Chris' Pioneer Spec 4 hack job

The 2N5087's did not work out for a sub. Temperature co-efficients must have been different, went way squirely under a load. I have thusly swapped those out with a pair of 2SA979's a 100 volt rated part, compared to the 50 volt 2SA798, which run at 66.5 volt. The 979's lack the gain of the 798's we'll see how it affects performance.
 
Big caps going in....
 

Attachments

  • 100_2637.jpg
    100_2637.jpg
    98.3 KB · Views: 35
Pioneer was a firm believer in the Star ground method..... All big caps in......Meter amp board next then this puppy is done..
 

Attachments

  • 100_2639.jpg
    100_2639.jpg
    94.4 KB · Views: 38
  • 100_2638.jpg
    100_2638.jpg
    99.3 KB · Views: 49
laatsch55 said:
The 2N5087's did not work out for a sub. Temperature co-efficients must have been different, went way squirely under a load. I have thusly swapped those out with a pair of 2SA979's a 100 volt rated part, compared to the 50 volt 2SA798, which run at 66.5 volt. The 979's lack the gain of the 798's we'll see how it affects performance.
Click to expand...

Lee you should find out why you have 66.5V. That is a problem that needs to be fixed. It should only be about 28V
 
Unless a feller wants to unwrap 20 something wires the meter board is left in place. Not much room, but the effort/benefit ratio isn't there to take it out.
 

Attachments

  • 100_2641.jpg
    100_2641.jpg
    97.1 KB · Views: 39
  • 100_2640.jpg
    100_2640.jpg
    85.9 KB · Views: 34
Joe the only thing I can see in the way of that 66.4 volts going to the collectors is a paralled 470 ohm resistor in series with a 330pf cap. Is that enough to drop it to 28volts???
 
Nothing you can do except use the correct device here Lee. The Spec4 has 66+ volts across the front end by design, the Spec2 has ~28V, much more normal.

Just use the rigth transistor, the 5087 gave you odd results because they were breaking down. The 798's are in the same boat. The 2N5401 looks like the only reasonable device for this location.
 
Gepetto said:
Nothing you can do except use the correct device here Lee. The Spec4 has 66+ volts across the front end by design, the Spec2 has ~28V, much more normal.

Just use the rigth transistor, the 5087 gave you odd results because they were breaking down. The 798's are in the same boat. The 2N5401 looks like the only reasonable device for this location.
Click to expand...


How about a KSA992, Or Zetex 795A??
 
Joe, the Fairchild 5401's I have have a gain of just under 200. Should be ok, I'll pull one of the 2SA 979's and see how it does.
 
Got a miniature drawer full of em. That's almost as much as a trash sack full.
 
A pair of matched KSA 992FBU's. Well soon Know!!
 

Attachments

  • 100_2642.jpg
    100_2642.jpg
    88.2 KB · Views: 36
Joe the 992's worked out great. have another problem. On the meter amp board had an NPN and a PNP TO-220 reversed. I think I have wounded a cap....
 

Attachments

  • Spec 4 freq Response.jpg
    Spec 4 freq Response.jpg
    90.1 KB · Views: 32
Was not a wounded cap, but a TO-126 was bad. hoking up to the AP now and enjoying the "Pig" pushing the Oppo. Sweet combination. Jan's making some coffee from resh ground beans, the kid didn't get any time. The judge even questioned on record why the case was even brought, proceeded to ream the county attorney on just who forgets their kid in the car, recited a list from a 2009 Washington Post article ranging from a rocket scientist to a pediatrician . He also mentioned there was a dramatic increase after the law stating that infants be in the backseat and TURNED TO FACE THE BACK was passed. The Wyoming law he was prosecuted under is so vague the judge said," Any parent out there could be prosecuted uner this law. Tell me County Attorney, does every parent need to be in jail? Now the state says it's criminal to forget??"

Juries and good judges are what keep us from being a totalitariain regime......

Political rant iver. The cat wants kitty cuddles and the AP is warmed up.
 
You must log in or register to reply here.
Back
Top