Difference between 2270 & 2275: Design mistake, underrated parts

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In Reply to: Marantz 2270 vs. 2275 posted by sonicjohnny on December 30, 2003 at 17:50:13:

It was brought up to date after Marantz discovered they made a mistake with a component on the tone PC board of some of the earlier model receivers.
The bane of the early Marantz 22XX line was the 2SC458 transistor and underrated electrolytics. It seems that when the model 2X line was designed (Model 22 for instance) the low level audio circuits were powered by 25VDC. With the advent of the 22XX line some of those circuits, specifically the tone board was migrated into the 22XX line. The power supply voltage was upped to 35VDC for better headroom. It slipped through the cracks that the older circuit was designed for a lower voltage.
Two very common problems exist because of this mistake; A channel will cut out after warm up, or will crackle loudly. If you look at the circuit of a 2270 Tone Board you can see that this is a later schematic, but some of the badness still exists. Electrolytics C407 and C410 (one channel) are still 25 volt caps. The second problem is that one of the transistors used was an Hitachi 2sc458, this device is not rated at 35 volts either.
If you are restoring or repairing a 22XX receiver, replace the 25 volt caps with 35V or higher caps (don't use tantalums), replace the 2SC458's with something better such as the 2sc1000.
Otherwise, the 2270 is no better or worse sonically than any of the other 22xx receiver models IMO. Neither is the 2238, etc. I have a 2250B, and have heard many of the other models as well, and as long as they're not pushed past their power limits, I don't hear a big difference between the various models.
-LP

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Follow Ups Full Thread

Topic - Marantz 2270 vs. 2275 - sonicjohnny 17:50:13 12/30/03 (6)

Difference between 2270 & 2275: Design mistake, underrated parts - LowPhreak 03:01:30 01/02/04 (0)

Re: Marantz 2270 vs. 2275 - trippin28track 18:31:21 01/01/04 (0)

Re: Marantz 2270 vs. 2275 - blues535i 09:06:02 12/31/03 (0)

Re: Marantz 2270 vs. 2275 - Bambi B 09:06:01 12/31/03 (0)

Re: Marantz 2270 vs. 2275 - Roi de Myphi 18:53:13 12/30/03 (0)

Re: Marantz 2270 vs. 2275 - airtime 18:12:34 12/30/03 (0)

Follow Ups

Difference between 2270 & 2275: Design mistake, underrated parts - LowPhreak 03:01:30 01/02/04 (0)

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