Marantz 2275 Restoration - 1974

Discussion in 'Audio Visual' started by aokman, Oct 25, 2009.

  1. aokman

    aokman Member

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    Hey guys, thought i just scored a Marantz 2275 amp from someones garage that they were going to throw out! and it looks like its going to be a great restoration project :)

    Thought you guys might want to follow along and see if i can pull the restoration off. It is truly an amazing amplifier build quality wise, i have never seen so much attention to detail inside. All made in Japan of course with Nippon caps are far as the eye can see :thumbup:

    Rated power is 2 x 75W @ 8ohm

    After some initial testing ive found:

    - Instrument lighting requires replacement - may go down the LED route

    - Volume control scratchy - going to strip the front end and clean the pots

    - Right channel weak - unknown yet, i was turning the volume up and it tripped the relay but i think it was because i was overpowering as i switched to the left channel and i couldn't get anywhere near the same level without going deaf ;)

    Will look at recapping it depending on how it turns out, i hear both sides of the story and it depends if the right caps can be sourced for it.

    Anyway thats a starting point, ive never tried something like this before but im going to give it a go and start by stripping it down for a good clean :)

    [​IMG][​IMG]

    [​IMG][​IMG][​IMG]
     
    Last edited: Oct 25, 2009
  2. flu!d

    flu!d Ubuntu Mate 16.04 LTS

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    Early receivers rock.

    I remember my neighbor had an early Pioneer SX-1010 which sparked my love for Pioneer receivers to this day.

    With a 100wpc power amplifier section it was built like a brick shithouse.

    Good luck with the restoration dude!
     
  3. goodguy82

    goodguy82 Member

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    sell it on ebay, someone will pay good money for it if they collect this stuff :thumbup:

    All the oldskool amps are made in japan with good caps ect, compared to the china shit now.

    how much did you pay for it??
     
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    aokman

    aokman Member

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    Got it for free :) was helping someone clean out their garage - and saw the back of the amp sticking out of a plastic bag. I inquired about what it was and i got those magical words we all love..."you can have it if you want, was just going to throw it out"

    Looked on ebay and around on the net and they are a sought after model...
     
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    aokman

    aokman Member

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    ok i made a start on it today and got all the front fascia off along with the VU meters and PCB shields - quite a job mind you...

    ill tell you what though im half tempted to cut every wire inside the amp and fit proper connectors inline it is such a pain not being able to pull a board out because the wires cant be removed :(

    So far ive found most of the instrument bulbs are blown and they a fed a 8v AC supply directly off the transformer. May pose a problem to the LED's unless i can squeeze a AC-DC converter in somewhere :)

    I attacked the main volume control with deoxit and stopped the scratching after 2 hits however the right channel is still very quiet. Trying to track down the source but an interesting note is if i touch the volume pot with my finger i can send a hum through to the right channel at a normal volume compared to the left.

    Tried metering out the double gang volume pot which is rated @ 250Kohm (B) according to the service manual but ive only been seeing an output of 2k (full counter-clockwise) through to 50k (half way) back to 2k (full-clockwise) so im stumped at the moment as to what type of potentiometer it is LOL...

    [​IMG][​IMG][​IMG]

    [​IMG][​IMG][​IMG]
     
    Last edited: Oct 25, 2009
  6. mtma

    mtma Member

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    You're measuring the loudness tap with the volume wiper or something like that.
     
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    aokman

    aokman Member

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    yup im going to pull it out so i can test it properly to make sure both gangs are working properly. Looks the weak channel might be a preamp problem.

    Going to try to recap the entire unit as it seems to be the first step before looking at anything else. Most the of the smaller integrated caps will be easy to find however the primary filter caps 55v @ 13000uf are going to be hard to source, so far the closest i found is a 63v 15000uf Nippon Chem-icon :)

    Also picked up a 1A bridge rectifier from jaycar tonight to trial in the illumination circuit for the LEDS :)
     
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    aokman

    aokman Member

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    Ok last update for the night - did tried out the deoxit on some of the RCA connectors and it works great :) like new again...

    Also finishing removing and labeling the wiring for the lamp assy, cleaned up the front end of the amp and wired up the bridge rectifier to the old illumination connections. I now have a nice 7v supply at 1A which is more than enough for some LED action :D

    Currently looking at what replacements are available for the filter caps, exact ratings do not exist anymore, closest i can get is 15,000uf @ 63v i would prefer slightly more capacitance so the can is the same size but im trying not to push it too far... Voltage is irrelevant but i could get away with a 50v cap according to the specs as the supply is 48Vdc but its cutting it to fine for me.

    So far i found:

    NICHICON Marantz labelled KG GOLD TUNE 15000uF 63VDC - 85c rated
    Nippon Chemi-con 15000uf 63VDC - 85c rated

    [​IMG][​IMG][​IMG]
     
  9. itachi46

    itachi46 Member

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    great work man and yes led is the way to go with those lights.. for some reason they seem to die out within months on mine :s i've given up trying to replace them >.<
     
  10. TERRA Operative

    TERRA Operative Member

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    The bigger caps on the power filtering circuit will be fine. Just make sure the caps in the audio line are all the same capacitance value and equal or greater voltage.

    The Nichicon FG (Fine Gold) series of caps is excellent for audio use (unless you can find the original brand an series to keep it authentic).
     
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    aokman

    aokman Member

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    ok a little more progress, repainted a little of the back around the main in and preout. Finished cleaning up those connectors also :)

    Both channels are working fine now, the internal switch for the main in and preout was oxidized and causing the preamp signal not to be fed back into the amp...

    also finished building the bridge rectifier circuit which will supply this Marantz with LED goodness :) has 2 outputs 1 for the needle which needed some tweaking for brightness and 1 for the 7 blue LED's for the main backlight :thumbup:

    [​IMG][​IMG][​IMG]
     
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    aokman

    aokman Member

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    order was placed tonight for all the new parts from the USA :D

    Ordered all new Panasonic FC caps for all boards in the amp including some of the tantalum caps. Ordered new filter caps as well as a new power supply relay :D

    Taken me almost 2 days to compile this list and crossreference with the parts manual not to mention finding substitute caps for the ones not stocked. Doesn't help that Marantz labels every cap as a electrolytic with no mention of type or polarity :(

    1 2 P10247-ND CAP 470UF 16V ELECT FC RADIAL 0 0.47000 $0.94
    2 2 P11258-ND CAP 330UF 50V ELECT FC RADIAL 0 1.30000 $2.60
    3 2 P10347-ND CAP 220UF 63V ELECT FC RADIAL 0 0.90000 $1.80
    4 2 P11183-ND CAP 220UF 10V ELECT FC RADIAL 0 0.39000 $0.78
    5 2 P10323-ND CAP 100UF 50V ELECT FC RADIAL 0 0.44000 $0.88
    6 6 P11196-ND CAP 47UF 16V ELECT FC RADIAL 0 0.34000 $2.04
    7 2 P11230-ND CAP 22UF 35V ELECT FC RADIAL 0 0.34000 $0.68
    8 12 P11250-ND CAP 10UF 50V ELECT FC RADIAL 0 0.18800 $2.26
    9 2 P13197-ND CAP 15000UF 80V ELECT THA 0 23.93000 $47.86
    10 1 Z2633-ND RELAY PWR DPDT 5A 24VDC 0 7.26000 $7.26
    11 22 P11212-ND CAP 10UF 25V ELECT FC RADIAL 0 0.12500 $2.75
    12 2 PF2105-ND CAP 1.0UF 250V METAL POLYPRO 0 0.79000 $1.58
    13 26 P10312-ND CAP 1UF 50V ELECT FC RADIAL 0 0.13700 $3.56
    14 2 P10294-ND CAP 100UF 35V ELECT FC RADIAL 0 0.38000 $0.76
    15 2 P10271-ND CAP 220UF 25V ELECT FC RADIAL 0 0.38000 $0.76
    16 2 P11199-ND CAP 220UF 16V ELECT FC RADIAL 0 0.48000 $0.96
    17 4 P10290-ND CAP 33UF 35V ELECT FC RADIAL 0 0.34000 $1.36
    18 12 P11213-ND CAP 22UF 25V ELECT FC RADIAL 0 0.13700 $1.64
    19 16 P10315-ND CAP 4.7UF 50V ELECT FC RADIAL 0 0.13700 $2.19
    20 12 P10269-ND CAP 100UF 25V ELECT FC RADIAL 0 0.15300 $1.84
    21 2 P11181-ND CAP 100UF 10V ELECT FC RADIAL 0 0.34000 $0.68
    22 10 P4540-ND CAP .22UF 63V STACK METAL FILM 0 0.13300 $1.33
    23 10 P4671-ND CAP .47UF 50V STACK METAL FILM 0 0.18200 $1.82
    24 4 P5560-ND CAP .22UF 50V ELECT NHG RADIAL 0 0.24000 $0.96
    25 2 P10296-ND CAP 220UF 35V ELECT FC RADIAL 0 0.48000 $0.96
    26 2 P10776-ND CAP 100UF 100V ELECT FC RADIAL 0 1.01000 $2.02
    27 10 P10314-ND CAP 3.3UF 50V ELECT FC RADIAL 0 0.13700 $1.37
    28 10 P1175-ND CAP ELECT 4.7UF 25V SU BI-POLAR 0 0.15300 $1.53
    29 2 P1195-ND CAP ELECT .47UF 50V SU BI-POLAR 0 0.24000 $0.48
    30 5 478-1890-ND CAP TANTALUM 3.3UF 35V 10% RAD 0 0.65000 $3.25
    31 5 478-1834-ND CAP TANTALUM 1UF 25V 10% RAD 0 0.46000 $2.30
     
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    aokman

    aokman Member

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    Update for the weekend, didn't get to spend alot of time on it but i did manage to pull out the tone board and give it a good clean up i deox'd all the pots and contact switches and contact cleaned the PCB ready for new caps :)

    [​IMG][​IMG][​IMG]

    [​IMG][​IMG][​IMG]
     
  14. 3Tone

    3Tone (Banned or Deleted)

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    Awesome thread! *subscribed* I too am a big fan of old school amps and the sound they put out.

    Best of luck with your adventures dude.
     
  15. itachi46

    itachi46 Member

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    wat are you going to be using this for when you're done? i simply ended up using it as an amp more than anything >.<

    edit: also mind showing me or pm-ing me details on the LED mod? very interested.. im kinda tired of replacing those stupid bulbs -_-
     
    Last edited: Nov 2, 2009
  16. OP
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    aokman

    aokman Member

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    im going to turn it into my stereo amp i think, ive already had a play with it as is and i just love the sound it puts out more than the other amp, so much warmer and musical. Can only imagine what it will be like with all new caps and recalibrated :)

    happy to show you the LED mod, what would you like to know, its basically taking the output winding from the transformer for the lighting and putting into a little bridge rectifier from jaycar, then filtering it with a cap and passing it on to 2 outputs with 2 different resistances :)
     
  17. itachi46

    itachi46 Member

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    well i dont quite understand why u needed 2 outputs did you use different types of led for the needle from the others? <if so why? >.<
     
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    aokman

    aokman Member

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    1 output has a different resistor on it for the needle, because its a single focused white LED it was too bright running at its native power level so i had to hold it back :) and it gives me more control over the lighting level of the backlight and needle seperately. The other output if you were wondering is to pass out the AC again for the rest of the bulbs that are remaining.
     
  19. itachi46

    itachi46 Member

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    ah.. i understand now... so which lights did u not convert to LED?
    and also how did u clean those pcb to that extent o.o
     
    Last edited: Nov 2, 2009
  20. itachi46

    itachi46 Member

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    ah ic well those lights rarely die for me anyways its usually the needle lights that die -.-.. now how did you clean those pcbs.. SPILL :p

    also what exactly is involved in calibrating? >.<
     
    Last edited: Nov 2, 2009

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