Another Akai MG1212.......

  • Thread starter Thread starter j.harv
  • Start date Start date
One of my VFD's blew in front of my eyes.
Actually it was on a desk I was trying to get going again and the display was already faulty.
I watched the wires literally glow red like a toaster and fry the wires.
 
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One of my VFD's blew in front of my eyes.
Actually it was on a desk I was trying to get going again and the display was already faulty.
I watched the wires literally glow red like a toaster and dissolve the wires.
Click to expand...

Now it's a party.

j.harv I do have a bad feeling it is something unfortunate with the display itself. Doesn't mean it's not worth trying to figure out still. I had forgotten the control track relay wasn't working now. When I have a chance I'll see if I can garner any clues from that.
 
I'd still be interested to know if the dead LEDs are actually functioning at the component level, since that would help figure out if a power surge has burned them out, or whether the logic to enable them has failed. If the LEDs are actually cooked, chances are parts of the VFD have gone too.
 
Great post, thanks so much for sharing.
I have "repaired" (cleaned and fixed a few things) two Mg614 and love to see how the big brothers improves on every step.

And just for fun, but i am sure you may already know much more than me about this...
Sun Studios - U2 - Rattle And Hum
 
I was aware.
Also Billy Idols 'Rebel Yell' was done on one of these as well. Amazing punchy track. Still enjoy listening to it.
 
Just curiosity, do you have enough tapes for it? Or is there some way to fill the old ones with any other VHS kind of tape?
 
I personally have quite a few new tapes and you can actually record over old tapes as well. You may have done this on your Mg614 have you?

I haven't gone down the road of actually testing what tape replacement would work.
 
Hi Sweetbeats

I saw this comment and pic of yours...

"Yeah. See pic below. I think mine have been modified with chase-lock sync capability...maybe. Both of mine have the 15-pin DSUB connector on the front...clearly not factory. Not sure yet what they're for."

View attachment 98764



This looks like an attempt to wire up the recorder controls for SMPTE control. My Akai mg1214 has this on the front as standard.

From the Akai Brochure...

" A synchronizer jack allows for quick and easy connection of the MG1214 to almost every popular SMPTE synchronizer for synchronous recording with other audio or video machines."

You can synchronize two of these (Akai mg1214) via a separate synchronizer. You can't just plug one into each other and expect them to lock together. It won't work.

If this modification of yours on the Akai1212 has been done right you may be able to lock it together with another Akai mg1214 or even lock it with a Protools rig.
 
Dreverb said:
Just curiosity, do you have enough tapes for it? Or is there some way to fill the old ones with any other VHS kind of tape?
Click to expand...

I have some tapes. New and used. They're getting harder to come by. I'm always keeping an eye out for them. As for reloading the tape shell. I heard Maxell XLII EE tape is what can be used. I'm keeping an eye out for that stuff too. Would be a fun experiment to try and reload a cassette.
 
j.harv said:
I have some tapes. New and used. They're getting harder to come by. I'm always keeping an eye out for them. As for reloading the tape shell. I heard Maxell XLII EE tape is what can be used. I'm keeping an eye out for that stuff too. Would be a fun experiment to try and reload a cassette.
Click to expand...

Yeah, Dreverb, that's the most common presumption I've heard for the tape type that is loaded in the MK20 and MK20J tape shells is something most equivalent to Maxell EE formulation tape, but I'm not even sure that comes in 1/2"? My understanding is the tape itself was manufactured by TDK. The EE formulation is unique but is, I believe, basically a +6 tape. I think the closest other alternative would be LPR35. Reloading with VHS tape stock would be a BAD idea...poor audio quality and too thin. I've heard of people reloading with 456 or SM911, but this is also not ideal because I believe the stock tape in the MK20/MK20J shells is a 1mil class tape; 456 and SM911 are a 1.5mil class.
 
deslog said:
Hi Sweetbeats

I saw this comment and pic of yours...

"Yeah. See pic below. I think mine have been modified with chase-lock sync capability...maybe. Both of mine have the 15-pin DSUB connector on the front...clearly not factory. Not sure yet what they're for."

View attachment 98764



This looks like an attempt to wire up the recorder controls for SMPTE control. My Akai mg1214 has this on the front as standard.

From the Akai Brochure...

" A synchronizer jack allows for quick and easy connection of the MG1214 to almost every popular SMPTE synchronizer for synchronous recording with other audio or video machines."

You can synchronize two of these (Akai mg1214) via a separate synchronizer. You can't just plug one into each other and expect them to lock together. It won't work.

If this modification of yours on the Akai1212 has been done right you may be able to lock it together with another Akai mg1214 or even lock it with a Protools rig.
Click to expand...

Yes I agree that's what the modification on mine is for...machine synchronization. I suspect the MG1214 circuit was replicated in my MG1212s...I'm guessing a studio had purchased them and when the MG1214 came out with its sync capability (it was manufactured concurrently with the MG1212), they added the modification in order to synchronize their two MG1212s for 24-track operation.

I haven't looked in my Timeline Micro Lynx documentation to see if there's a schematic and control unit settings guidance for the MG1214. If there is that would make it relatively easy for me to sync my two MG1212s, but that would just be for novelty fun. I don't really need the 24-track count. My Micro Lynx has the optional 3rd transport add-on card; could sync the MG1212s and a Tascam 58, and have them chasing SMPTE off of my Ampex 16-track. I would have to sacrifice a track on the Ampex and on the Tascam, but that would still give me 46 tracks! I'd do that just to watch all the machines lock up and chase when I hit PLAY on the Ampex. :D

Ahhhh the simple little things in life. :D:D:D
 
Just been doing a little prodding around to see if I can figure out the control track issue. As I reported earlier, the control button is not triggering the control relay. I don't think the button is faulty, because the red LED that indicates the control track lights up when pressed. I took the cover off the control relay and to see the innards for movement. The relay does click when I power on the Akai and also when I press the reset button. But the control button isn't doing anything. The Sync button right beside it is doing it's job.

I did some continuity checks and I am getting continuity between one of the legs of the button and a connector on the system contorl 2 pcb. The connector is right above the relay. Just stumped why it's not tripping it.
Is it possible a relay can still be faulty even if it's clicking and the contact is clearly opening???
 
The contact can work but if the contact is dirty or corroded it may not pass the current through.
 
There are a couple different things that can go wrong with DC relays...bad contacts that prevent signal flow (but my experience is there is intermittent connectivity), bad contacts that prevent the relay coil from holding (the relay coil gets energized by a control source, and when the coil is energized contacts close that pass continued power to the coil to hold it closed after the control source ceases...think of pressing PLAY...it starts the transport in motion but you don't have to keep holding the PLAY button for the transport to continue...the PLAY button is the control source but the state is held after the button is released). In your case the control track relay is not directly controlled by an operator function, but rather logic that responds to other inputs. I don't know for sure because I haven't studied the schematics, but since the change was sudden I suspect there is a logic issue that is either not passing signal to the control relay, or the relay is not getting the initial command or holding current to either initially close or stay closed. Can you test if control signal is teaching the relay, and measure if the relay coil is being energized when it is supposed to be energized and staying that way when it is supposed to hold?
 
sweetbeats said:
Can you test if control signal is teaching the relay, and measure if the relay coil is being energized when it is supposed to be energized and staying that way when it is supposed to hold?
Click to expand...

Not sure how I'd go about doing that. The only way I've tried testing it during recording. I'm pretty sure it's not doing anything as the counter is all over the place. So it's not striping the control track. And as I mentioned earlier, with the cover off the relay, it's not closing when the the control button is pushed. It only activates when powering the machine on or off, or when pressing the reset button.
It's another function I guess I could live without. It's just gonna be a pain when trying to locate certain parts of a recording via the counter if need be.
 
Yeah I can understand how that sucks, big time, not having that feature. Is there any way you can put up a video, a sort of dramatic re-enactment of what you were doing when the *poof*ing occurred, like what touched what and all?
 
sweetbeats said:
Yeah I can understand how that sucks, big time, not having that feature. Is there any way you can put up a video, a sort of dramatic re-enactment of what you were doing when the *poof*ing occurred, like what touched what and all?
Click to expand...

Basically what happened was I had the control pcb unmounted from the frame it was screwed to. It was sitting at an angle like in the picture i have posted. The left underside bottom of the pcb was more or less touching the metal and that's what it shorted out on.
I think this didn't have anything to do with the control funtion not working now that I think of it. Because I remember trying some recording tests before I blew the fuse and the counter was still not counting properly while I pushed the control button to stripe the tape. Just the LED was coming on. I'm pretty sure it was not functioning from the start.
Just the VFD and record function LED is what got affected by the short. I stupidly did it again yesterday. Was holding the control pcb and it slipped while the power was on and blew the fuse again. VFD went out, replaced the fuse and it's back to where it left off. Thankfully it didn't take any more of the display out.
I wonder why they designed it so you had to have a separate track to control the counter. Would have been easier if they used a tradional tape counter. That would have also not had to use up any track space.
Any way... here is the picture of the board and frame how it was when it shorted...

IMG_20170115_133126.webp
 
The control track is much more precise than a mechanical counter. This was important for the onboard auto locate and pinch facilities that were part of the MG series' marketing regimen.

Get yourself some of that squishy quilted rubber shelf liner and ALWAYS put it in between unmounted boards when working on a unit with it powered. Always. Save yourself the headaches and heartaches.

I would try replacing the relay.
 
sweetbeats said:
I would try replacing the relay.
Click to expand...

Think I'm gonna try this as a last resort. I have an electronic supply near me that has racks of these relays, IC's etc.... you name it.
The only thing I get confused with is the numbers. Do they have to match exactly? The relay I want to try and replaced ise marked 'Omron G2E-182P 12 VDC'
Do I have to try and find this exact number, or would there possibly be a compatible one amongst the many they have? That's the thing that confuses me with ICs and other components. They have so many. Alot look identical and numbers don't always match. Is there a specific voltage??
The last time I was there I remember seeing some relays that looked identical. But I know that's not the way to ID them.
The employees there aren't that knowledagble either, from what I have experienced. Kinda lazy people.
 
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