Sony PS-X60 turntable auto return voltages low

[Stevescivic]

Hello everyone,

After being repeatedly disappointed by the moron technicians at my local vintage store that I opted to take turntable repairs into my own hands.

My Sony PX-X60 turntable's auto return function doesn't work properly. The lamp that illuminates the photocell in the turntable is nice and bright but when I do a measurement on the 2 test points as specified by the service manual that I cannot get more than 0.08 volts where the spec calls for 1.1 volts DC even when the neon lamp's variable resistor pot is cranked to the max.

The unit has not been previously been recapped although the stereo shop that did the supposed repair claims they replaced some electrolytics but which ones it is unclear.

That being said, does anyone know how to properly read a circuit diagram and tell me (or teach me) where to look to figure out why the photocell's test point shows the incorrect voltages?

Thanks,

 

[Oilmaster]

Can you please describe exactly what means "auto return function doesn't work properly" ?

Does it not initiate arm lift and return at all (keeps spinning forever with the stylus on the record)
or
Starts lifting and moving but not fully to the end.
or
Does not respond to buttons
etc.

There are dozens of mechanical possibilities, besides the electronic ones

 

[Stevescivic]

Auto return gets to the end of the record and keeps spinning and the tonearm doesn't know to "end playing" and lift the tonearm and return to the home position. If you stop the record player it lifts the tonearm and returns it home and stops the platter. Definitely positive it is not mechanical as the auto return is based on a light based shutter system that exposes a constant on neon lamp into a photocell when it approaches the end of the record that it trips the return function and then the tonearm will return back to the resting position.

I cracked open the service manual and did some measurements at the photocell’s test point on the main board and measured that the voltage was quite low. SM states that to get the voltage up at the test point is to turn up the power supply trim pot for the neon lamp until the photocell test point shows 1.1 volts. I cranked the trim pot for the lamp to maximum and could not get the voltage past 0.08 volts at the test point. Oddly auto return has worked consistently since I cranked the voltage for the lamp to as high as I can get it. There obvioauly has to be an issue still and I want to fix the lower than expected voltage for the photocell.

Now a bit of background:
1. We are the original owners of the TT
2. Auto return issue was brought into a shop to fix and they replaced a burnt out neon lamp and a few caps on the main board. They never said which ones nor could I see any indications of any cap replacement. The shop here is shady at best.
3. Voltages at the test points of the main power supply say that TT should be -13.5 volts and +13.5 volts between ground and two separate supply test points. I was able to adjust power supply trim pot to -13.5 and +13.55 volts respectively. If I dial the trim pot one way or the other then it affects both readings. In other words the trim pot is like the centering point for voltages and changing it will simply shift the amount of voltage in either the - ve or + ve voltage test points.
4. Turntable only ever suffered from auto return issues. The drive motor has always been consistent. Buttons, tonearm movement, drive motor never had problems.

The key issue here is why I cannot get a 1.1 voltage reading on the photocell test point. Based on a low voltage reading that it believe the main board where the photocell connects to is suffering from low voltage. I suspect the caps are going bad because their ESR goes up with age which can impact circuit voltages.

Hopefully I have explained myself good enough.

Thanks

 

[Oilmaster]

You are right about verifying (and possibly fixing) the power supply section before anything else.

To start out with your observation regarding the seemingly linked +/-13.5 volt rails: that is correct. Sony went a little cheap here by defining only one reference voltage for both rails (most often each rail has it's own reference voltage), by means of D106 and RV101, which define the negative rail voltage through setting the base voltage of Q103.

The same principle applies to Q101, but.... no reference zener and tuning trimmer....
Instead, an 'output sensing circuit' is made via R102 and R103. Since Q102 must be turned on (thus Vbe to be above 0.55V) the base voltage of Q103 must be a bit higher than the common ground (0V) rail, and thus R102 is a little smaller (10kOhm) than R103 (11 kOhm).

Due to the R102-R103, "floating" between the positive and negative rail, the reference voltage driving the base of Q101 (and thus the output voltage of Q101) depends on the voltage in the middle of R102-R103, which is referenced to the negative rail.

Long story short: the positive rail voltage is directly depending on the negative rail voltage, with the latter set by RV101.
If you ever run out of "enough" voltage (i.e. less than +/- 13.5V) then the typical issue is a fading zener diode, D106 in this case, a 15V 500mW.



Regarding the low brightness / voltage of the rejection lamp, first do a couple of checks.
Beforehand, zener diode D107 is the weakest part here, together with power resistor R108.
Secondly Q104 could be tired, but the following may tell that.

Hence, can you measure:
- the voltage across D107 (should be around 6.0~6.5 V)
- the voltage at the kathode of D107 (should be around -17.5V as indicated)
- the voltage at the emittor of Q104 (should be around -11.2V as indicated)
- desolder one leg of R108, lift it a little and measure the resistance of it

 

[Stevescivic]

whoa, MY GOODNESS! You sir are smart! I will do some measurements once I get the house tidied up and the kids are in bed. Can't do anything without breaking things when they're running and screaming.
Will report back soon

Thanks!

 

[Stevescivic]

You are right about verifying (and possibly fixing) the power supply section before anything else.

To start out with your observation regarding the seemingly linked +/-13.5 volt rails: that is correct. Sony went a little cheap here by defining only one reference voltage for both rails (most often each rail has it's own reference voltage), by means of D106 and RV101, which define the negative rail voltage through setting the base voltage of Q103.

The same principle applies to Q101, but.... no reference zener and tuning trimmer....
Instead, an 'output sensing circuit' is made via R102 and R103. Since Q102 must be turned on (thus Vbe to be above 0.55V) the base voltage of Q103 must be a bit higher than the common ground (0V) rail, and thus R102 is a little smaller (10kOhm) than R103 (11 kOhm).

Due to the R102-R103, "floating" between the positive and negative rail, the reference voltage driving the base of Q101 (and thus the output voltage of Q101) depends on the voltage in the middle of R102-R103, which is referenced to the negative rail.

Long story short: the positive rail voltage is directly depending on the negative rail voltage, with the latter set by RV101.
If you ever run out of "enough" voltage (i.e. less than +/- 13.5V) then the typical issue is a fading zener diode, D106 in this case, a 15V 500mW.

View attachment 1419946

Regarding the low brightness / voltage of the rejection lamp, first do a couple of checks.
Beforehand, zener diode D107 is the weakest part here, together with power resistor R108.
Secondly Q104 could be tired, but the following may tell that.

Hence, can you measure:
- the voltage across D107 (should be around 6.0~6.5 V)
- the voltage at the kathode of D107 (should be around -17.5V as indicated)
- the voltage at the emittor of Q104 (should be around -11.2V as indicated)
- desolder one leg of R108, lift it a little and measure the resistance of it

Just so I get this correctly...I would attach my black probe to ground (black wire on the power supply) and then use my positive probe to touch the above mentioned test points?

 

[lissenup]

I have the same table which exhibited exactly the same issues. I made it simple by just going ahead and replacing all electrolytic caps. Solved my problem 100% without too much thinking. Great table by the way. If you have not done so yet, try a Denon 103 on it. Magic in my opinion.

 

[Oilmaster]

Just so I get this correctly...I would attach my black probe to ground (black wire on the power supply) and then use my positive probe to touch the above mentioned test points?

yes

 

[Stevescivic]

I have the same table which exhibited exactly the same issues. I made it simple by just going ahead and replacing all electrolytic caps. Solved my problem 100% without too much thinking. Great table by the way. If you have not done so yet, try a Denon 103 on it. Magic in my opinion.

Isn’t a DL-103 a MC cartridge? My receiver I don’t think is set up to handle MC carts only mm carts no?

I am very new to the realm of TT so apologies for the noob questions.

 

[Oilmaster]

Your STR-7800SD is MM only

 

[Stevescivic]

Yeah that is what I thought. I do actually have one integrated amp (Technics SU-8080) that I believe I can switch between different phono impedences which I believe is what distinguishes the difference between MC and MM carts.

 

[Stevescivic]

You are right about verifying (and possibly fixing) the power supply section before anything else.

To start out with your observation regarding the seemingly linked +/-13.5 volt rails: that is correct. Sony went a little cheap here by defining only one reference voltage for both rails (most often each rail has it's own reference voltage), by means of D106 and RV101, which define the negative rail voltage through setting the base voltage of Q103.

The same principle applies to Q101, but.... no reference zener and tuning trimmer....
Instead, an 'output sensing circuit' is made via R102 and R103. Since Q102 must be turned on (thus Vbe to be above 0.55V) the base voltage of Q103 must be a bit higher than the common ground (0V) rail, and thus R102 is a little smaller (10kOhm) than R103 (11 kOhm).

Due to the R102-R103, "floating" between the positive and negative rail, the reference voltage driving the base of Q101 (and thus the output voltage of Q101) depends on the voltage in the middle of R102-R103, which is referenced to the negative rail.

Long story short: the positive rail voltage is directly depending on the negative rail voltage, with the latter set by RV101.
If you ever run out of "enough" voltage (i.e. less than +/- 13.5V) then the typical issue is a fading zener diode, D106 in this case, a 15V 500mW.

View attachment 1419946

Regarding the low brightness / voltage of the rejection lamp, first do a couple of checks.
Beforehand, zener diode D107 is the weakest part here, together with power resistor R108.
Secondly Q104 could be tired, but the following may tell that.

Hence, can you measure:
- the voltage across D107 (should be around 6.0~6.5 V).
- the voltage at the kathode of D107 (should be around -17.5V as indicated)
- the voltage at the emittor of Q104 (should be around -11.2V as indicated)
- desolder one leg of R108, lift it a little and measure the resistance of it.

Hence, can you measure:

- the voltage across D107 (should be around 6.0~6.5 V).
- the voltage at the kathode of D107 (should be around -17.5V as indicated)
Anode side: - 22.7 volts DC
Cathode side: - 16.67 volts DC
Delta across diode: ~ 6.03 volts

- desolder one leg of R108, lift it a little and measure the resistance of it.
Desoldered one leg and measured 120 ohms.


So it appears that the Q104 transistor is bad? If yes, what is a good solid replacement from Mouser?

Thanks!

 

[w1jim]

Hello everyone,
After being repeatedly disappointed by the moron technicians...

All audio, no attitude...
Sorry you were having trouble with your PS-X60 (I love mine) but finding people to fix this old stuff is a challenge and is just going to get worse.

 

[Stevescivic]

All audio, no attitude...
Sorry you were having trouble with your PS-X60 (I love mine) but finding people to fix this old stuff is a challenge and is just going to get worse.

Yeah, it is ridiculous how BAD these techs in my town are. Honestly, I'm no hot shot by ANY stretch of the imagination but at least I have some competencies that were good enough to FULLY rebuild 2 SX-1050's without a hitch. When I sold one of them the buyer was blown away at how nice my work was and how good it sounded compared to the old vintage stuff that hasn't been restored.

At the end of the day these so called "vintage" or "retro" stores are nothing more than a cash grab for them as they likely pick up all this gear at rock bottom prices at estate and garage sales. Nothing wrong with making a buck but do so honestly and with some integrity. Thank goodness for AK folks....

 

[Oilmaster]

Good for the measurements, but you forgot one.
With the resistor soldered back in place: the voltage at the emitter of Q104 (and when you are on it: with RV102 in either extreme position)

The voltage on the anode side of the diode is the main -24V rail.
The fact that it is a little lower indicates that your mains voltage is either low, or that the main filter/buffer caps C102/103 are tired. Now there is no need to be dead straight on having 24V; the whole circuit/unit will work at even +/-22V power rails.

 

[Stevescivic]

Good for the measurements, but you forgot one.
With the resistor soldered back in place: the voltage at the emitter of Q104 (and when you are on it: with RV102 in either extreme position)

The voltage on the anode side of the diode is the main -24V rail.
The fact that it is a little lower indicates that your mains voltage is either low, or that the main filter/buffer caps C102/103 are tired. Now there is no need to be dead straight on having 24V; the whole circuit/unit will work at even +/-22V power rails.

Weird... I posted it but edited the post because of formatting and it must’ve been deleted the line

Q104’s emitter voltage is - 5.36 volts DC with RV102 cranked to the maximum.

 

[Stevescivic]

I am prepared to order all new electrolytic caps for my turntable but I wanted to ask the following:
1. Do I need to use any low leakage caps anywhere based on the circuit diagram? Judging by what I sort of know about circuits that it doesn't appear that I need to use Nichicon KL caps and can make do with PW caps.
2. For the cap values less than 4.7 uF I opted to use WIMA stacked film caps. I'm assuming that is actually a better choice than going with electrolytics?
3. For the 2SC1419 transistor... that has a lower than expected emitter voltage. What is a suitable Mouser.com replacement?

Thanks!

 

[Oilmaster]

Q104 might be the problem, but I equally suspect Q106 and would order a new one by default when making up an order anyway.
Since Q105 is the same, order two and replace both.

An available adequate sub for that is KSC945C rank G
Actualy, that sub can handle a little more base and collector current, making the circuit a bit more robust.
Double check to order the C version wich means center collector (Mouser KSC945CGTA)

A good sub for Q104 (2SC1419) is KSD526 (Mouser 512-KSD526Y).

Nichicon PW or Panasonic FC will be very good capacitors for this unit.
There is no audio signal at stake, and no special low-ESR or low-leakage is required.
Absolutely no reason to go for Wima film caps.
This is just a control circuit.

 

[Stevescivic]

Thanks for that information.

Regarding the film caps... I was thinking of using them just to eliminate as many as I could out of the unit for the sake of long term reliability. That being said, there is a probably a good change that in 30 more years when the tt needs yet another set of new caps that chances are the TT or myself would be dead anyways and it won't matter at that point

 

[mcdmgb]

I am reopening this thread hoping to get some help. Like the OP, my Sony PS-X60 has an arm return problem. In my case, the return is intermittent. I have recapped the table in an attempt to address this problem and a speed stability problem. The speed stability of problem seems to have been fixed, but the arm return problem remains. One problem that I am having is that I can't get the B+ Voltage adjustment to work. There always seems to be a 0.15-0.2 volt gap between the two voltages. I quit trying to get it to the +/- 13.5 volts when I got it to -13.53v and +13.73v. Measuring D107, the anode measured -20.95v and cathode -14.95v. The emitter on Q104 measured -9.05v.

Since I'm having problems with the B+ voltage adjustment, are the readings for D107 and Q105 suspect until I resolve the B+ adjustment issue? Any help on this is appreciated.

Also, as another piece of information which may have no bearing on the B+ voltage issue, during the recap, I found that C106 (2.2uf, 250v) had vented. Its been replaced with a 2.2 uf, 350v cap. Possible cause/effect with what I'm seeing now when the original cap vented?

Thanks