JVC RC-880C Radio sounds great, tape sounds awful

A

amoorey

Member (SA)
Superduper said:
Whichever gear you’re grinding by the testing, probably won’t be a gear much longer if you don’t resolve the issue soon.
Click to expand...
The problem is that I can’t see any gear grinding. I e looked everywhere. Nor do I see anything out of alignment or broken. Not that I know what every single connection should look like. The head pushes up and down easily. The head swivels easy with light manipulation. The big white gear does not move but perhaps it’s for the other direction. Currently it’s stuck in reverse. It seems to be a problem with the system trying to turn the head. I guess next steps are to take it apart again and try to get more access to the area beneath the head where the little spring and gear is. I’m going extend some ribbon wiring so I can operate the mechanism without having to install it back into the case each time. IMG_3855.jpeg
 
thinkchronicity

thinkchronicity

Member (SA)
I feel for you and am rooting for your success! I'm not familiar with the mechanisms of reverse decks, but i can say you will crack it (hopefully not literally..), just a matter of time and study. Study the path of levers etc starting from the change direction lever. Discover how that works. Good luck.
 
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Superduper

Superduper

Moderator
Staff member
I could see that there is a white gear behind the main capstan that is trying to turn. Also, I don't really think that the head should be able to easily manually swivel due to the way that it's gear underneath is meshed with a lever. Also when you take the deck in/out, the autoreverse linkage to the switch is easy to get out of alignment. Regardless, every boombox deck has some differences and won't be the same. It's clearly a mechanical issue and you have the boombox in front of you, you'll have to figure this out.
 
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BoomboxLover48

BoomboxLover48

Boomus Fidelis
Never give up!
I have an AKAI GXC-735D auto reverse cassette deck that I took lots of time and fixed most of it. The problem I have now is with the play head not locking in place when you hit play on the feather touch button. I made over 15 attempts to fix it, but all ended up in vain. Still cannot figure out how it locks in place. :sadno: :sad:
 
Tinman

Tinman

Member (SA)
It's hard to tell if it's grinding or if it's something rubbing but that small white gear on the left does look like it's shuttering trying to move.
I agree, it doesn't seem like the head should be able to swivel easily.
I would assume that it should be locked into one direction or the other.
If you can't see what's going on in there, you'll probably have to take some more of that mechanism apart to investigate.
It could be something simple like a spring that popped out of place or something bad like a broken lever, gear, etc.
 
A

amoorey

Member (SA)
BoomboxLover48 said:
Give the head a little assistance to turn when it prompted to change the direction and see what happens.
Click to expand...
Good idea, thanks for the help! It’s currently stuck in reverse and while playing without a tape, I can easily move the head clockwise. I can move it from 9 to 11 then it stops. It also moves and up and down easily while I work at turning it with my finger.
IMG_3858.jpeg
 
A

amoorey

Member (SA)
BoomboxLover48 said:
Give the head a little assistance to turn when it prompted to change the direction and see what happens.
Click to expand...
Thanks for the help! Once I engage the change direction switch, at first it dropped a bit but didn’t turn. I tried helping it with my fingers while engaging the change direction switch and nothing happened. I could move it clockwise a bit further than 11 o’clock. I got it to maybe 1,2 o’clock but nothing happened else wise. I pushed it (not excessively) and it went a bit more and I heard a click. I stopped, hit the stop play button which is the only way to stop the clicky/buzzy sound once engaging (then releasing) the change direction switch. No change. When I engage the change direction the head drops for an instant but doesn’t turn.
 
A

amoorey

Member (SA)
Tinman said:
It's hard to tell if it's grinding or if it's something rubbing but that small white gear on the left does look like it's shuttering trying to move.
I agree, it doesn't seem like the head should be able to swivel easily.
I would assume that it should be locked into one direction or the other.
If you can't see what's going on in there, you'll probably have to take some more of that mechanism apart to investigate.
It could be something simple like a spring that popped out of place or something bad like a broken lever, gear, etc.
Click to expand...
Thanks so much for the help. The head is definitely not locked when in play mode. I can easily swivel it up and down and move it clockwise.
 
A

amoorey

Member (SA)
I’m not sure how the change direction switch is supposed to work but it goes through some stages as shown here in this video depending on how far it’s pressed down. Dumb question - how are you supposed to use the change direction lever normally? Stop play then engage switch? Engage switch while tape is playing? Thanks.

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amoorey

Member (SA)
I got deeper into the mechanism and can now see under the head. Anyone know what it’s supposed to look like? See anything wrong?

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IMG_3865.jpegIMG_3862.jpeg
 

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A

amoorey

Member (SA)
Short clip here to show movement of the gear below the head. I can’t try it powered because not enough slack in power ribbon cable. I hope to add more length tomorrow. Partly because the old hinged wire connector isn’t holding the wires very well. Any nudge and they come out.

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The head is not turning because of a metal strip that seems to designed to do just that. I’m not sure what tells it when to get out of the way.

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A

amoorey

Member (SA)
thinkchronicity said:
I feel for you and am rooting for your success! I'm not familiar with the mechanisms of reverse decks, but i can say you will crack it (hopefully not literally..), just a matter of time and study. Study the path of levers etc starting from the change direction lever. Discover how that works. Good luck.
Click to expand...
Thank you! I appreciate the positivity. I’m slowly working my way through as you suggested. Amazing how much engineering and switches and levers and mechanics is in one of these things.
 
A

amoorey

Member (SA)
Superduper said:
I could see that there is a white gear behind the main capstan that is trying to turn. Also, I don't really think that the head should be able to easily manually swivel due to the way that its gear underneath is meshed with a lever. Also when you take the deck in/out, the autoreverse linkage to the switch is easy to get out of alignment. Regardless, every boombox deck has some differences and won't be the same. It's clearly a mechanical issue and you have the boombox in front of you, you'll have to figure this out.
Click to expand...
Thanks for nothing that the auto reverse switch can go out of alignment. I never considered that. Maybe it’s pushing too much and going past where it should? In the one video where I activate it by hand, without the lever, different things seem to happen depending on how far down, and how long, it’s pushed.
 
BoomboxLover48

BoomboxLover48

Boomus Fidelis
Now take some rest. You need a break! :yes:

Wait for a day or two, refresh and then work on it after getting input from our experts here.

In my early days I have gone to a panic mode and messed up mechanisms like this.
It is so easy to break that white gear mechanism or short something there.
 
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A

amoorey

Member (SA)
BoomboxLover48 said:
Now take some rest. You need a break! :yes:

Wait for a day or two, refresh and then work on it after getting input from our experts here.

In my early days I have gone to a panic mode and messed up mechanisms like this.
It is so easy to break that white gear mechanism or short something there.
Click to expand...
You’re right. It’s both addictive and frustrating at the same time. I’m trying to get it down before Christmas to give to my 19 year old son but he is in second year engineering so maybe it will be the gift that keeps on giving g and we can work on it together while he’s home for a couple weeks. :-)
 
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Tinman

Tinman

Member (SA)
Does the direction lever lock into something on the opposite side when it raises up or is it supposed to be engaged all of the time?
It's hard to tell if it's engaged in anything when you're turning the head mechanism.
You can spin the capstan (looks like the left one since the pinch roller is contacting it on that side) by hand to get the gears moving to see if you notice if anything is off.
If you press the play mechanism up while turning the capstan, it should lift the head assembly and get everything moving.
 
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