Panasonic RX-DT680 Cassette Deck Issues

[whiny_3800]

So I purchased an RX-DT680 back in June of 2024 from Facebook Marketplace. Everything worked except for cassette. It was owned by an older guy that owned it brand new since 1993. Anyways, I recently changed the belts because It would click when you hit the button but not move. Well now that I have replaced the belts, the decks only want to play in the forward direction. They won't rewind or fast forward, just click. When you play it in the reverse mode, the black reel will lag behind and eventually just stop. And then sometimes it will eat the tape no matter what way. I'm not very sound with all the functions of a cassette deck, especially a soft touch mech. Anyone had similar issues or know how to fix it?
TIA

 

[hopey]

It's the pinch rollers they are two soft and need replacing.

 

[floyd]

It's the pinch rollers they are two soft and need replacing.

Another thing to look at is the drive spindles where the pinch rollers contact the drive spindles sometimes will collect crud and dirt .. Not saying that's the case but it never hurts to look. If they look clean then there probably ok.

 

[Superduper]

It's the pinch rollers they are two soft and need replacing.

Pinch rollers function in the play mode. They pinch the tape against the capstan needle to ensure that the tape plays at the exact intended speed calibrated by the capstan (corresponding to motor speed). They are not engaged during FF or RW unless you are cueing, so this is irrelevant, although a typical failure is that they get hard like plastic and slick and no longer grip. Too soft is a symptom I have never seen.

FF and RW system often relies on levers and idler tires. You need to dig deeper and see if the idlers are working as intended, and also use isopropyl to unstick levers and rotating assemblies that have too much friction from built up grime and dried grease. On many boomboxes, there are often pulley and wheels present that have thin tires on the outside. The function might not be obvious at first but if you observe carefully during operation, they often swing one direction or the other to contact another wheel with a serrated outer ring to drive it. The tape deck has many moving parts and components, and they work together as a machine. Changing belts is a great first start, but you do need to evaluate and check everything else too.

 

[whiny_3800]

Another thing to look at is the drive spindles where the pinch rollers contact the drive spindles sometimes will collect crud and dirt .. Not saying that's the case but it never hurts to look. If they look clean then there probably ok.

I regularly clean my decks after 4-6 playbacks, but I appreciate the concern for dirt, but yeah they look very clean. The heads don't even have any wear on them, looks as if the decks were lightly if not even used at all.

 

[whiny_3800]

Pinch rollers function in the play mode. They pinch the tape against the capstan needle to ensure that the tape plays at the exact intended speed calibrated by the capstan (corresponding to motor speed). They are not engaged during FF or RW unless you are cueing, so this is irrelevant, although a typical failure is that they get hard like plastic and slick and no longer grip. Too soft is a symptom I have never seen.

FF and RW system often relies on levers and idler tires. You need to dig deeper and see if the idlers are working as intended, and also use isopropyl to unstick levers and rotating assemblies that have too much friction from built up grime and dried grease. On many boomboxes, there are often pulley and wheels present that have thin tires on the outside. The function might not be obvious at first but if you observe carefully during operation, they often swing one direction or the other to contact another wheel with a serrated outer ring to drive it. The tape deck has many moving parts and components, and they work together as a machine. Changing belts is a great first start, but you do need to evaluate and check everything else too.

This is very helpful, Thanks! Yeah and when I do get them to rewind and ff sometimes they make a rubbing or clicking noise so like you said, could be just dried stuff that's catching or something. You have to fiddle around with it to get them to play sometimes too, and it'll have a slight bit of warble. I am probably gonna have to tear the decks back apart. Might try using some contact cleaner too, just to see if it just needs some stuff broken down. Pinch rollers don't really feel all that bad, they're still spongy, but It may just need some little things cleaned back behind the reels. I've noticed sometimes when I hit ff/RW it sounds like its spinning but it doesn't actually do anything.

 

[Superduper]

I've noticed sometimes when I hit ff/RW it sounds like its spinning but it doesn't actually do anything.

That's a classic sign that the drive wheels aren't getting contact with the pivoting drive pulley which usually swings on a pendulum like lever. Things are sticking, might need lubrication in certain areas, but definitely not all. If you have access to a service manual, it sometimes provides lubrication points. Otherwise, just make sure nothing is gumming up the mechanism.

 

[whiny_3800]

That's a classic sign that the drive wheels aren't getting contact with the pivoting drive pulley which usually swings on a pendulum like lever. Things are sticking, might need lubrication in certain areas, but definitely not all. If you have access to a service manual, it sometimes provides lubrication points. Otherwise, just make sure nothing is gumming up the mechanism.

Thanks so much, I will look into it!

 

[hopey]

Pinch rollers function in the play mode. They pinch the tape against the capstan needle to ensure that the tape plays at the exact intended speed calibrated by the capstan (corresponding to motor speed). They are not engaged during FF or RW unless you are cueing, so this is irrelevant, although a typical failure is that they get hard like plastic and slick and no longer grip. Too soft is a symptom I have never seen.

FF and RW system often relies on levers and idler tires. You need to dig deeper and see if the idlers are working as intended, and also use isopropyl to unstick levers and rotating assemblies that have too much friction from built up grime and dried grease. On many boomboxes, there are often pulley and wheels present that have thin tires on the outside. The function might not be obvious at first but if you observe carefully during operation, they often swing one direction or the other to contact another wheel with a serrated outer ring to drive it. The tape deck has many moving parts and components, and they work together as a machine. Changing belts is a great first start, but you do need to evaluate and check everything else too.

This box suffers from soft rubber pinions Singapore is not Japan, I have first hand experience I switched out the rollers and works perfect. This is a 90s box so the rubber is just hitting that age for failure.

 

[whiny_3800]

This box suffers from soft rubber pinions Singapore is not Japan, I have first hand exIerience I switched out the rollers and works perfect. This is a 90s box so the rubber is just hitting that age for failure.

It says on the bottom that it was Manufactured in Japan, November of 1993. But made in Singapore. These were among the last boxes to be made in Japan. And if you do some research you will see that Singapore was one of the best countries with the highest quality electronics, besides Japan. I observed it was not the pinch rollers though. I took both decks apart and cleaned off the old grease and applied new lubricant. Luckily my dad still has quite a bit of cassette deck lubricant from RadioShack that I was able to use. However, even when using the service manual and putting it back together the correct way, it still does not work. I ended up finding an earlier DT-680 from 1991 for dirt cheap as the CD player had issues. The 91-92 were better quality than the 93-94 models. It was even a few pounds heavier. I ended up Stealing the Mech out of that one as it was still fully functional and looked brand new inside, even with the original belts. So it is now fully functional. I appreciate everyone's help but I just couldn't figure it out. I even took it to a Electronics technician with 40+ years experience in Stereos and boomboxes. He couldn't even figure out the issue. But in the end, it is now fully functional!