Marantz 1180DC restoration

[cbusuttil]

Unfortunately Bass and balance rheostats levers were snapped sometime before i purchased it. I could not source any identical ones but i did manage to find some 1072 ones, albeit very different. So what i had to do it “swap” the old wiper levers onto the original pots, or so i thought… until they arrived at home, lol. completely different, but the tip looked the same. So with some time and a lot of patience, i “fitted” them onto the original pot levers with a screw. Finally, some superglue was poured so that they stay firmly tight. They aren’t even noticeable with the face plate fitted as i made sure to keep the same protruding lengths! Now the only thing left is to source the knobs… which seems to be another headache..

 

[cbusuttil]

Checking how the “repaired” bass lever align with the others by fitting one of the knobs! Success!

 

[cbusuttil]

While at it, the wipers were polished with metal polish and lubricated afterwards! The carbon footprint was cleaned and lightly buffed too.

 

[Oerets]

It is such a sweet sounding amplifier.
Real detailed and plenty of power.

What speakers?

 

[cbusuttil]

It is such a sweet sounding amplifier.
Real detailed and plenty of power.

What speakers?

What i noticed was that the highs are really clean and crystal clear. Right now it's hooked to my '77 Yamaha NS690II but eventually it will be connected to one of my Yamaha NS1000M set. (Other set is connected to the Pioneer SX-1280, which i restored a while ago There's a thread on audiokarma about that restoration). The main reason why i am making sure that electronically it is in tip top condition, is because i cannot afford to have a 0.30$ signal transistor start popping and crackling on those speakers .... Yamaha NS1000 drivers are seriously expensive!!

I really hope they shine on this amplifier as well, as those speakers are really really picky.... (those beryllium drivers are really b*** and can uncover almost any defect!!!)

 

[Oerets]

I had mine connected to a pair of AR2ax the last time it was in use.

In reality every pair of speakers it was connected to sound great.

Might consider using a inline fuse holder like for car power supplies on one leg of the speaker wire. Using a fast acting fuse with a depending you personal listing determining the value. Start with a 1 amp and if you blow them just listening the move up a little at a time. I have used 8 amp IIRC before on a Carver/Advent setup.

 

[cbusuttil]

I had mine connected to a pair of AR2ax the last time it was in use.

In reality every pair of speakers it was connected to sound great.

Might consider using a inline fuse holder like for car power supplies on one leg of the speaker wire. Using a fast acting fuse with a depending you personal listing determining the value. Start with a 1 amp and if you blow them just listening the move up a little at a time. I have used 8 amp IIRC before on a Carver/Advent setup.

Thanks! great tip! i did think about putting some PTC ones but i think the fuse tip sounds better! I do think this is a very good amplifier indeed. And it seems they sky rocketed in value. a restored one goes around 1500 - 2000$, so well worth the effort. Not that I will ever sell it, but it's good to know that if you ever need to sell, you won't loose money! I think i already spent some 40 hours on this...

 

[cbusuttil]

The OCD kept kickin in my head re. those high powered resistors , so i replaced them with metal film and metal oxide ones. 33 ohm resistors wilhich feed the differential pair were uprated to 1% 100ppm as well. The 0.33 ohm 3 watt ones were uprated to 7watt ones. Many of the resistors located on those ceramic stand offs, were uprated in terms of wattage.

Here’s the final photo of the amp section:

 

[cbusuttil]

Protection Relay was disassembled and contacts cleaned with metal polish. I like the way the click sounds; so i opted to keep the original one.

 

[cbusuttil]

Top view of the unit. I fitted a small fan to help with the heat dispersion. Fan speed is fully adjustable via trimmer located on the PWM controller (fitted with glue on the transformer). And no, i didnt hear any buzzing noise in the speakers after installing this!

 

[Oerets]

Like how you did the fan. I pulled a 5 volt wall wart power supply apart and retrieved the circuit board. Thinking of doing something about the same on mine. Connect it to the switched AC line.

Having both the metal and wood cabinet for mine. Don't like the wood cabinet afraid of it not allowing for optimum cooling, so use the metal.

In the end just use the switched outlet and place the two little fans on the top over the heat sinks.
Sitting idle right now got the 1150 in service.

Did you eliminate the popping?

 

[cbusuttil]

The popping is still there, but its very faint, barely noticeable.. i guess i have to live with it that way!

Here’s what i did on mine: 5v 1amp wall adapter (thats what i had in hand and as shown in the photo, it sits near the relay pcb. try to use a good one, off a wifi router as those have good electrical noise dampening ), up converter from 5v to variable output up to 15v. then i set the fan in a sweet spot between enough cooling and noise …i found one which had the approximate screw hole spacing as the filter board. then i machined some plastic spacers for the fan to sit on. these seat on the pcb. nothing special, just simple spacers that you can even do with some plastic washers stacked on top of eachother.. the point if that fan is not to cool the power outputs, but to keep a stable temperature around the cramped components area… i suggest you do fit one, since as you know as much as i do (if more!!) these amps run really hot. i wonder what the biasing current is… im guessing minimum 50mA per transistor! Marantz specifies 60W power consumption while idle…

 

[cbusuttil]

ohh another thing… i suggest you do not clean the tone control rheostats as mine is sticking now. thank god i only did the Bass one… it gets a bit awkward when trying to set the bass. i tried many different lubricants, PTFE grease etc, nothing seems to work. i even slacked the rheostat pcb, but still no success. i hate it that i ended up sticking after all that work….

 

[Oerets]

Have you any Fader Lube?

That is all I ever have needed to use on sliders.

 

[cbusuttil]

Have you any Fader Lube?

That is all I ever have needed to use on sliders.

View attachment 2525175

Never managed to find in my country (tiny island, Malta) ... however i did work around it. the 2X Marantz 1072 sliders i bought were still smooth, so i swapped the sliding mechanism and the metal section which still has the original grease. works like a charm now!

 

[cbusuttil]

Components changed: all transistors and diodes with the exception of the phono amp section (because i do not use it) were replaced. All high power resistors on ceramic standoffs were replaced with higher wattage, metal film/oxide/ types! Every electrolytic capacitor was replaced with higher temperature one; audio caps in the signal path, low esr high reliability ones in the dc path. What a journey!!

Pre amp and linear power supply section (the transistors wrapped in kapton tape are the original matched ones. I opted to keep them like that:



Protection Relay and peak indicator board:



Filter Board:



2SK109:



Power Amp board:



8X Power Transistors:




Bridge rectifier and dual diode (from relay board):


All Capacitors from all boards. the 2X 18000uF main filtering caps are not in the picture; as stated, these have been uprated to 22000uF:



And that’s it!! Amp is up and running like new! Hopefully it will be good for another 30 years!

 

[cbusuttil]

Testing the Marantz with my NS1000M… sweet amp! i am getting the impression that the Pioneer SA-8800 and 9800 are more accurate and fast on the highs than the Marantz. might be wrong… but thats the impression i got…

 

[Oerets]

Have in the past owned of few of the big SA Pioneers.
Like the SA9500 and SA9900, yet still sold them.

About the best Pioneer for me was the SX1010. Took a good long while, yet it was eventually passed on to another more appreciative owner. Do miss it at times. But that passes....

More a Marantz guy it seems.
Have been for some time.

The 1180DC is one of those units that will make any speakers sound good have found to be true.
Not speaker dependent like I feel most Pioneer or Yamaha even Luxman Integrated amplifiers seem to be for me.

Sansui Onkyo Hitachi are others another brands that will sound great on a wide range of speakers.

 

[cbusuttil]

Have in the past owned of few of the big SA Pioneers.
Like the SA9500 and SA9900, yet still sold them.

About the best Pioneer for me was the SX1010. Took a good long while, yet it was eventually passed on to another more appreciative owner. Do miss it at times. But that passes....

More a Marantz guy it seems.
Have been for some time.

The 1180DC is one of those units that will make any speakers sound good have found to be true.
Not speaker dependent like I feel most Pioneer or Yamaha even Luxman Integrated amplifiers seem to be for me.

Sansui Onkyo Hitachi are others another brands that will sound great on a wide range of speakers.

Indeed that is something that i agree with. I hooked up my 1180DC to my Marantz HD77s, Yamaha NS 690s, NS300x, and the NS1000M, They all sounded very good. Don't get me wrong, I really really like this 1180DC, decent power and the bass frequencies are really beautiful - something i always felt the Pioneers lacked in... I also feel the sound that the Marantz outputs, is less tiring than the pioneers I've had/have. You can listen to it all day...Definitely warmer i feel. I also have a little MR230 (i think it's a 1530 in US) and that little receiver is really sweet sounding!

Ahh Sansui, never had one, but I'll look forward to get one!

 

[cbusuttil]

I read that the Sansui 9090DB sounds great too. but it's fetching serious money! Have you ever heard a 2385 or a 2500/2600? I think the earlier Marantz like the 2285, 2265 are warmer than the "B" ones