Repair of Oven Control Board - Maytag Range

[PR0b39]

My Maytag ('96) range has a problem on the control board which causes a blank display and no oven function. I have traced it to IC ULN2003AN (16 pin, hole mount). By heating up the IC I can get the display to light up and the oven to operate normally. It will stay on until there is a power disruption and then the display goes blank again. I find this IC listed in places like TI and Newark. Can I buy any of the ICs with the correct number or do I have to worry about things like size or other characteristics? I have some experience in electronics but not when it comes to replacing ICs. Also, I would like to socket it but don't know how to find the correct socket. I have tried, without success, to find someone in my area who does component level work because I really don't' have the soldering equipment to replace an IC. I guess I'll have to buy a few things. Better than buying a new stove! Thanks for any help you can provide regarding the purchase of a replacement IC and socket.

 

[Bluejets]

Explain what you mean by.......... "heating it up" and .........."stays on until there is a power disruption".

As explained in the data sheet, the chip is a series of darlington transistors.
If you buy the through hole version to suit your part number you should be fine.

Tests on these devices are commonly done with measured input and output signals using a multimeter rather than the tip of a burning stick.

If zero soldering skills, I'd suggest you get someone who has experience as you can really damage the board beyond repair if you do not know what you are doing.
Placing the chip in a socket is just adding another layer of future fault level.

 

[narkeleptk]

Can I buy any of the ICs with the correct number........... Also, I would like to socket it but don't know how to find the correct socket..

Yes you should just be able to buy the same part number. Looking at the datasheet you'd need a dip16 socket.

 

[PR0b39]

Explain what you mean by.......... "heating it up" and .........."stays on until there is a power disruption".

As explained in the data sheet, the chip is a series of darlington transistors.
If you buy the through hole version to suit your part number you should be fine.

Tests on these devices are commonly done with measured input and output signals using a multimeter rather than the tip of a burning stick.

If zero soldering skills, I'd suggest you get someone who has experience as you can really damage the board beyond repair if you do not know what you are doing.
Placing the chip in a socket is just adding another layer of future fault level.

Bluejets - Thanks for the reply! I heated up the components of the board selectively with a hair dryer (not a burning stick). I isolated individual or groups of components with cardboard shields. Often I get lucky and find an intermittent component using this crude technique. Also I use canned air as a circuit cooler sometimes. In this case, there is only one IC on the board and it is well separated from the other components so it was easy to isolate. About a 10-15 second blast of hot air causes the board to come back to life. Generally, but not always, it will continue to operate until there is another power outage (disruption) or I power cycle it myself. It then takes another blast of hot air to get it going again. Just this morning we had a very short power outage (~1sec) but that was enough to cause the IC to fail. Another blast of hot air brought it back.
I have a lot of soldering experience but not at the IC level. Back in the day I built two Heathkit TVs and several stereo amps from Eico and Scott. I also was a ham radio operator and learned my basic electronics on my own so I could pass the test. However this was before the days of ICs so just resistor, capacitors, transistors, etc. I am an Emeritus Prof. and, during my 40 years of work, I was in charge of an X-ray diffraction lab and a scanning electron microscope lab. Tons of electronics and I did my best to keep it all working without calling in outside help. Also had a good soldering station, which I miss. I am 81 years old and a bit shaky so, while I know how to solder and avoid damaging boards, I am not confident in my ability to do this job. I have tried to find someone to do it without success. If you know of someone who would replace this IC for me at a reasonable price then please put me in touch with them.

Thanks again - Paul

 

[PR0b39]

Yes you should just be able to buy the same part number. Looking at the datasheet you'd need a dip16 socket.

Thanks narkeleptk - If you know someone who would install this IC for me at a reasonable rate then please let me know!

 

[Bluejets]

The first problem with removing ic's from pcb is, they were never meant to be removed in the first place.
Everything on the board would originally have benn soldered (more than likely) using wave soldering i.e. everything at the one time.

To remove the IC, all 16 pins have to be heated at exactly the same time and exactly the same sufficient amount.
For the layman, this is not possible without expensive gear.

Only workaround is to get yourself a small pair of cutters especially for pcb work and snip off each leg of the device until the ic fall away.

Then go around every pin and wet with new 60/40 .7mm diameter solder as the stuff they use in the factory does not lend itself to device removal.
Then heat and remove one pin at a time.

Then with the use of some good quality solder wick, clean up the solder pads.
Note.....the use of some extra solder flux (available in small can like a tabacco tin) will assist here.
Some pads like the ground may need extra heat and care not to damage the track so a good quality iron with sufficient heat ability is required.

Once all clean you are ready to go.
Again I would caution on the use of the ic socket.
If not good quality and installed correctly, it will give you curry further down the track.

I would have imagined with your past endeavours, you would have at least a multimeter to test with.
The burning stick ( or hairdryer) really prooves nothing.
The ULN2003 test is not difficult, it's simply a seven part buffer.