Tower airfryer has no power

Thread Starter

6pac

Joined Dec 4, 2018
11
Hi there, I recently bought 4 airfryers from an auction, they are brand new and unused but when I plug them in 3 of them do nothing (no power at all) and 1 lights up briefly and pulses on and off (at about 1 second intervals.)
I have tested the fuse/power cord with a multimeter and this tests good. I then dismantled the outer cover to expose the PCB which also has a fuse soldered to it. Again this fuse tested good. I've traced the wires and found a thermal fuse, this is also fine.
I'm totally new to this so I consulted Google to try to understand the components on the board and how to test them. (I only have a digital multimeter but have ordered a capacitor tester and some new capacitors) There are no obvious burn marks on the board and all the solder joints are sound.
All the tests I have performed have been with the power off (unplugged at the wall socket) I've unsoldered various components to test them and up to now haven't found anything wrong.
Is there any likely suspect components in a circuit like this?
Thanks for any information you could give.
Best regards.
Andy
 

ebeowulf17

Joined Aug 12, 2014
3,274
Hi there, I recently bought 4 airfryers from an auction, they are brand new and unused but when I plug them in 3 of them do nothing (no power at all) and 1 lights up briefly and pulses on and off (at about 1 second intervals.)
I have tested the fuse/power cord with a multimeter and this tests good. I then dismantled the outer cover to expose the PCB which also has a fuse soldered to it. Again this fuse tested good. I've traced the wires and found a thermal fuse, this is also fine.
I'm totally new to this so I consulted Google to try to understand the components on the board and how to test them. (I only have a digital multimeter but have ordered a capacitor tester and some new capacitors) There are no obvious burn marks on the board and all the solder joints are sound.
All the tests I have performed have been with the power off (unplugged at the wall socket) I've unsoldered various components to test them and up to now haven't found anything wrong.
Is there any likely suspect components in a circuit like this?
Thanks for any information you could give.
Best regards.
Andy
Are you sure you're providing the right power? Auction equipment isn't always what it seems. Sometimes you get international equipment with different power needs.

Have you looked for schematics or service manuals online? Please share them here so we have some idea what you're working on. It's hard to diagnose a circuit without knowing what it is!!!

If you can't find manuals or schematics, at least share the make and model, along with the power requirements (honestly, probably even better to take a picture of the nameplate with model, serial number, power specs, etc.)
 

Thread Starter

6pac

Joined Dec 4, 2018
11
Great stuff, thanks for the reply.
I have no idea where I'd even start to look for schematics, (please forgive my ignorance) would these be available from the manufacturers website?
I do have the other info you mentioned, model number etc. I'll gather it together and post it asap.
PS
I'm in the UK and the item is 240v.

Thanks again
 

MaxHeadRoom

Joined Jul 18, 2013
21,651
If brand new at auction, is it possible they were returns maybe?
A pic of the board and any electrics may help, is there any kind of motor or fan in there?
Max.
 

ebeowulf17

Joined Aug 12, 2014
3,274
Great stuff, thanks for the reply.
I have no idea where I'd even start to look for schematics, (please forgive my ignorance) would these be available from the manufacturers website?
I do have the other info you mentioned, model number etc. I'll gather it together and post it asap.
PS
I'm in the UK and the item is 240v.

Thanks again
Schematics and/or service manuals may be available from the manufacturer - that would be the ideal - but they may not. Some manufacturers keep all tech info restricted and only make it available to authorized service reps. If you can't get it straight from there, you can just Google the make/model along with the word manual or schematic and you'll probably get lots of hits - there's kind of a cottage industry of websites publishing manuals that aren't otherwise available. To be honest, I'm never sure which ones I can trust, so I don't use them very often. Others on this forum could probably give better recommendations.
 

Thread Starter

6pac

Joined Dec 4, 2018
11
Hi max, yes customer returns but due to the condition they have never worked since leaving the factory so I assume it's a manufacturing issue.
Yes I can add pics of the board and there is a fan in there.
 

MaxHeadRoom

Joined Jul 18, 2013
21,651
It looks with a little patience they could be reverse-engineered, if there is standard IC part No's and not OEM μP etc, then it will be easier, they can't be anything too exotic for this kind of unit.
Obviously for the price they get them for, the UK distributor will just write them off for the auction cost.
What is the 8pin IC No?
Max.
 

Thread Starter

6pac

Joined Dec 4, 2018
11
It looks with a little patience they could be reverse-engineered, if there is standard IC part No's and not OEM μP etc, then it will be easier, they can't be anything too exotic for this kind of unit.
Obviously for the price they get them for, the UK distributor will just write them off for the auction cost.
What is the 8pin IC No?
Max.
Thanks max
I'm not sure which number I should be reading to be honest. I've added a pic, hopefully you should be able to read it.
 

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Thread Starter

6pac

Joined Dec 4, 2018
11
I can't seem to find anything on Google that relates to "any" information printed on the IC. I searched for ways to test a buck boost and it fried my brain :confused:

Is that component likely to be at fault, I don't mind replacing parts to illiminate them?
(It's all part of the learning curve)
Mind you, even if I wanted to replace it I can't find a like for like replacement with the info that's on it. :(
Am I missing something obvious I wonder? :oops:
 

ebeowulf17

Joined Aug 12, 2014
3,274
I can't seem to find anything on Google that relates to "any" information printed on the IC. I searched for ways to test a buck boost and it fried my brain :confused:

Is that component likely to be at fault, I don't mind replacing parts to illiminate them?
(It's all part of the learning curve)
Mind you, even if I wanted to replace it I can't find a like for like replacement with the info that's on it. :(
Am I missing something obvious I wonder? :oops:
Looks like SM, not SN. Only see it on the big Chinese sites, but it's out there. Here's one example:
https://lcsc.com/product-detail/PMIC-Power-Distribution-Switches_SM7055-12_C129310.html
 

Thread Starter

6pac

Joined Dec 4, 2018
11
*claps hands frantically*
Wow. That's brilliant I was searching for ages but couldn't find anything. Thank you, thank you, thank you. :D:D:D
I’ve ordered a few and I’ll let you know how it goes. Thanks for your time everybody.
 

Thread Starter

6pac

Joined Dec 4, 2018
11
Thanks max. Yes I agree, on such a basic circuit it’s only a matter of time before we find the issue, there can’t be that much to go wrong. (I hope :confused:)
 
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