Pioneer Spec 2 Meters Jump at Power On

mbottz

mbottz

New Member
I have searched this forum for weeks and found all the information to repair my Spec 2. For the repair I replaced the driver transistors Q4,5,6,7,12,13 with closely matched ON-Semi MJE15032G and MJE15033G Transistors as directed by Echowars. Also Replaced the Bias relays with new units as directed in another thread. Replaced the 2SA798 Differential pair transistors as well for DC-offset. Adjusted the bias voltage to 30mv after a 45 minute warm up. Adjusted the current limiting sensitivity with VR2 & VR3 per the manual. All checks out on the scope. Bias is very stable. DC-offset is 6mv and 9mv.

The unit plays beautifully, But......... the meters deflect at power on to between .1W and 1W as soon as the protection light goes out. There also seems to be a bit of decoupling noise on the right channel at power off as well.

What am I missing?????? :scratch2:

Is there somthing else in the protection circuitry that needs work?? Any help with this would be greatly appreciated.

Thanks

Mike
 
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Just a little pop

I measured the output with the meter and it is around a 300 to 500mv surge.
I dont think it will hurt the speakers, but is just annoying.
 
Sounds like the bias interrupt relay is fixin to go. search the Pioneer forum. Echowars has helped with this quite a few times. it is curable and is NOT the end of the world. You have a couple days reading ahead of you.
 
Already replaced it

Replaced the relay already as per Echowars Instructions. Already spent a lot of time researching prior to the repair. Thats why I am puzzled.
 
I have 2 Spec 2's I've done the same thing to and 1 still has a wee bit of turn on thump, while the other is dead quiet. It's a mystery but is still going strong after three years. I have not been gentle with them either.
Have you set bias and current limiters also??
 
I just cycled the power switch on the Spec 2 that has the thump and the symptoms are almost exactly as you describe on yours. I wouldn't worry if i was you.
 
Not really worried, but I just have this obsession for wanting things to work correctly. Other Spec 2’s don’t do it, so there must be a fix. Anyone got any Ideas??
 
Nothing to worry about. The way the protect works on the Spec 2, it is a bit slow to settle its DC offset, so a bit of a mild thwack or thump is par for the course. On normal-to-inefficient speakers it may be barely noticeable. On really efficient speakers, it may border on annoying.
 
The 2 thermal Varistors (Thermal Diodes for Biasing) are getting Leaky, Pioneer might have replacement parts for them...... I Had the same problem with mine until i changed them.
 
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