Hello. I was just wondering if you have came across any of this units that have no power as a result of short on the A/D Board? I have had two of these units now. I sucessfully rebuild the power supplies only to run in to the short on the 5VDC standby. With the power supply switch on, it will only read 1.8 to 2VDC. If I unplug the connector to the main board, it will give the expected 5VDC. I have tried to trace the short down with no luck. Any help would be greatly appreciated. Thanks in advance.
I know the supplies that I rebuilt are good...I tried them in another LCT2662 I have that is working. I was guessing it was one of the voltage reg. ics on the main board, but no luck so far. Just thought someone else might have ran across this problem. Thanks for the quick response....
RetroI know the supplies that I rebuilt are good...I tried them in another LCT2662 I have that is working. I was guessing it was one of the voltage reg. ics on the main board, but no luck so far. Just thought someone else might have ran across this problem. Thanks for the quick response....
Retro
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If it is a "low ohm" VCC to GND short. Measure caps looking for the lowest reading...may be just a little difference, but the closer you are to the short the lower the reading will be. You can also try hooking up your meter, one with 5 digit readout works best, to VCC and GND. Try to do it somewhere away from your lowest reading, and use a can of freeze spray to spray individual components. If you "hit" the shorted part the reading will fluctuate. You can test this by spraying the leads. Then you can also try the same set-up with hot air.
Good Luck,
Sam
I have not seen a supply problem that after replacing the caps found something loading down the 5v line. Guess it's time to get out the scope and trace. :)
Good Luck
Bill
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try leaving the remote unplugged and unplug the unit for 10 seconds and plug only the unit back in. If you get hot water without the remote connected but nothing after doing the same thing with the remote connected then your remote may have shorted out. Otherwise your circuit board may have had a short. In which case, call Noritz for a replacement.
Step 2 Check: Fusing Heater Lamp (H1) is open-circuited. <Check Procedure> Check the resistance across both ends of the Fusing Heater Lamp (H1). The Fusing Heater Lamp is open-circuited if the resistance is infinity.
Step 3 Check: Thermoswitch 1 (TS1) is operational. <Check Procedure> Check the resistance across both ends of the Thermoswitch 1 (TS1). The Thermoswitch 1 is open-circuited if the resistance is infinity.
Result: NO Action: Change Thermoswitch 1 (TS1).
Step 4 Check: Fusing Unit Interlock Switch (S2) is operational. <Check Procedure> Check continuity across terminals when the Fusing Unit Interlock Switch (S2) is turned ON. • Across S2-1A and S2-1B • Across S2-2A and S2-2B
Result: NO Action: Change Fusing Unit Interlock Switch (S2).
Result : YES Action: Change DC Power Supply (PU1).
Step 5 Check: Thermistor (TH1) is open-circuited. <Check Procedure> Check the resistance across CN15-2 and CN15-3 on the Fusing Unit side with CN15 disconnected. The Thermistor is open-circuited if the resistance is infinity.
Result: YES Action: Change Thermistor (TH1).
Step 6 Check: The following voltages are supplied from the Master Board (copier: PWBA). <Check Procedure> Check voltage across a Master Board (copier: PWB-A) pin and GND when the Power Switch is turned ON. • Voltage across PJ10A-7 and GND DC24 V when Fusing Heater Lamp (H1) is OFF DC0 V when Fusing Heater Lamp (H1) is ON • Voltage across PJ10A-10 and GND DC24 V when Fusing Heater Lamp (H1) is OFF DC0 V when Fusing Heater Lamp (H1) is ON
Result: NO Action: Change Master Board (copier: PWB-A).
Step 2 Check: Fusing Heater Lamp (H1) is open-circuited. <Check Procedure> Check the resistance across both ends of the Fusing Heater Lamp (H1). The Fusing Heater Lamp is open-circuited if the resistance is infinity.
Step 3 Check: Thermoswitch 1 (TS1) is operational. <Check Procedure> Check the resistance across both ends of the Thermoswitch 1 (TS1). The Thermoswitch 1 is open-circuited if the resistance is infinity.
Result: NO Action: Change Thermoswitch 1 (TS1).
Step 4 Check: Fusing Unit Interlock Switch (S2) is operational. <Check Procedure> Check continuity across terminals when the Fusing Unit Interlock Switch (S2) is turned ON. • Across S2-1A and S2-1B • Across S2-2A and S2-2B
Result: NO Action: Change Fusing Unit Interlock Switch (S2).
Result : YES Action: Change DC Power Supply (PU1).
Step 5 Check: Thermistor (TH1) is open-circuited. <Check Procedure> Check the resistance across CN15-2 and CN15-3 on the Fusing Unit side with CN15 disconnected. The Thermistor is open-circuited if the resistance is infinity.
Result: YES Action: Change Thermistor (TH1).
Step 6 Check: The following voltages are supplied from the Master Board (copier: PWBA). <Check Procedure> Check voltage across a Master Board (copier: PWB-A) pin and GND when the Power Switch is turned ON. • Voltage across PJ10A-7 and GND DC24 V when Fusing Heater Lamp (H1) is OFF DC0 V when Fusing Heater Lamp (H1) is ON • Voltage across PJ10A-10 and GND DC24 V when Fusing Heater Lamp (H1) is OFF DC0 V when Fusing Heater Lamp (H1) is ON
Result: NO Action: Change Master Board (copier: PWB-A).
If you have the original fuse, it's the number stamped on one of the end caps after the three letters denoting the fuse type. Most manufacturers also print the fuse rating on the power supply circuit board ("Caution: replace fuse only with...")
I have one of these sets in the shop now, but I haven't opened it yet. Post a reply if you can't find the fuse type and rating, and I'll let you know what my project uses.
I assume you already know fuses in TV sets don't blow by themselves, but indicate another part is shorted. Check the diodes, transistors and power ICs in the power supply before plugging the set in. If you see any bad capacitors, fix those also.
If the caps are bulged out on the top, then they are bad. I usually replace all nine of them just to be on the safe side. Also, you might want to check your 5vdc standby voltage while it is still hooked to the main board. I have ran across a few with no standby light that is caused from a short (which I can't seem to find) on the main board. The voltage always reads 2.8vdc instead of 5vdc on these. Hope this helps.
This is usually caused by damaged capacitors (Akai uses very cheap
components) on the power supply board. There are nine large
electrolytic caps that have to be replaced. Hope this helps you out.
I know the supplies that I rebuilt are good...I tried them in another LCT2662 I have that is working. I was guessing it was one of the voltage reg. ics on the main board, but no luck so far. Just thought someone else might have ran across this problem. Thanks for the quick response....
Retro
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