Received this vintage Marantz 2270 receiver to track down the cause of distortion in one channel when playing. There was a combination of issues with the receiver and since it is in very good condition restoration work was requested to get the unit back up to original operating specs. The 2270 is a very nice piece of vintage Marantz with an exceptional phono section which once restored sounds very nice. Lastly the receiver’s lighting was converted to LED which I am please to say I have now found a LED kit that I really like. Along with a thicker vellum diffuser the kit is not overly bright and closely resembles the original lighting but without all the extra heat and short life of the incandescent bulbs. I really like the original blue look of the dial and tuning meters which over years of burning the diffuser paper the dials tend to look green. Here are some pictures of the work.
First up was the power supply. New capacitors, and speaker protection relay.
Next it was on to the preamp or “tone” board in the service manual. To gain access to this board it is easy to remove the faceplate and tone control board. New to this restoration but I really like them is the small electrolytics in the signal path I replaced with high quality Wima stacked film caps. In listening to the receiver after I am starting to really like the upgrade.
On to my favorite part of any 2270, the phono stage. This board gets a few upgrades in addition to caps I also replaced the 2sc458 transistors with KSC1845 since they are notorious for becoming noisy. Also, you can see the little ceramic diodes were replaced with high quality silicone diodes.
On to the amp boards. These are a bit labor intensive to remove since I remove the output transistors from their heatsinks. This gives me access to the boards to replace the tantalum capacitors, two electrolytics and in this case I changed the input differential pair since the amp had an unstable offset. After working on the board the outputs were cleaned and regreased with non-conductive thermal paste before being reinstalled. The bias and offset adjustment trimmers were cleaned and checked to see if replacement was necessary. Unfortunately, I did not take a before shot.
The large chassis mounted filter caps were replace and upgraded to 10000uf caps. Also, bypass film caps were added.
All controls were flushed and lubricated. The push switches on these get especially dirty and cause havoc. Next it was on to the lighting. Here was the unit before, obviously no face plate.
Two of the dial lamps were out, along with the stereo lamp, and the tape indication lamp. It was hard to get a good picture of the finished product since I think the LEDs mess with the camera and look brighter then they actually are. But here she is…
In a dark room this receiver looks incredible and sounds even better. For this work I used Panasonic FC series high temp capacitors for the electrolytics. Panasonic THA series for the filter caps. Panasonic ECQ stacked film along with the Wima stacked film caps. The bias holds very well and offset is within 3mv of 0. Hope you enjoyed the write up and any question shoot me an email firstname.lastname@example.org