Hello everyone,
I have frequently used this site for help and can usually solve my issues by searching existing threads. However, I have a specific question regarding a recent project.
A couple of weeks ago, I acquired a Marantz 2270 that was sold as "powers on, otherwise untested." The unit was stuck in protection mode, but it is in great physical condition and appears to be completely untouched inside.
Here is what I have done so far:
1. Measured the power board: The voltage at J802 and J803 fluctuated between 8V and 24V (instead of the expected 35V DC).
2. Replaced most of the capacitors, transistors, and diodes on the power board. This brought the unit out of protection mode.
3. Cleaned all knobs and buttons with DeoxIT and successfully set the bias and DC offset.
Currently, the left channel has random scratching noises. After testing with an external power amp and preamp, I confirmed the issue is coming from the preamp section.
While reviewing the schematic, I noticed two different revisions based on serial numbers: SN 1001 to 3900 and SN 3901 to 4900. My unit has the number 34969 stamped on the chassis and engraved on the rear, so I am confused about which schematic to follow.
Could anyone help decode my chassis serial number to determine the correct service manual version?
I have attached pictures of the serial number for reference.
I have frequently used this site for help and can usually solve my issues by searching existing threads. However, I have a specific question regarding a recent project.
A couple of weeks ago, I acquired a Marantz 2270 that was sold as "powers on, otherwise untested." The unit was stuck in protection mode, but it is in great physical condition and appears to be completely untouched inside.
Here is what I have done so far:
1. Measured the power board: The voltage at J802 and J803 fluctuated between 8V and 24V (instead of the expected 35V DC).
2. Replaced most of the capacitors, transistors, and diodes on the power board. This brought the unit out of protection mode.
3. Cleaned all knobs and buttons with DeoxIT and successfully set the bias and DC offset.
Currently, the left channel has random scratching noises. After testing with an external power amp and preamp, I confirmed the issue is coming from the preamp section.
While reviewing the schematic, I noticed two different revisions based on serial numbers: SN 1001 to 3900 and SN 3901 to 4900. My unit has the number 34969 stamped on the chassis and engraved on the rear, so I am confused about which schematic to follow.
Could anyone help decode my chassis serial number to determine the correct service manual version?
I have attached pictures of the serial number for reference.