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sx 1250 tuning knob shaft damage help

M

maclvrbr

Super Member
I picked up a pioneer sx 1250 that at some point had taken a direct blow to the tuning knob. The knob had driven the shaft into the receiver breaking the fastening point for the tuning shaft dial. A picture is attached, for those with the knowledge please tell me which parts I need to repair this with. Also the tuning dial string will need to be restrung, it is still attached but is on the shaft incorrectly. i appreciate the responses. The dial glass was also broken.
 

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I'm not completely sure but there should be some kind of cir-clip with a nylon washer to keep the shaft from moving aft in the retaining housing. A nut simular to a pot shaft retaining nut should hold the bearing/housing in place and is installed from the front.
The dial restring is shown in the service manual.
I never liked it when the tuning knob would move in and out. I would shim the tuning shaft to a fine point and eliminate the play. It just feels classy with no play.
 
There's an exploded diagram of the shaft assy in the S.M. . (See below). Washer / Nut / Nylon cover.

Clipboard01.jpg
 
Thanks so very much those are the parts I need. The speaker relay will not engage. AWR 106 readings are.
1- -61v
2- 61v
3- 0v
4- 0v
5- 0v
6- 76v
7- 20v
8- 5.4v
9- 13v
10- 23v
11- 64v
12- 0v
13- 2.9v
14- 1.3v
15- 2.3v, according to a thread here pins 13,14 and 15 should be much different, any suggestions? thanks
 
maclvrbr said:
I picked up a pioneer sx 1250 that at some point had taken a direct blow to the tuning knob. The knob had driven the shaft into the receiver breaking the fastening point for the tuning shaft dial. A picture is attached, for those with the knowledge please tell me which parts I need to repair this with. Also the tuning dial string will need to be restrung, it is still attached but is on the shaft incorrectly. i appreciate the responses. The dial glass was also broken.
Click to expand...
OK...I have a SX-1050 Parts unit....What are you looking for?

Tuning shaft is the same part # as SX-1250
 
Joe; Looks like the cover, nut and washer on the front are gone. The shaft (with the weight) may be stripped so he may need that too. See diagram on post #3.
 
After installing Q5,6,7 and D 3 and 4 still unable to get negative voltages. Pin 1 stabilizer 106
1 -61v
2 61v
3 0v
4 -.6v
5-102mv
6 76v
7 20v
8 1v
9 13v
10 23v
11 62v
12 mv fluctuating
13 2.9v
14 1.3v
15 2.2v I am sure I have done something wrong I would appreciate the help.
 
Pin 15 is the input voltage to the -65V regulator (should be something like -85V). My fault...you didn't have that voltage available on your first measurement either. The voltage comes from the small(ish) fuse and diode board on the underneath of the receiver. The same diode bridge generates the +/-85V, so I'm assuming that the bridge and the two fuses are OK (Fu1 and Fu2, 1A), but check them out with an ohmmeter. There are no fuses after the diode bridge, only a couple of 10 ohm resistors, so it's certainly possible that the one for the -85V is burnt and is now open. Probably a good thing to have replaced the parts you did anyway, as one of them was probably responsible for the death of the resistor (if that's how it all went down).

I also notice that all your raw voltages are low...I assume that is because you have this on a DBT...?
 
I am on a DBT, I traced back a bit from pin 15 and to the input of R4 (awr 107) and got -71v, on the other side of r4 got 2.3v , sounds suspect. R4 is a 10 ohm? 2w resistor. Should this voltage through r4 be closer to the -79 v into it? Thanks
 
That was the issue R 4 on the 107 board, I had a 10 ohm 2% resistor available and just tried it, after installation speaker relay engaged and was able to produce music using the cd player I have. I have no idea the wattage 2% is.
 
The manual says 10 ohm 2W.

If your resistor watt rating is too low, it's gonna fry and you'll be doing this all over again.
 
Sure was just using to get a temp diagnosis. Negative voltages still good. Now after moving to the protect board recap and trans the receiver will not allow the relay to engage. Please help this greenhorn, thanks Glen
 
maclvrbr said:
Now after moving to the protect board recap and trans the receiver will not allow the relay to engage.
Click to expand...
Pretty vague. You replaced the resistor and it started working. Then you did 'something else' with the protection board and now it doesn't.

So, a detailed description of what was done would be called for.
 
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