I have a Pioneer 828 purchased in 1974. Lately, it has developed the following problems: excessive noise and static which is punctuated by occasional “pops” and “scratching” sounds as if a stylus is being drug across a vinyl record. Some of these sounds are VERY loud. This noise comes through both channels and is unaffected by volume control knob. (i.e. noise is same intensity whether volume control knob is off or turned to any intermediate level.) This noise comes on at random, sometimes while the receiver is playing normally, and does not appear associated with length of time receiver has been on, temperature, time of day or any other variable. Any ideas or thoughts??? Thanks.
SX 828 Pioneer Receiver
- Thread starter Sassie
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jd3rdcoast
Super Member
Find the Top 10 Worst Transistors list here on AK via Google search until SE is fixed. Then get copy of 828 schematic from hifiengine.com (free download with registration).
You can cross reference the bad ones on list to your circuit boards transistor list or view schematic.
You can cross reference the bad ones on list to your circuit boards transistor list or view schematic.
Not a bad run at all from something purchased in 1974. Wish we could say the same for anything bought new these days.
From what you are saying it could be a few possibilities as said above, power supply, oxidized switches, transistors. If it’s common to both channels I would focus on the common element first, the power supply.
Many times folks do more of a refrub by changing electrolytic capacitors, transistors , clean switches pots instead of isolating the specific part causing the problem.
The knowledgeable technician can call in here for advise from the experts
From what you are saying it could be a few possibilities as said above, power supply, oxidized switches, transistors. If it’s common to both channels I would focus on the common element first, the power supply.
Many times folks do more of a refrub by changing electrolytic capacitors, transistors , clean switches pots instead of isolating the specific part causing the problem.
The knowledgeable technician can call in here for advise from the experts
Show this to your tech.
https://audiokarma.org/forums/index...ilure-prone-whatever-and-replacements.731653/
https://audiokarma.org/forums/index...ilure-prone-whatever-and-replacements.731653/
Head Amp ( aka Phono Eq Amp) has 6 2sc458's. Notorious for crackling and popping. Note: ALL source signals except AUX &Tape monitor goes thru the Head Amp. End note.
AF Unit has 2sa725's and 2SC1312. 2SA725's contribute strongly to the "Rice Krispies" effect and are considered one of the top 5 transistors to replace on sight! 2sc458's are also on the shoot on sight top 10.
2sc458's replace with KSC1845
2sc725 replace with KSA992's
2sc1312's repl with KSC945's
The rest as I remember are fairly trouble free. Don't mess with the J-Fet's on the AF Board.
AF Unit has 2sa725's and 2SC1312. 2SA725's contribute strongly to the "Rice Krispies" effect and are considered one of the top 5 transistors to replace on sight! 2sc458's are also on the shoot on sight top 10.
2sc458's replace with KSC1845
2sc725 replace with KSA992's
2sc1312's repl with KSC945's
The rest as I remember are fairly trouble free. Don't mess with the J-Fet's on the AF Board.