Apart from the recap, have you cleaned the pots? I wasn't able to get the right readings on my scope when trying to fix speed problem on Sony PS-X70. After recap and replacing many parts, cleaning all pots and readjusting them fixed it. Label and match the pots first so you roughly know how to readjust it after cleaning would be my advise 🙂. Pots RV107-110 are interdependent and changing one might lead to having to change the others.
After recap I am planning to clean the buttons of front control panel....and look also to that pots...and any other suggestions that I will get....🙂
If it will spin , I should consider to buy a scope also....
If it will spin , I should consider to buy a scope also....
Hi,
So,recap of the mainboard finished , symptoms are the same (need push the platter , when spinning CW seems to keep steady rotation of 33 RPM , when spinning CCW reach full speed eventually).
No other function work from buttons , only the arm goes to sitting position toward the arm rest when Power On.
Here are the voltages:
IC108
- pin1 = -2.5V
- pin4 = -14.63V
- pin7 = -0.44V (!)
- pin8 = +14.64V
Q117
- B = -0.12V
- C = +32V
- E = 0V (!!)
Q118
- B = -0.18V
- C = -31V
- E = 0V (!!)
Q119
- B = -2.4V
- C = +32V
- E = -1.9V
Q120
- B = -2.4V
- C = -31V
- E = -1.9V
I see wrong voltages on the emitters of Q117 and Q118 which seems to be related with voltages of pin 7 of IC108.
Also wrong voltages on Q112 - Q114 which are different from voltages specified in Service manual :
Q112
- B = 0.2V
- C = 0.5V
Q113
- E = 0.2V
- B = 0.025V
Q114
- B = 0.005V
Q115 is Ok with B = 4.7V
My question is if IC108 is faulty or Q117 & Q118......
Regards,
Bogdan
Top
So,recap of the mainboard finished , symptoms are the same (need push the platter , when spinning CW seems to keep steady rotation of 33 RPM , when spinning CCW reach full speed eventually).
No other function work from buttons , only the arm goes to sitting position toward the arm rest when Power On.
Here are the voltages:
IC108
- pin1 = -2.5V
- pin4 = -14.63V
- pin7 = -0.44V (!)
- pin8 = +14.64V
Q117
- B = -0.12V
- C = +32V
- E = 0V (!!)
Q118
- B = -0.18V
- C = -31V
- E = 0V (!!)
Q119
- B = -2.4V
- C = +32V
- E = -1.9V
Q120
- B = -2.4V
- C = -31V
- E = -1.9V
I see wrong voltages on the emitters of Q117 and Q118 which seems to be related with voltages of pin 7 of IC108.
Also wrong voltages on Q112 - Q114 which are different from voltages specified in Service manual :
Q112
- B = 0.2V
- C = 0.5V
Q113
- E = 0.2V
- B = 0.025V
Q114
- B = 0.005V
Q115 is Ok with B = 4.7V
My question is if IC108 is faulty or Q117 & Q118......
Regards,
Bogdan
Top
Update: IC 108(uC4557C) exchanged with a new one --> symptoms changed also , now platter spins backwards (after a little push) and keep a steady rotation (slower than 33RPM in my opinion).
Some voltages are changed also :
IC108
- pin7 = +0.6V (all other are the same)
Q117
- B = +0.6V
- E = +0.067V
Q118
- B = +0.6V
- E = +0.06V
All other voltages from Q112-Q115 are the same as before.
Regards,
Bogdan
Some voltages are changed also :
IC108
- pin7 = +0.6V (all other are the same)
Q117
- B = +0.6V
- E = +0.067V
Q118
- B = +0.6V
- E = +0.06V
All other voltages from Q112-Q115 are the same as before.
Regards,
Bogdan