Hi APEXHIFI,
thanks for your help. Testing the tensions on the regulator (IC202) was one of the first things I did, along with the other ones beginning with number 1 (they all have to do with mechanisms control). I decided to give it a second try and tested the voltages again. When touching pin 16 with the positive lead of the multimeter (neg to the ground), the tray motor started spinning and the laser sled moved to its idle position.
Switched the unit off and on again. Miracle, the CDP brought back to life: all the functions worked as expected, tray, display, selection, not to mention the audio.
Great, isn't it? Nope. I actually had the unit back to work several times before. Everytime I had it working, it died again at the following power-up.
Including this time. I verified it's not a mechanical/electrical contact problem. After all, I didn't fix anything, I just made testing. Of course I tried to touch the pin 16 again but no luck.
You could think the IC is the culprit. Maybe, maybe not. At this time, anything is possible.
thanks for your help. Testing the tensions on the regulator (IC202) was one of the first things I did, along with the other ones beginning with number 1 (they all have to do with mechanisms control). I decided to give it a second try and tested the voltages again. When touching pin 16 with the positive lead of the multimeter (neg to the ground), the tray motor started spinning and the laser sled moved to its idle position.
Switched the unit off and on again. Miracle, the CDP brought back to life: all the functions worked as expected, tray, display, selection, not to mention the audio.
Great, isn't it? Nope. I actually had the unit back to work several times before. Everytime I had it working, it died again at the following power-up.
Including this time. I verified it's not a mechanical/electrical contact problem. After all, I didn't fix anything, I just made testing. Of course I tried to touch the pin 16 again but no luck.
You could think the IC is the culprit. Maybe, maybe not. At this time, anything is possible.
It looks like there's a RC reset circuit on IC305, it's formed by R341 (10Ω); C357 (470/10), and D341 (11EQS04), the one becoming very hot.
All these components work. I shorted the cap and tried again. No way.
At this point one or the other ICs could be the problem.
I attach the schematics. The red delimited area is supposedly the RC reset circuit.
All these components work. I shorted the cap and tried again. No way.
At this point one or the other ICs could be the problem.
I attach the schematics. The red delimited area is supposedly the RC reset circuit.
Attachments
I would expect the reset circuit to be in the main power supply. You can look at the MPU and search for the reset line, follow that back.
I didn't read everything, but first of all you have to ground the body. Then you should have immediately disconnected all the cables of the laser part from the motherboard and tested the motherboard
The components around IC305 are just power filtering, not a reset. The resistor is too low value. I would expect a 10k more than a 10R.
Id check on the other chips in the chipset (not IC305 - that's a DAC and may not need a reset) for pins labelled "reset" and trace them back to how its generated.
Ill try to take a look at the schematics when I have time,l to make some more suggestions.
Id check on the other chips in the chipset (not IC305 - that's a DAC and may not need a reset) for pins labelled "reset" and trace them back to how its generated.
Ill try to take a look at the schematics when I have time,l to make some more suggestions.
Thank you everybody.
I was able to replicate the "resurrection" of the unit by touching several pins of IC202 (M5290P) while testing tensions. When I turned the unit off and back on, well, it was dead again. But I repeated the sequence several times and I had it back to work almost every time.
Attached you’ll find my drawing of the reset line, I think is complete. Reset coming in on pin 21 of the main ribbon cable is connected to three other ICs, please refer to my drawing. Voltages on test points look ok, with minimum variations. I think one the ICs is the culprit, maybe IC202 itself, I could easily replace it.
PS Even when the unit seem to work normally, the same components get hot (the 2 resistors I put in place of ICPs, the op-amp, D341 and a couple of other transistor in the PSU.
I was able to replicate the "resurrection" of the unit by touching several pins of IC202 (M5290P) while testing tensions. When I turned the unit off and back on, well, it was dead again. But I repeated the sequence several times and I had it back to work almost every time.
Attached you’ll find my drawing of the reset line, I think is complete. Reset coming in on pin 21 of the main ribbon cable is connected to three other ICs, please refer to my drawing. Voltages on test points look ok, with minimum variations. I think one the ICs is the culprit, maybe IC202 itself, I could easily replace it.
PS Even when the unit seem to work normally, the same components get hot (the 2 resistors I put in place of ICPs, the op-amp, D341 and a couple of other transistor in the PSU.
Attachments
It looks like the M5290P has a reset output on pin 8 so that could easily be your problem. There's also a delay capacitor on pin 7 which generates a delay before the reset line goes high.
Have you checked the voltage on the pin8? It should be low at switch on then go high in a few milliseconds. If it's permanently low, that's your problem.
As a test, you could lift pin 8 (or cut the track) connect the RST test point to 0v via a 1k resistor then manually connect the test point to 5v a few seconds after you have powered it all up.
You could try replacing the capacitor on pin 7 of this chip with one of twice the value to slow down the reset a bit - that may cure it if components are getting a bit slow in their old age!
Have you checked the voltage on the pin8? It should be low at switch on then go high in a few milliseconds. If it's permanently low, that's your problem.
As a test, you could lift pin 8 (or cut the track) connect the RST test point to 0v via a 1k resistor then manually connect the test point to 5v a few seconds after you have powered it all up.
You could try replacing the capacitor on pin 7 of this chip with one of twice the value to slow down the reset a bit - that may cure it if components are getting a bit slow in their old age!
Hi m-tagg,
Excellent. I would not increase that reset capacitor timing capacitance. The timing capacitor is on pin 7 of the M5290P as mentioned, see attached.
It is possible the reset signal is not getting to the boards if a conductor in a ribbon cable is broken. That can easily happen while the unit is being worked on if you have a PCB out. Once you have a proper reset signal your current draw may return to normal levels.
Excellent. I would not increase that reset capacitor timing capacitance. The timing capacitor is on pin 7 of the M5290P as mentioned, see attached.
It is possible the reset signal is not getting to the boards if a conductor in a ribbon cable is broken. That can easily happen while the unit is being worked on if you have a PCB out. Once you have a proper reset signal your current draw may return to normal levels.
Thank you all.
Testing the ribbon cables is one of the first things I did and, knowing them are so fragile, I repeated the continuity test several times during this odyssey. They seem to be ok. I also tried to move roughly the PCB and the Laser unit, but everything seems to be ok.
As far as the tension, on pin 8 I have about zero when the unit is off, and 4.8/9 when is on. According to the schematics it should be 4.4. All the other tensions are as indicated.
Still have D341 getting hot even when the unit appears to work ok.
@anatech - I found a Kikusui 5512A, 100MHz, 2 Ch. analog Oscilloscope (working) plus a Heathkit IG-18 audio generator (sine and square) not working and with cracked meter, not the transparent window, just the black plastic lower part. The seller also adds a broken Daewoo VHS player and a Technics SL-P210 CD player with tray blocked. Total price for these four items is 90 Euros. Would it be worth?
Testing the ribbon cables is one of the first things I did and, knowing them are so fragile, I repeated the continuity test several times during this odyssey. They seem to be ok. I also tried to move roughly the PCB and the Laser unit, but everything seems to be ok.
As far as the tension, on pin 8 I have about zero when the unit is off, and 4.8/9 when is on. According to the schematics it should be 4.4. All the other tensions are as indicated.
Still have D341 getting hot even when the unit appears to work ok.
@anatech - I found a Kikusui 5512A, 100MHz, 2 Ch. analog Oscilloscope (working) plus a Heathkit IG-18 audio generator (sine and square) not working and with cracked meter, not the transparent window, just the black plastic lower part. The seller also adds a broken Daewoo VHS player and a Technics SL-P210 CD player with tray blocked. Total price for these four items is 90 Euros. Would it be worth?
Hi m-tagg,
Voltages before regulators are pretty dependent on the mains voltage. After the regulators they can still be approximate, depending on the circuit and resistors used.
D341 decouples the +5V supply on the D/A converter. The only places high current can flow would be C357 (470uF 10VDC), C345 (47uF 16VDC) and IC305. C344 should be a film type and I guess it could go leaky. My first suspects are the 470uF, then the 47uF. I really do not trust any cap lower than 16 VDC ratings. Something should be getting warm, and the 10R resistor should be okay. What is the voltage drop across D341? Here looking at that +5 VDC line with an oscilloscope would be my test. Q209 should be quite warm I would think.
Kikusui is a good brand. If it's working fine it should be good for 90 Euro alone. I don't know what your local prices are like. The IG-18 is a decent generator, you may be able to glue the meter together. That is where the zero adjuster is, so it would be nice to have it working. You can adjust it without. The VHS is something you can decide on, it would be useless unless you wanted a VHS player. The Technics might be fun to fix and use. They are typically pretty reliable. If he has a scope, he probably tried to fix these things. Either that or they were pulled from the dump or e-waste. So the two test instruments are worth 90 Euro alone as long as they work.
Voltages before regulators are pretty dependent on the mains voltage. After the regulators they can still be approximate, depending on the circuit and resistors used.
D341 decouples the +5V supply on the D/A converter. The only places high current can flow would be C357 (470uF 10VDC), C345 (47uF 16VDC) and IC305. C344 should be a film type and I guess it could go leaky. My first suspects are the 470uF, then the 47uF. I really do not trust any cap lower than 16 VDC ratings. Something should be getting warm, and the 10R resistor should be okay. What is the voltage drop across D341? Here looking at that +5 VDC line with an oscilloscope would be my test. Q209 should be quite warm I would think.
Kikusui is a good brand. If it's working fine it should be good for 90 Euro alone. I don't know what your local prices are like. The IG-18 is a decent generator, you may be able to glue the meter together. That is where the zero adjuster is, so it would be nice to have it working. You can adjust it without. The VHS is something you can decide on, it would be useless unless you wanted a VHS player. The Technics might be fun to fix and use. They are typically pretty reliable. If he has a scope, he probably tried to fix these things. Either that or they were pulled from the dump or e-waste. So the two test instruments are worth 90 Euro alone as long as they work.
N.B. getting hot isn't always a problem. Is it:
a) hot to the touch but you can happily leave your finger on it
b) so hot that your finger sizzles like a cooked sausage
(a) is fine - these parts could just be supplying a load of current to the power hundred digital filters. (b) is not so good....
a) hot to the touch but you can happily leave your finger on it
b) so hot that your finger sizzles like a cooked sausage
(a) is fine - these parts could just be supplying a load of current to the power hundred digital filters. (b) is not so good....
Hi APEXHiFi,
You're absolutely correct.
I'm not sure if that resistor is there to discharge that supply on power off, or to help the diode. The data sheet would let us know what the expected current should be.
Just in general, a diode in that location running warm or hot would have my interest. Who knows? I've worked on many Sony CD players and haven't noticed a diode running warm - or the chip for that matter. The capacitors should be room temperature.
You're absolutely correct.
I'm not sure if that resistor is there to discharge that supply on power off, or to help the diode. The data sheet would let us know what the expected current should be.
Just in general, a diode in that location running warm or hot would have my interest. Who knows? I've worked on many Sony CD players and haven't noticed a diode running warm - or the chip for that matter. The capacitors should be room temperature.
Not totally sure, but I think the resistor is there as a small amount 9f impedance before the 470uF cap so that the PSU at that cap is really smooth (reference?). I suspect the diode is there to charge the cap nice and fast at power on.
If my assumption is correct, the diode should be cold, but the resistor warm.
But without analysing the whole circuit and scoping it i
I'm guessing!
But without analysing the whole circuit and scoping it i
I'm guessing!
Thinking about it though, if that 470uF cap is dead or dying, it could be pulling a lot more current than it should be and keeping the diode in play. What voltage are you seeing across the diode? I would expect that with a 20 ohm resistor in parallel with it, the voltage drop should be very low unless its pulling quite a lot of juice, which it shouldn't be!
Sorry, 10R resistor. That means that you'd need 50mA current draw there to get to a 0.5V drop across the resistor to get the diode to conduct. That's more than I would expect in that bit of the circuit, although not impossible. Perhaps worth swapping out the 470uF cap as suggested above.
Hi anatech and APEXHIFI, thank you very much for your help and guidance.
@anatech - caps C357 and C345 have been replaced with salvage (but tested) components. C344 is a capacitor in a resistor-like package, pink body and color rings. There's a lot of them on the PCB. It’s 22nF and it seems to be ok, I tested it out of circuit: both the MM and the component tester read the same value.
Voltage across the diode is about 0.13v (power on, not working state).
Q209 becomes hot, almost as hot as the diode.
@APEXHiFi - D314 gets hot, I mean you can’t touch it for more than half a second. The 10Ω resistor is hard to reach with the finger, but it seems to be at room temperature.
I keep thinking the problem is one of the ICs in the PSU, but if you think it makes sense, I can easily replace the above mentioned caps, the diode (w/ equivalent) and/or even the IC too (M5290P).
Attached are a couple of pics of the PCB, with detail of the infamous zone.
PS @anatech - huge thanks for your advice about my possible purchase, greatly appreciated. I contacted the guy, he’s on vacation now and will be back on 17. Analog scopes in Italy are variously priced, but you can take a non serviced one for 80/90 euros (40Mhz) up to 150 euros or more. 100MHz models are on the higher zone. If the scope alone worth 90 euros, I’m pondering to buy the whole lot. I can have fun repairing the CD and then sell it, the signal generator is more like a vintage gadget compared to what’s available today both in terms of performance, waveforms available, control, distortion etc. But I’d love to put my hands on it. I can use the VCR to improve my repair skills and then give it away as a gift.
@anatech - caps C357 and C345 have been replaced with salvage (but tested) components. C344 is a capacitor in a resistor-like package, pink body and color rings. There's a lot of them on the PCB. It’s 22nF and it seems to be ok, I tested it out of circuit: both the MM and the component tester read the same value.
Voltage across the diode is about 0.13v (power on, not working state).
Q209 becomes hot, almost as hot as the diode.
@APEXHiFi - D314 gets hot, I mean you can’t touch it for more than half a second. The 10Ω resistor is hard to reach with the finger, but it seems to be at room temperature.
I keep thinking the problem is one of the ICs in the PSU, but if you think it makes sense, I can easily replace the above mentioned caps, the diode (w/ equivalent) and/or even the IC too (M5290P).
Attached are a couple of pics of the PCB, with detail of the infamous zone.
PS @anatech - huge thanks for your advice about my possible purchase, greatly appreciated. I contacted the guy, he’s on vacation now and will be back on 17. Analog scopes in Italy are variously priced, but you can take a non serviced one for 80/90 euros (40Mhz) up to 150 euros or more. 100MHz models are on the higher zone. If the scope alone worth 90 euros, I’m pondering to buy the whole lot. I can have fun repairing the CD and then sell it, the signal generator is more like a vintage gadget compared to what’s available today both in terms of performance, waveforms available, control, distortion etc. But I’d love to put my hands on it. I can use the VCR to improve my repair skills and then give it away as a gift.
Attachments
Hi m-tagg,
There is only one reason for a diode to get hot that isn't a high speed rectifier in a switching supply. Excessive current. Your meter isn't reading what is really going on there. That diode is too hot. The regulator transistor will also be running too hot as a result.
You need an oscilloscope. The one you found sounds like a really good instrument, I'm glad you're going to get it. The signal generator is a pretty good one, and more convenient to use than the digital ones. Of the modern generators on my bench, I also have an old, crappy Kikusui 418A signal generator. Why? There are times you need a semi-clean signal or square wave. It needs to be adjustable more than accurate to a frequency or level. You satisfy the signal needs, and if important you can measure amplitude and / or frequency. Testing speakers for T/S parameters is a good example of that, or just finding a resonant frequency.
If you get it working, install new capacitors. Keep in mind that some equipment can test components as good when they are not. I check caps for capacitance and DA at various frequencies. Cheap cap checkers only measure time to charge, hardly a good test.
There is only one reason for a diode to get hot that isn't a high speed rectifier in a switching supply. Excessive current. Your meter isn't reading what is really going on there. That diode is too hot. The regulator transistor will also be running too hot as a result.
You need an oscilloscope. The one you found sounds like a really good instrument, I'm glad you're going to get it. The signal generator is a pretty good one, and more convenient to use than the digital ones. Of the modern generators on my bench, I also have an old, crappy Kikusui 418A signal generator. Why? There are times you need a semi-clean signal or square wave. It needs to be adjustable more than accurate to a frequency or level. You satisfy the signal needs, and if important you can measure amplitude and / or frequency. Testing speakers for T/S parameters is a good example of that, or just finding a resonant frequency.
If you get it working, install new capacitors. Keep in mind that some equipment can test components as good when they are not. I check caps for capacitance and DA at various frequencies. Cheap cap checkers only measure time to charge, hardly a good test.