connections can break where they solder to the board very easily especially if the card slot has been moved around quite a bit from someone installing mods. If the wired connections for the ribbon cable are fine and the card slot pins themselves are fine then most likely a failed HU6280 chip.

[mmmonkey]

Cheers for the reply.  Yep, they are all good.  Sounds like I'll swap chips over one at a time to see if it comes to life.  I'm guessing the only source of the chips are other PCE based consoles, I see that gamedoctor.hk used to sell salvaged ones.

[Keith Courage]

Yeah, they can only be sourced from other consoles unfortunately.

[Ergot_Cholera]

This is the mmmonkey whose guides got me to attempt console modifications many years ago now?

[mmmonkey]

Cool, thanks for the info Keith.

Yep @Ergot_Cholera - would be the same mmmonkey.  Glad you found the site useful :-)

[soop]

Holy shit!  MMMonkey, you got me into modding too!  I was on your site the other day!  I'm sorry I can't think of anything to help you out here, but thanks for the well written guides, you've helped a lot of people out

[mmmonkey]

It's always nice to know I've helped someone 

I've done a trade for the PC Engine, so I own the duff one now. I will return to it another time to it - going to enjoy playing some games again for a while!

[NightWolve]

Ah, you're the same mmmonkey of those PCE mod/info guides, I see. I wouldn't have made the connection unless somebody pointed it out, long enough time passed by after finding your site.

https://mmmonkey.co.uk/pc-engine-rgb-mod/
wayback.mmmonkey.co.uk/pc-engine-rgb-mod

I used your nice HuC6260 photo in my YPbPr/Component guide as a base. It was a good idea to color the RGB and Sync pins appropriately (including using yellow for H/V Sync).



Good to know you visit here.

[thesteve]

before you get too far try Rock On
the game music doesnt wait for the video chips to start so often if the RAM and 6280 work, you will get sound
without a probe or scope it gets a bit tougher from there
full stop system check the CE pins on the 6280 to see what chip is currently active
there are 3 CER for the ram chip CE7 for the 6270 and CEK for the 6260
the 6270 also has a RDY pin which tells the 6280 to wait if low (often with a bad 6260 6270 or connection to 6270 this pin stays low)
also seen several 6280 with dead CE pins that simply dont ever go low (mostly CER)