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Steff1968

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My heat press stopped working and have been quoted £130 for a new control board but obviously they can't be sure this is the issue.
How do I check that the press is receiving power.
I have a multimeter available but its knowing where to take the readings. I have changed the fuse and cable without success.
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How to check voltage on heat press. IMG_20200214_194703 - EletriciansForums.net
 
Hi - please be careful if that is live, as there is 230V exposed once you open that box.

As I look at your nice pic (wish everyone did this) I fancy I can see a conductor fallen out of the plug on the board. This seems to be the transformer 24V output and if so, it would stop the board from working if it has fallen out. Anyway, it can’t be good :) .

How to check voltage on heat press. 2F2D0585-E2AB-4245-9366-08866E80013E - EletriciansForums.net
 
Well spotted @Wilko

FYI that device is a solid state relay (SSR) not a transformer
But yes, you are correct, without both leads connected it will not switch on the heating element.
 
Thanks for the replies.
There is no mains power connected

I had already spotted that wire was out and slotted it back in after I'd taken the picture.
This happened earlier when I disconnected it.
Is that the plug where I would take a voltage reading.
The last time I used the press, it was at temp and the digital display was obviously on also.
These things normally smell when heating up but it seemed stronger.I put that down to the fact I hadn't used in a few weeks.
At this point I noticed the display was off and there was also a faint burning smell which seemed to be coming from the circuit board.
Could that SSR be the problem.

Thanks again
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Think of the ssr as a relay that turns the heater on and off.

Often when they fail, they fail in the stuck on position.
 
Probably won't be the SSR then...
There is no power getting to display.

Thanks
 
The board is powered by a small SMPSU in the bottom left-hand corner based on a monolithic DIL IC that is located vertically below the 3 barrier strip terminals. It looks to me like yours has gone pop. They often either blow the package top off or leave scorch marks on the board - look at its lower row of pins to the immediate left of the transformer and I think I can see dark marks. The input rectifier and fusible resistor may well have failed too. If the chip is indeed blown up, from experience of these circuits I would say it is the root cause of the problem and not a symptom of trouble elsewhere, hence a replacement board will work OK.

If those are not scorch marks and no further signs are visible, unfortunately, I cannot recommend troubleshooting as a DIY job because it really needs an isolating transformer and some experience working on live circuits. There is 325V DC on that little chip when operating, connected to the mains, so it can bite rather hard if you slip up. In any case, the chances of satisfactory repair are small without the necessary equipment, and the replacement board is a more sensible option.

If you replace the board, you'll need to fix that detached lead to the SSR properly. The lead would have been crimped into the contact before it was inserted into the plastic housing. Simply pushing the wire back in is not a permanent solution. Perhaps they can send you a replacement connector with the leads attached? Otherwise, you'll have to extract the contact from the housing, solder the lead and re-install it.
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How to check voltage on heat press. monolithic switcher gone ban - EletriciansForums.net
 
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Thank you for taking the time to view and write such a detailed reply.

Not sure if close up that l is a scorch mark or just the pic quality.

Looking above it when zooming in doesn't look too healthy though.

Trying to use a multimeter to check the power inlet and fuse... Not getting anything.. But I may be in contact with the wrong part.

Thanks again
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How to check voltage on heat press. IMG_20200218_185007 - EletriciansForums.net
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How to check voltage on heat press. IMG_20200218_185033 - EletriciansForums.net
 
Yup, that looks pretty normal for a blown-up single-chip SMPSU. Those little holes in the top of the LNK363 shouldn't be there, the internal micro-explosion blew them through the plastic, and that's a typical scorch mark on the board. There's probably a big hole in the bottom of the package. As usual a few innocent bystanders (the partly-desoldered resistor and diode, probably the rectifier, current FB resistor, maybe fusible resistor and a few other bits) have bitten the dust too.

I think you'll be needing a new board at this point. Technically it can be repaired but won't be cost-effective in this case and I'm not offering!
 
Again Lucien thanks for taking the time to reply.
What is is cause of this... Could it have been prevented or is it just something that can happen in time.
I remember a few years ago I got someone to solder a new power inlet... And noticed a few days later than the switch remained illuminated even when switched off.

And could you point me in the right direction for checking the voltage on the fuse and power.

And that... Is it a Jst connection... How would I know what size that it is to order a replacement.


Sorry for all these questions.
Thanks again.
 
These little all-in-one PSU chips are highly stressed parts and not terribly reliable. It's a quart squeezed into a pint pot that is ready to burst out without much provocation. A more substantial power supply would have a separate power transistor and control IC.

The switch remaining illuminated means that the input and output leads on the switch are the wrong way round, so that the indicator is always fed instead of being controlled by the switch. I did wonder why there were bits of insulating tape stuck on the inlet which is not normal. I can't see clearly enough to know how it is wired but the line from the inlet seems to visit the fuseholder first and I'm not convinced the switch isn't in the neutral alone which may be incorrect, but that won't blow up the PSU.

You don't need 230V kicking about to prove that the power would get to where it needs to. I would check for continuity with the power off as it's safer. From the line and neutral pins of the plug to the red and black leads at the screw terminals on the board, should each be a fraction of an ohm. If there's no continuity, check in stages from inlet to switch to fuse etc. just follow the conductor along.

Re the connector, JST, Molex, TE, sorry I can't say for certain. If it were on the bench in front of my I'd go through my parts bins or the RS catalogue looking for a match. You would probably have to buy 100 contacts at 20p each so it might be easier to get a lead sent with the board.
 
Thanks Lucien...

I will try and bluff my way to get a reading of some sort..

If not I will order these parts also don't think they are that expensive...well the SSR costs a bit.

Cheers
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It's seems that all connections from the power are fine when tested for continuity... Although I don't think that rules out the SSR as being okay.

But I will buy the board and try and get a new connector for the Jst Molex.

Thanks again
 
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Do you have any reason to suspect the SSR? It's not involved with the PSU burn-up so unless that was triggered by a mains spike there's no evidence of the SSR having suffered abuse. In any case, the most common failure mode is to fail on, so there would be constant (maybe excessive) heat.
 
No Lucien...
I know very little about this stuff... Was just guessing because I couldn't test it.
Even better if I don't need to replace it.
The two bare wires that have came out of the plastic connector..
Would I be able to join the wires with a new connector as its beyond repair.
And the wires seem to head into the heating element.

ThanksHow to check voltage on heat press. IMG_20200218_225039~2 - EletriciansForums.net
 
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