Pioneer SX-3500

It was 1980 and the transition from the analog realm towards digital (tuners) was just around the corner when Pioneer introduced the SX-**00 line with “Flouroscan” display technology. The ‘coolness’ factor of those blue bars moving effortlessly to the music left many a entry HiFi enthusiasts dreaming of owning one to complement their lava lamps.

Coolness factor aside, the solid audio engineering that went into the circuitry design always hid a potential unrealized under “Mass Production” pressures. 

It was however, a solid performer in it’s category and time priced at about $850 2024 dollars.

The SX-3500 was rated at 20 watts per channel into 8 ohms however, during our final testing after all modifications, this example produced over 2 times that at over 42 Watts of clean output with Both channels driven simultaneously! This is an example of what you hear about with classic gear being “under rated”

One reason some people get into the Classic HiFi scene is their discovery of vinyl. The 3500 had a very good discrete complimentary low noise phono amplifier to begin with. 

We took the design up a notch by replacing the entry level audio capacitors that were incorporated originally with modern high grade “Gold Series” audio caps from Nichicon, bringing this piece up a notch sonically.

Particular attention was taken with the front end of the phono amplifier where we selected high accuracy Poly Stacked Film capacitors!

All transistors were upgraded to much higher performance KSA992’s and their compliment, this really supercharged a solid phono design into the best performer it can be.

The real power behind the punch of an amplifier is the large main filter capacitors. You will almost never see anyone replacing them on a 3500 (or many other models for that matter), why?...

Number 1, they are quite expensive and bench testing at 1khz will often show them within spec, but test them at 20hz and 15khz and you almost always see a different story. BESIDES, THEY ARE OVER 40 YEARS OLD!

Number 2, To gain access to them on this amp you need to do a complete teardown of the chassis to access the pads on the PCB in order to change them,…not a very easy job to do and very time consuming!

We do though…

 and if you go through that much effort why not upgrade the value by a couple thousand microfarads and use premium 

“Fine Gold” caps from Nichicon…Yeah, now that’s putting the tiger in the tank!

At this point in the restore, it is essential to address the #1 killer of output transistors in classic gear, poor heat conduction due to old dried out heat transfer compound.

To address, we remove the complete heatsink assembly along with the outputs and strip them down to the bare components and insulators and clean off all the old crusty failing heat sink compound and refresh it with a modern version of High Density, Non Curing Thermal paste to protect the device for decades to come.

The Tuner required alignment which was performed in accordance to the Pioneer Service Manual.

After alignment the tuner worked flawlessly and we have to agree with everything that classicreceivers.com has to say about the SX-3600 which has the same tuner as the 3500.

• Tuner is not recapped however there were no issues observed during calibration.