• Please note that there are a few updates and clarifications made in the Audiokarma Rules, mostly relating to advertising and the addition of the new "Paying it Forward" & "Giving back" forums in the AudioKarma Audio Marketplace section.

Nakamichi ZX-7 Dubbing Trouble

iandoerner

iandoerner

Member
So I just had the pleasure (hopefully) of purchasing a fairly high-end system from a well respected bandleader/composer 2 weeks ago and have been busy in my limited free time testing out all the equipment. Unfortunately, I have come up with a number of issues through the testing process. This question relates to a Nakamichi zx-7 cassette deck.

The play function of the deck works perfectly, however, dubbing is a bit of another story. When dubbing vinyl yesterday, I came across a problem with left channel being a bit quieter upon playback than the right channel. The levels are the same when listening through the “source”, however, when playing back the recorded tape, the left channel was noticeable quieter than the right by about 10 decibels. I tweeked the “sensitivity levels”, turning up the left side and down the right, but this time when I played it back, the left channel was completely dead, the right was fine. I then recorded again and didn’t move the setting at all and upon playback, the left channel had come back but was still a bit quieter than the right.

It seems to be a bit of an intermittent issue, wondering if anyone has any ideas on what might be causing this problem. Thanks!
 
Register to hide this ad
I'm assuming you followed the correct level/bias calibration procedures before you started recording.

Not meaning to insult, it's just that the ZX-7's manual calibration controls offer enough freedom, so as to completely ruin a recording.

I have one as well, and it is possible to duplicate the same issue, with an improper calibration.

If you followed the correct procedure, and you have de-mag'd and properly cleaned the heads, than the problem could lie elsewhere. (dirty switches-to bad caps-to poor connection at rec head, ect..)
It could be a mechanical alignment issue, with regards to the Rec Head, some sort of issue, related to poor or inconsistent tape/head contact...

There are others here far more qualified than I, whom I'm sure will speak up.
 
Last edited:
Vidguy hit the most likely cause. Intermittant playback is usually the Source/Tape switch. Toggle it back and forth quickly 20 times to burnish the contacts and see if that helps.
 
Not familiar with this deck, but if head cleaning doesn't help then the rec level or rec balance pot is likely dirty. Especially if not moved for a long while. You will need some switch cleaner spray.
 
DeOxit for switches, level controls, and probably first - all the interconnections, plugs and jacks between components.

A good head cleaning would also be in order, and a check on all calibration and levels just to be sure they aren't wildly different from each other.
 
Thanks for the suggestions! I'll do an overall clean of the deck, and try and figure out how to calibrate it properly, i have little doubt this problem is probably due to my own ignorance. When i first bought this deck a few weeks ago, i remember fiddling with some of those dials out of shear joy, probably threw something out of wack. I've never really operated a tape deck with this much "freedom" before, so this is all a bit new to me. I'll have an update on the progress tonight or tomorrow.
 
Okay, so I followed the manual's instructions on azimuth adjust, level adjust, and bias adjust. The azimuth adjust worked just as it should have. However, I could not make the left side or the right side bias high enough. With both sensitivity knobs turned all the way clockwise(Louder), i can still achieve about 10 dB under the machines proper calibration setting. Also, the levels appear to be jumping around +/- 5dB. What is this about?
 
Looks like bias problems, or it could be the heads themselves. As well as possible problems with recording electronics.

Naks have also the dreaded "Orange Cap" disease where a whole batch of orange film caps used degrade over time. Doesn't matter what they were, they pretty much all failed, so many units in all lines need those replaced as well as general servicing over time.

Sounds like you'll need to get your deck to a good and knowledgeable service person and shop.

Perry is one, and NakTalk can help with others.
 
I just would like to point out, that if the bias knobs have been tweaked a lot, it is possible that they can get so far out of range, that it seems impossible to calibrate properly.

The manual talks about this, and there is a procedure outlined to try to get it in the ballpark.

Look this over a and give it a try, using a good, known tape

I had the same issue with my ZX-7, when I bought it I could not calibrate bias, but once I did what the manual suggested, I got it working. It did take a few tries, however.
 
If the 15kHz signal appears to be jumping +/- 5 dB, then it is very llikely Orange cap disease, (OCD). Both my ZX-7s exhibited similar issues, and I had to replace them in order to fix it. The newer ZX-7s seemed to be better, I just restored one for an AKer and his were all perfect. Stable, no noise. As Vidguy pointed out, you don't say what tape or condition of the tape was thatyou used though, and that is important. Crappy condition tapes give crappy results, especially on a deck with full keys to the kingdom recording capability. Also, if you adjust the bias a lot, you have to go back and re-adjust the 400Hz level again. It is a back and forth process. It may just be a weak bias. If it has no trouble with a Type 1 ferric tape, but a lot of trouble with a Type IV, that may be the cause. If the 400 Hz level is jumping around that much, it is not bias, as bias has no effect on 400Hz, and you have a more serious problem, like the OCD discussed.
 
Try this:

-push Level (400hz) button and adjust the BIAS (not Level) for maximum output. Then while still in Level (400), adjust Level for zero meter.

-Then set bias and level using normal procedure.

If no better, then change orange caps as has been suggested. Also clean all pots and switches.

Use a good, new tape like Maxell XLII.

Make sure capstan shafts and left guide are spotless.
 
Calibration of the ZX 7 takes a bit of back and forth to get it exactly right. I calibrated mine last nite to a NOS TDK SA X tape and it took a while to get it to dial in. If the azimuth knobs are so far out that you run out of rotation for adjustment skip it and move to bias adjustment@ 15 hz as this more likely than not is very far out of spec for this tape In fact in order to even get the azmuth to dial in last nite ( RED cntr DOT) I had to kinda skip that and move on to the bias adjustment and at least get that into the ball park and then go back and start the entire process all over again. Then I went batk anfd forth between the 400 HZ for rec lev and the 15 hz for bias until I had a stable signal @ 0 for both. Keep at it and dont get flustered by the process.:thmbsp:
 
Last edited:
Thank you all for the responses, crossing my fingers its not the dreaded Orange Cap Syndrome. Luckily, if it is, i have a great tech close by that can help. Got really busy this week so haven't been able to continue tweaking or trying out the methods you all suggested. Will continue work on Friday, i'll let you know what happens then...
 
Okay, got my hands dirty this weekend working nt he Nak. I cleaned all pots and switches, and heads. Messed around for a while with the azimuth, level and bias controls. Pushed buttons, pushed buttons faster, and finally for some unknown reason, everything came into its right place. Cleaning defiantly helped, and the azimuth tune correct the left channel drop issue i had at first. I got the sx and ex settings perfected, dubbed a few vinyls, everything sounded great. So far so good...although the zx setting is still out of whack.
 
Might try Skiping the amimuth adjustment for ZX for the moment , move to bias and level for ZX/ metal tape, as it sounds like these 2 are so far out of spec for metal tape that the deck in confused and hunting. Bring them both back to NEAR being nornal then go back to the beginning by starting at azimuth cal , bias cal then level cal. Again you may have to move back and forth between bias cal and level cals to dial this in and to get a nice reading. Go slow.
 
You must log in or register to reply here.
Back
Top Bottom