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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!
NOTE ON BEFORE STARTING REPAIR
1. Forced discharge of electrolytic capacitor of power supply block
When repair is going to be attempted in the set that uses relay circuit in the power supply block, electric potential is kept charged across the electrolytic capacitors (C101, 102) even though AC power cord is removed. If repair is attempted in this condition, secondary defect can occur. In order to prevent the secondary trouble, perform the following measures before starting repair work.
Discharge procedure
1 Remove the AC power cord. 2 Connect a discharging resistor at an end of lead wire that has clips at both ends. Connect the other end of the lead wire to metal chassis. 3 Contact the other end of the discharging resistor to the positive (+) side (+VH) of C101. (For two seconds) 4 Contact the same end of the discharging resistor as step 3 to the negative (-) side (-VH) of C102 in the same way. (For two seconds) 5 Check that voltage across C101 and C102 has decreased to 1 V or less using a multimeter or an oscilloscope.
MAIN C.B D101
3
C101
C102
4
2
2
Select a discharging resistor referring to the following table. Charging voltage (V) (C101, 102) 25-48 49-140 Discharging resistor (�) 100 220 Rated power (W) 3 5 Parts number 87-A00-247-090 87-A00-232-090
Fig-1
Note: The reference numbers (C101, C102) of the electrolytic capacitors can change depending on the models. Be sure to check the reference numbers of the charging capacitors on schematic diagram before starting the discharging work.
2. Check items before exchanging the MICROCOMPUTER
Be sure to check the following items before exchanging the MICROCOMPUTER. Exchange the MICROCOMPUTER after confirming that the MICROCOMPUTER is surely defective.
2-1. Regarding the HOLD terminal of the MICROCOMPUTER
When the HOLD terminal (INPUT) of the MICROCOMPUTER is �H�, the MICROCOMPUTER is judged to be operating correctly. When this terminal is �L�, the main power cannot be turned on. Therefore, be sure to check the terminal voltage of the HOLD terminal before exchange. When the MICROCOMPUTER is not defective, the HOLD terminal can also go �L� when the POWER AMPLIFIER has any abnormalities that triggers the abnormality detection circuit on the MAIN C. B. that sets the HOLD terminal to �L�.
� Good or no good judgement of the MICROCOMPUTER
1 Turn on the AC main power. 2 Confirm that the main power is turned on and the HOLD terminal of the MICROCOMPUTER keeps the �H� level or not. 3 When the HOLD terminal is �L� level, the abnormality detection circuit is judged to be working correctly and the MICROCOMPUTER is judged to be good.
FRONT C.B
MAIN C.B In some models, it is PIN (. OVER LOAD DET DC DET AC DET Q110 HOLD SW POWER AMP POWER AMP POWER SUPPLY
MICROCOMPUTER
PIN101 CON601 1 2 1 2 *
HOLD (
*
PIN number is different depending upon microprocessor.
Fig-2-1
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