Nakamichi 480 (I've been a bad boy!)

Replaced Capacitors in the Nakamichi 480. There was no way of telling which way around they went, so the ones which had the label pointing up went in the same way, and vice versa. Still wont erase or bias tape. :-(
 
Turns out there are two transistors that may need replacing as well (2SC945's). Will be waiting another 1-2 weeks for these to come in.
 
Hi Derek, if the transistor replacement still not fix your deck, check the resistors (especially the power ones) on the bias oscillator.

I've managed to fix the eating tapes issue on my silver 480, the new belt (replaced by the previous owner) was too tight and too thick so the supply capstan spins faster than the take up capstan.

The playback head height was also very misaligned, there was no sound in the right channel and there was only the edge of the tape on the erase head gap.

Now the deck is "safe" for the tapes (it can play a C120 without damage) but the cam offset needs to be realigned (the head base bounce when putting the deck in play mode after making a recording, I think I'll make a video).

And of course the bias oscillator doesn't work !
 
20tajk7 said:
Hi Derek, if the transistor replacement still not fix your deck, check the resistors (especially the power ones) on the bias oscillator.
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Which ones are the resistors? Do you have a location number on the circuit board or a photo? I'm not very savvy with circuit board components. Good to hear you have made progress with your 480. These machines sure take time to get right.
 
I have found a component sitting on my work bench that must have fallen off the circuit board whilst I was soldering. Will have to try and find where it came from and put it back in, see if that fixes the problem otherwise will wait for those other parts to arrive. This is pissing me off, I have already put all the covers back on and placed the deck back into the cabinet. :banghead:
 
I got the Nakamichi 480 repaired and recording again! Pictures attached show the new yellow capacitors. In the process of putting these on I knocked off a diode or resistor (not sure what its called) its like a tube thingy, this is also pictured. Thought that the repair didn't work until I saw this part laying on the bench. Got home today and re-soldered it back on and the deck is fine now, records perfect.Another picture shows the Nak BX-1 transferring a tape to my 2nd pc and the Nak 480 in record mode underneath it. It is recording a little higher than the VU meters show, this is manageable, on a normal type 1 tape on the test recording it was hitting peaks of +8db and wasn't distorting, even still I would like to keep within reasonable db of +2/+3 to give reasonable frequency headroom.



















 
That was quick work, Derek. If it was just a nudge that knocked the resistor off the board, it may have been loose before the capacitor replacement.

Nnado.
 
Elite-ist said:
That was quick work, Derek. If it was just a nudge that knocked the resistor off the board, it may have been loose before the capacitor replacement.

Nnado.
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I have tried recording to 3 tapes and am noticing way too many minor tape dropouts for the condition of them. Am going to try recording onto one of the same tapes in the JVC this afternoon. Something doesn't seem right with the Nak, as I have had no trouble with these tapes before and they all came from the same person who cared well for them.
 
It seems that I have a bad batch of tapes here, recorded to the same tape with the JVC and what do you know, same minor tape dropouts. I can't fault the nakamichi for that. Now I just gotta find some decent tapes to record on. Don't get me wrong, its not "unbearable" but I strive for perfection with my recordings and most of these same batch of tapes have been exactly that, even being 2nd hand. Will make some changes and see how the nak goes with the next clapton album, it sure does record with a nice 'punch'. How tapes can confuse you like that sometimes. On the brighter side I have some Sony Metal XR's on the way, much looking forward to that, Mannheim steamroller will give those puppies a good test in the dynamic section, will try some digital sources too.
 
Just recorded Eric Clapton Self titled to the Nak 480 on BASF Chrome Extra 90, results are excellent, no tape dropouts, glad to see the deck is working as intended now.
 
Dreaded tape drop-out - I haven't had a cassette malfunction in that way, yet. However, I don't record as much as you do, Derek. But soon enough I will have a tape go bad on me, and most likely towards the end of my recording session. That's why I like to monitor all my recordings with headphones as I am making them and follow up with at least one complete playback through my system speakers at a decent volume.

I may add another Nakamichi deck to my system. I want one which can take over regular duty from my Esoteric deck. It's good to hear your 480 is in active service, now.

Nando.
 
as an afterthought D2, try just erasing that tape on another deck, (no input), then try to re-record on the 480.
also, that tape may have come in very close proximity to something either magnetised or an electrical transformer or somethin'.
did you have it close to your face while using an electric shaver by any chance?
you do know that electric shavers make excellent bulk erasers don't you?
you can also use them to degauss the old tv screens.
 
Elite-ist said:
Dreaded tape drop-out - I haven't had a cassette malfunction in that way, yet. However, I don't record as much as you do, Derek. But soon enough I will have a tape go bad on me, and most likely towards the end of my recording session. That's why I like to monitor all my recordings with headphones as I am making them and follow up with at least one complete playback through my system speakers at a decent volume.

I may add another Nakamichi deck to my system. I want one which can take over regular duty from my Esoteric deck. It's good to hear your 480 is in active service, now.

Nando.
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All of my tapes are 2nd hand that's why I'm bound to find a few duds in the pile. Earlier this year I had the pleasure of scoring 40 brand new sealed TDK AD60's ($30 with postage), absolutely flawless. Also 7 new TDK SA 90's ($47 with postage), again flawless and very pricey. Good Idea re the headphones, was doing that last week on the JVC, most times can't help myself and just listen to the original source through the speakers at a moderate volume. Tapes recorded on the nak will have to be played back as its only a 2 head, its doing very well and am about to do some more recording today. I notice it really likes BASF Chrome extras.

Re erasing George, I used to do this and didn't notice any benefit. Even after the 2nd and 3rd erase pass on that tape I was having trouble with, it was still the same. In certain cases it might help if the tape itself wasn't actually at fault. Maybe I should get my hair clippers out? :laughing9:
 
It happens to me too sometimes to notice dropouts when re-recording some chromes from BASF or typeI's, this will not happen with SA's from TDK which are very suitable for repeated re-recordings... Some tapes simply don't like to be re-recorded :banghead:.
 
VintageShadow said:
It happens to me too sometimes to notice dropouts when re-recording some chromes from BASF or typeI's, this will not happen with SA's from TDK which are very suitable for repeated re-recordings... Some tapes simply don't like to be re-recorded :banghead:.
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The only tapes which I have had trouble erasing are very old metals. All others have been fine, maybe do a 2nd erase pass if possible. And keep that erase head pristine clean :)

The tapes in question were TDK AD90/AD60/AD46. They were just worn from a dirty car deck, more so a very slight rail roading of the tape which was hard to see. Caught me out. All tapes recorded since have been great, using basf chrome extras at the moment (yes also 2nd hand), the Nak likes them.
 
The EXTRAII's are still not pure chromes, Derek. They are 85% chrome and 15% ferricobalt as i remember, i tried to re-record a very old chromedioxide of them and i simply ruined it, the tape is fine like new but it simply doesn't accept a new recording no matter what i tried.
 
VintageShadow said:
The EXTRAII's are still not pure chromes, Derek. They are 85% chrome and 15% ferricobalt as i remember, i tried to re-record a very old chromedioxide of them and i simply ruined it, the tape is fine like new but it simply doesn't accept a new recording no matter what i tried.
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I have one of them, I will try the same and report back to you with a photo of the tape.
 
Done many hours on this Nakamichi 480. It was finally time to replace all the belts/idler, a challenge I had been avoiding for some time, as the mechanism is quite complicated. 3 Layers involved here, 4 belts, 1 idler tire. It has been sitting in my storage room for about 3 months.

There were 3 springs that had to be released between a couple of the mechanism layers, I had to do this 4 times, as I made some mistakes on re-assembly, learning the hard way of course. One time I didn't have the mode sensor in the notch of the cam gear, another time a spring on the idler assembly was missing. Can't remember the other two times, it sure gave me good practice on working with a Nakamichi 'Classic' type Mechanism. After doing this I feel much more confident to work on them, if more of these decks come along in the future. They really are a well built mech, heavy type.

All pulleys cleaned, capstan bearings cleaned/oiled, reel tables, cam gears lubed. Head aligned and demagnetized, speed calibrated (using a 3khz test tape recorded in Perry's Dragon). It certainly sings nicely after a service. A great learning process too.

Playing back recordings made in the Nakamichi BX-300 produce stunning results, the two decks seem very compatible. Tried quite a few pre-recorded tapes as well with good results. The 480 will mainly play back pre-recorded tapes as it seems to handle them extremely well. I also want to preserve the heads in the BX-300 for making quality recordings on mostly brand new high end tapes.

I have a BX-1 to service as well, full belt kit and pinch roller waiting to install. That will be the next project.






















































 
I see, Darcy, was wondering for a minute where that 4 year old thread came from...but seeing George again was great!
 
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