• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Pioneer SX1250 Troubleshooting

H

Harpsteve

New Member
I am a newbie to the forum. Great forum it is. I pulled my SX 1250 out of 20 years of storage. I tried to turn it on and it would not power up because the 12A fuse was blown. I replaced the fuse, switched it on and it “popped”. There are no speakers attached so the pop came from within. It’s in great physical shape and clean. I have the service manual, a volt/ohm meter,a soldering iron and time. Ready to get this bad boy working again.
I did not know where to start troubleshooting cause I am concerned about powering it up again.
Any suggestions? Thx
 
Register to hide this ad
You came to the right place. The Gurus will surely show up shortly and get you on your way. Good Luck!
 
The fuse blows obviously because of a short. The ? is where? You can do some ohmmeter measurements with power off to verify possibly where it is. With certain connections hardwired it can come down to method of elimination to where the short resides. Possibilities include, the output transistors, rectifiers, filters, transformer etc.
Since the rectifiers are on two pcbs with plug in connectors that is an easy place to isolate the transformer secondary wires from the big ecaps and output transistors (bjt) as a quick test.
Read up and make a dim bulb tester(DBT) as that will usually save the 12A fuse from blowing.
If you search there are many threads that have similar issues and some have resolutions. For some one new to troubleshooting and understanding electronics it becomes a course in its self and skills tools etc necessary to perform the task. That’s a lot to learn for someone new to this. You will also read how many run into problems taking on such a task and dig themselves a hole that they can not escape without assistance and additional cost because of damages done. You might want to have someone knowledgeable in a 1250 to do this service for you.
 
Last edited:
This is indeed a big bite to chew…if you’re dead set on trying to fix it yourself, your first step should be to build/acquire a DBT before you power on again. In the meantime, you can pop the cover off and see if there’s anything damaged or burned to possibly give some clues as to where you need to start testing/troubleshooting.
 
A
rcs16 said:
The fuse blows obviously because of a short. The ? is where? You can do some ohmmeter measurements with power off to verify possibly where it is. With certain connections hardwired it can come down to method of elimination to where the short resides. Possibilities include, the output transistors, rectifiers, filters, transformer etc.
Since the rectifiers are on two pcbs with plug in connectors that is an easy place to isolate the transformer secondary wires from the big ecaps and output transistors (bjt) as a quick test.
Read up and make a dim bulb tester(DBT) as that will usually save the 12A fuse from blowing.
If you search there are many threads that have similar issues and some have resolutions. For some one new to troubleshooting and understanding electronics it becomes a course in its self and skills tools etc necessary to perform the task. That’s a lot to learn for someone new to this. You will also read how many run into problems taking on such a task and dig themselves a hole that they can not escape without assistance and additional cost because of damages done. You might want to have someone knowledgeable in a 1250 to do this service for you.
Click to expand...
rcs16 said:
The fuse blows obviously because of a short. The ? is where? You can do some ohmmeter measurements with power off to verify possibly where it is. With certain connections hardwired it can come down to method of elimination to where the short resides. Possibilities include, the output transistors, rectifiers, filters, transformer etc.
Since the rectifiers are on two pcbs with plug in connectors that is an easy place to isolate the transformer secondary wires from the big ecaps and output transistors (bjt) as a quick test.
Read up and make a dim bulb tester(DBT) as that will usually save the 12A fuse from blowing.
If you search there are many threads that have similar issues and some have resolutions. For some one new to troubleshooting and understanding electronics it becomes a course in its self and skills tools etc necessary to perform the task. That’s a lot to learn for someone new to this. You will also read how many run into problems taking on such a task and dig themselves a hole that they can not escape without assistance and additional cost because of damages done. You might want to have someone knowledgeable in a 1250 to do this service for you.
Click to expand...

I appreciate the feedback and the wisdom. I have some aged electronics experience but not with Stereos.
I might do a quick look to determine if I need to bail or push a little farther down the road. Do no harm first! This is a really nice stereo and I want keep it that way.
 
I appreciate the feedback and the wisdom. I have some aged electronics experience but not with Stereos.
I might do a quick look to determine if I need to bail or push a little farther down the road. Do no harm first! This is a really nice stereo and I want keep it that way.
 
It could be something as simple as a paperclip thats dropped onto the PSU.

Whats the history, was working before storage?
 
elvi said:
It could be something as simple as a paperclip thats dropped onto the PSU.

Whats the history, was working before storage?
Click to expand...
It worked fine for years. I noticed one of channels ( I think A speakers left side) stopped working. All the others worked fine i.e. the B speakers. I stored it when a got home stereo with all the newer audio interfaces.
 
You're in good hands with rcs16...lots of knowledge about those big 1250's and the electronics in them. Yeah, my first choice would be a very detailed look inside with a fine tooth comb. Forget about replacing the fuse and plugging it in again..this issue needs to be addressed and remedied. If the visual look over doesn't yield anything obvious, then it's time to get out the multimeter. Absolutely..if you are going to tackle this yourself, get or build a dim bulb tester..they are very easy to do and cheap and very good insurance against blowing that expensive stereo up! Google DBT or go on YouTube. Also, get a good copy of the schematic for it..equally invaluable. Try Hi-Fi Engine or invest in a good reproduction copy. These guys are extremely knowledgeable about these units and if you listen to them, follow their instructions to the letter, go slow about doing it and ask questions, then you'll probably be ok. Remember, there are NO stupid questions when it comes to vintage gear.
 
You must log in or register to reply here.
Back
Top Bottom