Maker Pro
Maker Pro

Help please

KrisBlueNZ

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Nov 28, 2011
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Sorry for the delay!

You can do a basic check by measuring the power supply voltage to the LM324. That's the 14-pin IC near the top of the board. Here's a diagram of it:

324pinout.gif

This shows it viewed from above. Measure the DC voltage between pin 4 (V+) and pin 11 (GND) on the IC. I assume you have a multimeter?

Making this measurement is potentially VERY DANGEROUS. You need to measure it with the power ON, and there are mains voltages all around inside that cabinet, and in parts of the board. You should treat EVERYTHING in the cabinet, and on the board, as live.

You should work with one hand in your pocket - usually the left hand in your back pocket. This makes it difficult to hold two probes, so you should get a friend to help. Hold one probe each. Rest your hand on some part of the cabinet near to the board, so you have good control over your hand and the meter probe. Touch the end of the probe to the outside of the pin, where it enters the socket. Don't push hard, and don't push sideways, or the probe may slide off and bridge two pins together.

The main thing I need is to trace out the circuit diagram of that board.

You'll need to remove the board and take photos of both sides. I need to see them in good illumination conditions (see https://www.electronicspoint.com/threads/how-to-take-photos-of-circuit-boards.267883/) and the pictures need to be from directly above the middle of the board, with the board square (i.e. not rotated) in the photo. That's so I can match the two sides up into a single image that shows the components and the tracks. This makes it a lot quicker and more accurate to trace out the circuit.

Also can you tell me what experience you have working with electronic devices.
 

shrtrnd

Jan 15, 2010
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Yeah. Considering your problem, my first guess would be a bad heating element. A shorted one would cause excessive voltage/current on your control board. And open one would allow excessive current through the
remaining heating elemets. If you can get data on your heating elements, there will be a resistance for each element. If you can't get data, you should be able to individually disconnect each heating element and read the resistance of each one. One or more elements way out of tolerance for the other ones would be suspect.
 

KrisBlueNZ

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Yeah. Considering your problem, my first guess would be a bad heating element.
If you read the whole thread, you would know that the problem is on the circuit board. He has had to replace it seven times and each time, that fixed the problem.
 

davenn

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Sep 5, 2009
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If you read the whole thread, you would know that the problem is on the circuit board. He has had to replace it seven times and each time, that fixed the problem.

Yeah but the board has been replaced SEVEN times. has he really been sold 6 dud replacements

I still go with shrtrnd that it could be the element or assoc bits OFF the board that has a fault that is killing the boards
its the common denominator!! :) and to put it mildly bloody logical LOL

I would have stopped LONG before the 5th or 6th replacement brd to consider what the heck is killing them all


Dave
 

KrisBlueNZ

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The heater current doesn't flow through the board, so I don't think that's a likely explanation, but I agree there is probably something causing the boards to fail. I think the first step is to find out how the board has failed, then investigate what could have caused that failure.
 

KrisBlueNZ

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Phillips3236, what's happening with this issue? Did you see my post #23?
 

KrisBlueNZ

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I guess Mr. Phillips must have died of hypothermia!
 
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