Nakamichi BX-2 Cassette Deck - Electrical Adjustments & Calibration (Part 2 of 2)

Wrapping up this Nakamichi BX-2, I will install a new repay, and perform the basic calibraionsnwe can all do in accordance with its service manual - meters, levels, azimuth, and a recording check.
The relay I change at the start is the main head relay and can cause poor channel response, the type is a DPDT G5V-2-12DC.
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[@dnadoc2010]

Thanks

[@rafacq]

Your videos are really awesome and give folks like me an inspiration to not be afraid to open our vintage cassette decks and try to bring them back to their original luster. At 71, I vaguely remember my first deck. It was able to flip the cassette and continue playing the second side. No it was not a Nakamichi, I think it was an Akai Invertomatic!, Model CS-50. My first 3 head deck with Dolby C I bought in 1984, a JVC KD-V6 which I still have. Recently I got the vintage cassette decks bug. Oh No. After many years wanting to buy a Nakamichi, I finally bought my first one (they always seem to be out of my budget). I found a BX-300 which considering is about 40 years old, still plays and records nicely. When first turned on, pressing rewind seems to skip/slide a second then kick in. Playing a cassette right after powering on, can cause a tape to be chewed. Forwarding a tape all the way then rewinding then forwarding, basically warming the deck, solves the issue. I can then play tapes all day long and no chewing! I removed the cassette plate and looked at the idler wheel and it looks pretty thin. I already ordered a replacement. Can a bad idler wheel cause a tape to be chewed/eaten? I know it is related to the rewind/FF but not sure if it impacts playback. Thanks again for the great videos. You have a new subscriber! Regards... Ralph

[@pwrestoration]

Thanks for your kind words Ralph. The idler tyre would definitely benefit for being changed here, for the fast forward firstly, but yes on these decks the take-up (IE the retention of torque on the tape during playback) is also controlled by the idler tyre. As it's slipping, it sounds like your pinch roller is doing its job but your idler is not taking up the slack. It can be a difficult job to change it out, but it would solve your issues I think. It will have shrunk over the years and lost it's friction. From memory I think part one of this video series details how to change it out, it's pretty involved! Be careful not to break the idler wheel though, they can be fragile! Good luck!

[@markstewart1807]

Really enjoyed your video's on the BX 2 very interesting ❤

[@LuxmanPD272]

Very informative and clear.

[@amitanaudiophile]

Very nice to watch your videos. I also having Nacs BX 10.but not having test cassettes

[@pwrestoration]

Thanks! You can pick one up off eBay for £10-£20, they're very useful 🙂

[@QuoPaperPlane]

The CD player you have partly showing, is it the NAD 5440?

[@pwrestoration]

I think it was!

[@LutzSchafer]

When you record and play back the tape speed is irrelevant. For the speed you need a calibration tape. Same form azimuth ...

[@pwrestoration]

The speed is relevant. You can double check calibration by recording a tone, and playing it back. It should be the same in hertz

[@LutzSchafer]

@pwrestoration i would expect that the tape speed would not change between recording and playback even if way off the nominal velocity. Therefore you won't see a change in frequency regardless of the set speed right?

[@MikeDS49]

17:15 Record/playback of a tone on the same deck will cancel out any speed problem. If it records slow, the tone is laid down more closely together on the tape as an effectively higher frequency with respect to a reference. This is cancelled out when the tape is played back slowly over the head, dropping the frequency again. Using this effect though, you can create a higher quality recording if you only record and then play the same tapes on one deck. Boost the tape speed, and you will a much better quality sound and pushing the tape hiss frequency much higher. I think the Fostex 4 track compact cassette recorder does this.

[@MrSlipstreem]

That also pushes head bumps further up the frequency range making them more troublesome as well as putting the record and playback EQ out. You won't get anywhere near a flat overall frequency response at anything other than the speed the deck is calibrated for, ie, 1 7/8 IPS.

[@MikeDS49]

Great video. Yeah, it looks pretty hard to use 15 kHz for azimuth alignment. The wavelength is so small, that variation being displayed is over half a wavelength and drowns out any fine adjustment. Which direction do you go in when the L & R channels are 180 degrees out of phase? I've seen another KZbin channel use coarse alignment with a much lower frequency, then fine with 10-15 kHz. Like you, I simply split the difference and use my 3150 Hz speed calibration tape created by a third party. I guess using the levels would also work. And then of course, you have to adjust the az anyway for any tapes created on a badly adjusted deck!

[@pwrestoration]

When I really don't know which way to go, what I do is hook up the deck and listen to a tape. A good prerecorded one. Usually when its way out, it sounds awful. I play with the azmuth screw and adjust it by ear, then back on the oscilloscope and it's usually very close. I like to adjust azimuth now with 6.3k, speed with 3k and volume levels with 400hz. Seems to work - sometimes all of them will be great and 10k will be lop sided. Sometimes that's just down to the tape or the age of the unit. Gotta find that middle ground!

[@MikeDS49]

@@pwrestoration Agred. Sometimes the ear is the best tool!

[@dean6816]

Great video thanks. I'm new to oscilloscopes, will a cheap digital one be ok for azimuth adjust or do you recommend any other type?

[@pwrestoration]

You can get a used one pretty cheap but it must have two channels, 20mhz is really the type to go for

[@dean6816]

@@pwrestoration cheers for the advice 👍

[@elvisspringsteen72]

My BX-2 has just stopped playing. Damn! It had a speed issue before. I got the correct speed by tuning my guitar and adjusting the speed until it matched. I used the opening chords to Springsteen’s ‘Human Touch’!

[@pwrestoration]

This is actually genius

[@chickenfoundation9323]

Got a odd problem with a bx-125, when the bottom cover is installed the right channel is dead , but when I remove the cover it plays, but when I connect any rca the meter for the right channel maxes out and plays 60hz tone I believe , so the only way to get the right channel to play is with no bottom cover and no rcas connected, also when the cover is off and no rcas it plays fine but if you touch any bare metal the level drops

[@pwrestoration]

Check your chassis for a dead short, it might be live. Use DC volts. Put your multimeter probes in your output RCAs too. Other than that your bottom cover is causing a short, or there's a short on the unit somewhere is my guess. Don't plug it into an amp or speakers. Use the headphone port to diagnose.

[@chickenfoundation9323]

@@pwrestoration it’s definitely grounded since the left channel works perfectly fine with the cover on and rcas connected , only the right side is having the problem

[@meredithharvan5632]

What does the relay that you replaced do? I have an issue with BX-2 when the record button is pressed it won't engage pause and set the deck in rec- standby mode, any thoughts?

[@pwrestoration]

Check through leaf switch that is for record protection

[@homersimpson6844]

Great video, one question. I have a test cassette recorded with Nakamichi deck. If I want to adjust the output playback on a Technics deck the 0db Nakamichi corresponds to +3bd Technics is that correct? Thank you

[@pwrestoration]

It can be difficult as a lot of deck vu meters just don't correspond well to each other. I can't comment on the comparison of that particular deck but you'd have to look in your decks service manual. Chances are if the technics has never been played with it'll be fine so leave it. There's a lot of things to consider, such as the frequency of the tone. If it's 400hz that decks response may be better compared to a 6000hz tone. The only constant is the instruction in the service manual and testing in accordance with that. Good luck but if it sounds fine, it probably is! 😄

[@homersimpson6844]

@@pwrestoration Ok thanks for the info 👍

[@mitchflanagan8901]

Great video 👍

[@sethuvisvanathan]

hi i hv the same deck. but when i press the play switch nothing happens. the main board IC was replaced with a original taken out part from another BX2 deck. still the problem continues. what cld be the issue

[@pwrestoration]

When you say nothing happens, something must happen. Does it mechanically play but no sound?

[@sethuvisvanathan]

Mechanically not playing. seems the command is not going after switch pressing. replaced the Main LOGIC board IC. not working still

[@paulb4uk]

A lot of the test tapes and tape torque setting cassettes are not only expensive but very hard to find .Aliexpress has a head height thing but Its £76 .I have a multimeter but no scope so i am going to buy the Nak T-100 Analyser software its on the microsoft store ,i have a toshiba laptop spare .You have adjusted all the most important things i never use dolby so calibrating that is pointless to me .Nichicon and elna caps are the ones i see leaking most often ,the duratool desolder station from cpc has been a great tool can remove things from boards in seconds .

[@MikeDS49]

I've seen somewhere one person created his own tape path adjustment cassette. He removed the front part of the flared out area of the shell, and glued in a trimmed down a plastic locker mirror at 45 degrees. I've seen calibration compact cassette tapes created by using a pro 1/8" reel-to-reel deck that removes the shell entirely.