Akai 4000ds mkII pitch problem

A

Aillo

New member
Hello,

I have recently brought my Akai 4000ds mkII from Montpellier to Istanbul, for using in my homestudio as I used to do in France. I have it since 6 years, with my portastudio 464 and I use them both in my homestudio to basicly get "tape effect" for some individual tracks in my multitrack digital mix.

First thing I have done: I changed the top nut of the capstan sleeve, because it wasn't blocking enough. Then I opened the machine and cleaned almost 80% of the mechanical parts, greased as well when necessary. Dismantled, cleaned, greased and reassembled both table blocks. Cleaned but couldn't demagnetize the heads and other metals touching the magnetic tape because I lost my demagnetizer. I will ordered a new one.

Now I am in a situation where I composed some music in collaboration with a plastician/video artist and wanted to record the stereo master of one song onto tape, I mean the whole session mixed down to 2 tracks. There are a lot of acoustic guitars in the recording (between 2 and 8), used as traditional guitar (melodically, arpeggios etc.) but also with different objects (such as ebow, fork, sticks, coins) for sounds. There is also percussion, voices and tanbur. The problem is the mid frequencies around the two bottom strings of my guitar does wierd, irregular pitch changes on tape and I use those strings quite a lot. They are very vibrato like but sometimes too much. It doesnt make any seasickness mood. Its pitch kinda flutters quite openly. So I was wondering can magnetized heads can corrupt sound as this or my problem is elsewhere, around pitch roller or the capstan. Or maybe it is me and my amateur Akai device isn't that top after all. By the way, I am quite sure that the motor has a good tork and it is regular.

Thx in advance for your answers,
 
I don't know what this model has for Electricity settings, but I would check that - the cycle frequency and voltage. Does the pinch roller spin freely - no binding spot ? have you ever replaced the pinch wheel ?
 
garww said:
I don't know what this model has for Electricity settings, but I would check that - the cycle frequency and voltage. Does the pinch roller spin freely - no binding spot ? have you ever replaced the pinch wheel ?
Click to expand...
Thx for your answer garww.
There are two switches for electricity 50hz/60hz and 220v/110v. Do you have an idea what does the first one do? I didn't replace the pinch wheel but it seems to be ok. I cleaned it with water, didn't use isopropyl alchool. The plastic is hard but intacte and turns well because I greased the metal part. Also, it is quite impossible to stop it when turning with the capstan.
I have noticed an hour ago that the capstan sleeve isn't the original one, I have seen some images on the net. And when it turns, the movement is a bit ellipsoid. Do you think this can be the cause?
 
It sounds a lot like a problem with the pinch roller, or possibly the belts. The 4000 is a single-motor deck and if the belts haven't been replaced they have probably stretched a lot. Likewise the pinch roller can go squishy and stop gripping the tape properly. That's usually the cause of pitch fluctuations.
 
The cycle frequency of the local ELECTRICAL SYSTEM IS HIGHER OR LOWER > So if you had 60Hz juice, a 50 setting (geez, now I forget)would play slow/fast??? No harm. Speed is just off

Those speed bushings can be a problem. If it fits the shaft good, maybe the capstan is bent a bit. A hard idler isn't normal, so there will be interaction with that. A little slop in the key fitting shouldn't be big deal.

It's probably about ready for deeper maintenance - like lubing the motor
 
Ya, I order new belts the same day I buy a deck, if they are available. My older Roberts 770 needed the belt, but the 771x didn't. I think that was a heat factor as the tube version can get really hot.

OH, you can place the end of a tape close to metal parts in the tape path and see how strong the magnetism is
 
Thx for all the information garww and jpmorris.

I didnt replace the belt. While cleaning it, I noticed it was a bit loose but in one piece. Now I defenitly suspect it. I ll change it. The pinch wheel looks still fine to me but if the problem persists, I ll change it too.

I will share my results once it will be done.
 
The pinch wheel has to be grippy enough. You should be able to nudge it looser and tighter against the capstan with a finger while it is playing
 
garww said:
The pinch wheel has to be grippy enough. You should be able to nudge it looser and tighter against the capstan with a finger while it is playing
Click to expand...

Sorry, I couldnt understand what you mean in the second sentence, could you re-explain it to me in different words? You mean I should be able to stop it by pushing when it is turning with the capstan in play mode?
 
By the way, the plastic part of the wheel is grippy, not that soft but grippy. I can feel it easly with my fingers.
 
You can get some belt spray at NAPA : )

I don't use any. I've boiled some belts before, but that's about it. A product from a specialty house might have some merit. I've got some pretty old rubbers and some do need to be replaced - others have enough alignment and tension that the rubber may not be a issue. I'm thinking I may have six recorders from the early '60s that transport fine and then I have some from a period after that have idler rubber problems ? I wouldn't know the history of Akai rubber, or, anything
 
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