Manual release of pinch rollers on AKAI R2R? (looking to repair)

IanMcI

Active Member
This machine looks to have sat for awhile, but is in very clean condition. I'm somewhat familiar with the inner workings of R2Rs, but I can't get to square one with this AKAI GX-77, because the pinch rollers are stuck in the up position, and they need to be down in order to access two screws that allow for the removal of the face plate, giving me access to the parts I need to work on.

Anyone know of a way I can "trip" the pinch rollers, so I can get to those screws? With that face plate on, I see no way to do this. I'm hoping for some trick or such, so I can get traction on this repair. Thanks!

Ian
SF Bay Area
 
Do you have the service manual?
https://www.hifiengine.com/manual_library/akai/gx-77.shtml

AKAI manuals usually detail the disassemble procedure...

Edited: the disassemble is at page 7 of that manual. The picts show the rollers removed, perhaps you need to remove them before the screws... But the images refer to "screws" all the time, not rollers...

Try to follow the exact order of the procedure, look at the # on the images, and see what happens..
 
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Yes, I do have the service manual, as downloaded from Hi Fi Engine. And, yes, the manual makes it clear that there is a step-by-step process one needs to follow to successfully dismantle the machine. However, there are two screws behind the pinch rollers that are only accessible when the pinch rollers are in the down positions, and mine are stuck in the up position, blocking access to those screws. I'd hope there might be a simple workaround in the vein of: "Use a screwdriver to lift the lever connected to the thingamabob to release the pinch roller mechanism...".

It looks like I'll have to circumvent the proper order of dismantling in order to get to whatever part is preventing the pinch rollers from descending. Though, it may be that if I get that far, I'll be able to service the machine without access through the front (which, in a circular fashion, should then allow me to get to those screws and... ). Just a bit more work involved, and a greater likelihood of my going down a rabbit's hole, if the problem preventing the proper functioning of this machine is rather simple.

I'll work on it a bit more today, and will update if progress is made. Thanks for the input!

Ian
SF Bay Area
 
Some success! I had to pretty much remove every chassis screw I could in order to loosen things enough for me to pull the electronics away from the inner-workings. This allowed a much better view of a lever that was preventing the white-plastic main gear from turning. Once I got that gear moving, the pinch rollers began retracting. This allowed me to get to those screws that were holding the face plates on. And with those off, I was able to take the control panel cover off. Everything now looks to be accessible, at least as far as being able to lubricate any pivot points.

There are undoubtedly a number of issues I'll have to tackle (as far as my abilities go), but two that stand out are:

a) A loose spring. I found this spring when I turned the machine over. I don't know if it was loose before I got in there, or if I somehow popped it from its purpose. This is going to be tough, unless I can find some place in obvious need of a spring.

b) The right-hand tape tensioner just will not move as freely as I'm sure it is supposed to - not at all as freely as the left-hand tensioner. I've been lubricating it, but it appears I will have to dismantle it to find the problem.

If I can find solutions to these two issues, I'll button things up and hope for the best. I do believe there may be electrical issues, but these may be related to some safety shutoff that has power coming and going. I'm hoping in response to stuck mechanics that are now loosened up. We'll see.

akai-guts-2.jpg akai-guts-1.jpg

Ian
SF Bay Area
 
I'm fixing right now 2 AKAI machines, but older than yours, so not too helpful to compare parts or mechanisms. Anyway, post any pict of weird things you find in there, I'm quite familiar with AKAI machines.
 
So far, only that spring is giving me problems (in terms of what goes where). Try as I might, I couldn't get the right-side tape tensioner to loosen to the extent I believe it should. I'm afraid that, even if/when I find the proper place for that spring, I will not have been able to bring this machine back to life. It may be that I'll have to leave it to a future enthusiast to get it back up and working.

Ian
SF Bay Area
 
Here's a photo of where I believe the spring is meant to go. Note that in the diagram from the service manual, the post to which the spring attaches (red arrow is pointing to it on the left), has two grooves in it: one is for the circlip that hold the post in place, and the other is for the spring (14). This post is just below the loading wheel.

I can't see where the other end of spring attaches. There are no other posts like this, and no obvious place for that spring to go. If anyone can check their 77 to see, or share that info if you know, I'd be much obliged.

I have, otherwise, pretty much reassembled the machine, with the exclusion of housing and fascia plates. I believe I still have full access to the areas in question.

The fuse that blew originally (and which I replaced), blew again at some point. I believe that something mechanical is causing the fuse to blow, as when some part will not budge, so the fuse blows to save the electrics. Not sure about this, though - electrics are not my strong point.

Ian
SF Bay Area

spring-1.jpg
 
I wonder if this is the issue: I've just noticed that there is what appears to be a tab protruding from the black-plastic plate that has the post with spring (green arrow points to this in the diagram). Note how this is missing in the photo. It appears that it may have broken off.

I think the spring maintains tension between the post, which is protruding through an oblong hole in the black-plastic part (the sliding part to which the loading wheel is attached) and the black-plastic part itself, perhaps as a shock absorber of sorts to lessen the blow when the loading wheel reaches the top of its travel, or simply to ensure that the loading wheel is fully "seated" in the up position.

Ian
SF Bay Area

spring-2.jpg
 
OK! Yes, that is where the spring goes (still not sure what its exact function is), and the tab to which the lower end of the spring attaches is broken!

I pulled a screen shot from someone's page and highlighted what this person did as a fix for a broken tab: bent the spring end and inserted it into the hole in the tab. Brilliant? Maybe... I'm not sure I want to go this route.

In other news: I put in a new fuse and tested things as they stand, and the machine functions as expected. I haven't checked every function, as I haven't loaded a tape, but at least things appear to be working as they should.

Ian
SF Bay Area

screen-shot.jpg
 
Seems that fix is effective. Probably better than gluing a new plastic tab. Looks like some sliding mechanism.
 
It's the sliding mechanism that holds the loading wheel, which would go on that brass-looking post. The sides of that slide go into slots in the guide that allows for the up and down movement of the loading wheel.

My fix was to use a small screw set into the hole to hold the spring-end, rather than bend the spring and poke it into that hole. Seems to work.

HOWEVER! Here's the real problem: on my machine that slide's upper left-hand corner (red arrow is pointing to it in the picture below) will sometimes (well, it will always, eventually) catch on the edge of the metal casting into which it is meant to fully "nest" when in the up position. In that up position, that black-plastic slide trips a switch that does whatever is meant to happen when the loading wheel is in that up position.

But, if it catches on that edge, as mine does, it is kept from reaching its uppermost point of travel, so doesn't trip that switch!

That, I think, is the whole crux of the matter in question. It could be that I can remove the slide and round over that corner to prevent its catching on that edge. That will require further dismantling of the machine, and that's a bit daunting. Perhaps a very small file or knife point will allow me to soften that corner without the need for the slide's removal.

I'll leave things as they stand for the time being. If I run into other issues, I'll probably begin a new thread, so as not to confuse the matter.

And, while this has been a fairly in-depth back and forth about a smallish issue, I do hope that my presenting it as I have will serve as some resource for anyone looking into the working of their own AKAI GX-77. Thanks!

Ian
SF Bay Area

slide-corner-1.jpg
 
I posted picture in your other thread the other day showing this is in fact where the spring goes - the tab breaking is a well known issue and the fix is a tap screw in it's place (Like Pics below). That's the problem when you start multiple threads. Anyways, glad you figured it out. If you do start yet another thread, I would suggest the tape forum since that is where most owners of this deck hang out (e.g. spring issue has been discussed there many times).
04.jpg
IMG_0342.jpg
 
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Thanks, that is the solution I went for! It seems to be working well, as far as I'm able to tell.

Yes, posting multiple threads isn't the best way to go about this. I'd hoped to spark feedback on different things as my focus changed during the "discovery" process. And I have been coming across different threads as I learn to to better phrase my search terms.

Anyway, thanks for the encouragement and for helping me understand my AKAI!

And, as an addendum of sorts, because I haven't been having the issue with the loading wheel with tape in place, as I had without, I have to think that the tape helps keep the loading-wheel slide steady/centered as it tops out.

Ian
SF Bay Area
 
Have you had the FF/REW speed issue? This is also common and manifests itself in motors not getting enough voltage to move the reels when one is mostly full and the other mostly empty. The fix is rather complex, and involves adding two relay boards, but folks have figured it out. All GX-77's will have this issue at some point in their life.
 
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