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edi
USA
3 Posts |
 Posted - 01/29/2008 : 09:31:59
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Hello, I need advice. I have a Willem Dual Power Programmer. Purchased 1.5 years ago. It now has a problem. With no EPROM plugged into the programmer, 3 parts become very hot. The 34063A regulator, 7805 regulator and 100 uH inductor become very hot. Does anyone know if this is a known problem with the Dual Power programmer ? There is definitely a short circuit condition since the voltage regulators become hot. Also the Vcc on the 74HC04 chip (pin 14) is 4 volts. Is normal voltage 5 volts ? Does anyone have a good and quick answer for a repair ? Thank you for the help. |
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| Reply #1
Pilsener
Norway
3 Posts |
Posted - 01/29/2008 : 10:52:31
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| Replace the 34063A regulator and the 7805 regulator to see if it's the regulators themselves that's faulty. These are not expensive, so it's worth a try. If the new regulators also gets hot, you just have to unmount the logic chips one by one to see which one is overloading the regulators. |
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| Reply #2
ZLM
2945 Posts |
Posted - 01/29/2008 : 11:31:44
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| visually inspect all the parts soldering point, and see if there are anything wrong/shorted. |
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| Reply #3
LJerni
USA
2 Posts |
Posted - 05/11/2008 : 06:14:46
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| If regulators are bad, it is usually caused by a shorted component down the supply chain. If you replace the regulators and still have a shorted part in the circuit, it will probably damage the new regulators as well, so locate the bad part first. Insure you know the correct location of each individual IC so you can put them back in the right socket. Be sure you're grounded and to power down, then power back up after each step. Since most IC's are socket mounted, Start with the first IC in the supply chain after the power regulators. Continue to remove the IC's 1 at a time. Once you have removed an IC, don't reinsert it until after you've found the bad one. Store them in a static free place such as a carbon foam pad. Once you've located the bad part, it is possible that there was more than one. Reinsert the IC's one at a time, then power up the unit after each and check the regulators. |
LJ |
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| Reply #4
nealg58
USA
2 Posts |
Posted - 12/10/2008 : 01:39:33
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| If both the 7805 AND the 34063 are getting hot, I would check both transistors that are used to switch the VPP power on. Also the filter capacitor on the output of the 34063 regulator. A shorted transistor (either or both) and/or shorted filter cap will cause the 34063 to overhear (drawing more current than normal) which would cause the 7805 to overheat. The 100uH inductor is overheating because most of the power being produced by the 34063 goes through the inductor. The other IC's on the board are powered by the 7805 through a 1N4001 diode. |
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Repair of Dual Power Willem
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