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Old 4th October 2013, 09:25 PM   #1
TV7 is offline TV7  Australia
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Default Marantz 1250. Evolution in sound?

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First time posting in solid state as I was strictly a tube guy, my daily listener is a pioneer SA-400 and the weekends sees the big mac MC275 and C22 warm up for sheer listening pleasure. I bought this marantz because I cannot find a 1300DC and at 125W per channel I should be happy right? well almost.....

Picked this fine amp up from ebay, paid a premium price for it as they are almost unobtainium in Australia and am looking for any suggestions on re-refurbishment. Common sources of issues/annoyances ect....

Also for anyone who may be able to help, I attempted to set the idling current on the amp channels. The right was fine, having plenty of swing with the trimmer but the left barely reaches the 10mV at full turn of the pot, this drops slightly as the amp warms up. Power supply is fine. The big twin cap and other lytics seem to test fine on my sencore LC53. Any help and sharing of experiences is greatly appreciated as I have only re-built tube gear and am banging rocks together over here with SS....

Attached is a pic. The face still had the original marantz plastic cover, hence the AS_NEW condition. All considered an excellent amp.
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Old 4th October 2013, 09:44 PM   #2
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Well ... there is plenty of good and plenty of bad

the good ones
--Marvelous tones
--Nice sonics
--Plenty of power
--Joyful phono stage
--Plenty of Functions
--Looks ...

The bad ones
--Got your self a pile of dead or half dead capacitors
--Got your shelf a gozillion of contacts that sooner or later will need cleaning
--Overall gain is kinda too much and input sensitivity low to cope with modern sources
--The complexity and style of make ( plus the plenty of functions ) will introduce crosstalk in most of stages of the amp and present bad channel separation


The total picture will be a powerful machine with plenty of tone ready to cope with almost any kind of speaker and/or music ... Keep only one active source at a time and its going to be quiet .

Now most of these problems like cross talk and ch. separation will never be fixed the rest of the problems can be fixed it will cost alnost nothing but will consume plenty of time .

Fixing the bias problem is not a solution you will not get away with it you need to fix the all machine cause otherwise something else will fail and soon if you put it to everyday use .

For the bias it could be a number of things while everyday suspects are capacitors , trimmers soldering and semis . If you need a free schematic i have one you are welcome to it .

Kind regards
Sakis
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Old 4th October 2013, 09:51 PM   #3
TV7 is offline TV7  Australia
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Thanks for the reply Sakis, I'll take that schematic if you please. I have a downloaded service manual but it's a bad resolution and not very usable..... do you mean just the electrolytics or signal caps that may be bad? usually I only like to change caps that need it and keep others that may not have such a hard life.....
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Old 4th October 2013, 10:10 PM   #4
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Bad practice ...if you replace then do it for all given the chance many of them inside can be beefed up from many aspects like capacitance voltage and temp .

email me for the schematic

PS
I don't think that capacitors have to do anything with your bias problem but need to be replaced one way or another ,

Kind regards
Sakis
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