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Pioneer Spec 1 Transistor Rebuild
- Thread starter PioneerPro
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- pioneer spec 1
ohm470k
Active Member
These things are better than you think. Good for checking capacitors too. Certainly not the most accurate but they can tell you more about a component than your budget multimeter.If I can re-up my suggestion in #29 above to get yourself one of these cheap component testers. They give you pinout of what you are removing (as long as it's not blown). So you don't need to guess or search the AI-poisoned internet or wait for true knowledge from AK experts for pinouts. I spent $16 on this one because it had a plastic case. If I had to do it again, I'd splurge $29 on this one for the attachments. These aren't pro tools like the Peaks. They are just to give you a quick check of components coming out and going in. Really essential for beginners.
Do not use that one specially for identify pinouts, they have a well know flaw and it gives wrong pinouts.
(ask me how do I know
)
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PioneerPro
Active Member
The new parts from Mouser came in today and here is what I did so far.
In the AWR 094 Power Supply Board I replaced the transistor in the Q3 Position with a brand new KSC2383 transistor and it is facing towards the Q1 transistor.
I also installed the new Zener Diode in place of the one that was just below the Q3 position. I did not replace any of the resistors yet but I have new ones.
I turned the Spec 1 on and retested the 1 thru 15 pins for their power readings and here is what I am getting.
Pins 1 thru 5 are 44 Volts
Pin 6 is 66 Volts
Pin 7 is -66 Volts
Pins 8 thru 12 are -44 Volts
Pin 13 is 35 Volts
Pin 14 and 15 are 24 Volts.
My next move is to plug the Preamp into an amplifier and a Tape deck and see if things are working now. Is this a good move or a bad one? What else should I do at this point with the 2nd Zener Diode and the new resistors that need to replace the old resistors with cracking paint on them. (see previous pictures) None of the 3 output transistor on this board are getting hot, just barely a tiny bit warm.
Thank You All For your guidance.
In the AWR 094 Power Supply Board I replaced the transistor in the Q3 Position with a brand new KSC2383 transistor and it is facing towards the Q1 transistor.
I also installed the new Zener Diode in place of the one that was just below the Q3 position. I did not replace any of the resistors yet but I have new ones.
I turned the Spec 1 on and retested the 1 thru 15 pins for their power readings and here is what I am getting.
Pins 1 thru 5 are 44 Volts
Pin 6 is 66 Volts
Pin 7 is -66 Volts
Pins 8 thru 12 are -44 Volts
Pin 13 is 35 Volts
Pin 14 and 15 are 24 Volts.
My next move is to plug the Preamp into an amplifier and a Tape deck and see if things are working now. Is this a good move or a bad one? What else should I do at this point with the 2nd Zener Diode and the new resistors that need to replace the old resistors with cracking paint on them. (see previous pictures) None of the 3 output transistor on this board are getting hot, just barely a tiny bit warm.
Thank You All For your guidance.
I don't really understand this place, with a functional unit shot gunning swapping parts is ok, but with heated stressed parts, we are conservative and don't want to change the because is a ''paint'' issue.
Good luck.
Not outputs, regulators, and they get warm.
You have a functional power supply board now, since no test equipment is available inject signal to see if the unit produce sound is the way to go, yes. That if and only if no problems were introduced on previous work.
Good luck.
PioneerPro
Active Member
PioneerPro
Active Member
Well, here we go again. I retested the readings of the pins this morning and all but 8 thru 12 are the same. 8 thru 12 are all 10 Volts now where yesterday they were -44 Volts. After that I changed the 3 transistors as you see in the pictures here and that made no difference whatsoever. There must be another short somewhere.
Attachments
Between the server compression and the blurry pictures I can't see well.
What transistors did you change? Please state the designator, Q...what?
What voltages do you have on R4?
What voltage do you have on the emitter of Q2?
Use the images previously provided or the service manual, schematic reading is not needed.
Please provide good quality images.
What transistors did you change? Please state the designator, Q...what?
What voltages do you have on R4?
What voltage do you have on the emitter of Q2?
Use the images previously provided or the service manual, schematic reading is not needed.
Please provide good quality images.
What are you trying to say reposting this image?
PioneerPro
Active Member
FOUND IT FOUND IT FOUND IT
Q4 and Q6 are facing the wrong way. They were both A628 Transistors that I replaced with KSA1013 transistors. The A628's are BCE Pinouts and the KSA1013's are ECB Pinouts and so they needed to be rotated 180 degrees from how the originals were facing.
Now here is the question, Where did I get my A628 Pinout info from. I thought it was a good reliable source, I got it right from Audiokarma.
How did I finally find the correct info? From LesE's post at the top of this page. The schematics drawing the the different transistor Pinouts.
All 1 thru 15 Pin readings are perfect now.
So now that this Spec 1 is good, it is going in the garbage for ****ing we me so much.
Q4 and Q6 are facing the wrong way. They were both A628 Transistors that I replaced with KSA1013 transistors. The A628's are BCE Pinouts and the KSA1013's are ECB Pinouts and so they needed to be rotated 180 degrees from how the originals were facing.
Now here is the question, Where did I get my A628 Pinout info from. I thought it was a good reliable source, I got it right from Audiokarma.
How did I finally find the correct info? From LesE's post at the top of this page. The schematics drawing the the different transistor Pinouts.
All 1 thru 15 Pin readings are perfect now.
So now that this Spec 1 is good, it is going in the garbage for ****ing we me so much.
Man this is a bizarre thread. I'm out.
Good work OP
Good work OP
PioneerPro
Active Member
You know what I really hate? When you are having an issue and you find a great thread addressing the same problems you have but when the original posted finally gets the item fixed the thread just abruptly ends with on a good clear solution.
The problem the whole time was the Pinouts on the transistors and how I could not find the correct information.
To anyone who finds themselves in this situation please remember to look in the one line Hifi Engine service manual for whatever you are working on. There you will find Pinout information that should be correct. The new transistors you order will have the correct Pinout information in the Datasheet on Mouser or Digikey or where ever you bought them.
Please contact me directly for more information and guidance.
Thank You, Ray
The problem the whole time was the Pinouts on the transistors and how I could not find the correct information.
To anyone who finds themselves in this situation please remember to look in the one line Hifi Engine service manual for whatever you are working on. There you will find Pinout information that should be correct. The new transistors you order will have the correct Pinout information in the Datasheet on Mouser or Digikey or where ever you bought them.
Please contact me directly for more information and guidance.
Thank You, Ray
PioneerPro
Active Member
I was working on a Nakamichi BX 125 a couple of months ago. I was not getting sound out of the left channel. I found a used broken deck for $40 and bought that too because it had a bad cassette mechanism but good electronics. I was given about 18 different things to check and was called a dipshit for even touching the deck without proper training and after all the was said and done, it turned out to be the output volume Pot. Apparently this is a double sided Pot and has one side for left and one side for right channels. The Pot is problematic and the wipers fall off on one or both sides. I took the Pot out and took it apart and low and behold one wiper just fell out. This was a very very common problem with the BX 100, 125, and 150 and anyone that ever worked on one knew this.
If you saw the movie Contact you more likely learned what Occams Razor is. A scientific statement that, All things considered the most logical or common answer is usually the correct one.
If I would of just asked a Nakamichi pro he would of told me this and I would of been done in a day instead of a month after spending $2 instead of $50. I now have two working Nak BX 125's that had the same issue and I repaired both in the same exact way.
Live and learn.
If you saw the movie Contact you more likely learned what Occams Razor is. A scientific statement that, All things considered the most logical or common answer is usually the correct one.
If I would of just asked a Nakamichi pro he would of told me this and I would of been done in a day instead of a month after spending $2 instead of $50. I now have two working Nak BX 125's that had the same issue and I repaired both in the same exact way.
Live and learn.