CH1030B Board problem

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Tony P

Member
I have several 'modules' that I have made with various sensors etc all feeding back to a CH1030B board which in turn activates relays via it's Darlington driver.

My problem has only just started. For some reason when I now connect the CH1030B board to the v+/v0 the normal 5.1v drops to 1.2v thus making the board useless.

I have removed the 18M2 and the Darlington chip and tested them on other project boards and they work fine but still I get this voltage drop even with the chips removed.

My question is: is there a component on the board that may have failed? if so which one?

I have tested the resistors and they seem fine. I have inspected the solder joints with a powerful magnifying glass and they seem fine.
 
P

Paix

Senior Member
Looking at the project board documentation and the schematic at appendix B, page 7. With the two chips removed, there isn't a lot that is left to go wrong. Checking the resistance between the V+ line and Ground should give you a clue or two.

You don't mention how long you have had the board or how it may have been stored, but looking at the schematic, with the two active components removed, really leave only a few more obvious options.

Looking at the schematic, check The resistance to ground from the +V input, assumed to be to the top left in the diagram. This should be the same as at the left hand side of R1 to ground and from the right hand side of R1 to ground.

Check that the test jumper is not connecting the +V rail to ground with a jumper, solder or wire connection.

Check the capacitors C1 and C2 for any signs of obvious damage. The electrolytic could be slightly bloated or may have dried out and be causing a low impedance path to ground. Check your board for any hairline solder splashes.

Depending where the board has been stored, then look out for any bits of wire that may have got in between connectors/sockets from other work.

There is really not much there to go wrong! Certainly nothing that you shouldn't be able to find with a decent multi-meter and magnified MKI eyeballs and a good light.
 
T

Tony P

Member
The board is almost new and has been happily working for several days. The fault appeared last night when I tried to download another program to the 18M2

I have the same resistance on both sides (1.2 Mohm)
 
D

Dartmoor

Member
Back to the first post . . . There is mention of v+/v0?
I have used this circuit board for a number of projects & I am sure the supply is referred to as v1+/v2+/v0?

There is no mention of how the power supply/supplies is/are wired, and there are 3 options provided on the board?
5.1v is not a common household battery voltage? Perhaps you have used a 7805 regulator to provide 5v on v1+ from a higher voltage on v2+ (one of the three options) and accidentally connected the v2+/0v supply momentarily the wrong way round when you tried to download another program to the 18M2?

Apparently, connecting the supply the wrong way round can blow up the 7805 and leave the 18M2 & 2803 chips unharmed. (ok, I did it once & learned!).
Anyway, just a thought? - hope it helps!
 
hippy

hippy

Ex-Staff (retired)
As others have noted, with the chips removed there is little that can go wrong with the board. It is odd that the voltage drops and yet a V+ to 0V resistance check shows no shorts or low resistance.

It could be that some component lead or wire has shorted to the board or it picked up some residue that shorted the board which has now detached itself, or perhaps what was connected to the board was drawing too much current which caused the voltage to collapse. It could be a short that is caused by placing the board on a surface and make sure that you are not inadvertently placing it on an anti-static or conductive mat.

It would be worth disconnecting everything but power supply connections from the board, removing the chips, powering up and measuring the voltage again.
 
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westaust55

Moderator
A schematic and some photos showing what and how the external modules are connected to the CHi030B board might also help reveal potential causes of the problem experienced.
 
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westaust55

Moderator
If the supply voltage dips significantly with no external devices connected and the main chips removed from the CHI030 then options would be:
1: soldering for external devices has created a short
2. Decoupling capacitor has failed short circuit
3. Your power supply to the CHI030 has developed a fault and fails on a mA load

Have you by perchance added a 78L05 voltage regulator as indicated as an option?

There not a lot to work with for folks here - comes down to more testing with a multimeter.
 
T

Tony P

Member
My board is wired for two inputs, 5v and 12v
I have changed the decoupling capacitor and things have improved slightly. i.e the voltage hangs around 3.1v for a few seconds and then jumps to 5v
I have assumed that this is a power supply fault and am on my way to buy new batteries, battery box and switch.

Watch this space :)
 
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