Wega B4610 (part 1)

January 17, 2023

Today on the workbench is not just a machine, but a true beast to behold! The Wega B4610 which falls in the category of 10 Inch tape recorders due to the diameter of the tapes. This monster of a machine is in need of a thorough overhaul, but before we get started, let's take a moment for a closer look at the machine together with some information about its operation and how it got here.

For those who don't know, Wega is actually a brand of Sony. Stranger still, if you search the internet for the Sony TC-755, you will come across almost the same type of tape recorder, with the biggest difference being the appearance. The Wega B4610 is essentially a black version of the TC-755 (which is silver). There are also minor differences that are mostly limited to the design.

Because the two are so similar, I use the manual for the Sony TC-755 to describe the functions.

(Click on the images to enlarge)

  1. This function alone can be called special, should the tape rub against the edges of the reels during playback, you can change the height of the tape with this screw. This function is also on both sides of the machine.
  2. The pressure lever ensures that the tape is kept under tension. In addition, the lever is also a sensor which tells the machine whether tape is running past it or not. When there's no tape runs past the lever, it drops down, causing the machine to switch off automatically.
  3. The pause switch brakes the reels to a standstill, but the motor continues to run. This allows you to start playback or recording immediately when the pause switch is raised again.
  4. An important function is the speed setting. On this tape recorder they are expressed in centimeters. 19cm stands for the higher 7½ IPS where 9.5cm stands for 3¾ IPS (IPS stands for Inch per second, the distance in time the tape travels).
  5. Also important is the size of the reel. 26.7cm represents the large 10" reels where 17.8cm represents the 7" reels.

The well-known functions are located on the right side of the device. rewind, stop, play and fast forward.

  1. This switch is used to hold the machine in record mode.
  2. The holding of the recording mode (1) is used after you have pressed the two buttons for the channels to be recorded. The buttons are designed separately so that the left and right channels can be used separately for mono recordings, of course they can also be operated simultaneously for stereo recordings.
  3. You use the equalizer according to the type of tape that is used. For example, there is the standard ferro (Normal). improved ferrous (Special) and finally the ferro-chrome combination (Fe-Cr).
  4. The bias selection is used in conjunction with the selected tape speed. The bias control determines the volume level at which recording takes place. The function of the bias is to reduce noise during playback and recording.
  5. The Mic Attenuator is a function that is used when recording with the microphone. You use this switch to scale the volume level of the microphone. Should a microphone come in very loud during recording, the attenuator can be used to bring it to an acceptable level.
  6. Strangely enough, connections are not described in the manual, in this case the connections for the microphone(s).
  7. Volume control of the microphone(s). Which are two separate buttons on top of each other.
  8. Volume control of the incoming sound from an external source (not microphone). These buttons are also made separate to control both channels separately.
  1. With these switches you can choose to listen to the incoming sound (source) or the sound from the tape itself during recording.
  2. The power button, with which you switch on the device.
  3. The volume control for the outgoing sound.
  4. Connection for headphones.

Of course, the large VU meters should not be overlooked, they display the volume of the sound in decibels (above) and saturation in percent (below).

There are two adjusting screws under the gauges that you can use to adjust the meters if they deviate.

In the middle of the device is the tape counter. This keeps track of the position of the tape in Inch per second.

Finally, there is of course the rear. Here we find the connections for power and audio.

With the overview done, it's time to look at what's wrong with the device. Below is a short video in which I test the machine before I get started.

The problem is quite easy to find, the pinch rollers do not engage when I turn on the device. This could have many different causes. But with some manual guidance, the rollers can still be put in the right position. It seems that the mechanical parts of the rollers are stuck, this can be seen from the fact that the rollers respond to switching on and off but simply cannot move.

So the task is to make this part of the mechanism work again, for this I have to disassemble the machine to the point that I can lubricate the various parts.

Furthermore, the device still works reasonably well, the rotation of the reels is sometimes a bit sloppy, but otherwise there is really little to criticize.

In short, it indicates that this is a fairly solid built machine, even after so many years of service and many years of standstill, it still springs to life when you turn it on and with some help you can actually get good quality sound out of it.

I almost forgot to mention, the tape recorder also has its (semi) original plastic cover. Although it is the correct type of cover for the tape recorder, it says Sony in the top right corner. So the hood probably comes from a Sony TC-755. The fact that there is a cover and even without deep scratches or cracks is quite unique.

Time to start dismantling, the NAB adapters are the first to be removed. I do this by turning the top ring counterclockwise (1). With this you unscrew a set of clamps internally (2 & 3). After this I pull the shaft up in the middle and turn it to release the adapter (4). Now the adapter can then be removed (5).

After this I take off the hood that covers the heads. It is held in place with two prominent screws. Normally this would require special tools to get it loose. In my case these are tightened by hand so I can unscrew them without the use of any tools.

The hood underneath is attached to two pins with friction, with some guidance you can remove it with your hands, no screw is needed. After this we have a clear picture of the part where the tape is read, written and erased. As well as part of the transport that guides the tape past the heads.

Interesting to see is the Sony logo on the cast piece of metal. Although we have a Wega here, it is clear to see that we are actually working with a disguised Sony machine.

In addition, it is also special to mention that the Pinch Rollers are not made from the usual rubber, but of plastic. This is something I see for the first time and I actually like it. Plastic does not decay like rubber does. These pinch rollers will certainly last a good few years compared to their rubber counterparts. It does mean that the rollers must be pressed firmly against the capstan during use in order to have a grip on the tape.

The next step is to release the panel where the main control is located. Two screws hold this panel in place. When removing, the panel is also stuck on both ends with adhesive. The adhesive substance is still very 'sticky' even after many years, so the panel must be removed with care to prevent it from bending.

Next is the main panel, but not before we take the pressure levers off first. It is also held in place with a special screw. This time I can't get them off by hand so try it with two awls first. This doesn't want to work though and I have to look for alternatives. in the end I succeed by using pliers which I clamp on the screws with a cotton ball, with this you won't damage the screw. I turn the pliers until I feel that the screw comes loose, then I take the screw off by hand, after which the lever can be taken off. Of course I do this for both levers.

The main panel can now be removed. It is secured with four screws in the corners of the panel. After loosening the top two screws, a small panel comes loose at the top. Normally this is also glued, but in my case the adhesive has worn down. After the screws, the large panel is also attached with adhesive strips. These are still very strong so I have to pull the panel off very carefully without bending anything. I have laid the device down to be able to do this with care. The panel eventually comes loose, I lift it out as straight as possible so it doesn't get caught on the many axles sticking through it.

With the main panel loose, we look at a fairly naked Wega B4610. This gives us a good view of many of the mechanical and a few electrical parts of the machine. We also see the two belts that the device has.

Now that we are at a point where we can really start work, let's make an overview of what exactly needs to be done to this machine:

The belts will both be replaced. The thin belt for the tape counter is in dire need of replacement. The thick belt for the transport section is in better condition, but since I bought the new belts as a set, this will also be replaced. In addition, there are also signs of wear on this belt, which increases the risk of slip.

The mechanical parts also receive attention, the many hinge points get new grease and if necessary I will adjust them afterwards.

Internally and externally I clean the machine, the outside is generally very sticky and there are places where some sticky liquid can be found, the origin of which I have not yet identified. There is also a lot of grit inside, mostly from the brakes that are under the reel holders.

We focus on the read/write part, there are 3 screws and 2 circlips that have to be loosened to separate the display part from the rest.

The display part and accessories

We start with the repair of the read/write part, since not only are the sticking pinch rollers located here, but also because the main belt passes under it. I use the manual with an 'exploded view'

Here is an overview that also shows the read/write part, which you can see at the top of the image.

We zoom in even more, here you see the 3 screws and 2 circlips that have to be loosened to separate the read/write part from the rest.

First I remove this bracket, although not necessary to loosen the whole thing, it is more convenient to loosen it now because it creates a little bit more work space when I start tinkering with the rest of the later.

I notice that there is an oily residue on the underside of the bracket. This should not be there (in my opinion). Which is not a good sign, I suspect I have to take apart the entire read/write part to clean everything.

The oil can also be the cause of the Pinch rollers sticking!

The three screws are in cavities (red arrows), I use a thin screwdriver to unscrew them. Note that the bottom screw is a different size than the other two. For now, I'll leave them in the hole.

Then I remove the two circlips. I do this by means of an awl. The left circlip is smaller than the middle one. There is also an O-ring under the middle circlip.

When the clips are loose I remove the brackets that are over the axles, again there is another O-ring under the middle axle. When these steps are completed, the read/write part is separated from the rest of the machine.

Before I lift the read/write part I bend this bracket away, this gives me more room to play, the cables in between run towards the heads.

After this it is a matter of lifting the part out. It is important to lift the whole assembly as straight as possible, since both capstans run through it. As soon as these pins become free, the read/write part can be set aside.

See here the capstans and flywheels of the device. These are now loose in the device. Striking on the flywheels are the holes along the edges of the wheels. In both flywheels two holes are drilled in different places. These holes ensure that the wheels are balanced. Probably both wheels were not perfectly balanced after manufacture, after which these holes were drilled to compensate for the imbalance.

Although it might not make much difference when reassembling I will put both wheels back in the same place where I removed them. It could be that reassembling them in reverse can actually cause imbalance.

For now, I'll take the flywheels out of the machine and put the read/write part back in place. Time to loosen the pinch rollers!

For this I use the following page from the manual. Here's a view of the complete display part.

Before disassembling the pinch rollers, I check them again now that they can move independently of the rest. It strikes me that it is the left roller that runs very stiff, the right one, on the other hand, runs very smoothly.

Nevertheless, I completely disassemble both rollers, I have noticed that behind every part that I loosen a layer of creamy oil can be found. The origin of the oil is not yet known to me, but I find it everywhere. It's going to be a big job to clean everything!

The rollers are disassembled in several steps. Mainly circlips keep the rollers in place. The rollers themselves consist of no less than eight parts! It is important here to keep track of which part has to go back where.

When releasing the last clip, it shoots off at high speed. I hear it fall on the floor on the other side of the room... By shining the flashlight over the floor I finally manage to find it. At the same time I see how dusty my floor actually is.

To make sure that I know where all the parts have to go back, I use this handy container. Each box has a number that I write down on a post-it note. This way I keep it clear and will know exactly where which part belongs.

All that remains is to remove the brackets on which the rollers rest. The bracket on the right side comes off without any problems, but the left bracket is firmly fixed. I try to pry it loose with the awl, but the awl itself bends under the pressure. Finally I manage to get the bracket loose by pushing it up bit by bit with a screwdriver levering underneath.

I check the axle but see no damage, otherwise it looks very dirty. I clean the bracket and shaft, lubricate everything again and put the bracket back on. The bracket now moves much smoother which means that the rubbish in between was causing the friction.

As mentioned earlier, there is a lot of dirt and oil on the various parts. Because of this, I decide to loosen the moving parts to clean and re-lubricate them. However it doesn't go quite according to plan when I unscrew this metal plate (which is under a lever).

The plate comes loose and falls through the openings to the bottom of the recorder. I try to fish it out with tweezers but it's just too deep to reach...

In an attempt to get to the part, I decide to loosen the bottom panel, I planned take it off anyway so why not now. I loosen the many rotary knobs with an allen key via the side where a locking bolt is incorporated in the knob. I put the other switches in the middle position so that the panel does not scrape along when removing.

Finally, there are four more screws in each corner that hold the panel in place. Once these are out, the panel can be lifted off with care. This exposes the entire front of the recorder.

Although I don't gain much leeway with this, I now manage to fish the part out of the recorder. I clean the plate with contact spray, lubricate it again and put back it back in place.

After this I go through many other hinged parts, clean them, re-grease them and put them back.

After lubricating the pivot points, the flywheels follow. Inside are two fabric rings that are glued. They are very dirty and there is some old grease on it. All I can do is run a cotton ball through it which does make a difference.

After cleaning, more lubrication follows. The holes in which the flywheels will rest also have two points on the bottom that need to be lubricated again. I wipe off the old grease and when the two points are clean I lubricate them again.

Before the flywheels can go back, one more step remains, replacing the main belt. Because the display part is still loose, there is only this copper plate that has to be loosened to get the belt out of its place. Under the copper plate there is another one made of plastic, which in turn leans on the shaft which is connected to the main engine.

As usual, I compare the old and new belt before replacing it. In this case, the new belt is smaller than the old one. Could the old one be stretched? Or is the new belt actually too small?

There is only one way to find out, I replace the old belt with the new one and put the two plates back on the main motor shaft.

Placing the flywheels back does not go according to plan...

The wheels slip out of place when I tighten the new belt around them. I decide to try another way, I remove the belt from the wheels and first put the read/write part back, it holds the wheels in place after which I can tighten the belt without the wheels slipping away.

If I carefully slide the read/write part over the flywheels, the whole remains stuck. It turns out that the capstan has two plastic rings that come up with it. I push these back into place with tweezers, after which the display part falls into place and fixes the wheels position in turn.

When I tighten the belt back on the flywheels, the whole stays in place now. I give the belt a twist and the flywheels turn without much friction. Despite the fact that this belt is a bit smaller, everything still seems to run smoothly. The belt itself will likely stretch to the correct length with time. 

Everything is looking good for now, the read/write part can be connected to the rest of the machine again.

After a final cleaning and lubrication I put all the parts back together and the pinch rollers can also be put back on the axles.

And so the whole display part is put together again in no time.

Before I continue I test whether the pinch rollers now jump back without sticking, I operate the rollers by hand and then release it. The rollers return neatly to the rest position. With this I can now finish this part.

The next step in the repair is the holders of the reels and the associated mechanism.