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Author Topic: 3M M79 anyone?  (Read 6180 times)

Tom Van Den Heuvel

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3M M79 anyone?
« on: July 09, 2004, 11:56:11 am »

Hey Fletcher (and everyone else reading)

A guy in my area is selling an old 3M M79 2"24tr for about 2K,
I know it hasn't been maintained in perfect working order as the seller told me he did no recap job on it since he bought in 1996, that's a bit scarry but the price leaves room for some tech work...
I've never worked on a M79 before, i just know not all techs will do the job.
Any opinions?
Thanx!

TOM

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Rail Jon Rogut

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Re: 3M M79 anyone?
« Reply #1 on: July 09, 2004, 03:37:35 pm »

The 3M79 is a very simple machine to work on.. your concern should be the wear on the heads... and finding spare parts like pinch rollers.

The other thing to check is that the 3M79 didn't do Input Switching - so they've all been modified to do switching.. some mods weren't that great.

Rail
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drumsound

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Re: 3M M79 anyone?
« Reply #2 on: July 09, 2004, 03:57:21 pm »

A $2K M79 will cost you more than $2K.  Any machine for that price is priced that way for a reason.  I don't care what name is on the front.  
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mcsnare

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Re: 3M M79 anyone?
« Reply #3 on: July 09, 2004, 11:55:29 pm »

An M79 is not a tape machine, it's a commitment, a way of life. I've owned 3 of 'em. PM me if you REALLY want to know.
Dave McNair

Erik

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Re: 3M M79 anyone?
« Reply #4 on: July 10, 2004, 07:23:25 pm »

They're great machines.

Recapping is not a major concern.

The most valuable part of the machine, like all the old machines flying around, is the heads.  Get a head report from www.jrfmagnetics.com and see how much useful life they have on them.

A $2000 machine with shot heads is no bargain.  A $2000 machine with 90% heads can be futzed with with part time for three years -- then just the heads can be sold for profit.

All the wear items remain available.  

The cards are simple, easy to work on, and plenty are floating around.  There are tons of mods and you'll want to have someone go through it, make sure all the correct mods have been done correctly, and that everything on the machine matches.

The logic board contains some hard to find parts.  Spares are difficult to come by, and as these disappear so will the machines.

--Erik
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Erik Gavriluk, Bomb Factory Recording Studios
"The modern trouble is not the use of machinery, but the abuse of it." --Gustav Stickley, 1909

trexrox

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Re: 3M M79 anyone?
« Reply #5 on: July 14, 2004, 07:20:55 pm »

Well, there are some component parts on the M79's that are not being made and haven't been for some time now...  

The Vactrol Vactec, which is an opto-coupler, are impossible to find, as the company stopped production of these over ten years ago.  They have a tiny lightbulb inside that WILL EVENTUALLY BURN OUT.  The Vactec controls the record and erase circuit, so without it, you can't record or erase a track properly.  You may end up with 16 of the 24 audio cards working, which you can move around as you track and overdub, since the playback will still be working...  The only permanent solution to this problem is a mod that replaces the Vactec with a currently available and common component.  The problem with that is, that noone (including John Klett, who is a huge proponent of these machines) has been able to come up with a mod that works because of the stringent requirements that ONLY the original part could fill (and there are no modern equivalents).

Also, there is a logic control chip (MC672) on all the audio cards and one or two on the logic cards that are almost impossible to find replacements for.  The last time I checked (in 2001), no new MC672 chips were being made and all I could find was NOS components, sometimes of which you would have to buy several at very high prices just to get one working chip.

In my experience, having been engineer and resident tech in two studios that operated multiple M79's, as well as owning one for two years, Those two components are a major mode of failure for an audio channel on these machines, as on every machine I had to repair about 1/3 of the channels with these components being bad.  Not only that, but they are maintenece hungry bitches in other respects, too... Now, since they are relatively easy to work on, it's not THAT big of a deal, but you will be working on it all of the time.

Aside from all of that, these machines are great sounding and very enjoyable to record on, though being slightly primitive compared to most decks in terms of autolocate functionality.  There are some available aftermarket autolocators that will take care of that, and I've been able to get two of these machines to lock together (or with any timecode source) with amazing accuracy.

I'd say 2000 is a decent price for an M79 with a good set of heads, especially if you are willing to bear the cost of maintence and replacement of worn parts.
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Jolly Ted

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Re: 3M M79 anyone?
« Reply #6 on: July 14, 2004, 10:16:28 pm »

We own 6 3M M79's and I agree with everything Will says above. The sound of these machines are great! But they are old and need to be maintained well.

As a FYI, we do have about 200+ MC672 logic chips if anyone needs any. Just PM me. Also have spare copies of service manual and the Factory Bulletins on the mods, if your machine doesn't come with the service manual.

Some of the mods that we have found really helpful include  rebuilding the power supplies for the M79...not hard to do. But what a big improvements in operation of our machines and the audio quality!!!

The audio boards can be easily updated for better quality sound. Fairly easy to do and the logic switching chips that have been a problem locating in the past we can provide. We had 100 made and we bought about 150 from an OEM source that had these just lying around! Somewhat expensive, but at least we've got plenty now. Happy to share them too.

Replaced most the bulb lamps with LED's...much more reliable and cooler operation. Plus the LED's don't melt the pushbutton lenses like the bulbs do. Re-lettered all the push buttons. The numbers are usually faded from the heat of the bulbs and just flake off. Then of course you can't see the numbers for the channels to arm, etc.  We have a good process for making internal replacement numbers for the push button lenses I can share with you.

The last M79 I bought cost $2200 and was in good condition. We made the above mods. The heads were in fairly good shape. Had them relapped by JRF and he gave us a report of 80% on the playback head and 70% on the Record head. The haeds are the major cost factor in a used machine...so as said before, get a head report befor buying.

Let us know if you get the machine and how it works out for you!

Best of luck! (in a positive way)

Ted Jolly
GRS


bobkatz

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Re: 3M M79 anyone?
« Reply #7 on: July 15, 2004, 11:00:43 pm »

If you are looking for weird chips, send me a PM and I'll check at Skycraft Surplus here in Orlando. They've got a boatload, all carefully catalogued. At least it's worth a try.
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Thomas Lester

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Re: 3M M79 anyone?
« Reply #8 on: July 16, 2004, 10:01:26 am »

bobkatz wrote on Thu, 15 July 2004 23:00

If you are looking for weird chips, send me a PM and I'll check at Skycraft Surplus here in Orlando. They've got a boatload, all carefully catalogued. At least it's worth a try.


Ahhhh...  skycraft  Very Happy   One of my all time favorite places.  I've built a few mic pre's and compressors out of that place.  Love it.  I try to visit there often when I'm in O'town.

-Tom

Tim Gilles

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Re: 3M M79 anyone?
« Reply #9 on: July 21, 2004, 02:23:11 am »

Wonderful to see some guys holding the torch aloft for the 3M M79.

One of my favorite sounding machines ever.

They always did need a lotta love.

Afficiandos always seemed to feel the maintaince was worth the effort.

Best regards.

Tim

Bob Olhsson

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Re: 3M M79 anyone?
« Reply #10 on: July 21, 2004, 10:35:50 am »

Tim Gilles wrote on Wed, 21 July 2004 01:23

Wonderful to see some guys holding the torch aloft for the 3M M79.

One of my favorite sounding machines ever.

They always did need a lotta love.

Afficiandos always seemed to feel the maintaince was worth the effort.

And then there's the downside like the time when Wally Heider informed 3M that they might like to pick up the 10 or so M-79s he had been leasing from them that were going to be sitting on the street the following morning!

If you ever put a tape on an M-79, PRAY that the machine had all the factory retrofit mods done to it!

Tom Van Den Heuvel

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Re: 3M M79 anyone?
« Reply #11 on: July 26, 2004, 04:58:01 am »

Thks a lot everyone for the feedback!
That's really nice of you all.
The downside?...I'm even more confused!..."to be, or not to..." Very Happy

Kind regards.

Tom VDH

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