Pionner SX-1010 Trips Relay Once After Sitting for 2 Days.

[markthefixer]

something in the speakers impedance profile, coupled with particular frequencies in the program material are causing over current trips.

4 ohm speakers ARE inherently harder on the amp driving them.

It is sensed across the emitter resistors.

you can hook up the 1010, then use the balance control to see if only one channel, or both left and right are doing it. if just one channel I would look closer at the speaker.
Then I would swap speakers L / R and see if it follows the speaker, or stays with the channel.

 

[Ben Rothman]

something in the speakers impedance profile, coupled with particular frequencies in the program material are causing over current trips.

4 ohm speakers ARE inherently harder on the amp driving them.

It is sensed across the emitter resistors.

you can hook up the 1010, then use the balance control to see if only one channel, or both left and right are doing it. if just one channel I would look closer at the speaker.
Then I would swap speakers L / R and see if it follows the speaker, or stays with the channel.

Hi, Mark. So I’m a little confused. Do you believe it’s the speakers causing this issue? Or the 1010 and the transistors on the protection and amp board? I should’ve been more specific. This issue I’m currently having is some new. I used my 1010 that I fully re-capped and put 80% new transistors in with the 4ohm speakers for about 2 years without any problems. The problem I’m having is that this not a common problem. It ONLY happens if I let the pioneer sit for 2 days then about 10 minutes after playing music it will quickly trip the protection circuit. After that one time, the 1010 will play perfectly fine. I don’t believe it’s the speakers because when they’re hooked up to the 1250, there’s no problem. I’m curious what you think is going on here. Do you believe it’s the pioneer and the old transistors (what I’m hoping for) or the speakers?

 

[zebulon1]

I would change the filters and leave the outputs alone. Sounds like something the Godfather would say?
The big filters could contribute to a voltage imbalance on power up. They are the filters for the unregulated rails but they (Or one of the two) could have some influence on the regulated power supply.
I would recheck the amp settings and make sure they are in spec's and stable.
Is this a better place to start on this issue?
Yes

 

[Ben Rothman]

I would change the filters and leave the outputs alone. Sounds like something the Godfather would say?
The big filters could contribute to a voltage imbalance on power up. They are the filters for the unregulated rails but they (Or one of the two) could have some influence on the regulated power supply.
I would recheck the amp settings and make sure they are in spec's and stable.
Is this a better place to start on this issue?
Yes

Hi Zebulon, I think that’s where I’ll start. I’ll replace all the remaining transistors and replace the filter caps. I won’t replace the outputs, but I will remove them and put new thermal compound behind them. According to pioneer can the 1010 run 4ohm speakers? I find it very unlikely for the speakers to be at fault here. It doesn’t make sense how the amp would go into protection just once after 10 minutes of use (no matter the level of volume) after sitting for two days. Any ideas?

 

[Ben Rothman]

I would change the filters and leave the outputs alone. Sounds like something the Godfather would say?
The big filters could contribute to a voltage imbalance on power up. They are the filters for the unregulated rails but they (Or one of the two) could have some influence on the regulated power supply.
I would recheck the amp settings and make sure they are in spec's and stable.
Is this a better place to start on this issue?
Yes

I forgot to mention that I have substituted my sx1010 for my unrestored sx1250. I did this to see if the problem was the speakers itself. From my understanding, both the 1010 and 1250 are rated to handle 4ohm speakers. Now testing this issue is somewhat hard as the sx1010 doesn't click in and out of protect unless it has been sitting unused for 2+ days. I put the 1250 in my setup 2 days ago and have been using all day everyday. I haven't been able to get the 1250 to go into protect. This makes me believe the speakers are totally fine and the 1010's remaining original transistors are to blame. Any thought on this?

 

[zebulon1]

Hi Zebulon, I think that’s where I’ll start. I’ll replace all the remaining transistors and replace the filter caps. I won’t replace the outputs, but I will remove them and put new thermal compound behind them. According to pioneer can the 1010 run 4ohm speakers? I find it very unlikely for the speakers to be at fault here. It doesn’t make sense how the amp would go into protection just once after 10 minutes of use (no matter the level of volume) after sitting for two days. Any ideas?

While your waiting on the filters, post the amp settings or let us know what you saw before you make any adjustments.
If after a few days sitting, power it up on the DBT. No speakers, no volume, no inputs and report the bulb activity when powered on. Just curious.
The filters on the 1010 have 4.7K ohm bleed/bypass resistors so the caps should bleed down fairly quick. Why two days makes a difference. High ESR?? This whole filter cap thing is probably a sideshow anyway. That's why having two meters watching the balance at the amps when powering up would help.

 

[Ben Rothman]

While your waiting on the filters, post the amp settings or let us know what you saw before you make any adjustments.
If after a few days sitting, power it up on the DBT. No speakers, no volume, no inputs and report the bulb activity when powered on. Just curious.
The filters on the 1010 have 4.7K ohm bleed/bypass resistors so the caps should bleed down fairly quick. Why two days makes a difference. High ESR?? This whole filter cap thing is probably a sideshow anyway. That's why having two meters watching the balance at the amps when powering up would help.

Hi, what do you mean by post the amp settings?

 

[Ben Rothman]

While your waiting on the filters, post the amp settings or let us know what you saw before you make any adjustments.
If after a few days sitting, power it up on the DBT. No speakers, no volume, no inputs and report the bulb activity when powered on. Just curious.
The filters on the 1010 have 4.7K ohm bleed/bypass resistors so the caps should bleed down fairly quick. Why two days makes a difference. High ESR?? This whole filter cap thing is probably a sideshow anyway. That's why having two meters watching the balance at the amps when powering up would help.

So I just powered the 1010 up with a DBT, and the bulb immediately went bright and then dimmed down, and then the relay clicked in.

 

[Ben Rothman]

I gotta be totally honest, I’m a little confused with what you guys are thinking. We know the 1010 worked fine for years with these 4ohm speakers. Never thought to even mention the fact about the speakers because I was so positive it had something to do with the 1010.

 

[Ben Rothman]

I made an interesting discovery. I moved the 1010 down my workbench and hooked up two sets of 8ohm speakers to speaker A and B. As this will simulate a 4ohm load. Depending on the song I play and how much base is in it. I can get the speaker protection relay to kick in at about between 10 and 12 Alcock on volume knob. What’s interesting is that the amp quickly goes into protect and out of protect at those volumes. After it comes out of protect mode it continues to play at those super high levels of volume. This amp is rated to run 4ohm speakers. I’m not exactly sure why it’s causing the amp to briefly go into protect. Don’t get me wrong I can barley be in the same room when the volume knob is is between 10 to 12 Alcock. Any suggestions?

 

[HPMguy]

Dead main filter caps. They are losing form when they sit for a few days and are way low on capacity. It's going into protect either due to excessive current draw or too much offset at the outputs, either of which can results from dead main filter caps.

They are just as old as the rest of the ones you replaced, and work as poorly under load. Since they lack capacity, when a large transient occurs the amp will "clip" as the voltage sags, resulting in DC current at the outputs. This triggers protection, as is should because you will fry the speakers running DC current through them for any lenght of time (seconds).

The reason it is more problematic on cold start up is that the dried out capacitors will re-gain some capacity when charged for a while.

It will sound better with new ones as well.

Stop running it at high power before you blow the outputs or fry a speaker or two, you REALLY need to repair it.

 

[Ben Rothman]

Dead main filter caps. They are losing form when they sit for a few days and are way low on capacity. It's going into protect either due to excessive current draw or too much offset at the outputs, either of which can results from dead main filter caps.

They are just as old as the rest of the ones you replaced, and work as poorly under load. Since they lack capacity, when a large transient occurs the amp will "clip" as the voltage sags, resulting in DC current at the outputs. This triggers protection, as is should because you will fry the speakers running DC current through them for any lenght of time (seconds).

The reason it is more problematic on cold start up is that the dried out capacitors will re-gain some capacity when charged for a while.

It will sound better with new ones as well.

Stop running it at high power before you blow the outputs or fry a speaker or two, you REALLY need to repair it.

Thank you so much for that response!
Did you see what I wrote about the 8ohm vs 4ohm speakers? My main setup is with 4ohm speakers. On my workbench I have a set of 8ohm klipsch bookshelf speakers. I couldn’t get the1010 to trip with just the 8ohm speakers. Granted I could only turn the volume up to about 1:30 before i pretty much went deaf. I then attached another set of 8ohm speakers to speaker B and played them both at the same time to simulate a 4ohm load. I was then able to get the protection circuit to trip. Do you think it’s just the main filter caps? Or is it also the transistors on the protection board?

 

[Ben Rothman]

Im wondering what is causing the issue. I thought I was so sure it was the remaining transistors, but now, I’m not so sure. Im going to replace those anyway, along with the filter caps. Does anyone have any idea what’s causing the issue?

 

[zebulon1]

Hi, what do you mean by post the amp settings?

I'm beginning to worry.
The Idles and DC Balance.
We need to see those readings. Procedure is in the SM. Note: Use mini grabber leads for the meter. Do not move test leads with the power on.
The Idle should be set to 25mv. The manual is wrong.
If you must:
Just replace the filters. If you have to re-paste the outputs, Do it after you sort out the current issue. The outputs are not the issue.
Yes - the 1010 should run the 4 ohm speakers. Something is not right with your SX-1010.

 

[Ben Rothman]

I'm beginning to worry.
The Idles and DC Balance.
We need to see those readings. Procedure is in the SM. Note: Use mini grabber leads for the meter. Do not move test leads with the power on.
The Idle should be set to 25mv. The manual is wrong.
If you must:
Just replace the filters. If you have to re-paste the outputs, Do it after you sort out the current issue. The outputs are not the issue.
Yes - the 1010 should run the 4 ohm speakers. Something is not right with your SX-1010.

Ok. I measured the bias and dc offset. The bias was 24.9 on the right channel and 25.1 on the left channel. The DC offset was zero.

so we know the 1010 can run a 4ohm load. I think the original transistors on the protect board and on the amplifier board are probably my culprits.

 

[Ben Rothman]

@markthefixer hey Mark, im not sure what I should be doing for my next steps. Should I go ahead and replace the transistors on the protect and amplifier boards?

 

[HPMguy]

Pioneers have trouble with the protection circuits at this age, many of the components are run close to their limits and will got bad. If you have not replaced the silicon components on the protection board, that is a good place to start BUT you need to replace the main filter caps -- the fact that you have an issue after sitting really points to bad electrolytic caps, and those are the only ones you have not replaced. Typical symptoms are dropping the speakers at fairly modest output and erratic protection relay operation. However, if you actually do have an over-current issue, eventually persistently getting it to go into protection will blow something up.

4 ohm speakers draw roughly twice the current at any setting than 8 ohm speakers, so if you are getting an over-current condition, the speaker protection circuit will cut them off. This is done by a relay in that amplifier, it disconnects the speakers from the amp. Naturally, when it clicks back in it will be at the same volume as it was before it cut out.....

There are plenty of threads on troubleshooting the protection circuits on this and similar amps, give them a read and see if you can figure out what the issue is. Horsing around with it won't fix it, you need to do the actual troubleshooting of the protection circuit.

 

[larryderouin]

One step at a time. There's a reason Mark wanted you to troubleshoot by powering up with the BALANCE over to one side or the other (minimizes or grounds the other channel signal at that point, effectively only allowing one channel to work, basically 1/2 the load vs both channels and full load @ 4ohms). Do the Cold startup on the 4Ω speaker and let it run on ONE CHANNEL (L or R). See if it trips itself at about 10 minutes or so. Report back results. It may take a week or so. DON'T get ahead, and have 77.3 things running around in your head. "What if's" will trip you up everytime. GO SLOW, Work the problem, Fix it. THEN do the overhaul. BTDT with a 1010. (Damn near gave MTF a heart attack when I did mine, but he Gibb's slapped me a couple times and it apparently took.) There's really good guys here, so listen to them and don't run off 1/2 cocked.

Seen too many times on AK, in the last 15 years where someone has a problem with a 1010, and gets ahead of himself the guys here trying to help going in 5 directions at the same time. It don't end well for the 1010 and the guy quits in the middle. It's a couple of orders of magnitude HARDER to visualize the problem when the unit is across country behind firewall. SLOW DOWN!!! Patience, Grasshopper. It's gonna take time, LOGICAL THINKING (sometimes it's harder when your 27 vs 67), and staying on course. Take pictures of each board (before and after, with replacements listed) and we can usually tell you if you either missed something or installed something backwards.

Time for a complete synopsis, BOARD BY BOARD.
Identify the board, and list each part replaced (Q1, C3, R47, etc) along with it's replacement that you have done. Do this vertically, One part per line. Identify the board by it's part #

Then detail the exact problem, (without getting the 1250 involved as it just confuses us old folks sometimes). Who, what, where, when, How.

What is connected to the 1010 (phono, tape deck, etc.) preferably no sources connected. Just the speakers and an antenna if needed for FM/AM work. Settings on all controls, time after cold start up after 2 days, did you flip or turn any controls, change channels on FM/AM(probably not likely but lets cover all the bases).

Bias L/R
OFFSET L/R
WALL VOLTAGE xxxVAC
List the Power Supply voltages vertically by pin # with + and - for Pos/Neg voltages and AC or DC (ie: +35vDC, -13vDC, 7.8vAC, etc.)

This is NOT going to be an overnight fix. It's gonna be slow, sometimes tedious, other times it seems boring as hell, but stick to one thing at a time and it'll get done faster and RIGHT!

Larry

 

[larryderouin]

Formatting for each board and parts lists......See this thread on the SX-7730(SX-737). This is how we'd prefer the lists from your 1010. Easy to read, and we would know exactly what was installed where. https://audiokarma.org/forums/index.php?threads/project-sx-7730-sx-737.979234/

 

[markthefixer]

@markthefixer hey Mark, im not sure what I should be doing for my next steps. Should I go ahead and replace the transistors on the protect and amplifier boards?

The cheapest and fastest way is to just replace all seven (or so IIAc) transistors.
I take it that the c1 & C2 0.22uf caps are film caps now. If not, make it so
q1 - q4 ksc1845
q5 ksa992
q6 ksc2383
q7 ksc2690
also do these, for a clean sweep of all POSSIBLE triggering problems.
d1-d4 1n4148
D8 1n4004
extra 1n4004 anode to pin 9, cathode (banded end) pin 10.

then if it STILL does it, we most rightfully look at the speakers, because they are irritating the power amps somehow.

Just BECAUSE Pioneer says 4 ohm load, they DON'T mean 3 or even 2 ohms. that's a huge "strain" on the power amps.

Then there's speakers that are legendary amp killers, that while they are called "FOUR OHMS", they have peaks and dips that can go down to 2 ohms.
2 ohms... not for these type of amps.