Pioneer SX-828 - April 2024 Service

Out of all of the smaller vintage receivers out there, the SX-828 is most likely one of my all time favorites. A good friend of mine even getting into separates used this integrated as his preamp, and if I didn't already have more audio equipment than I can appreciate, this one might have become part of the collection. 

My friend finally moved fully into separates and this amplifier sat in storage for a while. Before deciding to sell or trade it, he brought it by for a lookover and service. 

Most of the electrolytic capacitors remained for the new owner to decide if they wanted replaced. They were still working and testing ok, so they were left in as there were more critical components to put time and attention to in this particular amp. They tend to have overheating issues on the power supply PCB, some instability in the protection circuit, and some other maintenance was needed. 

 Here is the rebuilt power supply and protection board. Both received new electrolytic capactors, new semiconductors and heat sinks that outperformed the original. Some traces had to be repaired where heat had already begun to sink into the PCB. 

 The protection relay was replaced and a diode added for longevity and to protect the relay on power off. 

Troublesome transistors in the preamp stage were preemptively replaced as well. DC offset and bias pots were replaced with multiturn Bourns replacements when I encountered some instability in testing. Thermal compound was replaced on all 4 output transistors. 

Work was finished with a deep clean and detail of the component. The faceplate was cleaned and polished, all switches and pots cleaned and lubricated as well as all other electrical contacts in and out. The wood case was cleaned, treated and polished as well.