Trevor White
Classic not Plastic
Hi everyone,
I am embarking on a major service and restoration of my Australian delivered, Multi-Voltage, Pioneer RT-707. I thought that many of you might find this exercise interesting, and possibly helpful.
I have always had an analog stereo system. In 1974 I bought a brand new Sony TC-377, a fabulous machine at that time. I still have that machine, and after a recent lube and belt replacement it works well. But I had always wanted a better Reel to Reel machine. And then just a few months ago I was able to purchase an Australian delivered RT-707 that was in cosmetically outstanding condition, but had been stored in a humid environment (Queensland) for many years.
The machine was in desperate need of dismantling, cleaning and lubrication. The heads were heavily tarnished, but responded well to a good clean and polish. In fact after polishing I discovered that the heads had only a nominal amount of wear, and that the wear was very even. There was no evidence that the head alignment had ever been touched, so I was doubly lucky there. The two reel motors were in excellent condition without any sign of the corrosion found elsewhere. Unfortunately the Capstan motor was not so lucky. It was noisy, and the capstan shaft itself where the pinch roller runs was actually corroded and the corrosion had pitted the shaft! I have now been able to source another Capstan motor, which was in excellent condition, nice and quiet and with a perfect capstan shaft. Along with this I have also been able to replace the Pinch roller tyre.
The machine now works extremely well, plays (in both directions) and records with fantastic quality, and makes my old Sony seem a bit ordinary in the recording quality stakes.
But, my intention was always to overhaul the machine in more than just a mechanical sense. But I did not want to embark on a re-cap etc if the basic machine was not already in pretty good condition, and to my considerable good luck, it is very good. This gives me a solid base on which to perform an electronic overhaul which should then give this machine many years of additional life.
And so that brings me to the beginning of this adventure. There are a number of great threads on this topic, one in particular that has been of immense value to me by Smurfer77.
http://audiokarma.org/forums/index.php?threads/pioneer-rt-707-service-rebuild.702717/
As I progress, if you compare my machine with the pictures in Smurfers thread you may notice a few subtle, and some not so subtle, differences in the layout of the circuit boards with different implementations. There are obviously a few variations in circuit layout in actual service. I don't actually know what year this machine was manufactured. I'm hoping I may find something during the re-cap that might help me determine it's age.
EDIT: Turns out to have been manufactured in May 1981
(I have not started this pictorial thread with pictures of the machine itself. I'm sure everyone knows what a nice RT-707 looks like)
So, I have decided to start with the Power and Oscillator board, RWR-050 and it's embedded Equaliser board RWX-154.
Here is the board in situ. The rear panel is still in place here. The green, purple and brown wires in the foreground are going to the voltage selector on the rear panel.
Now with the rear panel removed.
Here are the transistors mounted on the heat sink.
If you look closely at this shot, and then look at a similar one by Smurfer in his thread, you will see that my board has a resistor just below the heat sink between the two righmost transistors. On Smurfers system there is a capacitor in this location!
http://audiokarma.org/forums/index....07-service-rebuild.702717/page-3#post-9586163
And now with the heat sink removed.
You can see more clearly now the different circuit layout between the two rightmost transistors.
The heat sink with the Mica shims ready to be cleaned.
The Power board from the other side.
The foil side of the power board with the EQ board pins de-soldered, ready to pull out.
And with the EQ board removed. It just slid out without any issues.
The EQ board RWX-154 in it's original form.
And with all the .01uF ceramic caps removed. The lovely little WIMA film caps lined up ready. I left all the Mylar caps alone. No real need to touch them.
And finally with the WIMA caps in place. This is the very first time I have performed this kind of job. I was more than pleased with how well it went, and how nicely the soldering went. It has given my confidence a good boost.
The Caps used on the RWX-154 EQ board were:
8 x WIMA .01uF 100V: http://mouser.com/ProductDetail/WIMA/MKS2D021001A00JSSD
So, that's it for my first post in this saga. On to the main Power and Oscillator board next
I am embarking on a major service and restoration of my Australian delivered, Multi-Voltage, Pioneer RT-707. I thought that many of you might find this exercise interesting, and possibly helpful.
I have always had an analog stereo system. In 1974 I bought a brand new Sony TC-377, a fabulous machine at that time. I still have that machine, and after a recent lube and belt replacement it works well. But I had always wanted a better Reel to Reel machine. And then just a few months ago I was able to purchase an Australian delivered RT-707 that was in cosmetically outstanding condition, but had been stored in a humid environment (Queensland) for many years.
The machine was in desperate need of dismantling, cleaning and lubrication. The heads were heavily tarnished, but responded well to a good clean and polish. In fact after polishing I discovered that the heads had only a nominal amount of wear, and that the wear was very even. There was no evidence that the head alignment had ever been touched, so I was doubly lucky there. The two reel motors were in excellent condition without any sign of the corrosion found elsewhere. Unfortunately the Capstan motor was not so lucky. It was noisy, and the capstan shaft itself where the pinch roller runs was actually corroded and the corrosion had pitted the shaft! I have now been able to source another Capstan motor, which was in excellent condition, nice and quiet and with a perfect capstan shaft. Along with this I have also been able to replace the Pinch roller tyre.
The machine now works extremely well, plays (in both directions) and records with fantastic quality, and makes my old Sony seem a bit ordinary in the recording quality stakes.
But, my intention was always to overhaul the machine in more than just a mechanical sense. But I did not want to embark on a re-cap etc if the basic machine was not already in pretty good condition, and to my considerable good luck, it is very good. This gives me a solid base on which to perform an electronic overhaul which should then give this machine many years of additional life.
And so that brings me to the beginning of this adventure. There are a number of great threads on this topic, one in particular that has been of immense value to me by Smurfer77.
http://audiokarma.org/forums/index.php?threads/pioneer-rt-707-service-rebuild.702717/
As I progress, if you compare my machine with the pictures in Smurfers thread you may notice a few subtle, and some not so subtle, differences in the layout of the circuit boards with different implementations. There are obviously a few variations in circuit layout in actual service. I don't actually know what year this machine was manufactured. I'm hoping I may find something during the re-cap that might help me determine it's age.
EDIT: Turns out to have been manufactured in May 1981
(I have not started this pictorial thread with pictures of the machine itself. I'm sure everyone knows what a nice RT-707 looks like)
So, I have decided to start with the Power and Oscillator board, RWR-050 and it's embedded Equaliser board RWX-154.
Here is the board in situ. The rear panel is still in place here. The green, purple and brown wires in the foreground are going to the voltage selector on the rear panel.
Now with the rear panel removed.
Here are the transistors mounted on the heat sink.
If you look closely at this shot, and then look at a similar one by Smurfer in his thread, you will see that my board has a resistor just below the heat sink between the two righmost transistors. On Smurfers system there is a capacitor in this location!
http://audiokarma.org/forums/index....07-service-rebuild.702717/page-3#post-9586163
And now with the heat sink removed.
You can see more clearly now the different circuit layout between the two rightmost transistors.
The heat sink with the Mica shims ready to be cleaned.
The Power board from the other side.
The foil side of the power board with the EQ board pins de-soldered, ready to pull out.
And with the EQ board removed. It just slid out without any issues.
The EQ board RWX-154 in it's original form.
And with all the .01uF ceramic caps removed. The lovely little WIMA film caps lined up ready. I left all the Mylar caps alone. No real need to touch them.
And finally with the WIMA caps in place. This is the very first time I have performed this kind of job. I was more than pleased with how well it went, and how nicely the soldering went. It has given my confidence a good boost.
The Caps used on the RWX-154 EQ board were:
8 x WIMA .01uF 100V: http://mouser.com/ProductDetail/WIMA/MKS2D021001A00JSSD
So, that's it for my first post in this saga. On to the main Power and Oscillator board next
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