Power Up Problem with a MX-132

I have this intermittent problem with my MX-132 preamp which seems to be becoming more frequent. I leave this unit on in standby mode when not in use and I power this unit up by using the standby power switch on the front panel. Several times now, upon pressing the switch I get no response. Thinking is it a faulty switch, I dig out the seldom used remote find some batteries and nothing happens with the remote either!
I finally got it to respond by turning the master power switch off for 60 seconds and powering it back up using the master switch again. It seems that the preamp is not coming out of standby mode. Has anyone run into this problem? TIA.

Common problem with the MHT100.....missing the MX132 schematic but if the receiver followed the lead of the earlier MX132......It is time for a tech to take a look at it.

Unless you're very handy with electronics, I'd agree with c_dk-- have a good Mac tech take a look at at. This unit has a very complex power supply with multiple regulators, transistor switching of some supplies, and relays for taking the unit in and out of standby. Also, if by chance you have owned this from new, and never had it serviced, there were a number of factory mods to be performed on it issued back around 2003, some of which could relate to this problem and others to other circuitry.

Thanks for the advice. I had a suspicion that it was more complex than I want to tackle. The previous owner said this unit received the updates, but who knows? Suggestions for service centers who can perform any needed upgrades? I am only a 2 hour drive from Binghamton NY. Audio Classics jumps to mind.

Classic_CJ said:

Unless you're very handy with electronics, I'd agree with c_dk-- have a good Mac tech take a look at at. This unit has a very complex power supply with multiple regulators, transistor switching of some supplies, and relays for taking the unit in and out of standby. Also, if by chance you have owned this from new, and never had it serviced, there were a number of factory mods to be performed on it issued back around 2003, some of which could relate to this problem and others to other circuitry.

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Do you think I am risking a catastrophic failure by continuing to use the unit?

This sounds like a problem with the stand by power supply. Off the top of my head, I can not remember if this model is like the MX130 in that it has some relays on the power supply board that like to fail. When their contacts get bad, you end up with no response from either the front panel power on / standby switch or the remote. On these preamps, it requires removal of the stand by power supply circuit board. They use these relays to both turn on the main power supply as well as to turn on certain power outlets on the back panel. I'd have to see that model in person to verify this. Another issue could be a shorted component on one of the circuit boards. I ran into this on a MX130. One of the input chips on the input circuit board was shorted causing a 5 volt line to be dead. When I unplugged that power line, the preamp fired right up. The MX series of preamps are nothing to fool around with if you are not experienced with servicing them. Even experienced techs get stumped with these preamps. Best to take it to or ship it to a Mac tech who knows these things.

JosephH said:

Thanks for the advice. I had a suspicion that it was more complex than I want to tackle. The previous owner said this unit received the updates, but who knows? Suggestions for service centers who can perform any needed upgrades? I am only a 2 hour drive from Binghamton NY. Audio Classics jumps to mind.

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Take it to McIntosh in Binghamton if you are only 2 hours away. The unit is well worth taking to a qualified tech. I do work for them in Florida and have seen a few MX preamps. They are not something you can just 'shotgun' without proper manuals and access to McIntosh parts. I believe the manual for that one is hard copy only. I didn't see it on their dealer dashboard and don't see it on sites like hifiengine.

Before you take it in (especially if you're handy with soldering), call the repair department at McIntosh and ask them about it, it could be a common problem that they can give you an exact fix for. My MX-119 went bad two winters ago due to static electricity. I called McIntosh and they had seen this problem numerous times. The service technician told me what IC's were suspect. For about $25 in parts and a couple of hours taking the thing apart, my problem was fixed. Unfortunately, McIntosh service has a multi-month backup for service. It depends on whether you can live without your stereo for a period of time. Again, the best thing to do is call first before taking or sending it in.

My post on fixing my MX-119:

http://www.audiokarma.org/forums/showthread.php?t=572103&highlight=feinstei

I was off Friday so I called Audio Classics and verified that they would be there all day. It turned out to be a 3.5 hour drive, but it was a beautiful day for a drive and well worth it. AC is an incredible place for any audio fan. I was fortunate enough to catch Ryan behind the counter. He was extremely helpful and very gracious with his time, showing us around and basically giving us the run of the place. He knew of the problem I am having and said some up to date firmware and a new IC would likely do the trick. Depending on the time to get the IC from McIntosh, the estimated repair time at 2-3 weeks. I cannot wait to go back. What a tremendous selection of classic gear for sale, as well as some very informative displays detailing the history of McIntosh. It was worth the trip just to meet Ryan, see their inventory and demo the newest gear. On the way back, the Mrs and I stopped at Hammandsport NY for dinner on beautiful Keuka Lake. I will keep you posted on the progress of the repair, but I know the unit is in good hands.

A silver lining there for sure.