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

[Ben Rothman]

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.

That makes sense. I have ordered the main filter caps as well as the remaining original transistors. My plan is to do one board at a time and then test the receiver afterwords. I don't believe these speakers are really 4ohm, my guess is that they are closer to 5 or 6ohm. They changed the label on the back of them midway through production, but from my understanding they didn't actually change anything internally. I've also used these speakers with SX-1010 for years without a single issue, so I find it unlikely that the 1010 decides not to like them anymore.

 

[Ben Rothman]

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

Hi Larry, you are totally correct. I need to slow down and tackle this one step at a time. Currently the only thing connected to the 1010 (besides the speakers) is a RCA to 3.5mm headphone jack cable. I unplugged my turntable as well as my CD player. I have gone ahead and ordered all the remaining parts that I need. I ordered the filter caps as well as the transistors. I am going to do one board at a time and then test the 1010 for an extended period of time to see if that solves my issue. Once I do that, I will go ahead and install the remaining transistors. Again, you're right I need to slow down and go about this in a methodical manner.

Ben

 

[Ben Rothman]

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.

Hi Mark, thank you for all your help so far! it has not gone unappreciated! I have ordered all of the remaining parts that I need to finish of the rebuild (Transistors, Diodes, and Filter Caps). Yes, C1 and C2 have been replaced with WIMA film caps. I don't believe these speakers are truly 4ohm. My belief is that they are 6ohm and can sometimes dip as low as 4ohm. I say that because the 1010 doesn't even get Luke warm. I have to really feel around the black grated part of the top to find a warm spot after playing this thing for hours upon hours. Like the other guys have mentioned here, I'm going to slow down on this process and fix it using a slow and methodical manner. My gut tells me that it is something to do with the protection board as it has all original transistors. The amplifier boards have had a partial transistor replacement, all of the known ones have been taken care of. With that being said, I do still plan on replacing the remaining transistors on that board as well. But I will do this one step at a time and then test and report back.

 

[larryderouin]

Ben. Ohm out the speakers to doublecheck. Reagan stated in Iceland in front of press after 1987 summit meeting with Gorbachov "Trust, but Verify" (Quicky History snippet... https://en.wikipedia.org/wiki/Trust,_but_verify ) which works really well here. 8 ohm speakers will ohm out between 6.5 and 7.5ohms on a straight meter vs. an impedance (ac rating ohms and I think resistance combination). 4Ohm will read 3.-3.3 or so. 5 to 6ohm will read accordingly. The higher the impedance the less load on the amp. But remember, Impedance changes with frequency, so you'll see dips in the impedence on a graph at certain point of frequency. Speaker graphs are usually 20Hz to 20kHz. Some speakers are notoriously hard to drive (lots of dip toward less than 2 ohms at different frequencies.).

 

[Ben Rothman]

Ben. Ohm out the speakers to doublecheck. Reagan stated in Iceland in front of press after 1987 summit meeting with Gorbachov "Trust, but Verify" (Quicky History snippet... https://en.wikipedia.org/wiki/Trust,_but_verify ) which works really well here. 8 ohm speakers will ohm out between 6.5 and 7.5ohms on a straight meter vs. an impedance (ac rating ohms and I think resistance combination). 4Ohm will read 3.-3.3 or so. 5 to 6ohm will read accordingly. The higher the impedance the less load on the amp. But remember, Impedance changes with frequency, so you'll see dips in the impedence on a graph at certain point of frequency. Speaker graphs are usually 20Hz to 20kHz. Some speakers are notoriously hard to drive (lots of dip toward less than 2 ohms at different frequencies.).

Hi, I'll definitely ohm out the speakers when I get a chance. I do not believe the speakers are the issue though. I actually looked back in my camera roll and realized I have been using these speakers with the 1010 for close to 5 years without a single hiccup. I can barely turn the volume knob past 10 without shattering my windows!

 

[markthefixer]

How I would check a speaker's apparent resistance across the spectrum:

After running the amp into a resistor dummy load 20 Hz to 20 KHz, and verifying the flatness of the drive, with a scope

I would hook in the unknown speaker with a known value series resistor. This will form a voltage divider with series resistor as R1 and the speaker would be R2.
As I swept the 20 Hz to 20 KHz, I would be monitoring the input voltage AND the voltage across the speaker.
The smaller the Speaker voltage gets, the lower the speaker resistance AT THAT FREQUENCY.

A R1 of four ohms, with a 4 ohm speaker would mean a 50% voltage drop at the speaker.
BUT
any DECREASES in amplitude below that 50% would signify a drop in speaker resistance, and it can be reverse calculated.

from 50% to 25% for example means there is just 2 ohms of speaker loading at that frequency - It wants to draw MORE current - thus disturbing the amp.

I say scope, because many do not have AC voltmeters accurate out to 20 KHz.

 

[Ben Rothman]

How I would check a speaker's apparent resistance across the spectrum:

After running the amp into a resistor dummy load 20 Hz to 20 KHz, and verifying the flatness of the drive, with a scope

I would hook in the unknown speaker with a known value series resistor. This will form a voltage divider with series resistor as R1 and the speaker would be R2.
As I swept the 20 Hz to 20 KHz, I would be monitoring the input voltage AND the voltage across the speaker.
The smaller the Speaker voltage gets, the lower the speaker resistance AT THAT FREQUENCY.

A R1 of four ohms, with a 4 ohm speaker would mean a 50% voltage drop at the speaker.
BUT
any DECREASES in amplitude below that 50% would signify a drop in speaker resistance, and it can be reverse calculated.

from 50% to 25% for example means there is just 2 ohms of speaker loading at that frequency - It wants to draw MORE current - thus disturbing the amp.

I say scope, because many do not have AC voltmeters accurate out to 20 KHz.

Hi Mark. I actually don’t have a scope but it’s on my to do list of things to get. My repair “test equipment” only consists of a soldering station, a variac, and a DBT. The speakers themselves say 4ohm on the back of them. I was using them originally with the 1010 before I did my partial restoration. As soon as I started using the 1010 it had transistor problems, stemming from the amplifier boards. Once I finished the original restoration, the 1010 played great on the 4ohm altecs. If you agree, I think my first step to figure out the issue is going to be replacing the remaining parts in the 1010. I’d like to remove the 1010 malfunctioning as a variable from the problem.

 

[larryderouin]

Have you got a Digital Volt Ohm meter????? Even a $6.95 cheapie from Harbor freight is better than nothing. You're going to need it to do various procedures like measuring voltage across a resistor, some can give you a reading on smaller capacitors, Taking voltages both DC and AC, doing 6 way diode test on transistors to verify DEAD or NOT.
Home Depot has a decent True RMS (aw **** I can remember the brand) meter for $69.00 that does all of the above.

 

[Ben Rothman]

Have you got a Digital Volt Ohm meter????? Even a $6.95 cheapie from Harbor freight is better than nothing. You're going to need it to do various procedures like measuring voltage across a resistor, some can give you a reading on smaller capacitors, Taking voltages both DC and AC, doing 6 way diode test on transistors to verify DEAD or NOT.
Home Depot has a decent True RMS (aw **** I can remember the brand) meter for $69.00 that does all of the above.

Yes I do have a digital volt ohm meter

 

[larryderouin]

Take your meter and ohm out the speaker on the back of the cabinet. (disconnect spkr from receiver 1st). That'll tell you 4 or 8 ohm definatively.

 

[markthefixer]

Take your meter and ohm out the speaker on the back of the cabinet. (disconnect spkr from receiver 1st). That'll tell you 4 or 8 ohm definatively.

We're way past that part. We know they are 4 ohm speakers, and they interact badly with the SX-1010 over current protect circuits.

The plan is to get new parts into the protect board and see if it continues.

The extra stuff is for checking the speaker for impedance dips at various frequencies that cause it to pull much more current -
for example: say it dips down to an apparent two ohms at 2200 Hz, that could be rightfully triggering the over-current protect-
That could be a characteristic of the speaker - like some legendary "amp-killers" or it could be a fault in the speaker.

 

[larryderouin]

I could have sworn I read that they came in 4 and 8 ohm varieties and there was ambiguity whether 4 or 8. Must have been another thread.

 

[Ben Rothman]

How I would check a speaker's apparent resistance across the spectrum:

After running the amp into a resistor dummy load 20 Hz to 20 KHz, and verifying the flatness of the drive, with a scope

I would hook in the unknown speaker with a known value series resistor. This will form a voltage divider with series resistor as R1 and the speaker would be R2.
As I swept the 20 Hz to 20 KHz, I would be monitoring the input voltage AND the voltage across the speaker.
The smaller the Speaker voltage gets, the lower the speaker resistance AT THAT FREQUENCY.

A R1 of four ohms, with a 4 ohm speaker would mean a 50% voltage drop at the speaker.
BUT
any DECREASES in amplitude below that 50% would signify a drop in speaker resistance, and it can be reverse calculated.

from 50% to 25% for example means there is just 2 ohms of speaker loading at that frequency - It wants to draw MORE current - thus disturbing the amp.

I say scope, because many do not have AC voltmeters accurate out to 20 KHz.

First off, I want to apologize for the massive delay. Life and school got very busy and I had to put the 1010 project on the back burner. I decided that I’m going to bring the unit to a tech who knows what he’s doing.