I have a Pioneer SA-8800 that I am having a problem with. I have replaced all electrolytic caps, transistors and diodes. The unit will start up on a 100w DBT, bulb gets very dim but the relay will not engage and I cannot make any idle current or DC offset adjustments. Checked all my work and cannot find anything installed incorrectly. Any suggestions would be helpful.
Thanks
Tom
Thanks
Tom
Replaced transistors and diodes ? Why ? Were they faulty before ?
Usually You only replace caps on those old amps.
If the relay is not engaging, it's probably in protection mode or protection circuit is faulty.
Newer transistors can lead to instabilities / oscillation problems.
Check if there is DC before the relay before going any further.
Usually You only replace caps on those old amps.
If the relay is not engaging, it's probably in protection mode or protection circuit is faulty.
Newer transistors can lead to instabilities / oscillation problems.
Check if there is DC before the relay before going any further.
Post your questions over on Audiokarma.org. There a specific Pioneer section that gets a lots of traffic. Pioneer Audio | Audiokarma Home Audio Stereo Discussion Forums
jeff
+1 on pioneer forum on AK, very helpful/experianced people there.
+1 on either excessive Vdc or failure in protection circuit.
Check for excessive Vdc by measuring volatge at pin 15 (left ch) of power amp to chassis.
Repeat for pin 20 (right), expect xx mV
+1 on either excessive Vdc or failure in protection circuit.
Check for excessive Vdc by measuring volatge at pin 15 (left ch) of power amp to chassis.
Repeat for pin 20 (right), expect xx mV
It is a NSA power amp design, known to be finicky. Uses fast drivers and RET bjts. Mtf @ AK is the expert as Tom probably already knows 🙂
Search the thread on AK about SX-3900 power amp section repair, it has a lot of useful information on servicing NSA pa’s
Search the thread on AK about SX-3900 power amp section repair, it has a lot of useful information on servicing NSA pa’s
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