Regulator getting very hot, plus a fix

[Steve]

We have recently had a couple of technical support problems relating to the regulator on the multiprogrammer (EB-006) and development board (HP-488) sometimes getting very hot. When this happens, the program stops working and the micro cannot be re-programmed. Also, the 4052 chip on the board gets very hot.

After some investigation by a lecturer at City College Brighton and Hove (thanks Gil!), the problem was found to be related to power supplies with excess ripple, and a fix was found.

To minimise this ripple, put a large electrolytic capacitor (100uF) between the +14V and GND screw terminals on the board (obviously make sure you connect the -ve side to GND).

The excess ripple seems to occur when a powered-up transformer is plugged into the power socket of the board. If the transformer is plugged in before it is switched on, then this problem does not seem to happen.

[Jonathan]

I've tried putting a 100uF capacitor in but didn't seem to make any difference. Infact it gets hotter with the capacitor in.

It sometimes gets hot and sometimes doesn't. I think it happens when I operate the 7 LED segment display.

[g-slocombe]

I had the same problem with HP488 when using a 9v psu but was ok when using 13.5v

[Cruster]

I think the 4052 may be being driven into SCR lock up on power up.
http://www.matrixmultimedia.com/mmforum ... =2&t=10953

[ardu]

I am using flowcode 4.5 with the E-Blocks I got for the course "Programming Embedded PIC Microcontrollers". I have had the problem ever since I started that after a while I cannot program the chip (PIC18F4455). (I have tried using other chips and the problem still occurs so it is not the chip.) After I saw the regulator getting very hot post I touched the regulator after I could not program the chip and it was very hot. When I usually start programming on a day, naturally the regulator is not hot. After a short amount of time it gets hot and programming does not work. I tried the 100 uf capacitor but the regulator still gets hot. I am using the 13.5 V setting on the switching power supply since the EB006 E-Block needs that. I have been using an on/off switch attached between the switching power supply and the EB006 since ever since I started using it so the power is not on to the EB006 until I turn the switch on. Therefore, based on the original post I should not be having a ripple problem. I am using EB006-20-8.

Have any other solutions occurred since the original post?

I am thinking about attaching a small heat sink to the regulator.

[EtsDriver]

I am using flowcode 4.5 with the E-Blocks I got for the course "Programming Embedded PIC Microcontrollers". I have had the problem ever since I started that after a while I cannot program the chip (PIC18F4455). (I have tried using other chips and the problem still occurs so it is not the chip.) After I saw the regulator getting very hot post I touched the regulator after I could not program the chip and it was very hot. When I usually start programming on a day, naturally the regulator is not hot. After a short amount of time it gets hot and programming does not work. I tried the 100 uf capacitor but the regulator still gets hot. I am using the 13.5 V setting on the switching power supply since the EB006 E-Block needs that. I have been using an on/off switch attached between the switching power supply and the EB006 since ever since I started using it so the power is not on to the EB006 until I turn the switch on. Therefore, based on the original post I should not be having a ripple problem. I am using EB006-20-8.

Have any other solutions occurred since the original post?

I am thinking about attaching a small heat sink to the regulator.

Your problems sounds like the regulator has some time been short circuited and has been burnt for that. Try changing it. When +5V regulator get hot enough, it cuts power, and works again when its been cooled down.

If the programming smd packaged PIC gets hot(all leds dont start up and etc problems), it means there is something wrong in +5V side or the programming PPP pic has been under high voltage on +5V side (been there, done that, burnt 120€ board, thanks to psu with faulty voltmeter).

In my school class, these boards which have the heating regulator, have more problems in use too( read the in use as : "WEIRD GHOST PROBLEMS when debugging circuits and programs.").

[ardu]

Thank you for your post. I do not have my stuff with me presently but sometime I will try what you said. Again, thank you for taking the time to make your post.