Pioneer SX-1010

I am attaching my voltage results from protection circuit. I am suspecting that pin 9 should be pulled to ground but that is not happening. Upon looking at board I noticed that owner put all nice new NEC transistors in here as well. Guess I am doing another board :(
Any confirmations on my thought process?
 

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  • Protection Circuit Worksheet.pdf
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The pin voltages look good on the Protection board.
It's looking at the amps which coincide with your previous posts.
Yes replace the transistors and diodes with the Audiokarma 1010 list.
Before you start on that job:
For kicks ground pin 9 to the chassis momentarily listening for the relay to engage "Click".
Can you tell if the protection relay has been tampered with?
There is a troubleshooting procedure for the 1010's protection (MTF has posted) but let's see how the rebuild goes. The NTE's the other guy installed cannot be trusted.

The last request was to check the DC Balance with the jumpers removed. Did you do that?
 
I did not check DC balance with jumpers disconnected as it seemed to stabilize after running for 10-15 minutes.
I wondered about jumping pin 9 to ground. I am finding that the relay still does not engage meaning I have a bad relay or not enough current getting to it? Are they known for bad relays? OMRON.
I can faintly hear the relay trying to engage but the contacts are not moving.
 
I have seen pictures of those relays getting toasted. You might want to replace that when you do the protection board. You could pull it and inspect it.
 
The DC balance should be stable right off the get-go.
Unplug the jumpers. You can leave them out for now.
Check the Balance once again. Report your results.

Even with running the set on the DBT you should get the relay to work.
Now that you know what the replay is doing. When operating the set normally (Without the jumpers), does the relay engage (Albeit ever so lightly)?
Still the NTE components must be replaced.
The relays can be a small turd to replace. If you have a spare relay - wire it into the circuit with only the coil connected and see if it works normally.
I'm worried that the wrong relay is installed, maybe a 48 volt one(?), as the previous owner had made questionable choices. Can you tell if the protection relay has been tampered with?
Try to figure a way to do this and not have the original relay connected. Maybe: Lift a pin (9) from the protection board.
Or just rebuild the protect board and replace the relay.

If you need a relay, below is the bible on the replacement. Lots of images on the web about this replacement procedure.

From my MTF archive: :D
--------start of: these models use ONE chassis mounted protection relay:------------------

models:
SX-727 SX-737 xxxxxxx
SX-828 SX-838 SX-850
!!!!!!!!!! SX-939 SX-950
!!!!!!!!!! SX-1010

4pdt chassis mount using upper ears 24v 653-LY4F-DC24 MOUSER.COM stock level 14 @ $11.61
or a substitute:
dpdt chassis mount using upper ears 24v 653-LY2F-DC24 MOUSER.COM stock level 51 @ $ 6.55

being chassis mount, conversion from double connected 4pdt to dpdt contacts is easy
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
to mount this relay use standoffs (mouser.com parts numbers) 15mm M-F aluminum,
need two per side for 30mm: 728-FM2110-3005-A due to the ears being on TOP instead of on the bottom!!


stainless preferred standoff from mouser 15mm (need two per side): 728-FM2110-3005-SS
728-FM2110-3005-A is 4.5mm od 3mm x 0.5 thread 15mm male female aluminum 0.63 /100: 0.43
728-FM2110-3005-SS is 4.5mm od 3mm x 0.5 thread 15mm male female stainless steel 1.07 /100: 0.74
728-FM1262-3005-A is 4.5mm od 3mm x 0.5 thread 15mm female female aluminum 0.59 /100: 0.40
728-FM1262-3005-SS is 4.5mm od 3mm x 0.5 thread 15mm female female stainless steel 0.97 /100: 0.67
 
I rechecked the DC balances and here is what I found. Running about 5 minutes, jumpers connected/disconnected, did not matter, Fluke 88 indicates a voltage fluctuation between 11.6mV and -39.2mV (average -3.5mV) for the outer board and 17.4 to 0.6 mV on the inner board (avg 3.1mV). I am sure they would get closer to zero as it warms up.
As for the relay, it has been removed at one time as indicated by some shoddy soldering and a broken mounting ear. Upon removal, I put in on my power supply and took it all the way up to 30 VDC with no click so I am okay with calling it "pooched". I measured 3.815 k ohms across the coil. Seems high but not sure what it should be. Contacts are okay and provide continuity when closed with no resistance measurable.
I am going to do the protection board and replace the relay as suggested and go from there.
DC balance - do I have an issue? Not sure why they would bounce like that - caps??
 
A good relay will ohm out around 350 ohms, - well I know it's under 1000 ohms for sure. So yea, it toast.
And:
The balance should be more stable. I'll read the whole Thread later tonight and check back on the issue.
I'd hate to have you go back into the amp again but the -40mV's could be an issue down the road. Re flow the traces? Swap out the Diff pair (Q1, Q2) for a matched set? :dunno:
Right now the amps are operational. We can worry about it later. Get the protection sorted first and see where that leads. Who knows whats in-store with this 1010?
Like I said I'll read the thread history.
 
Well after a long break from this unit, I am back at it again. Sorry about that.
So I repaired all the faults on the protection board, replaced all the transistors and diodes with proper ones. Owner had put NTE here as well.
I replaced the 24 volt relay and now it snaps to life about two seconds after power on and I think all the protection voltages are okay. Dragon is tamed and behaving as it should.
Now, when I turn it on, the signal strength meter swings to the far right and the tuning needle stays dead center and no sound. Thoughts anyone. Zeb and Loweran, I hope you are still here
 
What is the tuner supply voltage, It should be close to 13.5v's?
If its more don't mess with it until the PS is sorted. (This might of been done, I didn't want to reread the entire thread)
What about playing in AUX?
 
I have 12.9 VDC at the tuner and front end board.
I can receive some lower end AM radio stations which tells me we are on the right track.
Nothing comes up on FM stations and no stereo signal at all.
My antenna is nothing but a loop of steel and I think that is my problem.
Our house only has coax and I have no antenna for this receiver to work off of. My Pioneer SX-5 works great off the small antenna but I don't think it works for this one.
 
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Any thoughts? I dont have any fancy antennas and my other stereos dont need one to get reception down in my room. Can I make up something?
Am I even on the right track? The signal strength stays pegged to the right on FM, there is noise from the speaker and the FM STEREO light never comes on. By noise, I mean just noise, no music.
 
Pegged to the right is not good. If you have any small gauge wire, make a four foot loop and try that.
A known good antenna is best.
The meter should rest to the left when unpowered.
 
I took a piece of wire approximately 6 foot long last night and made it into the shape of a T and hung it from the basement rafters. I then hooked it up into the 75 ohm terminal and the ground ?? terminal to the left.
It made no difference. The signal meter does return to the left when unpowered. What does pegging to the right mean? I don't believe the signal strength is that strong across the board so I am thinking I have a tuner problem? I am going to check the three chips tomorrow for the voltages as listed on the schematic. Does this sound like a logical step? There is another thread going on a 1980 that sounds very similar to this one.
 
I am a novice when it comes to the tuners but I do have luck when working them. Reading the voltages is my first step, then reading the circuit voltages is next. This usually gets me in the ball park of where to begin troubleshooting.
The signal meter is part of the Detector circuit in the FM tuner so that's where you should concentrate your troubleshooting.
Connect a RCA patch cord from the "MPX" out to the right or left "Tape Mon" in jack and run the set with the tape monitor on as you would if a tape player was connected. Have the function switch selected to FM and listen/tune to an FM station. If you hear a station, then the front half is working. The signal is combined at that point, so you won't have stereo.
I have a feeling that the detector chip HA1137 is toast. You describe the meter as going full right when powered on - this is not a good sign. There isn't much compoen'tree in that area of the detector to go bad. The meter seems to work on a voltage differential controlled by the chip.

If you end up needing a chip this seller has good quality IC's. No affiliation.
eBay Seller
 
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Pardon me for butting in here, but the OP stated NEC semis not NTE. There's no relation and they were used stock in vintage gear all the time. So..not sure why these arent to be trusted...unless there's some confusion about which brand they are because I just noticed he's called them both.
 
Hopjohn, I thank you for pointing out the error of my ways. They are in fact NTE transistors and not NEC as stated. I work in an industry that is in love with acronyms and NEC is a company that I deal with in my trade all the time so I may have had a "brain fart" at that time and I hope that everyone will excuse me. As for the problem at hand, I still have no answer so I am going to pin out my IC's on my tuner board and see what I find. Wish me luck, I'm going in!
By the way, does anybody have datasheets for HA1156, HA1137 and HA1138?
 
Okay I went and checked all the voltages on the three IC's and I think it is safe to say that HA1137 is toast. Can anyone confirm from the sheet I have attached. I think there is probably more to it but I have to run some more tests. The transistor 2SC945 off of pin 8 on HA1156 may also be a problem?
 

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  • Tuner Circuit.pdf
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Good work! I think you are on your way to sorting this out. Does anyone know if this tuner will need alignment after the parts are replaced?
 
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