Odd problem with backup camera monitor- electronic gurus?

Bikersmurf

Expedition Leader
Last winter my monitor wouldn’t power on intermittently when it got too cold. I found if I left it on and wrapped a scarf around it. If I blew the heat on it it would come on and work perfectly. Fast forward, it has started doing it now when it’s warmer.

I’ve narrowed the problem down to the component pictured below. Wave a heat gun over it and it’ll turn on... put an ice pack on it and it’ll shut off. I’m going to ask the manufacturer, but I’m not overly optimistic... they’ve been helpful sending diagnostic info... but we’ll see.
2895CC66-21DB-40F9-9966-870E1EB4858E.jpeg2643B465-4150-4AF1-B616-E0BF10A18E2A.jpeg

It’s the small black square with 330 on it. Battery? Or?
 

luthj

Engineer In Residence
I would guess that is a capacitor, but I am not certain.

Are you sure its the black square (330 markings), and not the 100 uF electrolytic capacitor below it? The electrolytic caps are known for drifting over time.

Is there a white marking printed on the board next to it? RXX would be resistor, CXX capacitor. LXX for inductor.
 

Bikersmurf

Expedition Leader
Oddly enough google helped me identify it as a 33uH power inductor.
I’ll have to do some research to figure out it’s role... they are dirt cheap from China... hoping to find one more locally. I’ll have to talk to a buddy who fabricates underwater dive communication equipment and see if he can point me in the right direction.

Cooling only it shuts the monitor off... I did so carefully 3-4 times consecutively.
 

luthj

Engineer In Residence
That inductor is probably part of the boards regulated power supply. There will be a regulator chip, and it uses an inductor+capacitor to produce a stable DC voltage (likely 5V, or 3.3V) from the variable 12V input.
 

Bikersmurf

Expedition Leader
Mouser or digikey would likely have it. Probably 7$ with shipping.
It’s 1.29 for one or 3.30 for ten from China... I’m hoping the local electronics shop will have one in stock. Since it’s a small .30 part, I’ll give them a shot before ordering one.

If not I’ll give Mouser or Digikey a shot.

I’ll also check solder traces... but pushing on it did nothing so I’m leaning towards an internal break.

The replacement monitor is 180 usd... so a $10 part would be well worth trying.
 
Last edited:

gdlals

Member
I would guess this is a problem with the solder connection on the component or components in the general area where you are heating/cooling during your tests. If there is a poor solder connection then any amount of thermal expansion (heating) or thermal contraction (cooling) would cause this. This is a common manufacturing problem and tends to show up over time with the thermal cycling of the circuit. My guess is it isn't a bad component but a bad physical solder connection somewhere.
 

Bikersmurf

Expedition Leader
I would guess this is a problem with the solder connection on the component or components in the general area where you are heating/cooling during your tests. If there is a poor solder connection then any amount of thermal expansion (heating) or thermal contraction (cooling) would cause this. This is a common manufacturing problem and tends to show up over time with the thermal cycling of the circuit. My guess is it isn't a bad component but a bad physical solder connection somewhere.
Usually, if it's a bad connection to the circuit board, pushing on the component will make a difference. In this case, pressure made no difference. However, if the open circuit was internal, heating and cooling would make a difference. I'll inspect the connections closely, but will likely replace it for good measure.
 

gdlals

Member
Usually, if it's a bad connection to the circuit board, pushing on the component will make a difference. In this case, pressure made no difference. However, if the open circuit was internal, heating and cooling would make a difference. I'll inspect the connections closely, but will likely replace it for good measure.

Not so often on an SMD assembly like the picture, but good luck!
 

Bikersmurf

Expedition Leader
Not so often on an SMD assembly like the picture, but good luck!
I appreciate your thoughts, I’m not familiar with SMD assemblies. I’ll see what I can do to fix the connections. I’ve worked on a lot of electronics, but it seems you’re more knowledgeable than I. Thanks.

If the part is reasonable, I’ll pick up a spare so that once I tear open the monitor, I’ll be able to repair it with the least amount of downtime on the backup camera monitor.
 

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