Pioneer Receiver SX-408

audioPT · 1st March 2003, 08:22 PM

Hi!

One more time, I'm here to get some help.

A friend of mine put in the trash this:
::Pioneer Stereo Receiver SX-408::

I bring it to my workshop and found that it is

'dead'

.

So, any1 have a schematic for this?
I know it is very old, but you know the sound of that kind of equipment.
I must bring it to live!

Thanka in advance for some reply.

Pedro Martins

audioPT · 4th March 2003, 11:27 AM

Schematic, please!!

Thanks

Pedro Martins

mrfeedback · 4th March 2003, 12:06 PM

Can you post photo of outside and inside ?.
If so I can probably help you.

Eric.

316a · 4th March 2003, 12:45 PM

Check fuses , if the fuses are ok it may be the thermal trip on the transformer . If the thermal trip has gone open you could always short it to check operation but this may not be a safe method (I use a variac to bring the mains up slowly) , or if it's an inline type bonded to the transformer just buy a new one (sometimes they are impossible to replace) . Usually the trips go when the the ventilation holes on the top have been blocked , usually accompanied with the bass at full and loudness button depressed on the amp !

316a

audioPT · 4th March 2003, 12:58 PM

Hi!

Thanks for the replyes.

I've cheched some components and I found this:
- Fuses OK
- PSU working fine
- One 150 Ohm resistor going very hot!
- Lift up one side of the resistor and...
- Doesn't get hot anymore

This resistor connects with a 2SA720 that is shorted.
Please, let me know, as this is the cause of the problem, and as I can't get that 2SA here in portugal, can I use a BC640 in it's place?

They are pin compatible and the specs are:

2SA720
30V | 0,5A | 0,625W
BC640
100V | 1A | 0,8W

Photo:
Don't have a digital camera but I'm going to try my webcam.

All I know is that it is Beautifull!
Aluminium in front and the rest of the case black. Also have a tunning pointer with a light on it.

Thanks mrfeedback and 316a for the replyes.

Are these transistors compatible??

Best regards

Pedro Martins

Netlist · 4th March 2003, 01:32 PM

Yes, the transistors can be exchanged. Expect for the lower bandwith. 200 vs 50Mhz. But that's not too important IMO.

/Hugo

Tube_Dude · 4th March 2003, 07:11 PM

You can also use the BC327!

-50 V-0,8 Amps-100 Mhz-0,625 W

It is very comum here in Portugal ,but if you don't find one send me a mail because a have some !

Saudações

Jorge Santos

mrfeedback · 5th March 2003, 01:44 AM

Be sure to check/adjust bias current after replacing the drivers.
If the repaired channel works fine (it should), you should do the same to the other channel to conserve stereo matching.

Eric.

audioPT · 5th March 2003, 06:58 PM

Bias! Of course. The amplifier don't have any adjustements.
I've compared the good one with the repaired and the current was the same. Also substituted the 2SA720 with BC640 in both channels.
Wanna know if it works?
Yes!
And with the known sound of that kind of amplifiers...

Guys, Thanks for all the replyes!

Best regards,

Pedro Martins

survey · 21st April 2009, 02:59 PM

I have the schematic you want, but its to big to upload.

I can´t mail you either, I'm new here and my account is under moderation...

mail me
cheer's.

1st March 2003, 08:22 PM	#1
audioPT diyAudio Member Join Date: Aug 2002 Location: Right here	Pioneer Receiver SX-408 Hi! One more time, I'm here to get some help. A friend of mine put in the trash this: ::Pioneer Stereo Receiver SX-408:: I bring it to my workshop and found that it is 'dead' . So, any1 have a schematic for this? I know it is very old, but you know the sound of that kind of equipment. I must bring it to live! Thanka in advance for some reply. Pedro Martins

4th March 2003, 11:27 AM	#2
audioPT diyAudio Member Join Date: Aug 2002 Location: Right here	Pioneer Stereo Receiver SX-408 Schematic, please!! Thanks Pedro Martins

4th March 2003, 12:06 PM	#3
mrfeedback diyAudio Member Join Date: Feb 2002 Location: Perth, Australia.	A Picture Is Worth A Thousand Words... Can you post photo of outside and inside ?. If so I can probably help you. Eric. __________________ I believe not to believe in any fixed belief system.

4th March 2003, 12:45 PM	#4
316a diyAudio Member Join Date: Dec 2002 Location: West London	Dead ? Check fuses , if the fuses are ok it may be the thermal trip on the transformer . If the thermal trip has gone open you could always short it to check operation but this may not be a safe method (I use a variac to bring the mains up slowly) , or if it's an inline type bonded to the transformer just buy a new one (sometimes they are impossible to replace) . Usually the trips go when the the ventilation holes on the top have been blocked , usually accompanied with the bass at full and loudness button depressed on the amp ! 316a

4th March 2003, 07:11 PM	#7
Tube_Dude diyAudio Member Join Date: Mar 2002 Location: Aveiro-Portugal	Olá audioPT You can also use the BC327! -50 V-0,8 Amps-100 Mhz-0,625 W It is very comum here in Portugal ,but if you don't find one send me a mail because a have some ! Saudações Jorge Santos


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4th March 2003, 12:58 PM	#5
audioPT diyAudio Member Join Date: Aug 2002 Location: Right here	Hi! Thanks for the replyes. I've cheched some components and I found this: - Fuses OK - PSU working fine - One 150 Ohm resistor going very hot! - Lift up one side of the resistor and... - Doesn't get hot anymore This resistor connects with a 2SA720 that is shorted. Please, let me know, as this is the cause of the problem, and as I can't get that 2SA here in portugal, can I use a BC640 in it's place? They are pin compatible and the specs are: 2SA720 30V \| 0,5A \| 0,625W BC640 100V \| 1A \| 0,8W Photo: Don't have a digital camera but I'm going to try my webcam. All I know is that it is Beautifull! Aluminium in front and the rest of the case black. Also have a tunning pointer with a light on it. Thanks mrfeedback and 316a for the replyes. Are these transistors compatible?? Best regards Pedro Martins

4th March 2003, 01:32 PM	#6
Netlist diyAudio Moderator Join Date: Jan 2003	Yes, the transistors can be exchanged. Expect for the lower bandwith. 200 vs 50Mhz. But that's not too important IMO. /Hugo

5th March 2003, 01:44 AM	#8
mrfeedback diyAudio Member Join Date: Feb 2002 Location: Perth, Australia.	Be sure to check/adjust bias current after replacing the drivers. If the repaired channel works fine (it should), you should do the same to the other channel to conserve stereo matching. Eric. __________________ I believe not to believe in any fixed belief system.

5th March 2003, 06:58 PM	#9
audioPT diyAudio Member Join Date: Aug 2002 Location: Right here	Bias! Of course. The amplifier don't have any adjustements. I've compared the good one with the repaired and the current was the same. Also substituted the 2SA720 with BC640 in both channels. Wanna know if it works? Yes! And with the known sound of that kind of amplifiers... Guys, Thanks for all the replyes! Best regards, Pedro Martins

21st April 2009, 02:59 PM	#10
survey diyAudio Member Join Date: Oct 2008	I have the schematic you want, but its to big to upload. I can´t mail you either, I'm new here and my account is under moderation... mail me cheer's.

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