Pioneer SX3800

Brian Donaldson · 27th April 2005, 11:21 PM

Hey, Does anyone have a scematic for a Pioneer SX3800. Help save me $16.99
Thanks

EchoWars · 28th April 2005, 05:16 AM

I've spent $20+ for scats for amps that wouldn't bring $5 on eBay just to fix for my own satisfaction. Your 3800 is worth the expendature. Go for it...

Brian Donaldson · 28th April 2005, 01:01 PM

It seems the only problem is the sockets for the outputs are all broken up. I can't see the board well enough to tell for sure, but I think it is an emitter follower output due to the 3 wire ceramic resistor that both outputs are tied to. I may just wing it and bias it to 75 ma or so since everything is working.

It does feel like a decent piece of equipment unlike most of the junk made after 82 or so.

I only buy stuff that I think looks nice and is higher up the manufactures food chain. (60 wpc and up) The flagships are usually too expensive or junked out.

EchoWars · 28th April 2005, 08:27 PM

Ahhh!!! The plastic sockets on the outputs! I rebuilt a 3900 a while back where they all just fell to pieces. I found small female push connectors and did each transistors lead individually, although most tech's would probably just solder the wires on.

The build quality is pretty decent on these...maybe not up to 1975 standards, but good still. And when running it is a nice sounding unit.

Brian Donaldson · 28th April 2005, 11:11 PM

I did solder each wire. It sounds OK on FM. My Philips DVD 936 is playing stupid and won't read a disc right now, so I couldn't really give it a listen. It clipped at 35V peak with 4Ohm speakers (both sides driving) so it's pushing 150w RMS @ 4 ohm, not bad.

The strange thing is there are 3 pots per channel. 1 for offset and 2 that effect bias. I zeroed the offset and set it at 100ma bias. one channel was at 125ma and the other at 80ma, and 100 seemed like a good number. Do you know how the 2 pots work together. removing the board to backengineer the scem would be a beoch (and unnessisary) If you remeber something about it.

Not a bad buy for $30.

EchoWars · 29th April 2005, 03:20 AM

The 3900 had two pots for bias adjustment, and it was a oddball brocedure IIRC. Unfortunately I don't have the manual...it belonged to the owner.

100mA is a bunch of bias. I'd settle for half of that.

27th April 2005, 11:21 PM	#1
Brian Donaldson diyAudio Member Join Date: Jan 2003 Location: Texas, Love it or leave it	Pioneer SX3800 Hey, Does anyone have a scematic for a Pioneer SX3800. Help save me $16.99 Thanks

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28th April 2005, 05:16 AM	#2
EchoWars diyAudio Member Join Date: Dec 2002 Location: Left of the Dial	I've spent $20+ for scats for amps that wouldn't bring $5 on eBay just to fix for my own satisfaction. Your 3800 is worth the expendature. Go for it...

28th April 2005, 01:01 PM	#3
Brian Donaldson diyAudio Member Join Date: Jan 2003 Location: Texas, Love it or leave it	It seems the only problem is the sockets for the outputs are all broken up. I can't see the board well enough to tell for sure, but I think it is an emitter follower output due to the 3 wire ceramic resistor that both outputs are tied to. I may just wing it and bias it to 75 ma or so since everything is working. It does feel like a decent piece of equipment unlike most of the junk made after 82 or so. I only buy stuff that I think looks nice and is higher up the manufactures food chain. (60 wpc and up) The flagships are usually too expensive or junked out.

28th April 2005, 08:27 PM	#4
EchoWars diyAudio Member Join Date: Dec 2002 Location: Left of the Dial	Ahhh!!! The plastic sockets on the outputs! I rebuilt a 3900 a while back where they all just fell to pieces. I found small female push connectors and did each transistors lead individually, although most tech's would probably just solder the wires on. The build quality is pretty decent on these...maybe not up to 1975 standards, but good still. And when running it is a nice sounding unit.

28th April 2005, 11:11 PM	#5
Brian Donaldson diyAudio Member Join Date: Jan 2003 Location: Texas, Love it or leave it	I did solder each wire. It sounds OK on FM. My Philips DVD 936 is playing stupid and won't read a disc right now, so I couldn't really give it a listen. It clipped at 35V peak with 4Ohm speakers (both sides driving) so it's pushing 150w RMS @ 4 ohm, not bad. The strange thing is there are 3 pots per channel. 1 for offset and 2 that effect bias. I zeroed the offset and set it at 100ma bias. one channel was at 125ma and the other at 80ma, and 100 seemed like a good number. Do you know how the 2 pots work together. removing the board to backengineer the scem would be a beoch (and unnessisary) If you remeber something about it. Not a bad buy for $30.

29th April 2005, 03:20 AM	#6
EchoWars diyAudio Member Join Date: Dec 2002 Location: Left of the Dial	The 3900 had two pots for bias adjustment, and it was a oddball brocedure IIRC. Unfortunately I don't have the manual...it belonged to the owner. 100mA is a bunch of bias. I'd settle for half of that.

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