Marantz 1180DC, baby!

[dyche01]

I just bought a Marantz 1180DC off of eBay. The seller said that he didn't have speakers and couldn't verify that the unit works which, in my experience, usually means that it doesn't. But the price was right (even with shipping) and I like fixing old gear, so I took the plunge.

The unit arrived today, very well packaged and looking much better than it did in the photos. I plugged it in, expecting either smoke or silence, and instead got the most amazingly clean, deep, and rich sound! Right out of the box! The pots weren't even noisy, which was a bit of a disappointment as I had the Deoxit D5 out and ready to go.

The only issue I see is that two of the peak indicator lights (over the bass and midrange sliders) are permanently on. As far as I can tell there are no issue with the tone board itself, or with any of the other controls because they all appear to work like they should.

EDIT: The center light is actually the 'power' indicator. The stuck peak indicator light was for the left channel.

 

[PPstereo]

I can relate to picking up these later champagne dc era units cheap.

I pulled a pm 500 dc out of my local thrift shop trash. On good terms with the powers that be so I buy such things. Needed cleaner of both controls and cosmetics. But fine afterwards.

Seems they dont get the love the coveted silver gets. Oh well...

Not sure if its the same lineage of yours but... and btw yours is one helluva beast! Mine is no where near that brute power wise imo.

 

[Eric n Kc]

Hey,
Damn your gonna make me go down and dig mine out for a listen. Man I was crazy about 1180 dc's at one time. I must have been I have 2 of them. The first one I bought here on AK (first thing I bought on here actually ). I was told it was recapped by a shop down in atlanta. For some reason I picked one up on ebay a few months later. It was surely a bargain.
They are pretty as well as good sounding amps for sure.
Now your gonna have to chase down a sweet a$$ tuner for it set on.just saying. Eric

 

[mech986]

Very nice!

 

[FinalVinyl]

great find. I don't plug in stuff that old unless I thoroughly inspect it and test the power caps. you lucked out

 

[dyche01]

Hey,
Now your gonna have to chase down a sweet a$$ tuner for it set on.just saying. Eric

Ha! Way ahead of you! While I was waiting for FedEx Ground to deliver the amp I bought a super-sweet little Marantz 105 tuner from a guy in Oakland.

 

[dyche01]

great find. I don't plug in stuff that old unless I thoroughly inspect it and test the power caps. you lucked out

Good advice. I did pull the cover before I turned it on and looked for any smoked resistors or caps that were obviously blown.


So far my favorite feature is the "Contour" knob which, based on its effect, appears to be an adjustable "loudness" button that pushes up the top and bottom ends of the frequency response, probably along a series of Fletcher-Munson curves.

 

[JURB]

I saw one of those go for like $900CDN on the bay.

 

[turboyam]

Ohhhhhhhhh! is that cuter and nicer then a BPC one?!

 

[bluestime]

great find. I don't plug in stuff that old unless I thoroughly inspect it and test the power caps. you lucked out

He likes fixing things.

 

[dyche01]

Here are a couple of photos of the 1180DC in situ, playing with its new best friends: a dual 1245 TT and Marantz 105 tuner.

Still sounds super sweet!

 

[turboyam]

Ahhhhhh, You should send me this heavy piece right away, for proper disposal. I will gladly send you a nice, lightweight BPC, modern, black plastic receiver in exchange!.

 

[jwrauch]

Wow !! Great score !! JOHN

 

[Eric n Kc]

Hey,
Pretty sweet. Eric

 

[rxonmymind]

Nice!

 

[jblmar]

Nice find.
Still, I wouldn't ignore the Peak lights constantly being on. Something is wrong. Do yourself (and your speakers a favor) have the amp checked out or check it out yourself before hooking speakers to it.

 

[dyche01]

Yeah, I have noticed a handful of little issues that need some attention and I am planning a tear-down for this weekend. I will keep you posted.

 

[FinalVinyl]

a good starting point are the power cans. more than likely they're way out . every lyctic will be out. well worth the time and labor. wish I had one of those. the service manual is at hifiengine and tips on biasing the transistors are on the web

 

[dyche01]

Did a little work on the 1180DC this weekend. The main problems (some of which only emerged in the past week) were:
1. Persistently ON left-channel peak indicator light.
2. Busted/gummed up switch for speaker system B.
3. Intermittent loss of the right channel.
4. Faint 60 Hz hum through the phono channel.
5. Nasty pop in the speakers upon power up.

I was most worried about the channel cut out, which got progressively worse with time and seemed to be temperature dependent. This turned out to be the simplest problem to fix. The filter board was not properly seated and a couple of the switches on the bottom of the face plate were still dirty. I actually had to take off the face plate to get at a couple of them. The mute button, in particular was responsible for the temperature dependent fading in and out of the right channel. A thorough cleaning of the switches and reseating of the boards was sufficient to take care of all the channel drop out problems.

Looking over the phono/pre-amp board I noticed two broken traces. There was a clear tool mark on each one and the cuts were so clean that they appear to have been intentional. I brightened the edges with a bit of coarse Scotchbrite held in a pair of forceps and then bridged them with a bit of copper wire and solder. The hum in the phono channels is still there but seems fainter. I can only hear it when the volume is turned near max.

I haven't pulled the Relay/Peak Indicator board yet so the light is still on, but otherwise functioning beautifully. I love how it sounds through my old Polk Monitor 7's

 

[dyche01]

Update: I finally got around to checking the output offsets (for some reason I assumed they were okay) and found that both channels were way off (-1.2 v and -0.98 v). Once both offsets were trimmed to zero, the nasty speaker pop AND the 60 Hz hum in the phono channel went away!

Now, with no turntable attached to the phono input, all I hear at maximum volume is faint white noise.