Hi folks,
I found super automatic espresso machine in the local e-waste pile and it would not power on.
Clearly power supply failure (reasons unknown to me)
Both capacitors on the DC side blown but no other visible damage.
Replaced both of them, original 2x 47uF/200V in series, I used 47uF/400, no change.
There is 344V on the rectifier DC side but machine will not power ON.
Voltage measured on the PWM is as per picture below.
I ordered new Q0365R PWM since I couldn't find anything else failed.



Can anyone experienced give me some more hints what could have happened?
No blown fuses, only those 2 capacitors as you can see in pictures.
I checked every component in the PS part and didn't find anything suspicious. (visual inspection and measuring components)
Is it possible the IC failed to protect everything else?

Thanks for your time!

 

This is certainly an interesting project, well into the realm of recycling. But rather than start out spending money on parts, even obviously failed parts, it will make sense to evaluate the whole system and see if some terribly expensive component has also failed. Sometimes that does happen, while in other cases it might be that a connection in the line plug broke.
In this case a switching mode power supply appears to have failed. What are the power supply output voltages supposed to be? What do they power?? Switcher supplies are deceptively complex, and the circuits functions are not always apparent. An espresso machine will have at least one pump and at least one heater element, and a temperature control system. So it is very worth while to verify all of the individual different system parts and pieces are still present, at least. If somebody has already removed the $250 water pump module the repair cost might be excessive. Like getting a great deal on a used car that has no engine. Except that engines are easily available for reasonable prices. Sometimes..
I am not trying to discourage the TS, but rather suggest the best initial actions when seeking to restore a complex item that may not be all together or even complete.

 

This is certainly an interesting project, well into the realm of recycling. But rather than start out spending money on parts, even obviously failed parts, it will make sense to evaluate the whole system and see if some terribly expensive component has also failed. Sometimes that does happen, while in other cases it might be that a connection in the line plug broke.
In this case a switching mode power supply appears to have failed. What are the power supply output voltages supposed to be? What do they power?? Switcher supplies are deceptively complex, and the circuits functions are not always apparent. An espresso machine will have at least one pump and at least one heater element, and a temperature control system. So it is very worth while to verify all of the individual different system parts and pieces are still present, at least. If somebody has already removed the $250 water pump module the repair cost might be excessive. Like getting a great deal on a used car that has no engine. Except that engines are easily available for reasonable prices. Sometimes..

Thanks for reply!
The machine is untouched in great shape, both pumps and boilers are fine,
I tested everything including the brewing unit drive motor while cleaning the machine

I'm fairly certain the problem is the power supply part on the board.

 

OK, AND GOOD JOB!!! No missing expensive modules. That tells me it was not scrapped by a repair shop.
Now another option could be replacing the failed supply with a different one, rather than repairing it. So the questions now are: 1. Is the control computer a part of the power supply assembly, and 2. what voltage, or voltages, did the supply provide?? If a standard power supply would work, replacement could be an option.

 

OK, AND GOOD JOB!!! No missing expensive modules. That tells me it was not scrapped by a repair shop.
Now another option could be replacing the failed supply with a different one, rather than repairing it. So the questions now are: 1. Is the control computer a part of the power supply assembly, and 2. what voltage, or voltages, did the supply provide?? If a standard power supply would work, replacement could be an option.

Hehe, parts swapping is todays way to repair things, but certainly not the most cost effective or fun way.
Yes the board contains both PS and logic circuitry.
Service manual doesn't give any voltages or test points.
Replacement board is available for about $170
I have no doubt someone smarter than me would have the board PS fixed in no time.

Right now I'm in $2 for the capacitors and $3 for the PWM chip ... let's see where this goes

 

It is not an issue of "Smarter" but of being able to follow the circuit to the place where it does not work right. THAT is a bit different. Certainly having a circuit schematic makes the task simpler.

 

Jumping in here - what's the operating voltage? if it's 120VAC - maybe someone tried plugging it into 240VAC.

Is there a fusible link? Seen those go dead for no apparent reason. However, I'd guess there must be a reason or those caps would't have gone BOOM!

 

Jumping in here - what's the operating voltage? if it's 120VAC - maybe someone tried plugging it into 240VAC.

Is there a fusible link? Seen those go dead for no apparent reason. However, I'd guess there must be a reason or those caps would't have gone BOOM!

Thanks for reply!
Yes, operating voltage is 120V. I was thinking the same about overvoltage, perhaps someone used generator ... don't know.
Didn't find any fusible link, even those 2 fuses on the board are fine, all zero ohm resistors also OK.
Strange that only those 2 caps showed damage, when I took out the PWM there was absolutely no burn marks on it.
Generally when those fail it shows.
When it happened, the machine was in operation, since the brewing unit was not in home position.

 

Here is a late addition: Since the one board contains both the power supply AND the control logic, there is a fair chance that there is a problem with the control logic, which may have been caused by a power supply problem, or it may have caused the power supply problem. Both can happen. Have you discovered what the power supply output voltage should be?? And what voltage the logic works at?? If you knew the supply voltage, or voltages, it could be possible to test the system with an external supply to see if the logic portion was OK.
When a custom processor fails it is likely that the replacement is only available in the replacement circuit board, if it is available at all. That does happen.

 

Just to update, replacing the PWM fixed the problem
Working like new again!

 

OK, sometimes a problem comes from a single source. I am relieved that the repair worked for the TS.