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Sony TC-KA7ES Restoration: Seeking Solutions for Slow Speed Issue
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- Опубликовано: 29 июн 2023
- Join me on this journey as we delve into the restoration of the magnificent Sony TC-KA7ES, which, unfortunately, is facing a peculiar speed problem. Despite trying everything in our arsenal, from checking and verifying the take-up reel and supply reel tension, trying out three sets of pinch rollers, measuring the tension on each roller arm with a specialized scale, to even re-lubricating the reel shafts, the issue persists. If you've encountered this issue before or have suggestions on what to try next, we'd love to hear from you. Subscribe and like this video, and remember to share your thoughts in the comments. Let's figure this out together!
Отличное пособие! Хороший материал! Этот магнитофон моя мечта!
how about using plastic supply roller instead of the metal one?
Tried 3 sets including plastic left roller. No change.
@@hifirulezzz how about the take up reel motor?
@@EASMusicChannel 40g take up torque.
As always, a great video.
Thanks!
I noticed that when you resembled the capstans there was no spacer of any kind between the capstan and bushing/bearing. Usually there is a spring and washers. It could be a spacing issue and drive coil induction and FG is off.
I checked the service manual and there should be a washer.
There was a washer on each capstan. 24:12 for example. Washers are semi-transparent.
No not the pinch roller side. Other side of the bearing they should be a spacing washer. When you are lubricating the main capstan you can see the flywheel drops down hard onto the FG PCB. Have a look at the service manual exploded view.
@@ferrograph I have posted a time stamp so you would be able to see that spacer is on capstan shaft. Please stop.
@@hifirulezzz Sorry. Maybe it's the resolution of the video. I paused and zoomed in but I don't see a washer flywheel side of the bearing on the main capstan. "Please stop" - Do you mean you want me to unsubscribe?
@@ferrograph I want you to believe me, ok? If I wrote once that washers were installed, than It is. They are small size and half transparent. I receiving dozens messages daily. Stop mean read above.
I replaced all the belts on my akai deck, but the main belt was wider than the original. It made the deck noisy and it would stop playing. I put the original belt back and it plays normal and quiet now. I'm having same issue with my Yamaha K-850 it sill plays slow despite cleaning and new belts.
On page 32 of service manual you can see schematics for capstan and comparator boards, they share 9.2v rail from reels motor board, you can check if this voltage is correct. And for the IC on these boards you have values for every pin, I would check. I see three electrolytic caps on comparator board, 2 on reel board and three on capstan board, I would change them immediately. Hope you solve this, it's a beautiful deck.
Have you ever watched my video? I replaced 4 caps. Right capstan rotates with the proper speed. Electronics can’t change anything if it “think” that speed is correct.
@@hifirulezzz Don't need to be rude, I watch completely your videos, believe or not, I only try to help like some other people here, but perhaps you don't need it. I'm still think problem is electronic related. Good luck.
@@Rfx222 I didn't mean to be rude, sorry. Please read my other comments under this video. I closed the electronics question 2 years ago when had two KA5s and one worked fine when the other had a speed issue.
Best Sony tapedeck ever..
@@maxfactor4209 My favorite are 555esA/esJ. This deck is superior on electronics, but just a little bit. But I do not like the look of the KA series. Too squarish on my mind.
My KA6ES is running at 2.981, maybe is just how it is? it has had new belts and pinch rollers, personally i'll just live with it as sounds perfectly fine to me, maybe one day i'll strip it down again!
Sony decks with DD boards usually run 2,994 on the Dragon tapes. Dragon is a few Hz faster.
maybe the left capstan shaft is worn, if you have the same mechanism maybe try diferent capstan module with the same mechanism. i know is lots of work but maybe is this as it looks like is all about left capstan. if is worn it will not be stable.
Just FYI if you want a grease for these machines, one that is most likely to come out still effective after 30 odd years, it's Dupont Molykote, I suspect the EM-30L variety is the CURRENT product which I found the replacement from the original grease, but I'd have to dig more into it.
Just saying because this knowledge is fading away, in fact I cannot even find again the manual (that I am certain I have in PDF format) in which I have read about that grease.
Just a SAFETY NOTE for you @hifirulezzz: I have the same oiler dropper bottle that you have. You should NEVER leave it on the workbench... it's a recipe for eye stacking. Been there, (almost) piled an eye on it.
that one? www.amazon.com/Molykote-G-n-Metal-Assembly-Paste/dp/B01L7W603K/
@@hifirulezzz nono-no... unfortunately I cannot post links here and I can't even write down the name of the manufacturer's website.
It's the Dupont MOLYKOTE EM-30L lubricating grease developed for plastic components.
This more likely an electronic issue, not a mechanical issue as you have covered everything here. I highly recommend you check the quartz crystal value on the comparator PCB strapped to the back of the mechanism to see if it has the correct 'Mhz' value installed as outlined in the KA7ES Service manual. I swapped out this board from another ES deck into a KA6ES machine and the deck ran slow and I couldn't work out why. (The board may have been changed over at some point in it's life.) I discovered Sony used different quartz crystal values on these PCBs (they look identical) for the quartz speed lock on different ES decks using the TCM200 mechanisms, mainly on the KA series. They are NOT all the same! If the correct value is installed, check and measure the frequency of the quartz crystal. This is critical to obtain the correct speed. If all OK, then the CX20174 chip for the capstan could be at fault as I've replaced a couple of these now as they can fail. (Chips can still be sourced from UTSource website). Hope this helps
It is not. I had once two KA5s at the same time and one was working fine and the other had a speed problem. I had a chance to compare electronics. It did work exactly the same with the same frequency coming from the FG coil.
@@hifirulezzz Don't take anything for granted or discount nothing. Look in the service manuals and you will see Sony install different crystals. It may not have been the case last time but can you discount this time?
@@johnnyg1700 You don't get it. Speed is set for a right capstan, and the speed is correct. As soon as the left capstan doesn't obstruct the movement of the tape.
@@hifirulezzz That could be a capstan torque issue. Have you another deck where you can swap out capstan, flywheels and electronics. That will be the only way you'll narrow the problem down because you've come to a dead end right now.
@@hifirulezzz Try changing the belt as might be too soft. You rebuilt the mechanism with the original 30 year+ belt.
Could it be an electrical problem？
it is not.
I had the exact same issue with my k890es. Especially if I puled the supply roller while playing from the capstan, which resulted in a correct speed, a few Hz below 3kHz. After release, speed drops, no matter the amount of spring pressure of both the capstan rollers. Maybe an issue with the drive capstan feedback circuitry? A sort of a faulty 'new equillibrium" so to speak after releasing the capstan roller? If all pressure measuring is ok... Then it seems a electronic (direct drive/feedback coil) issue. But I am and the end of the road too.
It is not an electronic issue. See my response for other comments.
@@hifirulezzz I still think it's worth checking the feedback I gave you but your too stubborn to confirm it's not! Only trying to help but you won't listen.
@@johnnyg1700 I am not stubborn, I have seen this issue on 4 decks and spent months trying to solve it. 3 out of 4 have been fixed.
The width of the belt is not properly, must be wider - about 6 mm. This affects the speed between flywheels due to the convex surface of one of them.
The original belt is 3mm. Not sure what you writing about.
On Direct drive motor board, there's 2 SMD capacitors which always leaking and will eat pcb trace away if not replace. This normal issue for all Sony TCM-D200 transport. Replace them with higher grade small size EL capacitors would solve speed stability issue
He has changed iit already. He has mentioned it
@@danielfaradey7629 Thanks!
At first the belt wasn’t in the grove of the capstan. Maybe this was done to correct the speed difference. If the right capstan is this little bigger the left should go faster.
Maybe, but it is NOT a solution.
Do you have specs for flywheels? I mean diameters. One of them is probably out of spec, making the second one rotate a bit slower than it must.
I agree, it's either one of the flywheels not being the original from this unit or the belt being exceedingly slack... pretty much the only things that can produce this symptom. Excessive friction at the supply capstan or pinch roller bearing can be ruled out, I think. Also, tape slip at the takeup capstan seems unlikely since the speed is correct when it is the only one engaged.
@@mihaischitcu1917 Both are original. It is an idea of a closed loop - to tighten the tape left capstan shaft is smaller in diameter to make the path 2% less than the right one. The only think is that right capstan cant pull the tape over resistance of the left one.
There is one very easy test he could perform and that is to remove flywheels from a known working KA series deck to prove or disprove this.
@@johnnyg1700 Aha, waiting for parts ;)
@@hifirulezzz I know that, but the tape doesn't necessarily have to slip at the supply capstan; just the fact that it stretches ever so slightly in between them is enough for it to travel a little bit faster at the takeup side. I think on the Dragon they mention the exact speed difference, because there it is electronically controlled; when in reverse, the left hand capstan rotates a little faster, when in forward, the right one... I don't remember the exact difference but it's