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SA-9500 Relay going bonkers

02County

02County

AK Member
Came back from the three day weekend only to discover my trusty SA-9500 has misplaced a channel and clicks into protection mode on the other with even the slightest volume. Powering it up, it comes out of protection just fine and clicks over no problem. But no right channel at all. Left comes in fine but starts clicking out after a bit of volume. I've checks the connections and speaker wires to make sure there aren't any shorts. No idea what happened but am a bit worried about my amp. Bought the old girl from a genuine ozark meth head in a Toys R us Parking lot last year and really really like her a lot. Great sound, looks sweet and - until this weekend - was basically solid as a rock (unlike every other vintage item I've ever owned).

Does this sound like a relay issue?
 
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02County said:
Came back from the three day weekend only to discover my trusty SA-9500 has misplaced a channel and clicks into protection mode on the other with even the slightest volume. Powering it up, it comes out of protection just fine and clicks over no problem. But no right channel at all. Left comes in fine but starts clicking out after a bit of volume. I've checks the connections and speaker wires to make sure there aren't any shorts. No idea what happened but am a bit worried about my amp. Bought the old girl from a genuine ozark meth head in a Toys R us Parking lot last year and really really like her a lot. Great sound, looks sweet and - until this weekend - was basically solid as a rock (unlike every other vintage item I've ever owned).

Does this sound like a relay issue?
Click to expand...

Not necessarily, the relay may simply be affected by something else it's connected to.
But I would first want to start by making sure the preamp is working as it should, then move on to the main amp if it checks ok.
On the dead channel I would want to do some testing to see if there is actually anything coming from the main amp output, before the signal
reaches anything else afterwards (such as the protection circuit). The relay may not even be receiving a signal from the right channel for it to switch.
 
Okay - Good call. The only way I can think of testing that would be to switch the 9500 into separated mode and run the amp portion through a separate preamp (in my case, that would be another receiver). Is there another/better way to test if the amp is producing out of both channels?
 
02County said:
Okay - Good call. The only way I can think of testing that would be to switch the 9500 into separated mode and run the amp portion through a separate preamp (in my case, that would be another receiver). Is there another/better way to test if the amp is producing out of both channels?
Click to expand...
That would be fine as long as you don't try to run the preamp out into a source input.
 
Okay...I guess I'm confused. My plan at this point is to run a line level input through the preamp, connect the preamp through the separate 9500, which in turn will be wired to speakers. The idea being that the line level input is necessary to determine whether the amp is producing both channels. Is that right?

I currently run the SA-9500 through an eq, which requires running the amp in "separated" mode. In that mode, the amp is missing a channel and the remaining channel pops in and out of relay. Not really sure if that's relevant at this point, but just throwing it out there.
 
1. Since it could be the Normal/Separated Switch, with power off, actuate that switch 10-20 times back and forth (preferably along with some deOxit or other electrical contact cleaner and try again.

All other switches should be likewise cleaned or at least actuated multiple times if you have no deOxit to rule out bad contacts in the switches causing channel dropouts.

2. If still no good, remove the EQ from the picture to rule that out and run the amp in Normal/Connected mode with jumpers in place.

3. If still no good, run connections from a known good preamp to the "Main-In" connections of the 9500. If you don't have a dedicated preamp or receiver with preamp out jacks, use something like a portable CD player with Volume control, or your iPod/iPhone headphone out jack to RCA plugs. You don't want to send an unregulated signal at full line level to the main-in jacks of the amp which is why you need some attenuator on the signal.

4. If the problem is "cured" it lies in the preamp section of the 9500, if the problem remains it lies in the power amp section.
 
02County said:
Okay...I guess I'm confused. My plan at this point is to run a line level input through the preamp, connect the preamp through the separate 9500, which in turn will be wired to speakers. The idea being that the line level input is necessary to determine whether the amp is producing both channels. Is that right?

I currently run the SA-9500 through an eq, which requires running the amp in "separated" mode. In that mode, the amp is missing a channel and the remaining channel pops in and out of relay. Not really sure if that's relevant at this point, but just throwing it out there.
Click to expand...

All I'm saying is don't run the preamp out to the AUX, Tape or phono jacks on the other unit. Make sure you are running it to something which has "main amp in" jacks.
 
Cool - Thanks guys. Much appreciated. I'll mess around with it tonight and let you know how it works. Fingers are very crossed at this point....
 
Check your power amp for 2sa726 (instead of 2sa763) and 2sc1451 (instead of 2sc1628) transistors.

The 2sc1451 is guaranteed to fail. It is a weird round can that looks like it has it's own integral heat sink.

IF you find any - ESPECIALLY the 2sc1451 - GET THEM OUT - they are most definitely your problem in the power amp.

Use ksa992 and ksc3503 transistors to replace them. The lead arrangements from the original transistors to the replacements are DIFFERENT!!! Be VERY careful when figuring out the connections.
 
Thanks guys. I was able to identify the problem last night. It was the same one I always seem to have, which is gross user error. Seriously, this one caused some soul searching. I have no idea how I did this, but my AR-3as has three terminals, two of which are wired in series. You never guess which two were connected to the amp. :wtf:

But now that I'm done torturing my poor amp, everything works beautifully and that old SA-9500 has given me one more reason to love her.
 
02County said:
Thanks guys. I was able to identify the problem last night. It was the same one I always seem to have, which is gross user error. Seriously, this one caused some soul searching. I have no idea how I did this, but my AR-3as has three terminals, two of which are wired in series. You never guess which two were connected to the amp. :wtf:

But now that I'm done torturing my poor amp, everything works beautifully and that old SA-9500 has given me one more reason to love her.
Click to expand...

*Chuckle* I don't think you'll need to kiss and make up. But good to see it didn't require any repairs to resolve the issue.
 
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