From "Doorstopper" to Perfection: The Nakamichi MR-1 Restoration 🛠️

Añadido: 2026-05-18

[00:00:00]Hello, everyone.

[00:00:02]Today, I will be working on a Nakamichi MR-1 professional cassette deck, which was used on recording studios, and it has XLR inputs and outputs, and it's can connect external noise reduction decoder.

[00:00:22]All right.

[00:00:24]So, I check it up. So, technically, it works. So, capstans running. I cleaned the tape path. Tape is rolling.

[00:00:34]And I want both indicators are working.

[00:00:37]However, we are short on the output on one channel. Not the phones, no outputs uh show one channel.

[00:00:49]Come on.

[00:00:52]Uh-huh. Else the motor stopping.

[00:00:56]Famous sync your problem.

[00:00:59]And reel motor has a dead spot.

[00:01:02]All right. I haven't seen it before.

[00:01:06]At least now we see it.

[00:01:17]And we need to stop on the dead spot, then it will not start.

[00:01:22]All right.

[00:01:24]More work.

[00:01:26]So, clean up, replace belts, specifically the supply side tension belt, the small one on the front, uh capstan belt, and uh see what the motor does. Maybe just clean it up.

[00:01:42]And find the root cause why right channel uh don't shows on the output even if you playing both channels from the head.

[00:01:51]All right.

[00:01:52]So, let's start.

[00:01:55]Let's take a look inside.

[00:01:58]So, it has the similar tape transport as Nakamichi BX-300.

[00:02:05]No significant changes. Just looks a little bit more modern.

[00:02:10]Like preserved it better. Nothing like to talk about.

[00:02:17]Yeah, you see I [snorts] got XLR boards with op-amps which converts input and output from XLR towards uh from I come XLR mean uh what is this word?

[00:02:35]Balanced to unbalanced because inside the deck everything is unbalanced. So, we convert here from the input uh balanced to an unbalanced.

[00:02:46]And on the output we convert back from unbalanced to balanced. So, we have balanced outputs. Technically, you may get uh similar boards from China and upgrade any deck to this state.

[00:03:01]All right.

[00:03:02]Zip ties.

[00:03:07]Here is one not original. So, it was serviced before.

[00:03:12]All right.

[00:03:16]Let's see.

[00:03:22]I you see no separate Dolby board. Just like conversion output to the external noise reduction.

[00:03:30]It's It's a bias generator same as in BX-300.

[00:03:35]And playback amplifiers and playback head connects here.

[00:03:39]All right.

[00:03:42]Pretty pretty similar to BX-300 to tell the truth in design.

[00:03:48]Now, let's see what's wrong. Let's start from the tape transport.

[00:03:55]I will remove it and service.

[00:04:00]See you in a moment.

[00:04:02]Quick update. I removed screws from the tape transport and I had to remove the output boards just to get to the connectors which sits below this board.

[00:04:14]Now tape transport is fully disconnected. Three cables for the heads.

[00:04:20]All right. Record head cable connects right there.

[00:04:25]Playback here and erase head here.

[00:04:29]All right. Very similar design to BX 300s. Very close.

[00:04:34]Now I would have to gently pull tape transport out and this is a position port.

[00:04:41]I believe.

[00:04:43]All right.

[00:04:46]Oh, not position. It's It's probably speed adjustment.

[00:04:52]Do we have it? Pitch control. Yes.

[00:04:55]Right here.

[00:04:56]So, that's what pitch control.

[00:04:59]To adjust the speed of the motor.

[00:05:02]All right. See you in a moment.

[00:05:05]Finally, I removed the tape transport.

[00:05:07]It is a very tight space, so I had to remove front panel to do it gently and have access everywhere. So, and you pull it back right here. So, let's do it now.

[00:05:23]Now let me see. Check everything, clean up everything, lubricate it and so on. You may refer to my BX 300 videos. There is no difference.

[00:05:34]Completely the same transport. See you soon. Well, guys. I'm working to disassemble and I see even if belt the rear belt has been replaced, all right?

[00:05:47]Uh there is absolutely zero lubricant has been added to the bushings.

[00:05:52]And you may see this belt, which should give a tension here, it's already the dissolved. You see, it's pieces of it and a goo around it.

[00:06:08]All right, that's what I would need to clean and replace. Good we have already gear mechanism for reels.

[00:06:17]All right, let's me clean it up, put new belt here, and see what we will do with this motor.

[00:06:26]Now, cleaning may be annoying and not that easy, but you have to remove both pulley and clean them up because like the residue of the old belt is sticky.

[00:06:39]And specifically, we don't want new belts to get into our contact with this stickiness because they will degrade quicker. So, use isopropyl to clean it up, all right?

[00:06:54]Now, it's time to assemble and install the new belt. I hear a little bit more residue on these gears.

[00:07:01]I will clean it up and assemble.

[00:07:04]Now, here guys, I will be installing pure B belt from Mike.

[00:07:09]It's russellind.com.

[00:07:14]Oh, russellind.com.

[00:07:17]I'm not sure if you can see well.

[00:07:20]So, so far I found those to be pretty reliable and good quality belts.

[00:07:25]There are not many sources left, so I'll do my best.

[00:07:31]And that is how it's look assembled. So, when head is down, so you may see the left gear rotates freely.

[00:07:42]And once heads go up, this lever will This lever will prevent this left gear from rotating.

[00:07:52]And there is a friction mechanism between this black gear and their white pulley. So, that's makes the torque. And to adjust the torque, this uh leaf spring can be rotated to the positions. You see there are clicks you can set and it will rise and make a tension.

[00:08:11]All right.

[00:08:13]So far, it looks to be good tension, so I would not adjust for now.

[00:08:18]All right.

[00:08:19]Moving on.

[00:08:21]All right, everyone. I must have a little and continue testing.

[00:08:27]All modes engage now and counter works.

[00:08:29]And it did not work uh because this black wire from counter board, not counter sensor board, to the capstan motor board just like pulled out.

[00:08:43]I'm not sure why, because everything is tied together.

[00:08:46]So, all right. Now it works.

[00:08:51]And play stops. And that's Uh-huh. You see?

[00:08:58]Motor reel motor stops again.

[00:09:02]And for fast forward doesn't engage, you see?

[00:09:07]Only reverse engage.

[00:09:10]Oops, and then stops.

[00:09:21]All right.

[00:09:25]So, I have rather replace reel motor.

[00:09:29]I have one spare on the older tape transport I was disassembling uh from Nakamichi DR-1, believe.

[00:09:39]Right.

[00:09:40]Or disassemble and clean this one. But anyway, it's another full disassembly because I would need to remove both capstans to get to the reel motor and pull it out.

[00:09:53]Ooh ooh.

[00:09:55]Double work.

[00:09:58]And like I tested like with my finger.

[00:10:04]Problem is that's torque.

[00:10:08]Actually, torque maybe not that bad. So, let's use test cassette.

[00:10:12]Right. Give me a second. I will get it.

[00:10:16]Okay. Let me install the fast forward rewind torque measurement.

[00:10:23]110. Perfect.

[00:10:26]And 70 on reverse.

[00:10:29]That's not enough.

[00:10:32]110.

[00:10:34]90.

[00:10:36]90.

[00:10:38]90. All right. It's not very stable.

[00:10:42]I would prefer it to work more stable.

[00:10:45]And here is a play box torque tape.

[00:10:52]Oops.

[00:10:53]It started good, but then it stopped.

[00:11:01]Now, fast forward engages.

[00:11:04]Okay. It's 50 50 50. Now, it works.

[00:11:09]All right.

[00:11:10]This motor is unstable.

[00:11:13]See you soon.

[00:11:14]And now you may learn how much work is needed to get to this reel motor. So, we need to remove even bearing space for capstans.

[00:11:25]And we have to disassemble and for the front, remove the uh prevention mechanism which locks the door, and so on.

[00:11:35]Okay? And now I can get access to these two screws and those one nut to pull out this motor, but I will desolder it first.

[00:11:44]And I would have to do the same on the other transport to get the other motor.

[00:11:48]See you soon.

[00:11:49]And finally, motor is out, and it's also required to remove belt and front reels, because they've been preventing it to pulling out.

[00:11:58]And now I [clears throat] can replace it.

[00:12:03]Unfortunately, these motors are known for failures.

[00:12:06]I'm also have a set of new motors. I will measure. I believe I can make it work.

[00:12:14]Let me see. Let me pull new motors.

[00:12:19]Okay. This is a brand new motor.

[00:12:22]And as you may see, it's the same.

[00:12:28]The only difference, the shaft is 2 or 3 mm shorter, but for this case, it should work.

[00:12:37]Okay. Let me see. Let me measure parameters.

[00:12:41]I know this is a good motors. I tested them.

[00:12:44]I have a full box of them from South Korea.

[00:12:48]So, let's see if this will work. So, the good thing, you would be able to restore way more this older decks. Okay?

[00:12:59]See you in a moment.

[00:13:00]Okay. I'm installing the new motor, and it sits pretty well. The only thing, the shaft just there inside the white gear, and it's not looks on top of it like the older one.

[00:13:18]So, I believe maybe 3 to 4 mm difference, but it doesn't play much role in this case.

[00:13:26]Now, let's me install it back. Install reels and see how everything will work together.

[00:13:32]See you in a moment.

[00:13:35]Okay, I had to reassemble again. I found the small white uh piece of plastic also on the old motor. So, I disassembled and assembled it properly now.

[00:13:48]So, I'm moving on.

[00:13:51]Let's me install reels and see how everything will work.

[00:13:55]See you in a moment.

[00:13:57]All right, I have to rise for half millimeter position.

[00:14:02]So, you may see how everything works now.

[00:14:06]It gets in touch perfectly well.

[00:14:10]And uh lowest but good position, it still works fine. Good.

[00:14:16]I hope now everything will work as it should. So, let me assemble it.

[00:14:20]Well, guys, I'm assembled and I'm puzzled a little bit. When I apply external 6 V, this motor spins in both rotation pretty well. When deck is running and connected to the motor, the rewind works as it should, as you may see.

[00:14:38]It will work as long as I need unless I rotate right reel.

[00:14:44]All right.

[00:14:46]Uh fast forward just doesn't work.

[00:14:49]And if motor not connected, it produce proper +6 and -6 V to reverse it. If motor connected, it produces +6 and zero.

[00:15:00]So, some problem with the current, I believe. I need to validate. Maybe transistor is not that good anymore or whatever. Let me check.

[00:15:11]Well, guys, I tried to replace transistor. It didn't help. Then I installed it, connected the older motor, and it rotates in both direction. So, rather this motor has a higher current, so I cannot sure what's happening. I measure its circuits, measure the same in both directions when I running like 6 volts and current is good.

[00:15:34]Or there's some mechanical problem.

[00:15:38]Right. It's probably will be number three to disassemble everything again.

[00:15:44]So, I might decided to make experiment clean. I get another motor and it's rotates well in both directions.

[00:15:54]So, let me see.

[00:15:57]I want play back works.

[00:16:00]I'm not sure, so probably some mechanical issue prevented to rotate into the forward direction. I need to check.

[00:16:10]All right.

[00:16:11]I set transport into the fast forward reverse mode with cap motor.

[00:16:18]Both reels are rotates free, no friction.

[00:16:24]I set 2.4 volts and take a look in between there. Like, let me zoom in a little bit.

[00:16:33]Right. Take a look on the gears.

[00:16:39]Oops, I'm sorry.

[00:16:42]Tight place.

[00:16:46]Okay.

[00:16:48]Rotates easily.

[00:16:50]2.4 one direction.

[00:16:53]2.4 other direction. No friction. Like, nothing.

[00:16:57]Now, be careful. It's I'm puzzled. What's really happening and why it won't work.

[00:17:10]That's 60 mA at 2.4 volts in one direction.

[00:17:19]And exactly the same 60 mA at 2.4 V another direction.

[00:17:28]And it's a good torque for take-up reel in the playback mode.

[00:17:33]So, and with 6 V, we have a strong torque, really.

[00:17:47]Same on the opposite side.

[00:18:17]Exactly the same.

[00:18:19]I don't understand why it don't work in the tape deck.

[00:18:24]All right.

[00:18:27]And that's another day. I'm back, and I thought I had a DR-1 motor, but it appeared to be a BX-300 motor. I'm already replaced, and this one doesn't work from 2 and 1/2 V.

[00:18:39]So, I playing around. This motor one direction works with 2 and 1/2 V. Other direction is mostly works, but there is spot when it stops.

[00:18:50]So, what I will do, I will open this motor, clean it up, and rotate by 160° as I remember properly.

[00:19:03]That's where like it will not stop anymore. So, the problem with this motors, as we learned over the last years, that uh permanent magnet inside is not that powerful anymore.

[00:19:16]And there is a position when it's don't start rotating.

[00:19:22]So, we need to rotate our uh contacts on the angle, so it would always start rotating in both direction.

[00:19:32]All right.

[00:19:34]I have no other choice.

[00:19:36]This motor, it works perfectly, but I measured the consumption is like the 60 mV, whereas this one is 20 mV.

[00:19:45]So, I'm not sure how I 60 mV affect this on like uh 2 amp here transistors. So, they should like work smoothly like without any problems.

[00:19:58]And unfortunately, it works just in one direction, and in other direction, it doesn't work.

[00:20:05]I'm not sure why.

[00:20:08]But something weird is happening.

[00:20:11]All right.

[00:20:12]That would be another attempt to make it perfect running.

[00:20:18]And here, guys, you may see how heavily oxidized it's the contacts and the rotor.

[00:20:27]So, everything is way black, so let me deoxidize it and lubricate motor bearings, and let's see how it will work.

[00:20:37]Okay, guys, I cleaned this motor, and I was able to find a sweet spot. So, as you may see this red mark right here near my nail, and red mark here, I turned it about 15 to 20°.

[00:20:52]All right. And I tried like there was so many attempts like I I I I technically run full circle, and it was still stopping on like not pulling well from the initial position. So, like as you may see by turning by like 10 mm.

[00:21:10]Yeah, about 10 mm.

[00:21:13]Uh, I was able to find the spot when it don't stop. So, I'm using like 2.4 volts.

[00:21:20]I'm adding friction to the shaft with my finger and I'm give short pulses, right?

[00:21:27]Uh, very short. It It turns turns turns turns turns and then it stops, right?

[00:21:31]That means our spot is not good. Then again, like I change position and again do rotate one direction, see if it's not stops in multiple turns and then like um reverse position, right? And see if it's don't stop in the opposite direction.

[00:21:51]Um, that's the only way I was able to bring it back.

[00:21:55]So, now let me install it back and let's see how everything will work. See you soon.

[00:22:00]Well, this did help. It's finally we have real motor working.

[00:22:08]So, let this set up, fast forward, rewind, and play back.

[00:22:18]Works and don't stop.

[00:22:22]We have another issue.

[00:22:26]This motor starts like eight out of 10 times.

[00:22:51]I got it twice when it didn't stop. I require a little bit of rotation.

[00:23:00]I'm so exhausted with this deck, guys.

[00:23:08]Now it starts all the time. I'm not sure.

[00:23:12]I need more testing.

[00:23:22]I had it twice when it did not start. I had to rotate a little bit to start it.

[00:23:35]Maybe aged parts when that was happening.

[00:23:39]Here.

[00:23:40]Got it.

[00:23:42]And it's moved when it's powered on.

[00:23:57]Now that would be a huge surprise when you install your tape and it doesn't play, right?

[00:24:03]Okay. Again, you see it moved and stopped right away.

[00:24:09]And it has a good torque.

[00:24:14]Good signal levels.

[00:24:18]Ah, I'm so tired.

[00:24:21]See?

[00:24:22]So I'm continuing I replaced a capacitor right here, 10 by 16.

[00:24:29]And it did work first five times, but on the sixth it stalled.

[00:24:35]So it depends on the position as you may see.

[00:24:40]And if it depends on the position, I need to remove it again and check coils and check that everything is intact and everything works there.

[00:24:50]All right.

[00:24:51]See you. [sighs] Yep, I was right. Take a look.

[00:24:56]You see one open wire right here.

[00:25:00]This one.

[00:25:02]From this coil is going here and it's open.

[00:25:06]All right, let me fix it.

[00:25:09]All right, assembled again.

[00:25:11]So, it was how many five times this time.

[00:25:16]And it's not a record. My record is nine. It was 12 deck and it was nightmare.

[00:25:23]And the previous record with one well deck was six. It was IWA F990.

[00:25:32]All right.

[00:25:34]But it's close to the records. Now, let's see.

[00:25:38]Fast forward.

[00:25:40]Let's bring more light.

[00:25:45]95 reverse 95 95 90 95 90 95 90. Oh, yeah. Good.

[00:26:06]This works.

[00:26:08]Now, let's see playback.

[00:26:15]45 to 40 A little bit jumpy and nine on the left side.

[00:26:26]Perfect. On the right side a little bit jumpy, but it keeps pretty well now.

[00:26:33]Good.

[00:26:36]And now, let's try the tape.

[00:26:41]Fast forward, strong.

[00:26:45]Rewind, strong as well.

[00:26:50]And the And it's having a play and some music.

[00:26:55]Cool.

[00:26:59]Done the complex parts.

[00:27:02]Because this tape transport is is like pretty tricky to work on.

[00:27:08]All right. So, I thought it would be uh door stopper.

[00:27:14]Even if it's professional door stopper.

[00:27:17]But it looks like I would be able to fix it. Now, I have to find why left channel don't have output. And then we will tune it.

[00:27:26]So, let me start doing it. See you soon.

[00:27:29]Well, guys. And it works now, both channels.

[00:27:34]And the only thing I did while I was researching the real motor issue, I found the transistor with cracked solder and I soldered it by then. But I didn't pay much attention. Like I don't worry it is. I just I resoldered it connectors, resoldered it those cracked parts. And that's it.

[00:27:55]And now both channels works.

[00:27:59]Oh, pretty nice. Good results.

[00:28:03]Sound is nice and full.

[00:28:08]So, now it's time to tune in. Finally.

[00:28:12]It took a while, really.

[00:28:17]See you in a moment. Well, I'll continue tuning.

[00:28:20]Like first of all, I was puzzled there was no output unless I put output here because headphones is adjusted separately.

[00:28:30]Right now I have output and speed is 2966.

[00:28:36]And we need 3,000. So, let me adjust it.

[00:28:40]We have a port here, but it's in the middle position should be 3,000 even.

[00:28:48]Let me do it.

[00:28:50]If I can put anything like there is no room.

[00:28:54]Really, how I can put anything right here?

[00:28:59]If everything is is closed in this area.

[00:29:11]How do I do it?

[00:29:15]Should I remove this board again?

[00:29:19]Okay, let me do it with two hands.

[00:29:21]Probably would need to remove this board again.

[00:29:24]Well, well, with two hands I was able to make it 3,000 even.

[00:29:31]3,001 299999, okay, 3,000. Good.

[00:29:37]Now we can test and tune it.

[00:29:42]Ooh.

[00:29:43]It was so long.

[00:29:47]Okay. That one needs that one.

[00:29:53]Level.

[00:29:54]All right.

[00:29:56]Let's see level.

[00:30:01]Ooh.

[00:30:04]It shows plus six, it should be plus one, that's a bell.

[00:30:09]Why it's It's way too much. All right, let me see the service manual and adjust playback.

[00:30:23]Okay, I tune your azimuth, tune your levels, and now I play in minus 26 decibel tape.

[00:30:29]And it plays all frequencies on the exemplary level. Only 250 goes higher a little bit, so 12.5 10 Now it's 10.

[00:30:48]Now it's 6.3.

[00:30:52]1 kHz and 250.

[00:30:55]All right.

[00:30:57]Good.

[00:30:58]Moving on.

[00:31:00]All right, guys. I'm testing factory tape with Dolby B. There is plenty high frequencies.

[00:31:09]And I have you turn on Dolby B. It's It's having like exhausting how many there.

[00:31:18]And with Dolby All right.

[00:31:22]I tune it levels uh to properly match output levels and tape levels.

[00:31:31]Uh instruction like service manual, there is just not possible to adjust it.

[00:31:36]When you tune to minus 10 on the output and tries to pull to zero here, it just like don't have that much range. So, minus 10 on the output, minus 10 on the display, and it's uh perfectly well matches the levels of the uh reference tape. So, now I go when I play uh zero dB level, it shows zero dB. It doesn't show plus six anymore.

[00:32:02]All right.

[00:32:04]So, I believe they mean if you set minus 10, you have to tune to minus 10. You cannot tune to to zero. Maximum I can put is barely touches two two decibel is adjustment.

[00:32:18]All right.

[00:32:20]So, playback is fully tuned it. Now I will tune recording levels.

[00:32:26]And that's would be it. See you soon.

[00:32:30]Okay, I just tuned it bias. Uh it was a little bit off like plus 1.5 decibel on the TDK D.

[00:32:39]And that's 22.4 and this record is pretty well, just minus one decibel to the original level.

[00:32:47]Source tape.

[00:32:50]Source tape.

[00:32:52]Imagine that.

[00:32:54]All right.

[00:32:55]Nice deck.

[00:32:57]I just tune in type two and this type four and it's plays perfectly well. So, 400 gears, 1 2 Oh, it was 10 and 20. Sorry. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18.4 19 20.4 21 22.

[00:33:25]All right, 22.4.

[00:33:28]Good.

[00:33:29]And 24.4, still in phase.

[00:33:33]So, it's records really, really well, very linear without any ups and downs.

[00:33:40]Really professional deck.

[00:33:42]And I glad what I see.

[00:33:46]So, now let's me assemble it.

[00:33:51]And that's would be it.

[00:33:53]See you in a moment.

[00:33:55]And that would be the final part. Deck is assembled.

[00:34:00]Fast forward.

[00:34:02]Rewind.

[00:34:05]And play back.

[00:34:12]It plays really, really well.

[00:34:15]Enjoyable well. Like it has all frequencies on the output.

[00:34:20]And just like really, really good deck.

[00:34:25]Considering the BX 300 design, so it's mostly the same design with addition of the top metal frame here. This top panel is like made from a thicker metal.

[00:34:40]It's is pretty similar. There are input on the front.

[00:34:47]But that's mostly it.

[00:34:50]So, plays really nice.

[00:34:58]All right.

[00:34:59]Thank you for being with me for that long.

[00:35:02]Subscribe to my channel. I will post more interesting and challenging videos.

[00:35:07]This restoration efforts uh frequently gets derailed by the aged parts, by the difference design decisions, like and so on, like uh this deck was not the hardest to fix, but it took quite a few iterations, as you've seen, to make it work perfectly well. All right. See you on my next videos, and bye-bye.