Mcintosh MX 110 preamp/ tuner blown transformer help

BrianK

New Member
I dropped this off because it wasn't working, powered up but no functions worked. Tech informs me the main transformer is blown. Is this a lost cause or worth restoring? He said it would be upwards of $1000.00 to replace the transformer. I bought this along with a MC 225 power amp knowing the preamp had issues and I've been using just the power amp with a more modern preamp but have to plug the mc225 into the mx110 just to be able to turn off and on(no switch) without having to unplug. I've just been bypassing the mx110. I was hoping to utilize the mx110. Do I have any options that are worthwhile?
Thanks Brian
 
You can have the transformer rewound for +/- $500. Keep in mind that if the ps caps and seleniums haven't been updated then they will for sure have to be.

I would flip it over, take the bottom off and check the AC transformer output voltage where it connects to the seleniums. Red and orange wires.

Murray
 
I've had Doc rewind an MX-110 transformer a few years back. Total cost was about $450 just for the rewind and return shipping. Given the quoted costs form your tech, I'm suspecting that he _really_ doesn't want to deal with it and is telling you so with the quote. I'd suggest you take him up on it.

Now, to the root cause: What, exactly, does this tech say is the problem that has led him to think the power transformer is bad? These are known to go out but it is rare unless the unit has been allowed to run without being restored. That is, there are likely other parts that may have caused a transformer failure - if that is indeed the root cause. I'd not suggest a transformer investment be made until you know what the total outlay will really be.

To the switching question, you have the option of using a switched outlet to provide AC to the MC225. Given what you may be learning about your MX-110, what has been done to the MC225 to ensure it is able to run safely? I'd suggest you not run it if it is all-original.

Also, what is your top-end budget to handle restoration for these 2 units? They are certainly worth it if they are to be your main components.

Cheers,

David
 
He said caps were fried and that probably led to the transformer blowing. I'm just paying the $50 open up fee and doing nothing, that's why I'm here which I probably should have come here first.
The mc225 is getting a few caps replaced and one of the power tubes is bad so I guess I need a matched set for that which I said I'd deal with so he's just replacing some caps.
 
I have not have the pleasure of owning Mac equipment, but I do own some vintage tube pieces, if it were me I would not have the tech replace some caps I'd have him replace all the caps. My admittedly limited experience is if some are bad they all will go bad at some point. Save yourself the headache down the road.
Only my 2 cents.
 
He said caps were fried and that probably led to the transformer blowing. I'm just paying the $50 open up fee and doing nothing, that's why I'm here which I probably should have come here first.
The mc225 is getting a few caps replaced and one of the power tubes is bad so I guess I need a matched set for that which I said I'd deal with so he's just replacing some caps.

Good on the MC-225. There's plenty of posts here about which ones to swap out and how they affect the sonic characteristics. It is a fabulous amp when rebuilt.

On the tubes, similar discussions and opinions here at AK. I'd suggest you do not need tightly matched output tubes if the amp itself has been fully restored. I would suggest, however, that the tube sockets be thoroughly cleaned and the contacts tightened before you sink _lots_ of $$ in tubes. The desire for tube rolling is a natural consequence of buying tube gear but you need to be sure that the sockets are up for it.

Lastly, I'd strongly suggest you have at least one or 2 backup tubes that are _known good_ for each type you have the power amp. For the preamp section of the MX-110, the same tube types would be needed with the exception of 2 tubes: 6U8 and the 6D10. I say, known-good mainly because if you need to do any diagnosing, it is good to have a stash of backups for the tubes you'll need.

Hope that helps and congratulations on being able to bring one of the classic Mac combos (MX-110 and MC-225) back to life!

Cheers,

David
 
Is the mx110 worthy of restoration ? I'm currently using a PSE tube hybrid line stage preamp and a separate phono preamp (pro-ject tube box) all going to Klipsch Forte II . I am partial to vintage. I guess I'm gonna have to pack it up and send it to one of the gurus?
Brian
 
Well, I'll admit to being biased but I've had MX-110s off and on since about 1974 when I got my first one. There's something to be said about my coming back to it even after I go through some sort of a stoopid fit and sell one - then end up buying another to replace it.

Otherwise, I'll let some of the others here comment on what they like/don't like about it. You can also do some research on the '110 here as we've discussed this a number of times.

Cheers,

David
 
I actually got around to depotting a transfrmer for a McIntosh MC2250 yesterday. Posted in DIY and am looking for more insights as I pull it futher apart.
 
Resurrecting a long dead thread, but it looks like the power transformer in one of my MX-110z has taken a dump. No measurable AC or DC voltage at any of the contacts of the main diode pack. and 120 VAC is present at both black wires on the PT and the fuse is intact; I am still getting the MPX light to come on, and the filament PS is still producing voltage. Have I diagnosed this correctly? If I have to have this rewound, has anyone used this fellow's service lately?

Worth the rewind, see here
http://members.tripod.com/tubes_tubes_tubes/transformerrewindingservice/id48.html
He has rewound 3 MX110 transformers with perfect results and a good price....

Anyone have any suggestions for removing the PT? Unsolder the leads or cut them?
 
AA, sorry to hear about the '110. Sounds like some of the windings are intact if you're getting MPX light. If you're also getting filaments, then you've got an intact primary, I suspect.

Check the AC voltage of all the secondary windings next. If you've got AC at all , then disconnect any of them that are reading something. They'll bounce up in voltage when you unload them from the rest of the power supply.

If it does need rewinding, take _lots_ of pics, just cut the wires because it will be completely rebuilt with new wires you'll be trimming down to fit. The reason why I had to replace one way back then was because the one of the windings was leaking onto the chassis and throwing ~30 volts AC and creating that tingling sensation _and_ some nasty ground loops. Everything actually measured ok and the '110 actually worked fine otherwise.

Cheers,

David
 
Heyboer in Grand Haven Mi. might even have the specs on file.

They would use a new IE lamination core as I understand it for most of their replacement work.

While they did not have the specs on file for the MC2250, they looked, they would have built a new transformer to spec.

Their price was about 2/3rds the price that AC had posted for a stock one from Macs old stock.

I ended up using a new toridal. Amp now runs every day driving a set of ADS M15s as the shop system.
 
They have the recipe for the '110 - that's where mine was rewound. They did a good job, too.

Cheers,

David
 
Anyone know how to get this cover off? I have all four screws out, but it only seems to want to rock forward rather than lift off?

 
This is an image of a Mcintosh transformer. Usually after winding the transformer, the coil will be placed inside the cover and black tar will be poured to prevent resonance when the transformer is energized.

images
 
AA, there should be 4 securing bolts holding the entire transformer, including the bottom part of the cover onto the chassis. You have to get to them from under the chassis. Pull the bottom cover off and find them that way.

Cheers,

David
 
Worth the rewind, see here
http://members.tripod.com/tubes_tubes_tubes/transformerrewindingservice/id48.html
He has rewound 3 MX110 transformers with perfect results and a good price....

I have an output transformer for an Altec 1570B that I've wanted to get re-wound for years,but because of the voltages involved,almost 1KV,nobody wants to touch it.Apparently,a specially insulated wire is required for anything operating above a certain voltage level,and all of the re-winders I've contacted don't carry it,and have no interest in sourcing it.

They do list this model as an offering on their website,but I'd be concerned as to whether they are using the proper wire. Hmmmm.........
 


Red/Red and red-yellow CT all test open circuit. Everything else tests as it should. So far no response to an inquiry from Heyboer. Should I try to get the cover off before shipping?
 
Hello

It will be less expensive for you if you ship the transformer only (take it off the black tar) ! if they have to depoted it , it will take time and will cost you more ....
 
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