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Complete manual with clear schematic diagrams and printed circuit board layouts of two variants of the headset and the transmitter an old and a new version.
Also shows how the headset and the transmitter is opened and how transmitter and receivers can be adjusted and where to measure.
I had no problems to repair the headset using this service manual.
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Excellent printing quality. A complete and very useful manual with all details.
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This is a great site. I placed my order and by the next am it was available for download. Had some problems with some missing copy on some pages. Once I brought the error to the OMC's attention, the issue was resolved. I'll come back again.
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Mi spiace per non poter scrivere in inglese... ma sono veramente soddisfatto del servizio offerto. Grazie..!!
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The quality of this manual is good. It has all schematics and setup information for both the MDS-B3 and the MDS-B4. The scan quality is quite good, all pages are readable, This service manual also contains scans of the operating instructions from the User manual.
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7.3 AMP BLOCK TROUBLE SHOOTING
The repair flow of the AMP section
A
PowerON After 4 seconds Level is low. A signal from CN481. (Sound from the speakers) no output no Go to SMPS part output Level is low. yes Check the screws OK of D AMP ASSY. Check soldering of IC421,441(B-2) Waveform is not normal.
The LED lights. yes
B
CrossOver 50Hz?
The speaker relay is on. yes Control Assy Input, D AMP Assy yes
no
A
Turn to Bypass and try again.
The 8-pin IC is hot.
no
Solder shorting? no yes
SMPS Assy Voltage of IC32? Less than [ 10V ]
Check other symptoms.
C
Replace the hot IC, since it is no longer serviceable.
Solder correction
Replace IC32.
'+''-' of multi-meter is reverse.
Cases other than 2�4 below. 1
A
D
Check the resistance between G and S of the FETs (Q421, 431, 441, and 451) with the multimeter. "+" is assigned to G and "-" is assigned to S for the multimeter. Multi-meter : ADVANTEST TR6847 or equivalent FET : IRFB23N15D 2 30k� to 40k� 1k to 10k 3 0 to 1k 4
All FETs are O.K.
All FETs are O.K.
FET has been broken.
E
Check soldering at IR2011S (IC421, IC441)
Replace IR2011S (IC421, IC441)
Replace IR2011S located on the same side as the FET with low resistance.
Everything is all right, except for the waveform (resistance of R471 and 472 is 10 ohms or more). Accidental failure mode Everything is all right, except for the relay not being turned on. Although the VOL is minimum, there is output from CN481.
F
Replace R471 and R472 with new ones. Replace Q506 and Q507 with new ones. Solder shorting of VR3141 of the CONTROL Assy.
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S-W1EX
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