AKAI GX-95: Servicing the Mechanical Block
While electrically in very good working order, this deck had some nasty mechanical problems. Whatever cassette I tried, it was either skewing and ultimately destroying tape, or playing OKish but very dull. Even if I tried to adjust the azimuth. Turns out that the ceramic tape guidance armatures were broken and somebody repaired them with some kind of epoxy glue. Thus no matter how I tried to align the tape path, it was actually impossible. Furthermore, the nut that adjusts the supply side pinch roller axial position was bonded with the same epoxy.
This spells big trouble as the deck was totally useless, mechanics-wise. Thus I started a quest of hunting down a mechanical block from a dead or donor deck. Recently I managed to find what I was looking for but the price tag was a bit on the high side (about 80 E, shipping and handling included from Germany). Anyway, I'm happy that I finally found such mechanical block in good working condition. But as everything is relative, in this case, good working condition means that the tape path was intact and nobody messed up with the head alignment screws. However, the cam motor was totally broken. But there are a lot of small mechanical parts that can be salvaged. Take for instance the reel table motor which I used to fix the AKAI GX-F71 tape deck.
Anyway, I salvaged the entire sliding head block and two of the steel balls that the block slides on. In my deck, somebody lost two steel balls and the head block metallic plate could never be adjusted to be parallel to the mechanical block steel plate. That caused most of the head alignment problems. And also difficulties for the cam motor to operate the entire mechanism. I have also salvaged the pinch roller arms and the ceramic tape guide armatures. All of these have been transplanted onto my mechanical block.
Needless to say that I have dismantled everything and cleaned with either isopropyl alcohol (plastic parts) or acetone (metallic parts) and reapplied grease and Isoflex PDP 65 oil everywhere needed. I cleaned the flywheels of rubber residues. They were also dirty of some kind of unknown provenience yellowish greasy substance with a bad smell. Then I replaced the main transmission belt which powers the two capstans. Afterward, I installed the new cam belt and did the alignment as per the procedure described in the Service Manual.
Unfortunately, I took very few pictures because I was a bit overwhelmed by the amount of mechanical work involved in fixing this unit's issues. I'm not sure if I previously said it, but I'm not actually that comfortable working with mechanical assemblies. I'm more into electronics. But since I have no one to help me with the mechanical works, I had to learn everything on my own.
This is the mechanical block before servicing.
Viewing the mechanical block from above reveals the cam motor (leftmost side), the reel tables motor (center), and the direct drive capstan motor with the two flywheels (bottom side). The two trimmer resistors are used for electrical alignment of the cam motor operation.
Here are the two capstan flywheels already cleaned with acetone. There are some transparent friction washers that are easy to loose if you don't pay attention. The take-up capstan flywheel has magnets on both side: one side for the motor and the other side for the tachogenerator.
You can see here the take-up capstan motor tachogenerator PCB, the cam operations geared potentiometer, the reel tables DC motor, and the induction coils for the capstan motor itself.
Old belts are totally worn out. All of them have developed cracks and lost their elasticity. Because it was very brittle, I chipped the rubber of the idler tire when I removed it.
Now let's take a look at the parts that I replaced. Even though they are pretty much useless, I have mounted all of them on the donor mechanical block so that I won't loose them.
Head block plate and damaged tape guidance armatures.
Broken supply side tape guidance part.
Damaged take-up side tape guidance part.
Overview. The record and playback heads are in good condition. I will keep them in case I'll need it in the future.
View from underneath the supply side tape guidance armature.