PCE help diagnose video problem

[thesteve]

several pins look like they could be shorted
take a meter and check for adjacent pin shorts
or flux the pins and touch them with hot iron
the flux causes the solder surface tension to increase beading up clearing most shorts

[thesteve]

49 to 50
37 to 38
54 to 55
see the lines between the pins, they look like solder splash to me, but may or may not be causing a short

[Chrom_]

I'll check again very carefully for any shorts in the weekend. Thanks a lot for the tip. I'll keep you all posted

[Chrom_]

Though I must add that trying different hucards, I always have the same problem: bad palette on sprites and disappearing sprites (meaning possibly that the sprites are there but covered in trasnparent colour, so again a palette problem).

According to the following documentation (http://www.emulatronia.com/doctec/consolas/pce/vdcdox.txt), it is the HuC6260, not the HuC6270 that supplies the colour palette to the Video System. Excluding a problem with the RAM (that would result in far worst effects and also a variety of glitches depending on the loaded game), and despite the fact that the HuC6270 runs hotter than the others, at this point I'm suspecting the HuC6260.

It's also true that HuC6270 does Background character processing and Sprite processing, so it is indeed possible that something is wrong with it...

Any wrong assumptions in what I wrote above? Other ideas?

[thesteve]

Only thing is the tile/sprite info is supplied to the 6260 from the 6270
I have seen palette and scale issues on the 6260 but such failures have been rare

Sent from my VS920 4G using Tapatalk

[pnauts]

picture you provided is too bad quality to see if there some shorts.

[Chrom_]

No shorts detected on 6270. To be honest the chips look in perfect cosmetic conditions, and no bad soldering is evident at all. Would it just be a fried 6270? Does it fail like that?

[thesteve]

it does fail like that
it also fails white screen
it could still be another chip as the issue is missing/corrupted data but the 6270 is a good bet
have seen 6260 fail that way only once, 6280 failures tend to be more severe

[Chrom_]

Any known option to buy a replacement 6270?

[thesteve]

just in pce/tg16 systems

[thesteve]

just fixed a duo with palette/grafix issues
was solder bridges on the 6270

[Chrom_]

I need to source some flux then I'll surely try refluxing the chips. The problem is that in my case the contacts look perfect to the eye and no short was found with the multimeter. Was the short evident in your case?

[thesteve]

had 2 shorts
the first was causing grafix corruption (i saw it)
after fixing that one the colors were wrong
reflowed the 6270 and it fixed the colors

[Chrom_]

In the next few days I'll try reflowing anyway, just in case. I'll keep you posted. Thanks!

[Chrom_]

today I have refluxed all chips, including RAM and the one on the Hucard doughterboard but the problem is still there. At this point I'm almost sure 6270 is failing

With all those custom chips it's almost impossible to cheap repair the Pc Engine...