The BX998A was Philips' most expensive table top device in 1955. Now almost impossible to find for a normal price. But finally found one that is 95% complete.
The device arrived in a disassembled condition. And because the chassis was still connected to speakers, we will first do an assessment to see where the problems lie.
The device is still completely original and still has many problems. One of the biggest is nicotine deposits. Nicotine destroys many parts and leaves a sticky substance.
The assessment teaches us the following. The tube sockets in the power amplifier are burnt and make very poor contact.
The FM tuner is completely dead and does nothing at all.
Removing the nicotine layer goes well, but is a lot of work.
The output transformer of the mid/high amplifier is defective. Here it began to work for the very last time. The tar capacitors also all need to be replaced, they leak enormously. AM reception also works perfectly.
Having the FM tuner repaired shows that the FM mid-frequency amplifier is also not functioning properly and the amplification is much too small.
The middle IF transformer has a defective core. It later also turned out that the glue used on the coils was disintegrating.
Here the disassembly everything very carefully and neatly.
The last wire is under a ceramic capacitor. It was a bit difficult but I managed to get it loose.
The IF transformer in question was replaced because the core could no longer be removed.
Because the IF transformer has been removed, this is the right time to clean the chassis.
After cleaning the chassis looks like this.
The IF transformer has now been installed and the chassis has been partly cleaned.
After connecting the IF transformer and adjusting it with the measuring transmitter, the FM plays again as we would expect. We have noise between the channels and receive many channels on the FM.
And this is what the whole thing looks like at the bottom after this major restoration. Later we will adjust the IF with the wobbulator.
The chassis has now been thoroughly cleaned. Removed the output transformer. This one is interrupted as always.
The transformer has been in the freezer for 3 days. This causes the tar to fall apart and eventually the transformer comes out of its aluminum housing.
The core of the transformer is made in such a way that it is suitable for small powers. Because the amplifier does not amplify low tones, the power is not necessary.
The transformer came out of its home completely intact. With some policy and patience this can be done.
Removing the core is also possible without any problems.
And this is what the core looks like. The size of the core is 10mm X 16.5mm, so the core surface is easy to determine. This is in case you no longer have the original core.
The primary windings removed. There are 75 turns around the secondary core. Primarily it will be 3000 turns with a wire thickness of 0.1 mm. That gives you an output impedance of 8k ohms loaded with a 5 ohm speaker.
Winding the primary coil is of course done with a converted drill with counter.
Impedance measurement of the whole. using a 1k ohm resistor and a tone generator at 1Khz.
The first test of the output transformer.
The transformer without housing during the test.
Second test, put the whole thing back in its house, put the lid on and go.
And this is what it all looks like during the second test. Now to disassemble. Then the restoration of the chassis can begin.
To restore the chassis we only use original components. These are components produced in 2024.
The chassis ready to be installed on the repair stand. The front is a nasty nicotine slop mess.
Cleaning the potentiometers is done according to article RADIO HISTORICAL MAGAZINE - NUMBER 171 - 4 - 2019.
The wave range switches are a nasty nicotine mess. This is why pressing the keys is very difficult. The multiple button pressing safety mechanism is stuck and needs to be completely cleaned.
The EL84 will not glow. The tube base is completely green from oxide.
A 9.3 ohm electrolytic capacitor
This is the multiple button pressing security mechanism. You can see the glue at the bottom.
And this is the press stud unit where the multiple buttons pressed simultaneously security mechanism came from. Unfortunately it was not possible to remove the security mechanism. But with some filing work it finally worked.
Replacing the tube sockets in the bass amplifier. Because the tubes get quite hot, we use ceramic tube feet.
After the chassis has been completely restored, the question always arises: will the radio still play?
After restoration the chassis looks like this. With the exception of two tar capacitors and both power supply capacitors, all tar capacitors and electrolytic capacitors have been replaced. The power electrolytics seem to be ok for now. both tar capacitors still need to be replaced. One is on backorder. And I can already hear everyone shouting: this is not how you restore a radio, it should be yellow, green and purple under the chassis. Another cry, what an awful lot of work I will never do.
A strange design error in the BX998A. I have no idea how this design error arose. But you hear it clearly in the sound as a kind of hiss in the sound, but actually you hear noise because the if signal disappears for a short time.
And then even more work. Broken strings, incorrectly installed strings, even more nicotine filth. Every time my hands stick with that nasty sticky stuff. But there are still people who believe that smoking is healthy for you, it's unbelievable.
What else can I say?
This looks better clean and dry.
The front of the chassis is clean and the build has begun.
The faceplate is the same sheet and suit.
And this is what it looks like when it's clean. The strings of the tone controls have been replaced.
During construction we will check whether everything is OK and working. Everything that is clean is on the chassis.
Here's an overview from above. Frequently heard saying, better than new! No idea what that means.
And then the question does it all work. This is the first test of the tone control and you can hear the bass amplifier distorting quite a bit. But the power tubes are old and worn, the new ones are readyto mount.
I've been listening to this radio for a while. And at normal listening strength the chassis sounds incredibly good. And that with defective speakers and worn out tubes. But with the modification for the FM IF.
The mechanism can be operated with little force. It runs smoothly.
The string has to come here somewhere.
The left side of the chassis is almost finished. It is still missing the band spread pointer and light plate.
The right side of the chassis is in even worse shape. This is the multiple button pressing security mechanism of the right side.
Reinstalled the wave range selection lights on the right side and tested them. It's time to listen to the radio.
Clean.
The mechanism is back together and mechanically it works extremely smoothly.
The chassis still plays after this intervention.
Unfortunately, testing reveals the following problems. Wave range switching motor does not work properly, lights do not turn on. Shortwave 3 does not work. FM muting does not work. The next step will be cleaning the motor position switch. The adjustment is also incorrect, the wave range is half switched on.
This is the engine position switch. This side switches the indicator lights of the selected wave range.
This side of the motor position switch determines where the motor stops. There is a switch in the motor that ensures that the motor always turns one revolution. This must correspond with the motor position switch so that the contacts are exactly closed.
It was such a beautiful sight.
The timepiece was also cleaned. It turned out beautiful, but soon no one will ever see it again.
A test of the motor-controlled wave range switch, lots of squeaking and crackling. But the muting was not connected and then you get this. Switching between the wave ranges is timeless.
And this is the 80 meter band shortwave. This is what SSB sounds like without BFO.
Sprayed the switches with Vaseline spray against oxidation.
Cleaning the switches is quite important. Never use contact spray unless there is no point at all, it will cause more damage than you would like.
After cleaning I use Vaseline spray to spray the switches. This is to prevent corrosion.
The sliding switch should also be cleaned in the same way. This was also sprayed later with Vaseline spray.
And then it's time to test it all on the right speakers. This is the setup.
The setup seen from the top.
And then the question will the radio ever be able to play again after this complete renovation?
The scale lighting scatter plate is not original. This is what was in the radio. The metal strips on the side are corner lines, these are original, there was a thin white foil on top of it and on top of it was a metal strip with screws and nuts. The foil was as if wedged between them. I think, but I have no idea, no one bothers to record these kinds of details.
After hours of messing around with bent hands, we managed to get the scale on. After cleaning the scale you could also see the hands.
Just a shortwave station somewhere far away.
The Chassis is back in the cabinet for the first time after a long time. This without a dail because glass is very fragile. In my case I am missing the two wooden planks on the left and right of the dial. Someone made these two, thanks Paul, and now the holes for the buttons still need to be drilled. The first two are done.
A lot of time has passed with fitting and measuring.
It comes close to a bit of planing on the left and right and then it will be ok.
After a lot of trying and measuring, the stuff comes together. But now I have run into something strange about the dial resting on a beam that is glued to the bottom of the cabinet. The dial rubbers are bad, but to get the whole thing into the cabinet the dial has to be lifted a long way.
As a modification I placed the chassis 2mm higher on the bottom plate. It appears that at the beginning of production the dial is longer at the bottom. You can recognize this dial type by the fact that the Philips emblem is missing on the dial next to the treble control.
Then fit and measure with speaker shelf mounted on the bottom plate.
Provided the shelves with golden piping and the first layers of lacquer.
For the first time the whole thing is in the cabinet. Everything is still loose and still needs to be assembled. But it's starting to look like something now.
The chassis is back in the cabinet, the screws are back in and everything is secured.
And then the radio is almost ready. Still missing the two small knob, but hey, you can't have everything and who knows, maybe I'll find them one day.
And then the same question always comes up. Could the radio also play?
The capacitor on backorder will finally be delivered, about time.
The mold to make the capacitor is ready.
A beautiful yellow capacitor goes into the mold. What would come out except nothing do you think?
And yes, here we go again, I would never do that much work. It's a shame now that it looks like a tar capacitor, it was so beautifully yellow. Well, that's how it goes, what you do is nothing good, sigh.
The chassis at the bottom is ready!...
Close the bottom. Now two more rings.
Now with all the washers, nuts and bolts. And the shielding is properly connected to ground.
The back shot tells you that the project has come to an end.
The BX998A is a radio that has many negative stories about it. But also many positive stories. And there are some things but it is a pleasure to listen to this radio.
There are many ways to make an old radio play. Note the title Jewel - Foolish Games. We use Winamp shoutcast Yoradio Otto Zender. This is the beauty of technology, you can make it do whatever you want.
