I'm trying to repair a not so old toaster of mine and am looking for some advice please. I could just go out and buy a new one, but I'd like to try and fix this one if possible.
The problem with the toaster is that once you depress the toasters slide down to the (on) position, it just pops back up again immediately. I've had a quick look at it and made sure it's not just something like some crumbs stuck between the electro magnetic switch etc, and it's not.
One thing I can say is that the electro magnetic switch will initially go to it's activated position but then it will immediately deactivate again (thus the button just pops back up.)
I have checked this electro magnetic switch and the switch itself works properly. I have also pulled the four electrolytic capacitors on the board and check their ESR values which check out ok.
I have also re-flowed the solder joints on the back of the board just to check that there were no dry/cracked joints. However I'm now wondering if the controller chip (HT48R06A-1) on the board may have gone faulty somehow?
Any suggestions on anything to try please? Thanks guys
It not a mechanical problem I'm afraid. The slider arrestor does slide towards it's locking position looking like it's going to lock, however that's when the electromagnet should be active and lock it, but it's not.
The electromagnet does not activate at the point it should so the locking mechanism is released again releasing the slider back up. This is why I believe the problem to be electrical.
Ok I'll check the heater wires for continuity tomorrow. I know some of them work (I assuming all) as I can manipulate the toaster mechanism to get it working and can feel the heat from the elements.
The electromagnet on this toaster is actually soldered to the pcb so I think it's uC controlled. I did test it 5v and it activates as it should.
The slider arrestor does slide towards it's locking position looking like it's going to lock, however that's when the electromagnet should be active and lock it, but it's not.
Is there an internal switch to detect that locking position and tell the IC to activate the electromagnet? If so, perhaps the switch contacts are corroded?
I am saying yes as it checks out ok on my Peak transistor tester. In fact that was the first thing I went for too, mainly because those white wires to Q1's right go off directly to the electro-switch.
I've even changed all the electro caps tonight, tested the diodes (again) and tried another opto-isolator.. But still the same problem.
I'm thinking more and more now that somehow the uC has gone faulty. It has got power though as I'm measuring 3.2v between VSS & VDD.
Any more input would be appreciated though guys so unless your leaning towards to uC too please don't stop suggesting things. I'm enjoying the challange
Check the contacts on the main connectors. When you push down the lever it pushes two sets of contacts together (live and Neutral). if these contacts are pitted or bent then a bad contact causes this problem. CURE. Clean the mains contacts and using snipe nosed pliers bend them slightly closer together. This usually happens because the manufacturer uses cheap materials to save costs and the metal simply eventually bends away so contact is not made properly.
Check the data sheet (google) for the power supply connections on the control chip, sounds like a holtek, then see if there is dc power to the chip when the toaster is toasting, theres probably an x rated cap and resitor/zener or something like that from the mains supply as part of the dc power supply, my mouse repeller thingy went dead due to the 100nF cap from mains live going open.
Thanks for the further suggestions guys, but I got fed-up with the damn thing & finally binned it a couple of days ago. I got a new toaster from Tesco for £9
I was hoping I could actually buy the same type/make of toaster again so that I could exchange the IC to see if that was the problem or not, however the same type was not available any more.
Don't worry I always consider that before binning anything However all the parts only had short leads (including my newly fitted caps etc.) and I can't be bothered with short lead stuff as their options are
quite limited. I've got tons of bits anyway as I'm a bit of a hoarder so getting to use some of it is always a good thing
I must be tight or a hoarder too then, most if not all my circuits have bits of tinned copper wire soldered to the components as they ahve been re-used from a scrap telly.
Ferrites allways used to be a pain in obtaining untill I started scrapping stuff, now I've a box load, I've learned quite a bit too about ferrites and their construction, and a little about destruction!