hardware guys. help with this one?

[Bikerbob]

http://atariage.com/forums/topic/253985-fitting-pico-psu-in-stfm/?do=findComment&comment=3537075

 

I bought this pico psu, and it had this on it.. not getting any responses in the ST forum.. maybe everyone on vacation.. or simply not as hardware techy as the 8-bit guys

 

 

James

[eeun]

I've seen this on other circuit boards, mainly from China. From what I've read it's a leftover from the "no clean" flux used when populating the board.

[Rybags]

I wouldn't worry about it. I fixed 2 of my ~ 10 YO LCD monitors (cap replacements) and they had that sort of goop on some of the caps and elsewhere.

 

Supposedly it's multi purpose - can be fixing material to hold things in place or keep them seperated, it can also be used on solder joints to help prevent fatigue due to vibration.

[Bikerbob]

OK, so my point is.. this pico psu does not work.. it passes 12v through.. but does not produce any other voltage.. SO this residue is not the cause???

 

James

[Mclaneinc]

If it is indeed residue from the reflow then I'm pretty sure its non conductive so would not cause any shorts, the only other time in my limited experience of seeing gunk like that was when a cap leaked but it would be fairly obvious where it came from and that does indeed look like excess from a flow..

[Bikerbob]

Well.. at any rate this one is dead.. I get +12v +5vsb and thats it. nothing else. So try again I guess.

 

James

[Rybags]

Shouldn't +12 and +5 should be all you need to run an ST?

 

When I measured one it used something like 20 Watts. I would imagine most of the draw should be on +5V, not sure what +12 is used for, most likely drive motor and video generation.

[AtariGeezer]

The RS-232 Circuit uses +12 and -12, the monitor uses +12 in the Mode Select (Mono / Color) too...

Edited June 24, 2016 by AtariGeezer

[Bikerbob]

Well I will say good things about the hong kong vendor I bought it from.. I showed them the pics of the board.. rather than argue with me they refunded my money, and did not even ask me to return it. Much more than I would expect.

 

SO there are some good professional vendors on Ebay.

 

James