Popping in right channel SX-1250
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gener8tr
Well-Known Member
As always, start with a good cleaning of the switches and controls (specifically balance in this case) with some contact cleaner.
You'll have to remove the case, faceplate and perhaps bottom of the unit to get in there and clean it properly. Even if that does not cure the problem it's something that should be done so you haven't wasted any time or energy.
If that doesn't fix-er-up, there are several UBER-SMART techs on this site that can darn-near diagnose and explain how to repair almost every problem imaginable.
Just be ready to provide answers to a bunch of precise questions and perhaps post a few photos.
You'll have to remove the case, faceplate and perhaps bottom of the unit to get in there and clean it properly. Even if that does not cure the problem it's something that should be done so you haven't wasted any time or energy.
If that doesn't fix-er-up, there are several UBER-SMART techs on this site that can darn-near diagnose and explain how to repair almost every problem imaginable.
Just be ready to provide answers to a bunch of precise questions and perhaps post a few photos.
Dead center in the back of the unit is a set of pre-out / power amp in rca plugs, get a pair of interconnects and swap the left out with the righ in and vice versa. This will show whether the problem is coming from the preamp section, or if it is limited to the power amp section.
Simple, quick and easy to do.
If the popping doesn't move, it is the power amp, and while cleaning is GOOD, it won't make a difference in this case.
If it does move, then a cleaning will help eliminate a wide range of suspects.
If you don't have the extra interconnects, you can just turn it on without any, if there is popping, then it IS the power amp, as there is nothing GOING INTO the power amp.
Simple, quick and easy to do.
If the popping doesn't move, it is the power amp, and while cleaning is GOOD, it won't make a difference in this case.
If it does move, then a cleaning will help eliminate a wide range of suspects.
If you don't have the extra interconnects, you can just turn it on without any, if there is popping, then it IS the power amp, as there is nothing GOING INTO the power amp.
gburnham2004
Active Member
I am experiencing the same kind of issue with my SX 1250, Popping and cracking in the right speaker with it in Aux (CD) or Tuner. mode If I put the balance on full Left it still pops and cracks out of the right channel.
This takes about 30-40 minutes to begin happening and does not seem to happen when cold.
The U shaped connectors at the "Pre/Power Amp" only fit in a "Pre Out" to "Power In" Left to Left and Right to Right configuration.
With the inability to connect them as described "swap the left out with the righ in and vice versa" I scroll down to Mark's last line and pulled both U shaped connectors out and still had the pop/crackel, so I am assuming it is the Power Amp.
I do not understand what it means that there is nothing "GOING INTO the power amp"?
And the big question, how do I fix this?
My only experience with these old Pioneers was ten years ago or so I was buying them up off craigslist and would clean the pots and switches with Deoxit and that seemed to fix most of them. After downsizing I held onto the 1250 but other then cleaning pots and switches I am not very knowledgeable on how to fix electronics.
Any help would be appreciated
If you want to switch left/right at the pre-out/amp -in use a set of RCA plug patch cords as mtf suggested " get a pair of interconnects"
"I do not understand what it means that there is nothing "GOING INTO the power amp"?"
Pulling the jumpers in the back, means nothing is going into the power amps.
"pulled both U shaped connectors out and still had the pop/crackel, so I am assuming it is the Power Amp."
Sounds about the correct assumption, same as what mtf said. To bad the op did not follow up with a solution, welcome to AK's endless amount of dead end threads.
Obviously it needs troubleshooting but you say "I am not very knowledgeable on how to fix electronics".
So send it to "maybe just the power amp board" someone who has a 1250 and has worked on these before.
It's either a poor/intermittent connection or a component is going noisy after it warms up. Could be the input connectors (contacts &/or pins) on the power amp module need cleaning or input differential pair 2sa750 are going noisy or ?
Standard troubleshooting procedures "Methods of elimination and substitution"
Good luck
"I do not understand what it means that there is nothing "GOING INTO the power amp"?"
Pulling the jumpers in the back, means nothing is going into the power amps.
"pulled both U shaped connectors out and still had the pop/crackel, so I am assuming it is the Power Amp."
Sounds about the correct assumption, same as what mtf said. To bad the op did not follow up with a solution, welcome to AK's endless amount of dead end threads.
Obviously it needs troubleshooting but you say "I am not very knowledgeable on how to fix electronics".
So send it to "maybe just the power amp board" someone who has a 1250 and has worked on these before.
It's either a poor/intermittent connection or a component is going noisy after it warms up. Could be the input connectors (contacts &/or pins) on the power amp module need cleaning or input differential pair 2sa750 are going noisy or ?
Standard troubleshooting procedures "Methods of elimination and substitution"
Good luck
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gburnham2004
Active Member
Thank you for your response,
Yes RCA cables would work, never thought of it, have not been inside one of these in years. And actually that Pre-out/amp connection intimidates me a bit. A service tech who did some minor work on the 1250 8 years ago showed me how to wire in an EQ using those connections, but I know longer use the EQ so I just have the factory jumpers in it.
I am in the process of cleaning the pots and switches, I have a DMM but not sure if it works, need to buy a 9 v battery today and a 1.5mm allen wrench to remove the tuner and volume knobs.
I also have a service manual, so I will attempt to identify the Power amp and examine it.
Will clean every pin and connector I can find.
Also, I read some transistors are susceptible to salt air. The Receiver has been in Jacksonville for 10 years, Okinawa (ocean front) four years and Tokyo five years, all very close to the sea and salt air. I read in the thread linked below a deposit can build up at some "matching transistors" at the input stage of the Powre Amp.
Here is the thread and post from Fred Longsworth.
As mentioned I will clean switches, pots, pins and connectors and try to find the Power Amp and identify these transistors which may have gunk building on them from the salt air.
What is the "input differential pair 2sa750" are these transistors?
If I were in JAX I would just take it to the service guy, but where I live I do not have a car nor speak the language, so finding a repair man and getting this monster to them is quite a challenge. So if it something I can fix with the proper guidance I am willing to try, such as replacing transistors.
Thanks again.
"What is the "input differential pair 2sa750" are these transistors?"
Yes. Refer to the schematic.
If you are trying out the jumper test, do so with the power off.
Junk building up on transistors? Moisture has to penetrate the plastic encapsulation to get in and damage the devices. It happens. The legs going black does not mean the devices are defective.
Have you ever serviced electronics before?
Tools?
Salt air= corrosion so try cleaning the connectors on the power amp first. Contact spray, for the contacts, pink rubber eraser for the pins,use the end of a pencil, make a small starter hole, try that first. No wd40, zero residue contact cleaner or deoxit spray or alcohol. No need to remove the front panel. Bonnet and bottom plate Go to the AK database and download the service annual and schematics to familiarize yourself with the unit before you attempt service. Read up on circuit operation, similar threads on servicing a 1250, similar threads.
Seen way to many times folks doing more damage than necessary because of lack of experience so tread lightly.
Yes. Refer to the schematic.
If you are trying out the jumper test, do so with the power off.
Junk building up on transistors? Moisture has to penetrate the plastic encapsulation to get in and damage the devices. It happens. The legs going black does not mean the devices are defective.
Have you ever serviced electronics before?
Tools?
Salt air= corrosion so try cleaning the connectors on the power amp first. Contact spray, for the contacts, pink rubber eraser for the pins,use the end of a pencil, make a small starter hole, try that first. No wd40, zero residue contact cleaner or deoxit spray or alcohol. No need to remove the front panel. Bonnet and bottom plate Go to the AK database and download the service annual and schematics to familiarize yourself with the unit before you attempt service. Read up on circuit operation, similar threads on servicing a 1250, similar threads.
Seen way to many times folks doing more damage than necessary because of lack of experience so tread lightly.
I have a 3 component McIntosh system that I inherited. It needs to be serviced. In January I decided to learn how to restore it BUT, I wasn't going to start with the Macs. Instead I bought a cheap Technics receiver and "restored" it. I learned a LOT but was still not confident enough for the Macs. Since then, this darn hobby has taken hold. I've been working on Pioneer receivers almost every day, all day for 7 months and I am just getting started. I have around 20 Pioneer receivers. I've spent around $1,000 on soldering and test equipment, and I have fixed some really horrible receivers.
I say all of this because you have a receiver that is the envy of guys like me. If I was you, and you are determined to repair it yourself, I would learn on a lesser receiver.
My "guess", based on the tests you've performed, is it's a bad transistor on your main amp board as stated by others. But it's just a guess.
Since you have experience cleaning with deoxit, do that, I'm sure it needs it, but doubt that will solve your problem. Make sure you are using the correct Deoxit product. Learn when to use Deoxit D5 vs Fader.
I've never worked on a 1250, but I've worked on several QX-747s. The 747's are super difficult to get to the main amp boards. You have to disconnect a ton of wires and figure out how to "fish" the boards out. If the 1250 is remotely like that, it is not something you should attempt, you have a really good chance of f'ing it up.
Buy a small Pioneer receiver from the same era that the 1250 was made. Get one that is parts only and restore it. An SX-650 or 750 would be get training units, but even a 450 would be a good and inexpensive starter.
You need a really good soldering iron some 60/40 or 63/37 solder and you should make a dim bulb tester.
If you're able to restore the little receiver, you can resell it for what you paid for it and maybe a little more.
My problem is, I fall in love with them all and and don't want to sell them. I'm old and widowed, so no nagging wife telling me to stop, LOL.
I say all of this because you have a receiver that is the envy of guys like me. If I was you, and you are determined to repair it yourself, I would learn on a lesser receiver.
My "guess", based on the tests you've performed, is it's a bad transistor on your main amp board as stated by others. But it's just a guess.
Since you have experience cleaning with deoxit, do that, I'm sure it needs it, but doubt that will solve your problem. Make sure you are using the correct Deoxit product. Learn when to use Deoxit D5 vs Fader.
I've never worked on a 1250, but I've worked on several QX-747s. The 747's are super difficult to get to the main amp boards. You have to disconnect a ton of wires and figure out how to "fish" the boards out. If the 1250 is remotely like that, it is not something you should attempt, you have a really good chance of f'ing it up.
Buy a small Pioneer receiver from the same era that the 1250 was made. Get one that is parts only and restore it. An SX-650 or 750 would be get training units, but even a 450 would be a good and inexpensive starter.
You need a really good soldering iron some 60/40 or 63/37 solder and you should make a dim bulb tester.
If you're able to restore the little receiver, you can resell it for what you paid for it and maybe a little more.
My problem is, I fall in love with them all and and don't want to sell them. I'm old and widowed, so no nagging wife telling me to stop, LOL.
gburnham2004
Active Member
Thank you on the Transistor info, I downloaded the Service Manual and Schematic many years ago, printed and in a note book. I will refer to the transistors on the schematic, however, all I could find was the Schematic, a line drawing; not like a 3D drawing such as the component drawing indicating all the major components as far as I recall. I will look again and google it to see what the transistor looks like and examine it.
I won't do the Jumper test, I did the U style pin removal test MTF suggested above. so I guess I am looking at the power amp for an issue.
Yesterday, I cleaned all the switches and pots with D5 Deoxit, clicked them all 100 times each flushing them several times, plan to do one more round of cleaning of the S&Ps.
I have identified the Power amps next to the heat sinks and will clean all the pins and sockets with an electric contact cleaner and a rubber eraser as suggested. I did not understand the "make a small starter hole" statement. I have very tiny Q-tip (ear bud) type of things to clean inside the connector pin holes.
Don't worry no WD 40.
All I plan to do is clean and inspect at this time, I am very nervous about bending the tunner indicator or scratching the face or wrecking the Tunner string. So I am being super careful, and want to get the face plate etc back on.
I have not serviced electronics, about 20 years ago I began picking up old Pioneer Receivers and Infinity speakers off of Craigslist and cleaning them up, using them and when I would find a bigger and better one, I would sell off the lower one. I had a SX 1010, 850, 939 etc... I stopped collecting them in 2010, and downsized and sold off my 939 and 1010 and kept the 1250.
I have some minor tools, a DMM, but really I don't know how to use it well. Had some automotive electronic training 35 years ago, but I don't plan to get too deep into this thing at this time. I watched YT video where the guy rebuilt the PA board but then had to dial it in, so that freaks me out and I don't have those kinds tools or skills.
BTW, when I first bought this 1250, in about 2008, I hooked it up and played it for about an hour and BAM, loud cracks and pops scared the crap out of me, was worried I blew one of my Infinity tweeters and freaked out. So I took it to the bench and cleaned it pretty well. It has been crackle free, until about six months ago.
Thank you for the information and assistance.
gburnham2004
Active Member
Paul,
Thank you for your response, I have so far found the 1250 to be relatively easy to access all the Pots and switches. I watched YT video on a guy pulling the S&P out of a 1280 for cleaning, it was similar. I had a 1010 and they were more difficult to get to, but that may because Ihad not seen a video on it and just was digging in. I am not sure if they began engineering them better.
I have not got to a point of removing the Power Amp boards, and am not sure if I will. The connectors are very assessable but not sure about the removal process.
That you for your concern, but at this point I don't want this to become my hobby. I live in Japan and I have a small residency. Years ago I was into it much more, I think it was about 2005 I began collecting the old Pioneer, and believe it was just before it got real popular. I bought my SX 1010 for $100 in working and immaculate condition, many sets of Infinity RSM's for $100 a set ,this SX 1250 I got with a Duel TT, Pioneer EG in wooden case and a Silver faced Pioneer Tape deck all for $350.
I know I am very fortunate to have this unit and will do everything I can not to screw it up.
Right now, just cleaning it.
I do see on Japanese auctions site many Blue face low wattage units cheap and someday may play around with one.
My hobby, time and money goes into 1/35 scale models>
Thanks and if you have further ideas please let me know, all help is appreciated
Greg
Clean pots with fader lube as deoxit removes essential lubricants and if not there, will wear out the mechanisms prematurely.
The 1250 documents have the service manual and the schematics for component placement info that show the back side views
Using a lead pencil with pink eraser end, make a small hole in the eraser as a guide to place over the pins to clean them.
On the power amps modules, be very careful with that remote heatsink temp sensor, stv diode stack, as the wires are solid and easy to break. I suggest to put some glue where the wires enter the body to make them more secure and prevent breakage.
The 1250 documents have the service manual and the schematics for component placement info that show the back side views
Using a lead pencil with pink eraser end, make a small hole in the eraser as a guide to place over the pins to clean them.
On the power amps modules, be very careful with that remote heatsink temp sensor, stv diode stack, as the wires are solid and easy to break. I suggest to put some glue where the wires enter the body to make them more secure and prevent breakage.
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gburnham2004
Active Member
OK thanks, I cleaned the pots with D5 but have not closed it up yet. I will spray them well with Fader lube.
Thanks for the information
On the bottom of the power amp there are several wire connectors at the front end; two on each side, the pins were black with something, I cleaned them with D5.
Ah, OK I get it with the eraser, it will slide over the pins.
What kind of glue would you recommend ?
gburnham2004
Active Member
What pins are you suggesting I use the eraser on? The connecting pins on the bottom of the Power Amp?
Good to know the pots and switches are easy to get to. If you'd like to sell just the 1250 I'd be happy to pay you your original $350 and you can keep the rest of what your purchased with it!! LOL Livingston in Japan, that must be nice. Good luck on the receiver.
what is your preferred flavor of glue? i was using superglue gel right where the wires enter the body. i never have had a problem but sometimes the internet has me questioning my choices.
gburnham2004
Active Member
What exactly are you applying glue to?
gburnham2004
Active Member
Here is some pictures of the connection pins on what I believe is the Power Amp, top and bottom.
They were very dirty, black. Not sure what it was on them. They cleaned up pretty good.
IMG 7750 shows cleaned pins and dirty pins
Image 7751/52 shows the top set before cleaning
7755 is just a random shot
They were very dirty, black. Not sure what it was on them. They cleaned up pretty good.
IMG 7750 shows cleaned pins and dirty pins
Image 7751/52 shows the top set before cleaning
7755 is just a random shot
Attachments
Very good job cleaning those contacts. I believe it's silver oxide. Contact cleaner to the contacts inside the moulded housings.
Apply glue to where the solid wires enter the body of the stv3h, although they are covered by the braided sleeving but you can pull it back a bit to apply the glue and let it go back into position and let the glue dry.
Apply glue to where the solid wires enter the body of the stv3h, although they are covered by the braided sleeving but you can pull it back a bit to apply the glue and let it go back into position and let the glue dry.
