Marantz 1122DC Restoration

[MBuras]

Well I'm always a sucker for a new project. Next up on the list (at least worth posting about) is my first integrated, a Marantz 1122DC. It looks kinda pretty on the outside which is what attracted me in the first place.


But boy the inside is sure a dirty, dusty mess. I think this thing was in a home with pets and smoker. And maybe a smelly troll. Good thing theres no smell-o-vision here.


Ok. It's not the worst unit ever seen on AK but definitely one of the dirtier ones I've experienced. Might have to try the Windex washing solution.

Once it's a little more cleaned up I'll be cataloging the boards and ordering parts. I saw there was another one rebuilt back in 2014 but not a lot of detail. If anyone has suggestions or ideas I'm open to listening.

 

[rBuckner]

Pew, I do smell it from here! Oh, wait a minute, that was just me letting off "steam".

I've heard of bagging gear and placing sliced up onions inside to get tobacco smell out. I'd go for the Windex myself and leave it outside to air out.

 

[catrafter]

Ask boatdrinks77 about his method involving a luggage rack and repeated trips from Colorado Springs to Denver and back.


Tom

 

[MBuras]

Ask boatdrinks77 about his method involving a luggage rack and repeated trips from Colorado Springs to Denver and back.

Well that is quite a scenic drive. Might be worth it.

 

[MBuras]

Well I have to say the modular construction of this integrated is quite nice. Pull a few plugs, undo half a zillion screws and the whole thing pretty much comes apart. Front and back panels are on hinges and swing out for good access. It's like a shake the box model kit except it's an awesome Marantz amplifier.



Even the transformer is loose right now. Easy access to clean everything.

 

[catrafter]

Tom

 

[Bert 1100]

Nice ! I restored its little brother, the 1090, came out very nice....

 

[MBuras]

So today I started in on the cleaning. Chickened out on the windex/water bath. There's so much great access I'm just hand cleaning as usual. A shop vac, some green cleaner and paper towels have gotten me this far. Much improved I must say.


Not everyone would scrub around the power board standoffs where no one would ever see, but when I say I'm cleaning I mean it. And it's already smelling better too! Helps to get the dust out. I think that collects smells the most.

 

[MBuras]

Felt like I was just about done cleaning the chassis this afternoon and then grabbed the input board to reinstall it. Yikes! Tons of dust way down in there.


Looks like I'll be unsoldering all those inputs from the board so I can get the dust out of there.

 

[catrafter]

Looks like I'll be unsoldering all those inputs from the board so I can get the dust out of there.

Q-Tips?

Tom

 

[MBuras]

Yep. Been using them but there's just so much dust down in there I can't reach even with a q-tip. I swear someone dumped a vacuum dust canister into this thing!

 

[MBuras]

Ok. Input board is done and reinstalled. And the brackets/shield are back on the transformer and it's bolted back into the chassis.


Now I'm just waiting on parts orders from Mouser and DigiKey. I usually order from Mouser exclusively but they just didn't have the filter caps I needed. Long story I'll detail later. In the mean time the rest of this 1122DC looks like this....


And the amp board is off to the left somewhere. 2 years ago I never thought I'd have a stereo apart like this. Now I'm like eh, no biggie, I'll get it back together no problem. Also helps there's no tuner and associated dial string. Way easier to work on!

 

[MBuras]

Was cleaning up the tone board while I await my component order. Noticed one of the selector switches is actually just a long slide switch with multiple stops. I've had trouble with these before (in a Pioneer SX-780) and so decided to pull it and open it up for inspection/cleaning.


Sure glad I opened it up because this is what it looked like


Look how clean the middle is compared to the ends! Lots of black grime. Same thing I saw on the Pioneer switch and to boot it doesn't really come clean by spraying while it's assembled.

At this point I'll have to tell you that I burnished it and flushed it with Faderlube a few times to get rid of any residual dirt. As usually with me I forgot to take a finished picture before reassembly and resoldering. But trust me it's clean.

Today my parts orders showed up so I know what I'll be doing for the next week.

 

[Steven Tate]

That's a burned looking mess. That ought to be one happy switch after its first bath in 30 years.

 

[MBuras]

That ought to be one happy switch after its first bath in 30 years.

Yes sir! Don't know why but this type of slide switch gets much dirtier than any of the other push button types found on the Marantz 22xx series. Those are usually sparkly clean when I pull them apart.

Given how bad this rotary selector looked I decided to pull apart the 4 push button switches, which also transfer the push action into a lateral slide switch. They were all disgustingly dirty as well.



Everything cleaned up nicely afterward. Only mild problem was the solder ring for the corner posts came away from the board on two switches. They are only used to anchor the switch so I soldered them back in place and everything is good. No conductivity to worry about.

 

[Steven Tate]

It's amazing how all of that dirt finds its way into an enclosed switch mounted inside a metal cabinet.

 

[MBuras]

PE01 Tone Control Board = Done!

Here's what I started with:


As shown above all 4 of the push button switches and the selector slide were pulled from the board, pulled apart and cleaned. All capacitors (electrolytic, film, ceramic) and all transistors were replaced with modern equivalents.

Here is the end result:


And here are the details. None of the original parts were failing or damaged. Replacement was a personal choice. The only real change in spec was the local DC filter and that was increased to provide the best possible ESR/ripple rating in that position. I also thought the cataloging of the board could help future techs looking for details on this unit.

CE01/02 - 50v/1uf low leakage electrolytics [manual error says 0.47uf] were replaced with Panasonic ECW series polypropylene films. Plenty of space for these nice films on the upper right.
CE05/06 - 50v/4.7uf low leakage electrolytics were replaced with WIMA MKS2 polyester films.
CE07/08 - 50v/200pf ceramics were replaced with Kemet 5% C0G ceramics. 220pf was the closest available value. Important to try and stick with 5mm leads here. Makes installation so much easier.
CE09/10 - 50v/1500pf films were replaced with Nichicon QYX series polyester films of the same value.
CE11/12 - 50v/5600pf films were replaced with Nichicon QYX series polyester films of the same value.
CE13/14/15/16 - 50v/0.018uf films [manual error says 0.033uf] were replaced with Kemet MMK series polyester films of the same value.
CE17/18 - 50v/6800pf films were replaced with Nichicon QYX series polyester films of the same value.
CE19/20 - 50v/0.047uf films [manual error says 0.47uf] were replaced with Nichicon QYX series polyester films of the same value.
CE21/22 - 50v/3.3uf low leakage electrolytics were originally slated for Panasonic ECW series polypropylene replacements. Plenty of space to the left of the sliders but I apparently forgot to order them so used WIMA MKS2 polyester films I had on hand. Still a quality replacement.
CE25/26 - 50v/1000pf films were replaced with Nichicon QYX series polyester films of the same value.
CE27/28 - 50v/0.1uf films were replaced with WIMA MKS2 series polyester films of the same value.
CE29/30 - 50v/0.015uf films [manual error says 0.027uf] were replaced with WIMA MKS2 series polyester films of the same value.
CE31/32 - 50v/0.082uf films were replaced with Panasonic ECQ series polyester films of the same value. These were chosen because the lead spacing is larger in this position. The leads still need to be bent but there plenty of extra on the Panasonics.
CE33 - 50v/100uf electrolytic [local DC filter] was replaced with a Nichicon UPW series [low esr, high ripple current] electrolytic rated at 63v/180uf.
CE83/84 - 10v/100uf electrolytics were replaced with Nichicon UPW series [low esr, high ripple current] electrolytics rated at 16v/100uf.
CE85/86 - 50v/40pf ceramics were replaced with Kemet 5% C0G ceramics. 39pf was the closest available value. Important to try and stick with the 5mm leads here. Makes installation much easier.
CE87 - 50v/22uf electrolytic [board polarity markings reversed!] replaced with Nichicon UKL low leakage series of the same value.
CE88 - 50v/0.47uf electrolytic was replaced with WIMA MKS2 series polyester film of the same value.

QE01/02/05/06 - 2SC1222 to-92 transistors were replaced with Fairchild KSC1845FTA's. Same pinout. Gain matched.
QE03/04/07/08 - 2SA750 to-92 transistors were replaced with Fairchild KSA992FBU's. Same pinout. Gain matched.

 

[Steven Tate]

You know this is dirty pool. There is an 1122DC on CL right now that I have been trying to ignore. The price doesn't qualify as a bargain, but the more I see your thread.....the more I want in on the fun.

 

[MBuras]

Honestly the best part is not having to worry about tuner boards, tuner string, etc. Everything is modular and comes pretty much completely apart. From a service perspective it doesn't get much easier.

In my brief testing beforehand it sounded ok, with static due to dirt, but I'll be anxious to see if it's a keeper afterward. Wife is already balking because she likes FM. I could care less about radio.

 

[Steven Tate]

At 75wpc (Plus the Marantz bonus watts) I'll bet it sounds like a million bucks when you are done. Can't wait for that report.