Marantz 2275 Restoration Reproduction Lamp Housing

richiem46

richiem46

Retired and enjoying life and music!
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I received a Marantz 2275 yesterday from a seller on USA Audio Mart. It is pretty banged up, slight bend in the lower rear chassis and the balance slider is snapped off which did not show up in the pictures. The right channel is out but both power amps work so I will troubleshoot the pre/tone board after I re-build the power supply board. It looks like the power supply board has been worked on before, new relay and some of the caps and transistors but since I have the parts I will re-build it anyway to play it safe. The right power amp board has new output transistors installed and new driver transistors also.

My biggest issue is that the Lamp Housing is completely toasted, the tabs that held it in place are gone and it is quite melted. There were some available on the auction site but currently sold out. I messaged the seller to let me know when more were available.

In the meantime I will start working on restoring the amp. The tone slider will be interesting but I an hoping I can fashion something to allow me to attach the slider knob to the shaft as electronically the tone slider is fine.

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Have you placed jumpers in the preamp to main amp connections to see if both channels will function? The internal connections are a known issue.
 
Oerets said:
Have you placed jumpers in the preamp to main amp connections to see if both channels will function? The internal connections are a known issue.
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Yes I have, both power amps work but the right pre-amp section does not when connected to either power amp.
 
Look at the connector pins on the preamp board they get dirty and required cleaning.


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I found a 3D printing outfit here that will print me a copy of the housing for $75.00 Will post how that works out.
 
The service sent me a picture of the housing. I will receive it in a few days. We will be in Key West for two weeks starting on Jan 6th so I will not see the piece in person and evaluate how it fits etc until we return.

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Here is a picture of the old and new lamp housings before I installed the new housing. You can see that the two holes in the cross members on the 3D print are missing and the housing did not fit without them due to two protruding screw shafts being in the way. Once I drilled the two holes the unit fit quite well.

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What I should have realized before installing the housing is that it was translucent, not optically opaque like the original housing. The result is that light leakage from the disl LED bulbs illuminates the mode indicators above them. The unit is in "AUX" mode in the picture and the AUX and STEREO indicators are brighter but all the others are illuminated as well.

I will have to see if I can find some optically opaque paint that I can coat the inside of the housing with to eliminate most of the leakage.

In the meantime I am going to complete the electrical restoration of the 2275 and then go back and deal with the housing issue.

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It's great we can get these parts 3D printed - but dang, $75 seems steep? I've never had anything printed to maybe it's just a high priced service.
 
I agree, $75 is a bit steep, unfortunately the seller on Ebay whom I believe is an Ak'r has no stock right now so I gave this approach a try. Good educational experience! I ordered some paint and foil tape and will try to use both to correct the light leakage on the lamp housing.

In the meantime I restored the Tone board and replaced the main filter caps in the power supply and the 2275 is sounding MUCH better!
 
Here are a few pictures of the Tone and power supply boards that I worked on.

Tone Board before:

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Tone Board after being restored:
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Power Supply Board after being restored:

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I painted the 3D printed light housing and also installed foil tape between the lower dial housing compartment and the function indicators. I also replaced the vellum on the dial. For the first time I also replaced the vellum on the two meters which was quite the undertaking as I had never done it before. Here is a picture of the front dial after this work was done. It is from my phone camera and is a bit over-exposed but I am pleased overall with how it came out.

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richiem46 said:
Here is a picture of the old and new lamp housings before I installed the new housing. You can see that the two holes in the cross members on the 3D print are missing and the housing did not fit without them due to two protruding screw shafts being in the way. Once I drilled the two holes the unit fit quite well.

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Hi. The holes are missing there for a reason. I found it very hard to make them correctly when printed, therefore i drilled them in place using drill bit of a correct size based on the metal plate. So it's not a mistake, but rather conscious design decision :)
 
bitomaxsp said:
Hi. The holes are missing there for a reason. I found it very hard to make them correctly when printed, therefore i drilled them in place using drill bit of a correct size based on the metal plate. So it's not a mistake, but rather conscious design decision :)
Click to expand...

I figured there was a reason for the missing holes!
 
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