Got A BBB Problem: Boots W/ Black Bars

[K55]

Image is worth a thousand words here:

Got this se/30 recapped from uniserver (thanks btw, great work ) and everythings been fine and dandy until last night.

I left the system on overnight to unpack system 7.5 and I came back this morning to what you see above, boots fine, but displays the black bars above.

I thought it might be UE8 -> UC6/7 becusae of the video lines, so I checked the connections, didn't see anything, but soldered patch wires to make 100% sure that wasnt it and.....it didnt work . Any ideas on what could be wrong?

 

[techknight]

UE8 bad or trace broken. 

 

[K55]

Well I patched all the traces so the chip is most likely bad. I wish I knew someone in NJ that did smd work, but all anyone does these days is phones :-/ .

Does Uniserver do small smd jobs like this?

 

[takimoto]

Hi K55.

I think you can make narrow the situation by using voltage meter.Video data lines between UC6/7 -> UE8 were 2.05v or 2.36v when my SE/30 is showing ? icon.If there is line sticking 0v or 5v,video memory is dead,or trace is dead or touches another line.make sure have a look both UC6/7 side and UE8 side,If trace is broken,there will be difference(sounds like not this case,you patched lines...)

If all lines show you good voltage,I think UE8 is dead. 

Cheers!

 

[K55]

Just reporting in before I sleep, checked the line voltages, all of them were 2.39V except for 2 lines that were at 1.86V which makes sense because the minimum TTL input level is 2 V so the 2 inputs on the UC6/7 chips are never going high. It seems like UE8 is borked.

Thanks for the tip!

 

[K55]

Specifically the problem is with the lines that go to UC6, VID4 (2) and VID6 (5) are lower than on UC7 as are lines D(28) and D(31), Do the D lines have anything to do with the video signal?

 

[takimoto]

Data lines bring video data only when video ram is selected,otherwise bring instruction and data and everything.so we can't tell something comparing them.I thought Data lines to video rams are good because if there is problem,whole system won't be working.but is there possibility there is cut just before video ram?

 

[uniserver]

hey there how long before it started doing this, just curious?

UE8 is a common fail point with the SE/30, but usually it proves it self to be bad with in the 2 hour burn in.

I charge 25 to replace the UE8 if you want to send it over i can swap that out.

If it would have went bad on me here i would have swapped it out here and saved you the hassle...

Oh well Murphy's law… 

 

[uniserver]

or just replace it with this:

http://www.mouser.com/Search/ProductDetail.aspx?R=SN74HC166DRG4virtualkey59500000virtualkey595-SN74HC166DRG4

if you want to invest in a hot air station they are pretty reasonable these days!

http://www.ebay.com/itm/858D-110V-Hot-Air-Rework-Station-LED-Solder-Desoldering-Tool-w-110V-Stand-USA-/301828051023?hash=item46465a904f:g:yjYAAOSwk1JWchd9

 

[K55]

Morning all!

Quick post before going back to work.

hey there how long before it started doing this, just curious?

UE8 is a common fail point with the SE/30, but usually it proves it self to be bad with in the 2 hour burn in.

I charge 25 to replace the UE8 if you want to send it over i can swap that out.

If it would have went bad on me here i would have swapped it out here and saved you the hassle...

Oh well Murphy's law… 

Yeah Uniserver I was thinking about getting a hot air setup for future smd work, at some point the cost of repair/shipping everything to you will balance out with doing some of the repair work myself .

In terms of run time before it failed? Maybe 30 hours tops. I'll poke around a bit more tonight but I'll probably ship it to you for repairs.

Data lines bring video data only when video ram is selected,otherwise bring instruction and data and everything.so we can't tell something comparing them.I thought Data lines to video rams are good because if there is problem,whole system won't be working.but is there possibility there is cut just before video ram?

Nah all the traces are fine, its probably because the 2 video lines from UE8 are bad its causing some weird stuff on the D bus, the system works fine otherwise.

 

[takimoto]

OK!

Hope you get this SE/30 fine!

 

[K55]

Fixed :^)

Replaced the shift register and we're back in business. Probably will get a hot air gun for the next time.

Used some gallium solder but it doesn't work so good on older solder joints like these.

 

[Elfen]

Wash the board with some ammonia & distilled water and then chase it down with alcohol to get rid of any remaining cap goo. Dry with compressed air or a hair dryer.

 

[K55]

Don't worry Elfen, Uniserver did that already (pretty sure he gives every mobo a bath with his re-caps ).

Pic isn't cap goo but excess flux I cleaned up after that picture.

 

[uniserver]

it looks like before you replaced the ue8 you ran some lines to the vram first.

cool man.  hey it works.. so that is good!

 

[K55]

Trust me it was easier to rework the shift register than it was to solder the lines to the vram