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Marantz 1180dc re-cap help/advice/insight

Richs_Trains

Richs_Trains

Well-Known Member
Hey all. Thanks for all the help on the 140 and 170dc, next from the closet is a 1180dc. I have unboxed it, tested it, and removed the covers. The unit plays well and all controls operate. This unit uses boards with pins that are prone to failure and someone before has solder bridged all the pin connections in this unit. They have also replaced all the outputs on one channel. It also appears that the relay has been replaced. My goal on this one is to re-cap the power supply, power amplifier, and replace the filter caps. About 50% of the long soldered in board is accessible, so I will try to replace as many of the electrolytic capacitors that I can reach. I will also be replacing the mica insulators and thermal compound on the outputs. Some of the solder connections on the power supply look questionable, so I will re-do them also. I will probably need help along the way and hope there is someone familiar with this unit to guide me along. Thank-you! Rich
 
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Been awhile since I did two of these back to back. There are some good threads here. The amplifier is removable which makes that part easier. I don't recall having too much difficulty getting to every board and replacing all the capacitors, etc. I remember that the relay board on both had significant heat damage and required board repair. and new resistors. Best of luck!
 
If it’s anything like the 1122dc I worked on a few years back then don’t trust the manual. The 1122dc had the most parts list errors I have encountered. Physically check everything before ordering parts.
 
foldthe said:
Been a while since I did two of these back to back.
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Thank you for your insights and well wishes, any advice on the power supply to upgrade for the heat?
MBuras said:
The 1122dc had the most parts list errors I have encountered
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Thanks for the advice, I did already order the parts as per the SM, hopefully, I have whatever might be wrong, but I always replace like for like, one at a time. Rich
 
So, the offset adjustment says to use JN01 and JN05 for one channel and JN04 and JN06, but trying to follow the schematic (not my strong suit), it looks as if this is before the relay and once the relay fires it goes to the speaker switch and then the speaker terminals. Can I set the offset at the speaker terminals with speaker one engaged?
 
Well, since the power amp went well, I decided to tackle the relay board and the front half of the pre-amp. When I first opened this unit I noticed the peak indicator wires were re-soldered very poorly and it gave me pause. I also felt the relay had been changed since it was an Omron. I was right on both counts, someone who couldn't solder worked on this and when they replaced the relay they used the wrong pin type and forced it to work by drilling out the holes and running jumpers. It looks terrible, but it works and they destroyed the board more than I am able to repair, so it stays (luckily it can't be seen once assembled).

1180dc_10.jpg

They also replaced two transistors and did not trim the legs, ugh.

1180dc_9.jpg

I replaced all the electrolytic caps and I hope I didn't screw up because I have to re-assemble this before I can test it and I did two boards, which I usually do not do. Rich
 
Looks like someone was just in a hurry. I used to get angry and frustrated when I would find shoddy repairs, but then I just realized that it was my opportunity to learn more, especially with regards to using my imagination. I've made a lot of board repairs. some don't look great but they are always solid. I exhaust all possibilities before I start looking for a donor board. 1180dc boards would be very difficult to find unless someone on here would help. Maybe put up a request in barter town.

With regard to heat. This amp runs hot. I have two and they both run hot. I think it has more to do with design than anything. I have seen debate about increasing resistor wattage in certain areas for heat dissipation, with the critics being concerned about safety/protection. I believe there was a verified mod for the phono board that involved going up in wattage. You might try a search and read through some threads or maybe someone will chime in.
 
foldthe said:
This amp runs hot
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I replaced all the caps on the relay board with 105-centigrade caps, I don't know enough to make changes in values. Hopefully, new mica insulators and thermal compound will help a little. Getting the caps in the pre-amp board was a chore because all the boards have been soldered in place, but I managed to replace them all and it passed the DBT and is playing music as I type. Just have the back half of the pre-amp (which is much more accessible) and the filter caps which won't be here till Tuesday. So far, so good. Rich
 
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You are truly making a silk purse out of a pigs ear on this one, Rich. Great work! Did you get your DC offset adjusted that you were having problems with?
 
Steven Tate said:
You are truly making a silk purse out of a pig's ear on this one
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Thank you for the kind encouragement, Steven, yes everything is good, just waiting on the filter caps to finish it off. Wasn't really having a problem with the offset, just curious if I could set it at the speaker terminals. I have so much stuff I never worked on, feels good to pull some of these out and refresh them. Still hesitant about tackling a 2270, but I do have a 2226 that is completely dead and pretty beat up, so I can't really make it any worse! Rich
 
IIRC correctly yes you adjust with probes attached to the speaker terminals. I have two of the inexpensive parts express digital meters so able to both channels at the same time.

I recapped mine last year and it seemed easy enough. Left the big filter caps alone at that time.

I think it is a very nice sounding amplifier.

Plenty of power!

A looker to IMHO!
 
Oerets said:
I think it is a very nice sounding amplifier.
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I really like the variable loudness control, I was using this one several years ago but acquired a 3250 pre-amp with an SM-7 and it gives me a bit more power (150 watts per channel) with the same controls. Would really like to find a 3650 pre-amp but they sell for way beyond my budget. Rich
 
I had a guy coming by to purchase the 1180DC and went MIA on me. Then decided to make it a rainy day project seeing I had all the caps already.
Fixed it up and WOW! What an improvement from before. It was nice sounding and all that already, just after the recap it open it up so much more then before.

Make sure to get the one board pins (Mode) at 90* as up and snug as possible.
 
Well, I finally got up the nerve to tackle the filter caps. it went much better than expected. The lugs on the new caps fit into the holes for the old ones on the ground plate and after trimming a small piece off of the ground plate I was comfortable with the gap between the poles. I set the dc offset, but have a question about it. Setting at the speaker terminals, upon initial start-up the offset is around 500mv and drops steadily to 0mv as set. This seems to happen on both channels, is this an issue I should be concerned with? Thanks, Rich

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Looks Nice. Congrats. I recall that being the case for me. Does the relay click in a reasonable amount of time. Just checked mine. Click at 5 seconds. The second time was four seconds
 
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