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Akai AA-1200 going sporadically into protection mode

Roypercy

Roypercy

Super Member
Hi all:

My main rig is an Akai AA-1200 that has served me faithfully ever since I got it professionally serviced in 2019. I was recently away for ten days, and since I came back I hear the receiver sporadically kick into protection mode for a few seconds before coming back on. I've had a couple of listening session where this doesn't happen, and a few where it will go into protection a few times in a row and then play fine afterwards. This has never happened before. What could be the issue? What should I be looking for?
 
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Check the speaker outputs for DC voltage with a voltmeter. could be bad differential transistors or noisy 2SC1628 transistor in one channel causing DC balance level to spike cause the intermittant protect issue.
 
when the unit is in protect, there will be no reading on the speaker outputs. will need to go directly to the amp output/relay inputs to get a reading.
 
painttoad said:
when the unit is in protect, there will be no reading on the speaker outputs. will need to go directly to the amp output/relay inputs to get a reading.
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Agreed that no voltage will be present once it goes into protect, but if DC is found to be fluctuating (tracking up and or down exceeding typical DC balance spec), it can point to the troublesome channel. But yes going to the relay points can see the voltage after protect engages and relay drops out. Sometimes its hard to connect leads to relay contact points, so another option would be to connect 1 meter lead to ground, and the other lead to the point where both emitter resistor leads meet together (a lot easier to hook a clip lead onto an emitter resistor lead that to the relay points on the circuit board.
If a scope is available, this monitoring can be ever easier. Put channel A lead on the emitter resistor common point of left channel, and channel B lead on the emitter resistor common point on the right channel. DC Fluctuations can be easily seen using an Oscope
 
Thanks, everyone. I'll pull out my multimeter and check the DC at the speaker outputs.

There's a chance it was a simpler issue. When I was poking around last night I found that one speaker wire had nearly worked its way out of the speaker outputs at the back of the receiver. It's possible my wife was cleaning while I was away and dislodged something. I replaced the speaker wire more securely and the receiver has been playing without incident all morning. Could it be somethng this simple?
 
If you are asking whether it's all your wife's fault.. Well I'm not going to answer that. :biggrin:

But yes, an intermitted speaker connection could definitely cause the protection to flip in. Did you notice it happening in particular when for instance the floor was "moving" or other physical movement effected the amp/wire/speaker?
 
Okke 70s said:
If you are asking whether it's all your wife's fault.. Well I'm not going to answer that. :biggrin:

But yes, an intermitted speaker connection could definitely cause the protection to flip in. Did you notice it happening in particular when for instance the floor was "moving" or other physical movement effected the amp/wire/speaker?
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No, I didn't notice anything out of the ordinary happening to cause it.
 
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