Dax617 Posted January 2, 2007 Share Posted January 2, 2007 Both pieces power up, and I was able to get sound from the left channel but not the right, although the power meter is working for both. I have found the service manual on line but not the owners or operation manual. Does anybody know what the input coupling switch @ the rear of the mc2105 does? The options are "direct" or "normal". Thanks Quote Link to comment Share on other sites More sharing options...
Guest " " Posted January 2, 2007 Share Posted January 2, 2007 This is a very difficult amp and pre-amp to work on. You push here, it gives there, you push there it gives here. Not worth it for you. You should sell it to me. Quote Link to comment Share on other sites More sharing options...
Parrot Posted January 2, 2007 Share Posted January 2, 2007 That's very kind of you, speakerfritz [][] Quote Link to comment Share on other sites More sharing options...
Mike Lindsey Posted January 2, 2007 Share Posted January 2, 2007 Wow! This is better than the deal I just got on a MC2205/C28/MR71 for $500! Congratulations on a great find! Unfortunately, I know nothing of your questions, but there are many others here who are much smarter than I in this regard. Be patient, and they will come. Mike Quote Link to comment Share on other sites More sharing options...
Dax617 Posted January 2, 2007 Author Share Posted January 2, 2007 The face plates and lettering are in good cond. Only a little bit of "bubbling" around the headphone jacks. There is some surface rust on the chassis. I am eager to audition this duo on my khorns. see if Ilike the basic sound and maybe recondition them depending on price. Quote Link to comment Share on other sites More sharing options...
Dax617 Posted January 2, 2007 Author Share Posted January 2, 2007 It seems the c26 has issues as well as the mc2105. The preamp makes sound untill the volume is 1/4 then cuts out. Tried a different preamp thru the power amp -sound @ one channel only. then I tried the normal position @ the rear input coupling switch. No sound. Then I switched it back to direct- no sound.Meters are still pumping for both channels. Why would anyone sell mc euipment for $50? Ill post with updates. Any mcintosh owners feel free to advise. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted January 2, 2007 Share Posted January 2, 2007 It seems the c26 has issues as well as the mc2105. The preamp makes sound untill the volume is 1/4 then cuts out. Tried a different preamp thru the power amp -sound @ one channel only. then I tried the normal position @ the rear input coupling switch. No sound. Then I switched it back to direct- no sound.Meters are still pumping for both channels. Why would anyone sell mc euipment for $50? Ill post with updates. Any mcintosh owners feel free to advise. I can understand equipment being sold for some low amount of cash. The senerio could be they were free to the individual and the individual took the items to get repair estimates that came in too high. It is sometimes better to get something out of the deal than to soak more into it and continue to have the question of future uncertainty. Quote Link to comment Share on other sites More sharing options...
Parrot Posted January 2, 2007 Share Posted January 2, 2007 Exactly right, speakerfritz. Let's say, just for example, he got a quote for $1000 to make both pieces right. His wife says, "Are you crazy?!?!?! We've got a home theater receiver that's just as good. Get that junk out of here!" Quote Link to comment Share on other sites More sharing options...
thebes Posted January 2, 2007 Share Posted January 2, 2007 I was with TC yesterday when we hooked these up. I suspect thevolume pot on the pre needs some bad cleaning., but with meters showingpower going through to both sides of the amp and sound only coming outof one channel maybe it's not too bad. Nice looking beasties with only one of the lights out and prettyamazing they lit up at all since they been sittting in a basement foryears. TC check your forum Inbox for info on the TEAC dolby noise supppresor that also came along with the deal. Come on you Macsters give us a hand here. Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted January 2, 2007 Share Posted January 2, 2007 Both pieces power up, and I was able to get sound from the left channel but not the right, although the power meter is working for both. I have found the service manual on line but not the owners or operation manual. Does anybody know what the input coupling switch @ the rear of the mc2105 does? The options are "direct" or "normal". Thanks The input coupling switch when in the direct position will bypass a .22mfd input coupling capacitor that is in the input circuit when the switch is in the normal position. Basically the capacitor is their to block any DC Voltage Offset from say a pre-amp that might get into the amplifier otherwise. The safe way to use the amplifier is with this switch in the normal position if your not sure if a pre-amp has any DC Offset on its Output! edit: Actually after looking at the schematic a little closer the .22mfd would just block any DC Voltage from the Level Control(which you wouldn't want also) because Mac used a .47mfd right after the Level Control which would also serve to block any DC Voltage from the Input Gain Stages so I'm curious what Mac would consider the benefits of using the Direct Mode Option. If Both Power Meters appear to be working normal with the same signal being feed to both left/right channels then you might want to check out the Speaker ON/Off Switch located to the right of the Headphone Jack. If it happens to not be making good connections you could loose one channel and the power meters would still register as normal. If this switch hasn't been used much it could just not be making good connection and maybe needs some contact cleaner. You might try a pair of Headphones to see if you have sound from them on both channels. mike tn[] Quote Link to comment Share on other sites More sharing options...
Coytee Posted January 2, 2007 Share Posted January 2, 2007 Send it to Terry DeWick http://mcintoshaudio.com/dewick_repairs.htm He IS the McIntosh man! Nice guy to boot and many many people say, charges WAY to little for what he does. He's an authroized McIntosh service center. My understanding is, he won't "tweek" things to flavor their sound, he will put them back to McIntosh's specs. Probably not fair of me to put words into his mouth but I DO think he said something of that flavor to me once (when speaking of my MC-30's) Quote Link to comment Share on other sites More sharing options...
rcarlton Posted January 2, 2007 Share Posted January 2, 2007 I second the suggestion of sending them to Terry. Stands by his work, very quick. Very, very good prices. You will be pleasantly surprised. You should see how he restored a pair of MC-30's that were in a house fire. Quote Link to comment Share on other sites More sharing options...
Dax617 Posted January 2, 2007 Author Share Posted January 2, 2007 Great replies, all things I'll look into. Thank you for the input. My friend bought these on my behalf and I cannot fault the purchase for the money, he is looking out for me. Who knows I might get an 8b out of it like Thebes. I am just trying to pick up the pieces. In my experience if the power meters are showing signal the channels are there. Remember I am only a few hours into this venture and I am not committed. I have a working system. What is he best contact cleaner? I went to rat shack and all they had was this lubricant/cleaner/non flammable. I have some stuff from the way back from Dad that destroys the ecosystem @ work. I"ll try that tomorrow.Does anybody know if any of these solvents damage the face plate in any way? If you think it is better to buy a system working and complete for 1000 (what you would pay for the combo,possibly) or better to gamble let"s hear it. Quote Link to comment Share on other sites More sharing options...
rcarlton Posted January 2, 2007 Share Posted January 2, 2007 Deoxit works best. Should be able to get it at Radio Shack. Quote Link to comment Share on other sites More sharing options...
Parrot Posted January 2, 2007 Share Posted January 2, 2007 Be extremely careful with the lettering! You can damage it easy as pie. I'd recommend doing nothing at all as far as cleaning the front, or you may wreck the collector value totally. Quote Link to comment Share on other sites More sharing options...
boomac Posted January 2, 2007 Share Posted January 2, 2007 Regarding the amp: I had the same problem with my 2155. Both meters functioning and one channel out. Turned out to be a very inexpensive part. I forget what it was called but I'll call the tech that fixed it tomorrow and post the info then. Very common on Mac gear, especially when it has been dormant for a spell. Quote Link to comment Share on other sites More sharing options...
djk Posted January 3, 2007 Share Posted January 3, 2007 "Be extremely careful with the lettering! You can damage it easy as pie." Lettering is behind the glass on MC2105/C26, be careful of lettering on chassis. Quote Link to comment Share on other sites More sharing options...
boomac Posted January 3, 2007 Share Posted January 3, 2007 Your amp problem may be a bad opti coupler. It should not be an expensive repair! Quote Link to comment Share on other sites More sharing options...
djk Posted January 3, 2007 Share Posted January 3, 2007 "Your amp problem may be a bad opti coupler. " Doesn't have one. He probably doesn't have a 2105, probably a 2205. Quote Link to comment Share on other sites More sharing options...
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