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This is a high quality manual with clear schematic and components layout diagrams ; with service procedure included.
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This service manual for the Kenwood KT-990D was reproduced really well ,is very legible and manual is complete.Combined with the low price paid,in the future,I will be checking Owner-Manuals.com any time I need a manual.
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When I purchased this manual I had my doubts regarding the quality as the price was so reasonable as compared to other outlets.
The manual itself is of high standard the print is very clear as are the diagrams. Obviously with the diagrams one has to zoom in otherwise it is to small to be able to read.
Overall I am very pleased with the company who delivered as they said and with the manual they supplied.
I occasionally require a manual and now having registered with this company I shall order from them in the future.
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I was at first dubious about payiong for downloaded manuals but having done so, I was extremely impressed with quality of the two manual I ordered, well worth the small price I paid.
I would highly recommend these to my friends.
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reasonable price for the schematic - the service is perfect, all as expected and pointed by instructions - good scan of the original plans - thank you!
SD-AT1000W
TO CHECK AND CANCEL PROTECT CIRCUIT DETECTION LINE
1: In this model the microcomputer (IC701) detects the following malfunctions once power is supplied, and cuts off power from all the parts except for the circuit driving the microcomputer. Abnormal drop in the output voltage of each regulator (below approx. 1.5 V) Power is cut off instantly without display. Output offset over voltage of the 1-bit amplifier (above approx. DC 2 V) Mains overvoltage of the 1-bit amplifier (above approx. DC 5.5 A) Power is cut off instantly without display. Defects in the cooling fan or its drive circuit (when stopped) Power is cut off after �FAN LOCK� is displayed. Abnormal overvoltage or undervoltage of power supply. Power is cut off instantly without display if voltage is abnormal.
1 Abnormal drop in the output voltage of each regulator
Connect a measuring device (such as an oscilloscope) to the stabilizing output of the regulator, and turn on the unit. If the detected voltage is extremely lower than the voltage on the circuit diagram (below approx. 1.5 V), the regulator itself or the circuit is defective.
1
2 3 4 5
2 Output offset overvoltage of the 1-bit amplifier
Adjust the voltage of the output offset. If a protective operation is still activated, ICA401 on the 1-bit amplifier could be defective (the detection circuit of the speaker output DC voltage).
2: Criteria for abnormality, and checking and cancelling the detection line The criteria: The voltage of pin 2 (PROTECT) on IC701. The voltage of pin 7 (OFFSET) on IC701: Low (below approx. 1 V) (abnormal) and High (above approx. 2.5 V) (normal) . Detected as abnormal if a pulse signal is not input into the pin 1 (FAN LOCK) for 5 seconds. Detected as abnormal if the voltage of the pin 3 (+B CHECK) is lower than 1.2 V or higher than 3.0 V.
1 2
3 4
Checking and cancelling the detection line: Caution: If the PROTECT/OFFSET detection line is disconnected in case of or above, a protective operation does not function. The disconnection by output short-circuit of each regulator may cause the parts or PCBs to burn out and therefore do not disconnect the detection line when the cause is not identified. (Power supply can be detected with an oscilloscope or like during approx. 0.5 seconds after an abnormality is found. Note that the detection would be difficult with a tester as the voltage rises and falls rapidly.)
1, 2 3
� 10 �
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