Another Akai MG1212.......

[j.harv]

To start off....I'm not gonna do a detailed "story" thread, as I'm just not good at it and I don't know what I'm doing most of the time.

After seeing Sweetbeats thread on his recently aquired Akai's, curiousity got the best of me and I located one not too far from me and I got it on a trade. I'm a fan of the all in one recorders and I really love my 388s. And I want a project to mess around with over the upcoming long cold winter.

The Mg1212 I got is not in the best of shape as I thought. I made sure to ask the gentleman who was offering it, if he had used a random online picture of the unit. He did. He picked one of the nicer looking looking pics on the net of a mint condition Akai.(I hate when people do that)
Anyway, I did decide to make a trade and got it home.
It's a little rough. I went in knowing that there was no sound outputting. He said the transport was ok, or so he though, but as per usual with these machines it's not.
There is also some rust around a few of the knobs and switches on the face. That kinda sucks, because it cant be fixed. Some of the numbers have flaked off.Also 2 missing fader caps and the tape door cover was broke inhalf and glued back together. So I'll have to keep an eye out on ebay for parted out units for the cosmetic fix.

I plugged it in and it powered on. The tape transport went into action with out me pushing any buttons. It ejects, makes a clicking sound then closes only to keep repeating every 5 seconds
I plugged in a microphone and headphones and saw that a signal was inputting but alas, no output through the phones. If I hit the mic, sometimes I would get a quick distorted noise in the phones but that was it.

I decided to start by cleaning all the channel card faders and pots. Done! The faders are a pain to open up.
Then I went to look at the power supply. This where it got a little messy. There is a small battery for the memory on the power supply. It leaked! The underside of the pcb has lost some of the green masking. It looks like it flaked off. I carefully cleaned the pcb and got the dried up acid off.(pics to follow) And ordered another battery. While inspecting the psu, I noticed a small capacitor that was swollen. I had a replacement on hand and decided to replace it.
Then I tried the mic and heaphones again. Bam!!! Sound output!!!
Nice clean sound. So that got me excited. Gonna replace a bunch more of the caps. The psu is hardwired in so its a pain to work on.

Also have an idler tire on the way. I took the belts off to check them and they seem in good shape surprisingly. So they'll have to do until I can locate replacements.

So now I'm gonna focus on the auto ejecting problem...hopefully it has something to do with the bad battery.

Enough talk. Here are some pictures..

Getting started


Here is the blue battery< still waiting on a new one.


The battery damage under the psu


Small blue cap is the new one that fixed the audio...I think?

 

[RFR]

Whoo hoo!

As sweetbeats said. You got a movement.


Look forward to the progress of the both of you.

 

[sweetbeats]

Well I'll be...



COOL!

I can't see your pics. Anxious to see them when you get a chance to figure it out.

I've heard of the memory battery being an issue. Good job getting that sorted out and getting some audio to pass. Very cool.

Long-term I know I will have spares of cosmetic parts...I'm not sure when it will be that I know what I've got to spare, but I'm pretty sure I'll be making one of mine a working unit and the other a parts donor, so keep that in mind. Maybe we can pick off of the same carcass.

What did you get for the battery replacement?

Does yours have a DSUB connector and a remote jack that looks like an S-video jack down by the headphone jack?

Where did you get the idler tire?

 

[j.harv]

Well I'll be...



COOL!

I can't see your pics. Anxious to see them when you get a chance to figure it out.

I've heard of the memory battery being an issue. Good job getting that sorted out and getting some audio to pass. Very cool.

Long-term I know I will have spares of cosmetic parts...I'm not sure when it will be that I know what I've got to spare, but I'm pretty sure I'll be making one of mine a working unit and the other a parts donor, so keep that in mind. Maybe we can pick off of the same carcass.

What did you get for the battery replacement?

Does yours have a DSUB connector and a remote jack that looks like an S-video jack down by the headphone jack?

Where did you get the idler tire?

Okay pictures up.
Thanks about the parts. I know this will take a while, but it's good to know that there might be some spares in the future.

This is where I ordered the battery
3/V60R Type Computer Memory Battery NiMH

I'm hoping it's the right kind. The original is Ni-cad, but I heard you can substitute a NiMH.

And I got the idler tire from VST
https://www.vstservice.com/p-977-mg1212-idler-tire-1214-14d.aspx

They used to have belt kits too. But when I contacted them about it, they said they don't have them anymore as they are not in demand.

They have service manuals too, but they want $50. Cory, did you happen to locate any service manuals online? I'm searching with no luck.

I do have a remote jack but I don't see a DSUB connector. WOuld that be by the headphone jack too?

Now the transport isn't doing anything anymore. I took the big cam gear off from underneath to look at the small belt that drives it and now nothings happening anymore after putting it back on. Maybe I don't have the cam lined up properly.

I'm having alot of fun diving into this and now that the audio seems to be fixed, it's onto the dreaded transport.

 

[sweetbeats]

Thanks for getting the pictures up!

Am I seeing this right? Do the mixer channel strips plug in to the motherboard??

Thanks about the parts. I know this will take a while, but it's good to know that there might be some spares in the future.

Yeah, it will take awhile, but don't hesitate to keep in touch with needs. The biggest initial step for me is going to be assessing which of my units is the "keeper", and which one is the donor.

This is where I ordered the battery
3/V60R Type Computer Memory Battery NiMH

Oh cool...thanks so much for the link. That looks like a direct solder-in replacement! I think I should check out my PSU assemblies sooner rather than later...if the batteries aren't leaking yet it would be good to keep the damage from happening. That looks pretty nasty on yours! Might have to do some point-to-point repair wiring there.

And I got the idler tire from VST
https://www.vstservice.com/p-977-mg1...-1214-14d.aspx

They used to have belt kits too. But when I contacted them about it, they said they don't have them anymore as they are not in demand.

Ah...okay. Good to know. They were out of stock on the idler tires a couple weeks ago. How did you contact them? I emailed them about the belts and a service manual a couple weeks ago and never got a reply. Hey maybe if I bug them about belts too we can create enough demand for them to get some in stock...?

I do have a remote jack but I don't see a DSUB connector. WOuld that be by the headphone jack too?

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. Mine also have a nicely executed mod so you can manually shut off the capstan. Do you have the same little housing on the front for the headphone jack and remote connector? And I was wrong about the remote jack. It's not at all like S-video...it's a standard 8-pin DIN connector. Doh!

 

[j.harv]

Thanks for getting the pictures up!

Am I seeing this right? Do the mixer channel strips plug in to the motherboard??

Yes. Right into the mother board. They come out in groups of 3. Alot easier to work on than the Tascam 388.

Oh cool...thanks so much for the link. That looks like a direct solder-in replacement! I think I should check out my PSU assemblies sooner rather than later...if the batteries aren't leaking yet it would be good to keep the damage from happening. That looks pretty nasty on yours! Might have to do some point-to-point repair wiring there.

I cleaned up some of the solder. A lot of the points had a fuzzy corroded look to them. So I used some solder wick to remove them, then resoldered. Some of the pads were in rough shape so I could only do so much.

How did you contact them? I emailed them about the belts and a service manual a couple weeks ago and never got a reply. Hey maybe if I bug them about belts too we can create enough demand for them to get some in stock...?

I emailed them too. I didn't get a reply right away. Their reply went to my junk mail and I found it a few days later

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. Mine also have a nicely executed mod so you can manually shut off the capstan. Do you have the same little housing on the front for the headphone jack and remote connector? And I was wrong about the remote jack. It's not at all like S-video...it's a standard 8-pin DIN connector. Doh!

Yes. The same housing is there. Mine has a remote, headphone jack and where your DSUB is, I have a reset button

 

[sweetbeats]

Thanks much for the info.

How did you get to the power supply? I'm assuming it is below the transport?

 

[deslog]

My battery went as well. Ive replaced three of these in 2 x Mg1212's and one Mg1214. I actually added some wire to that the battery so it wasn't mounted to the PCB board anymore. It now is accesabble via the removable panel underneath. I couldn't stand to find down the track that it failed and spewed acid on the board again.

 

[j.harv]

Thanks much for the info.

How did you get to the power supply? I'm assuming it is below the transport?

Yep. Under the transport board.

 

[j.harv]

Just gonna update a little....
When I got this Akai, I had a problem with the tape door going up and down on it's own. and At the top of it's movement, it would make a clicking sound over and over.

Well, for anyone out ther who has this problem, I think I found the cause.
First off, I feel like a bit of an ass because I forgot to take pictures of the part out of the machine and a close up of the repair. I always do this. I remind myself, then I get so involved I put stuff back together without snapping some shots. I do have a couple pics to show though.

Underneath the Akai is a small panel that can be removed to access the flywheel,belts motors etc...
Also buried in there is a big white plastic gear. It has a bunch of channels in it.....Trying to find the right words for it. This big gear I discovered, is the main component that makes everything move in the transport section except for the idler. Upon removing this gear, with hesitation, I discovered a break in one of the walls of the channel grooves that is on the face of it. A small cylindrical post that is attatched to a steel arm is supposed to run through this channel. This raises the cassette door. The little post must have been dropping into the broken section and causing the door malfunction.....Sorry...I'm pretty bad at describing things sometimes.

Sooooo.....I ended up repairing the break in the channel wall by using some JB weld epoxy to build it back up.
The break was about a 3/4 inch long piece that broke off. I let it set overnight then got back at it the next day and re-assembled it. To add, my eject button wasn't working, or so I thought. But I pushed it after re-assembling and the transport jumped back to life. Everything moves smoothly and the tape door raises properly now. And it stays up. There is one tape part of the transport that is lagging a little. It's a little post that is the last one to move back into place after the door closes. It's just taking it's sweet time to return back to it's posisition. But I let out a little yell of joy when the transport started working. So gratifiying when you fix something. But the eject button is not always working. Sometimes have to press it real hard. I think it has just worn out, so I'm hoping I can source one. Im gonna try and reflow the solder on the back of it first.

Here is a picture of the gear back in place. The red arrow is pointing at the channel, the white arrow at the repair with the epoxy and the yellow arrow is pointing at the back of the little post that is press fit into the steel arm. I would also like to add, that on the other side of the gear is a series of more complex channels that move all the other components.




I think I'm just an idler tire away from getting this running....hopefully. The tire on there now is rock hard and not gripping. Hopefully playback and record functions are ok. Got the battery today, will install.

 

[sweetbeats]

Awesome post, and awesome job! I'm impressed with your resourcefulness and initiative to dig into the problem with the eject function!

Regarding your eject button and it's intermittent function: I haven't pulled mine apart at all, so I don't know whether or not this will apply, but if it is the type of button where when you push it it makes a metalized rubber pad come in contact with a carbon element pad, if it's that kind of thing often if you can separate the two you can clean both surfaces with iso alcohol and get it working better. Used to do this with old Atari 2600 joysticks.

BTW I thought your explanation/description of the actuator cam problem and repair was very understandable.

 

[j.harv]

Awesome post, and awesome job! I'm impressed with your resourcefulness and initiative to dig into the problem with the eject function!

Regarding your eject button and it's intermittent function: I haven't pulled mine apart at all, so I don't know whether or not this will apply, but if it is the type of button where when you push it it makes a metalized rubber pad come in contact with a carbon element pad, if it's that kind of thing often if you can separate the two you can clean both surfaces with iso alcohol and get it working better. Used to do this with old Atari 2600 joysticks.

BTW I thought your explanation/description of the actuator cam problem and repair was very understandable.

Thanks!
Here is a picture of what the buttons look like under the panel. I think this one was probably getting slammed at some point. I still have to try and reflow the 4 solder joints on the underside.

 

[jpmorris]

Yes, that kind of grooved cog is the sort of thing you'd find controlling the eject mechanism in a VCR. Glad you managed to fix it!

 

[sweetbeats]

Thanks!
Here is a picture of what the buttons look like under the panel. I think this one was probably getting slammed at some point. I still have to try and reflow the 4 solder joints on the underside.

View attachment 98784

I'm interested to know if re-flowing the solder joints does the trick. If not I'm pretty sure those switches can be sourced new.

 

[famous beagle]

Awesome work, j.harv! Good luck in the final stretches.

 

[technoplayer]

I was thinking the grooved gear was like what I see controlling the arm on older auto and semi-auto vinyl turntables.

 

[j.harv]

I was thinking the grooved gear was like what I see controlling the arm on older auto and semi-auto vinyl turntables.

Yes. My old Dual turntable has a similar cam that makes everything move.

 

[j.harv]

I just installed the new battery. I did it the way deslog mentioned earlier in the thread. I isolated it from the pcb and used a cable organizer to clip it close to the opening on the back. Just a precaution I guess. It would probably take forever for it to leak again.

Just a question.....would the length of the leads I soldered to the battery affect it's power to the board in any way? I used about 5-6 inches of wire.

Here it is....

 

[altruistica]

I wouldn't think leads that short would have any effect on battery position.
Al

 

[sweetbeats]

I just installed the new battery. I did it the way deslog mentioned earlier in the thread. I isolated it from the pcb and used a cable organizer to clip it close to the opening on the back. Just a precaution I guess. It would probably take forever for it to leak again.

Just a question.....would the length of the leads I soldered to the battery affect it's power to the board in any way? I used about 5-6 inches of wire.

Here it is....

View attachment 98801

Only if the leads were teeny-tiny gauge wire. Even 24AWG wire should be more than adequate for much more than 5-6".