Akai gx 77 issue

[NickH]

Hi all,

I just got my Grandfathers gx77. And there's a problem, albeit a not to serious one. The thing plays fine in both directions. And I did clean the heads very well, they look brand new.

The problem is when I rewind the tape. In FF it goes quite fast but in rewind it sometimes start fast and then slows down. But after it's been used for awhile and I rew it starts slow and speeds up a little. But not to much.


Any ideas? The belt seem to be in good condition.


Nick

[DaveInVA]

Thats the famous resistor problem that plagues that model. There are 2 current limiting resisters one each in the spool motor servo circuits and they change value or open up or get so hot they unsolder themselves. Just replace them with a higher wattage same value part.

Dave

[NickH]

Cool that sounds easy.



By the way which resistors are they????? I don't have a schematic for the machine so I wouldn't even know where they where. Can you point me in the right direction?


Thanks,
Nick

[DaveInVA]

Its been several years since I owned one and no longer have the service manual. Its a very common problem with that model. It shouldn't be to hard to find the culprit resister.

Dave

[NickH]

Ok I will try and hunt down a schematic. Then I will be able to figure it out. And in the mean time I will pull the top off and see what I can find.



Thanks,
Nick

[Scorpion8]

Ok I will try and hunt down a schematic.

HiFi Engine has the Akai GX-77 Service manual, or PM me for a copy.

[NickH]

Thanks Scorpion
After a little closer exam I think it is the belt thats the culprit. When I go into REW it slips on the pulley. I'm guessing it's stretched a little. I think I will go ahead and replace them.




Which looks fun *eyepop*

[Scorpion8]

Which looks fun *eyepop*

It's ALL fun! Ya gotta love this hobby. No other hobby (except perhaps owning a vintage auto) gets you so in tune with your stuff because of the constant fiddling and repair and upgrade and swappping and .....

It's a labor of love.

[NickH]

Ya sure my wife thinks the exact same thing LOL.



Now I just have to figure out how to get the belts off this thing LOL.


Nick

[Scorpion8]

Now I just have to figure out how to get the belts off this thing LOL.

Take it slow. Just remember that they were designed to be replaced, so if you think there's "so much" that needs to be removed to replace them, stop and think about it for a minute. It was designed so that a major rebuild wasn't needed just for "maintenance". Take pics, or write steps as you proceed. Keep the screws and such in a container safe aside on the workbench.

[NickH]

Oh I'm not worried.I have worked on way more complex things. I'm wondering if I could try soaking the beats in armor all over night. I wonder if that would bring some life back into them.



Has anyone ever tried this?


Nick

[Eminence1963]

I have used automotive belt dressing on idler rollers and belts with 100% positive results.
Only don't use it on a pinch roller as it will make the pinch roller too soft.
Another place to use it would b on rubber reel hold downs.... Just get a qtip and apply the stuff.
Do not, I repeat do not spray the stuff directly on to said items. Apply the stuff with Qtips only

[jdurbin1]

Those resistors are impossible to miss, BTW... look for large blue ones (or just large resistors) on the two small boards connected to the reel motors. I have a pic I can post if needed but like I said, they're pretty hard to miss.

John

[Eminence1963]

Those resistors are impossible to miss, BTW... look for large blue ones (or just large resistors) on the two small boards connected to the reel motors. I have a pic I can post if needed but like I said, they're pretty hard to miss.

John

Do U know what the values are for the resistors?
Radio Shach Have em?
Which way do they need to b installed

[jdurbin1]

I don't know the value, checked my pics and the markings were all facing away from the camera. Radio Shack is unlikely to have the right value in that wattage though.

John

[studeb]

i think they are 100ohm 3W on the schematic

[studeb]

i looked last night trying to revive one of mine.
100 Ohm 3 watt/

[Eminence1963]

i looked last night trying to revive one of mine.
100 Ohm 3 watt/

Did one of them fail?
Or did it get so hot that it just came undone from the board? Cold solder joint?
Inquiring minds wanna know!*Hi5*

[studeb]

This deck does not load.
The loading solenoid does not trip. i pulled it apart last night, cleaned are relubed the loader assembly. It was gummed up pretty bad, but the solenoid is still not tripping. I have to check the transistors diodes and power supply.
The motors seem to work, i can close the loader switch and FF/RWD work fine

[studeb]

Back to the OP, this SL Bender person has a kit to improve the motor control circuit.
He says that it is not always the belts that slows things down.

[Eminence1963]

I tried emailing him and got no replys
I dont think he's around anymore...
Did u try emailing him and getting a responce?