dewickt
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  • Hello. I restoring a MC-30 Serial 14757. II follow schematics SC-111-137 from 3.14.60. look similar to actual configuration. But i have mismatch, some resistor the i must found on unit are missing. R9 680K, R31 2.2Meg, R32 330K. And i check every value on my physical unit and i have 2x 1Meg resistor that don't match with drawing and a 1.2Meg that don't match. Regards.
    Hello sir. I was the extremely lucky recipient of an MC2505. It has no front glass but I have been playing it for a couple of weeks now. It sounds amazing but I would like to get it serviced so it will last for a long time. I was wondering what the wait time was for your services and if perhaps I could send this your way. Thank you sir.

    Bill

    wckaehler@gmail.com
    Hi terry its miguel I recently post about what paint is used on mcintosh unit and Mike replied to me that you where the person to talk to. And he mention to me that you work on mcintosh. I have a mcintosh mr 7083 that indeed of paint job and I've been trying to find out on the wed on what type of paint used on mcintosh unit but my research fail so pls. Help me, Thank you so much God bless you always . Migz
    Hi, Terry. Hope you are well and happy! I have a C32 with non working 18V power supply. I can't identify the + and - regulators as only a Mc part number appears in the manual. Can you help? Dan
    Terry:
    I have a MC2105 that's losing it's left channel as it warms up. I Need to get it repaired. Do you service this amp? What would be the approximate cost for repair and lead time. I imagine your a pretty busy man with Mc repairs.
    Thanks in advance
    Mark Laurint
    Email: Youdonomark@yahoo.com
    Hello Terry, I am new to this site, and am trying to learn to fly the system. I discovered your posts throughout, and thought it potentially a good idea to ask a question. I have a McIntosh C39 whereby it will intermittently shut down. Typically, i can then not successfully power it back up for very long stretches of time (days or weeks). I have disassembled the unit and inspected the PCB to which the power switch is connected. Tried compressed air inside the switch as well as connect cleaner to no avail. Is it likely the switch or maybe a bad relay, or something entirely unrelated to the power circuits. Thanks in advance.
    Hi, I am working on a Mac 1900 which had no sound. I manage to get sound but it is less than adequate. (1) the R ch is distorted with low volume, L ch seems to be at normal volume but there's a slight high pitched hum from both chs. I'd checked the 2 pre amps & power supply boards, they are not the problem. (2) I had to restring the pointer & realized that I was unable to align the pointer with the station dial because in this unit the tuning drum has no fastener or screw where you can remove it or loosen it. I have already tried adjusting the pointer adjustment screw (shown in the service manual) but got nowhere. In the Marantz Recs you can also make this adjustment by placing the pointer on a selected station and tune to it, by turning "a particular screw" on top of the FM/AM rotating station coil. Like in the Marantz Is there another way to make the pointer adjustment in the Mac 1900? Please put me in the right direction on these 2 problems? Thank You, Anthony
    Can temperature, though if they are both cool I would check bias voltage on the outputs, with the plate voltage at 440V the grid should be -44V.
    Thanks Terry. What exactly should I measure, and where?
    Voltage at each pin on the filter cans? Live after warming up?
    Or do you mean something else?
    The filter cans don't feel warm at all, by the way.
    Measure the filter can and compare, doesn't take much leakage to overheat the transformer.
    Hi Terry - Thanks for your info on my schematics question. I recently bought a tube tester, and after checking all my tubes I'll update my thread on fixing those old MC30's.

    Meantime, I have a question about the mint MC30 pair I bought from you and Tom. I noticed the power XMFR on one unit is much hotter than the other, and wonder what a normal operating temperaure is. After about 4 hours, one channel is >140F (60C) at the top side closest to the 6L6GC's.

    At the same time, the other XFMRs are at about 110-130F.

    I haven't opened the chassis of these amps, but have replaced all the tubes with NOS that I have retested and matched.

    Differences I see are the 6L6GC tubes of the cooler unit are better matched than those of the hotter unit, and the two units have some difference in heat dissipation by air by their locations.

    Is 140F or more a normal and safe operating temp? Also, is it normal to have such a large temp differential between two amps?

    They continue to sound like heaven...
    Hi Terry - a question about schematics and version Nos. came-up on my new thread, "My first MC30 rebuild" - if you have an interest and the time, we'd sure appreciate your help! :)
    Hi Terry, hope you are still around on the forums... do you have any suggestions for the mr 71?
    I would start with a new blue filter around the #1847 lamp behind the meter. As far as I know there are no new meters for the 77.
    Terry:
    The moderator suggested questions be directed to an expert via PM.

    I have an MR77 in beautiful shape. The problem is that the signal strength meter on the left is dim, has a green cast and a dark area. The other meter is perfect. I found that the good meter has a uniform milky white back while the "bad" meter rear light diffuser has a distinct milky brown color. The brown color is uniform across the meter and looks solid like it is molded in. Why is this? Do I have to get a new meter to correct the color and brightness? The meter itself works fine. The brownish overlay looks like it was glued on but it is on tight. I don't think heat would do this. The meter is located next to the vacuum tube multipath indicator.
    Thanks,
    John Lovda
    The 275 cage fits all 275 from the first production to present, the 240 cage is smaller in all 3 dimensions and can not be interchanged.

    Terry
    Mr Dewick,
    I would like to have you 'do' my MX-110. I am contacting you through this forum because I have been a 'lurker' here for some time. I have reviewed the posts on rebuilding this unit on this forum and I am simply not comfortable enough with my skills to take on a project of this scope ... you gotta' know your limitations! I've had a look at your site so I know you're backed up out the wazoo, but I'm prepared to wait to have it done properly. Can you give me any direction regarding shipping? I see you favor FedEx ground, which is easy. What's my best bet on a box? Are the boxes from Audio Classics to be trusted, or should I buy one from MC? Any direction you could give would be appreciated.

    Best Regards, Leo.
    Hello Terry, I have a fisher 800c that I recapped using a metalbone kit. After I was finished I noticed that the rec. will not work in fm, or phono stereo. The aux position works fine. the left channel has only a fraction of the volume level as the right channel. The fm and phono both sound fine in the mono position. I have cleaned the selector switch very well with no improvement. Do you have any suggestions I could try? Do you work on these units if shipped to you? Any help is appreciated Thanks Mike.
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