Robosapein V2 Bot PCB repair wanted

[Crashpro2003]

Anyone know of a good circuit board repair company that can fix a board without a schematic or board view?

[stj]

thats vague, what is it?
got any pictures?
fault description?


most things are repaired without a schematic.

[eccerr0r]

Have to assume it's the robot. but if it's visibly damaged it usually can be done without schematic. If it's not visibly damaged and there's no obvious signs (shorts, etc.) then it gets mighty hard without a schematic and repair costs increases rapidly due to debug time...of which a reverse engineered schematic may be needed/generated, which may end up above the cost of a new unit...

[Crashpro2003]

It's a circuit board out of a discontinued vintage Robosapein V2 Bot I'm Trying to repair. Board seems to be dead due to cheap wire insulation. It flakes and falls off, then shorts something out in all units. Bot is not working after being rewired. And I can not find the schematic or board views for it anywhere online. There appears to be a burn mark on the board which is circled in the attached photo. Although it could also be a blue company test check mark covered in flux, placed after manufacturer tested it. Not sure. Looking for someone to check over the board and fix it if needed.

pic2.jpg

pic1.jpg

Originally Posted by stj

thats vague, what is it?
got any pictures?
fault description?


most things are repaired without a schematic.

[stj]

the mark is marker pen under the glue.
the glue is the cause/problem, it becomes conductive when it gets old.
this is a well known curse in psu's and audio gear.
you need to get the glue off by lifting it with a small flat screwdriver or similar

[Crashpro2003]

Wow No shit? There is a lot it on the board. I know this sounds like dumb question. But does that mean that every component that it is in contact with is potentially shorted out? I thought it was just dried liquid flux. Thanks for the information.

[stj]

it's not going to be dead-short,
but it will have a resistance that drops as it darkens and ages - when it's really bad the glue turns almost black and very hard.
it can also be corrosive to the component legs

[Crashpro2003]

The glue on the board has the characteristics of rubber or contact cement. It stretches a lot before it begins to peel off. Don't want to scratch at it too hard so as to not damage any traces on it. I have found out that Mineral Spirits will help remove rubber cement. Will using it, sparingly, damage the coatings or other parts on the board?
Thanks

BTW You have been the greatest help to me so far.

[stj]

i dont think meth-spirit will damage anything, but i know acetone will.
test the spirit to see if it damages the connectors though.

[Crashpro2003]

Hi
I dabbed on Isopropyl alcohol (didn't soak board in it) to soften the glue and carefully picked all of it off. Bot still not working. Attention now is on the Main board marked with EW and numbered (6028-1G). Good call BTW. The mark on the board was made with a marker, not a burn mark. Shouldn't there be a copy of the schematic and board views for these boards out there somewhere?
Thanks again for all your help

[stj]

boardview is just a mac thing,
schematics are down to the maker to share or not.
that board you cleaned doesnt really need one,
it's clearly just a repeating pattern of transister switch circuits presumably to let the logic signals drive the motors.
if it failed it would only effect one motor

[diif]

Boardviews are most commonly known for Apple devices but it's not an exclusive thing, I have some from Dell. HP, IBM, Toshiba and some for graphics cards.

[petehall347]

probe the glue with your dmm and see if it really is conductive ..this is how i found it myself before i found it myself and reported it on the internet . sansui were bad for it .

[Crashpro2003]

Originally Posted by stj

i dont think meth-spirit will damage anything, but i know acetone will.
test the spirit to see if it damages the connectors though.

Think I may have found the issue of "no power." White smoke or heat mark on back of Main Board. Behind what might be a fuse or thermal cut off or coil for chip but unsure. It's labeled DY 4.000 See attachments. Tested across poles and it is open, no continuity. Also don't know what DY stands for or where to get a replacement. Any help will be appreciated again. Can you private message me with your thoughts on this? Being a Newb I have a tough time navigating this forum. Thanks again

[CapLeaker]

That is a 4 MHz crystal. That could be a failure point, but I think the problem is elsewhere, because you need to get power first.

[Per Hansson]

Check the area marked in a blue rectangle, is that trace broken or is it just an optical illusion?

[stj]

nice find.
it actually looks both burned AND on a through-hole to me.

[lotas]

No, these are the remains of rosin when this module was soldered manually.

[sam_sam_sam]

Look closely at all the soldering joints for ghosting rings around the the bottom of the joints or a lot of flux or corrosion on the soldering joints or cracked soldering joints ( I see some soldering joints that look very ? able
I would look at under a magnifying glass for what I have above )

After that then start looking up part numbers and see what they are and checking them for functionality

Both of them are very time consuming projects

I once fixed a battery operated magnet plate for steal plate crane lifting device that the hole board had corrected soldering joints I had resolder the entire board and did manage to get the device to work correctly again but it took several days to do this

The small red board on the main part of circuit board looks like it is some type of micro controller which could be damaged by the shorting of wires hopefully not

Please post a picture of power supply board as well because the issue might be on this board as well

[Per Hansson]

Originally Posted by lotas

No, these are the remains of rosin when this module was soldered manually.

You need to look in the blue rectangle I put, not the red circle drawn by Crashpro2003.