swanny
|
| posted on 15/2/13 at 04:16 PM |
|
|
pcb problem?
pic 1
pic2
pic 3
hello all
a while back we bought a cheap electric piano. it was fine apart from the power cable had to be jiggled a bit to get it to work.
now it wont work at all, so i tried to get a replacement 12v cable but couldnt get one to fit they all seem too loose. if you jiggle it for long
enough you can occasionally get power through to the keyboard but not for more than a second.
in an attempt to check the other end i took the pcb out where the socket is mounted and noticed that the yellow glue (?) is missing from one side of
the socket, though the welds underneath seem ok. could this be causing the problem?
anyone know where i can get pcbs mended if so?
Paul
|
|
|
|
|
tegwin
|
| posted on 15/2/13 at 04:48 PM |
|
|
I am going to assume you don't have a multimeter...so this is what I would do..
1. Check to see if the power supply is working properly... Get a 12V bulb from a car and some short lengths of wire (speaker wire or paperclips will
do if you are careful).
Wire the bulb to the power supply and see if you get a constant light from the bulb if you wiggle the cable/transformer about.
Assuming this checks out ok then:
2. Using the aforementioned wires/paperclips and double checking polarity (+/-) feed power directly onto the PCB in the appropriate place to see if it
is truly the socket that is at fault....
If the socket turns out to be faulty you could either replace it (maplins/RS sell them) or simply chop the jack off the end of the cable, de-solder
the socket and solder the wires directly onto the PCB...
I would expect a socket to be no more than £3 and a soldering iron around £15 if you don't have one.
[Edited on 15/2/13 by tegwin]
------------------------------------------------------------------------------------------------------------------------
Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
|
|
|
Macbeast
|
| posted on 15/2/13 at 05:39 PM |
|
|
The centre pins of those sockets vary in size - I think three different sizes. So a plug for a large diameter pin will fit into any socket but will
make intermittent contact aith the smaller pins.
But, as said - easiest solution is to forget the plug/socket and solder directly to the board. But be careful to get the pos and neg right.
I wouldn't use a car bulb to test - it will probably draw too much current and may fuse the power supply.
I'm addicted to brake fluid, but I can stop anytime.
|
|
|
swanny
|
| posted on 15/2/13 at 06:48 PM |
|
|
Thanks soldering straight onto the board sounds like a good solution, will check out the others.
One other question how do I ensure I wire the power supply the right way round onto the board ?
Or will it become obvious once I chop the plug and strip the wire?
Thanks again
Paul
[Edited on 15/2/13 by swanny]
|
|
|
bi22le
|
| posted on 15/2/13 at 07:25 PM |
|
|
negative is always on the outside of these positive in the middle
i have not looked at the pics as Im on my phone but negative on the pcb will be big and shout all over the place. positive will probably go to a
resistor or one component.
almost always a dry joint with these not always the actual connection. if you have an iron just heat up each terminal on the pcb untill it melts then
take off the heat. this will re seal the dry joint.
the wiggling over the years has loosened the soldiered joint.
good luck.
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
|
|
|
MikeRJ
|
| posted on 15/2/13 at 09:49 PM |
|
|
quote:
Originally posted by bi22le
negative is always on the outside of these positive in the middle
Usually, but not always! The connector polarity is very often shown in a diagram on the power supply. If not a quick check with a multimeter will
determine this.
Note that the fault may not be with the PCB mounted socket, it's possible for the wires to become broken inside the plug on the end of the power
cable. When the socket on the PCB is at fault, it's nearly always broken solder joints, putting some force onto the connector whilst looking at
the solder joints will usualy show up broken joints as you can see the pin moving within the solder.
|
|
|
Tazzzzman1
|
| posted on 16/2/13 at 09:27 AM |
|
|
Hi,
As others have stated...
The yellow glue is just added as a strain relief for the socket (constant pushing in out of the plug will cause stress on thE solder joints &
PCB). If the glue is missing/ cracked then it is most likely that one of the solder joints on the connector to the PCB has cracked. 1st I would check
these out and re-solder the joints. If the track/ pad on the PCB is broken then you can carry out a simple repair by using some strands of copper wire
to bridge the crack and solder. Afterwards make sure that you re-apply some apoxy adhesive over the reppaired track to prevent it getting worse, also
re-glue the socket back in place.
If it aint that then replace the socket. Easy to do as PCB is only single sided.....
|
|
|
ReMan
|
| posted on 16/2/13 at 09:27 AM |
|
|
quote:
Originally posted by MikeRJ
quote:
Originally posted by bi22le
negative is always on the outside of these positive in the middle
Usually, but not always! The connector polarity is very often shown in a diagram on the power supply. If not a quick check with a multimeter will
determine this.
Note that the fault may not be with the PCB mounted socket, it's possible for the wires to become broken inside the plug on the end of the power
cable. When the socket on the PCB is at fault, it's nearly always broken solder joints, putting some force onto the connector whilst looking at
the solder joints will usualy show up broken joints as you can see the pin moving within the solder.
+1
Show us a picture of the track side of the PCB
www.plusnine.co.uk
|
|
|
Macbeast
|
| posted on 16/2/13 at 09:40 AM |
|
|
More importantly, the polarity is usually shown in a little diagram on the device itself.
I'm addicted to brake fluid, but I can stop anytime.
|
|
|
