Denon DN-790R Belt Replacement and Capstan Motor Troubleshoot - Speed/ Wow & Flutter Instability
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- Опубликовано: 13 сен 2024
- Replacing the belts and fully servicing the capstan motor in order to solve a wow & flutter issue. Testing the tape path with a Sony mirror cassette and checking the frequency response.
I read on one of the electronics forums that my problem is due to the transport belt being loose I recently bought my Denon DN-790r and it worked good for about a couple of days and then the problem started so i will replace both belts and clean and lube anything that needs it. I don't have the specialized tools like you have but i will make do with what i have.
Your video has been very helpful.
Indeed a very detailed video. Found this in my RUclips feed after several weeks of searching for tape mechanism with closed loop and three discrete heads.
Thank you so much for watching and commenting!
Robimy to, żeby ci, którzy mają uszy, usłyszeli :)@@tomaszkluska6419
@@asbcustom Na pewno nie dla pieniędzy :)
Pozdrawiam gorąco i dzięki za fantastyczny film!
@@tomaszkluska6419 Bardzo dziękuję!
Ok partner, your video was very good, because I have the DRW-840 and DRM-800A and I was trying to find the same variation. So thank you very much.
Thanks Lewis!
Thank you. I was so frustrated with those two belts.
You're very welcome, glad I could help.
@@asbcustom I can't find your ebay sales and I also have a Denon DRS-810 that I may want you to service. I didn't see any cassete player links on the website, can you help?
@@chef223399 You may use the contact link on my Website to send a message, it comes to me directly. Thank you.
Thank you for the video it was very detailed and informative. and the video quality was very good and you spoke clearly so we could understand. Excellent video!
Cheers
Rob, thank you for your comments, I really appreciate it.
Просмотр принёс массу удовольствия. Благодарю вас.
Спасибо за просмотр!
I enjoy fixing Compact Cassette Tape Mechanisms. I fixed dozens of them. Most common one is the Tanishan based Mechanism that's easiest to fix, since it's one of most simple mech's. There are times when it will get very stressing, especially fixing quality, Full-Logic Selinoid Driven, Computer-Controlled Mechanisms with tiny springs and details you need to watch out for.
Thanks Verastaki for your comment, I'd love to see some of your repairs, have you thought of making a video?
Great idea at @22:00! especially for getting the brushes over and back on to the commutator without disturbing them.
Ah yes, thank you, that's why they put those slots in there.
@@asbcustom Of course stupid me reassembled similar motors a different way - by first engaging the brushes with the commutator, then using a convex ended guide rod to steady the shaft as I place the permanent magnet part into place. Next time I may do it the proper way! :)
Sorry @tomaszkluska6419, I inadvertently deleted your comment. My reply was: Robimy to, żeby ci, którzy mają uszy, usłyszeli :)
While doing similar work to yours, I observed tape flow for when (a) only the take up pinch is engaged, and (b) only the supply pinch roller is engaged. Listening in to a recording of white noise (one's own white noise reference tape as an example) I checked for any 'wobbling' of the azimuth. But if it's not quite steady in this scenario, but is fine when both capstans are engaged, then I guess it's not bad.
Interesting, I've tried removing the supply, but never the take up roller.
nice one, i can tell you a tip for the motors. instead of metal wire pins use capacitor with thick legs, put into clamp and put on top of it back of the motor and will be easy to asembly motor into brushes. im using panasonic 4700uf 35v. is big anouth. for cleaning brushed im using cotton buds with IPA and i just simply rotating between them and in most of the cases is good.
Thanks for the tip and for watching!
Got two Denon decks. DR M34HR and DR M10HX. I use the 34 for recording and the 10 for playback. Not expensive decks but they perform so well. Loved the video. Good Luck.
Thank you for watching and commenting!
@@asbcustom wondering - do you offer service/repair on cassette decks?
@@Bound2glory Thank you for watching, and yes I do. Please contact me from link on the About page here: www.youtube.com/@asbcustom/about
@@asbcustom nothing is coming up in the link?
@@Bound2glory There should be a button to reveal the e-mail address, they do this to prevent us from getting spammed. If it doesn't show, then please use my business e-mail at: www.asbcustom.com/contact.html. Thanks.
Maybe is tape path issue ; or bended capstan axel { rarely } ; many times good looking pinch rollers aren't good ???
At 32:17 onwards, is the free run, no load, 12V speed of these known? Near as I can tell no one has found actual specs on the MMI-6H2’s, and I’ve not seen any images where it’s ever advertised on the motor itself.
I ask because applying 12.05V, with no control lines (A or blank) connected, and no mechanism I recorded 6295 RPM using a contact tachometer.
I have clocked a motor at 6000+ RPM but I can't recall which one it was. I'm pretty confident that it was a control motor but don't know from which deck.
I realise that this video is now a bit dated, but some thoughts ..
Speed variations perplex me sometimes, assuming your work on the brush/commutator was effective, I guess I'd be looking at that motor controller. It could be based on the AN6651/AN6652 series or similar which was designed around a wheatstone bridge principle. Also might have been prudent to replace any transistors in there and caps. One more thing, may be look at the back tension too - did it fluctuate?; this can't be seen or even sensed by hand. I cured a very weird rising wow/flutter issue with a single capstan Sony (TC-206SD) by *eventually* disengaging the back tension! The back tension pad (although visually clean) was offering a varying coefficient of friction, an idler tyre had left its deposite behind and the pad just mopped it up, all macroscopically of course.
I'll stop bleating on now, promise! :)👍
That was my thought also, I changed that IC out and it made no difference. Finally located a NOS motor and it snapped back into spec. On another similar motor, I went through the same process and even a new motor didn't do the trick. It turns out I neglected to check the pinch roller pressure and it was way out on the high side. Bringing it into spec., also brought the flutter into spec. I do always check it as a matter of routine but forgot on this one. I find most of the issues on these decks are mechanical, not electronic.
Bleat away at your pleasure.
@@asbcustom The permutations of the things that can go slightly awry are so high, small wonder we sometimes seem to chase our tails! Glad you sorted it.
Thanks you, I’ve not seen this before.
Regarding tape flow: good shell too, the guides either side appear to be fairly steady. I wonder if the Denon would allow for variable pinch roller guide height setting? This old Sony I’ve been working on, does allow this.
Nice work on that motor.
As I recall, the supply side is adjusted to match the head guide, the take up side has no built in adjustment, but in a shop like mine, that's no deterrent at all if I need to correct something.
Great job Sir 👍
Thank you for watching!
Most of cassettes deck i throw out just for not getting part earlier i threw cassets almost 15 years ago to empty space ....now they look kind of cool i kept two of them ...how music player was back then
It's quite a wonder to me that the deck comes with 3 motors rather than just one. Apart from the capstan motor, what do the other two motors do?
Thanks for watching.
One is for the reels, the other controls the head stack. The separate motors are a much better design.
@@asbcustom Really interesting. (1) I believe the reel motor is certainly on for FFW / REW modes? (2) In playback mode - is the reel motor activated too, along with the capstan motor? Or is it just capstan doing everything? (3) I don't quite understand here - is the head stack motor in charge of turning the head + auto-reverse, or lifting the head for playback? (4) Which motor does the auto-stop function?
Yes, the take-up reel is active during play mode. No auto-reverse on this deck, but yes, the control motor elevates the head stack. Auto-stop isn't controlled by a motor in that way, the motors are controlled by the auto-stop function.
@@asbcustom Ah, and under play mode, will the reel *motor* spin at a reduced speed compared to FFW mode; or would it instead spin at full speed, leaving the capstan / pinch roller and tape to help slow the take-up reel down?
The take-up reel spins faster than the capstan, but at much lower torque. The capstan controls the tape speed, the take-up reel packs the tape.
Hi, I have a Phase Linear 7000 cassette player. The reel drive motor fails and stops once in a while, can it be serviced or what can I do to fix it ? Thanks ASB Custom...
I have no experience with that model but it could possibly be a bad connection or maybe a dead spot in the motor. Thanks for watching.
@@asbcustom I found a used motor on Ebay and it fixed the problem. I also replaced the pinch rollers with new ones. Thanks for your feed back, Lord bless you and your family !
@@biblequestionsanswered6572 Well done, glad you got it up and running, and the same to you and yours!
is the small belt on that motor for the heads? to make the transport go up and down?
My transport keeps going up and down continuosly and the tape does not travel.
Thank you
Yes, there is a smaller square control belt that also needs to be changed, these are normal maintenance items as they degrade over time. I hope this solves your problem, these are great decks!
@@asbcustom Well, I removed the transport mechanism and inspected for broken gears or gear teeth and found nothing all the gears looked good.
I cleaned the flywheels and the shafts and lubed the shafts also cleaned the large belt and it is still good. I also removed the pinch rollers and cleaned them, the left pinch roller "cradle" was a little tight so i loosened it.
I reassembled everything and tested it, I still have the same problem.
I fast forward the tape and that seems to help because the tape started playing but if i start the tape from the begging the head block starts cycling like before. So i am thinking that it is an electrical problem.
The arms at the left are those to detect the type of tape that is playing?
What are your thoughts?
Thank you
@Rob Hernandez Assuming that you changed the belt and it has the correct tension, then from what you describe it may be the cam switches. I posted an image here; postimg.cc/xJTfQp1T
These are very delicate and as far as I know, irreplaceable.
Additionally, when you say that you loosened the left pinch roller cradle, if you backed out that nut with the green paint on it in order to remove or "loosen" it, it must be set back up with a particular gauge. That nut sets the left tape guide height and will run skewed if incorrect.
@@asbcustom I did change the small belt with a new one but I don't know if it is the correct tension. I can see the motor and belt moving now I put a mark on the white pulley and I can see it moves everytime the head block activates and deactivates.
The cradle was scraping on the inner side of pinch roller cradle against the backplate so I had to loosen it just enough to clear.
The tape played fine.
I will check those finger switches.
Thank you
@@asbcustom If I remove the board will anything fall out of place? Or are the switches secure?
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Indeed