Post Reply 
Prime broken main board bad
04-20-2017, 04:49 PM (This post was last modified: 04-20-2017 04:51 PM by Bipman.)
Post: #1
Prime broken main board bad
Hi all

I picked up a bricked HP prime calculator and found the issue. The main board has been zapped at some time and it looks like someone opened it with a metal screwdriver. I've included the photos from DropBox in case you've seen it before. Is there a main board document somewhere describing component details?

Bipman

https://www.dropbox.com/s/ltjdzj0cht30ti...e.JPG?dl=0

https://www.dropbox.com/s/8iqqdjd4xz8x8e...3.jpg?dl=0
Find all posts by this user
Quote this message in a reply
04-20-2017, 04:57 PM
Post: #2
RE: Prime broken main board bad
(04-20-2017 04:49 PM)Bipman Wrote:  Hi all

I picked up a bricked HP prime calculator and found the issue. The main board has been zapped at some time and it looks like someone opened it with a metal screwdriver. I've included the photos from DropBox in case you've seen it before. Is there a main board document somewhere describing component details?

Bipman

https://www.dropbox.com/s/ltjdzj0cht30ti...e.JPG?dl=0

https://www.dropbox.com/s/8iqqdjd4xz8x8e...3.jpg?dl=0

I can't tell if that was just a bad job in terms of cleaning up rosin. Are there other clues that suggest it was "zapped"? Have you tried cleaning that spot with rubbing alcohol? If it's just rosin, then it will clean up very easily with alcohol.

Graph 3D | QPI | SolveSys
Find all posts by this user
Quote this message in a reply
04-20-2017, 04:59 PM
Post: #3
RE: Prime broken main board bad
Not yet, no. I've checked the voltage in and that seems OK but the machine does not boot up using any of the key combinations that are supposed to get it going. I presume if it was rosin, it would still work? I'll give it a go later.

Bipman
Find all posts by this user
Quote this message in a reply
04-20-2017, 05:07 PM
Post: #4
RE: Prime broken main board bad
(04-20-2017 04:59 PM)Bipman Wrote:  Not yet, no. I've checked the voltage in and that seems OK but the machine does not boot up using any of the key combinations that are supposed to get it going. I presume if it was rosin, it would still work? I'll give it a go later.

Bipman

Well, even if it were rosin, it would not necessarily boot if the issue is actually elsewhere. My point was that the picture does not make it clear that the spot was in fact the cause of the calculator not responding. I have taken apart a lot of new pieces of electronics and noticed that the soldering and clean-up process is quite sloppy. So if that is indeed just rosin, it would suggest that the issue could lie elsewhere.

Graph 3D | QPI | SolveSys
Find all posts by this user
Quote this message in a reply
04-20-2017, 05:36 PM
Post: #5
RE: Prime broken main board bad
Understood. I'll see if it will clean off first.

Bipman
Find all posts by this user
Quote this message in a reply
04-20-2017, 11:59 PM
Post: #6
RE: Prime broken main board bad
Just a guess on my part, but looks like someone was soldering as obviously evidenced by the rosin, melted corner on the cap to the right and the burnt edges on the chip on the left shown in the 1st image, (maybe trying reflash the board via JTAG?).

Tom
Find all posts by this user
Quote this message in a reply
04-21-2017, 12:07 AM
Post: #7
RE: Prime broken main board bad
A couple of the capacitors at the bottom of the photo look like they have been bridged together. I would assume they are not supposed to be like that. Seems like a botched repair job?
Find all posts by this user
Quote this message in a reply
04-21-2017, 04:49 AM
Post: #8
RE: Prime broken main board bad
I've looked at the rest of the boards below the main one and all looks OK so yes, a repair/solder job gone wrong looks likely. Not sure if it is worth repairing or getting another unit with a bad display etc. and swap the parts.

Bipman
Find all posts by this user
Quote this message in a reply
04-21-2017, 02:08 PM
Post: #9
RE: Prime broken main board bad
(04-21-2017 04:49 AM)Bipman Wrote:  I've looked at the rest of the boards below the main one and all looks OK so yes, a repair/solder job gone wrong looks likely. Not sure if it is worth repairing or getting another unit with a bad display etc. and swap the parts.

Bipman

Even if you were to have another one with a bad display, the display connector appears to be glued to the board. I imagine that it would be a fairly challenging task to swap displays.

Graph 3D | QPI | SolveSys
Find all posts by this user
Quote this message in a reply
04-21-2017, 02:20 PM
Post: #10
RE: Prime broken main board bad
I'm beginning to wish I hadn't got it now! Anyway if I can find a free (!) broken prime I'll give it a go.

Bipman
Find all posts by this user
Quote this message in a reply
Post Reply 




User(s) browsing this thread: 1 Guest(s)