Yes, it had been fiddled with before it came into my hands.
I believe it was an upgraded Alpha 7, which was done in 1999 as far as I can tell.
When I pulled the main board from the chassis, I found an oil-like substance beneath on the base of the chassis. The whole CDP has had a hard life, with grease deposits around the buttons and numerous marks. Poor thing!
I believe it was an upgraded Alpha 7, which was done in 1999 as far as I can tell.
When I pulled the main board from the chassis, I found an oil-like substance beneath on the base of the chassis. The whole CDP has had a hard life, with grease deposits around the buttons and numerous marks. Poor thing!
Right, after a bit of measuring, I found:
On SK204 (note that the DAC board was NOT plugged in when measuring these voltages due to access problems):
P18V was 17.3V
N18V was 17.7V
P5VDAC no reading
P5V was 5.1V
P11V was 18.4V
Couldn't work out what RLYV is, and couldn't locate it on the board.
On Z206 I measured 1.2V and 11.4V between adjust and I or O. Can't remember which was I or O. SW201C is the power switch.
Measuring FOK on SK201, pin 18 and using pin 1 as ground - the reading was 4.8V from the instant power was on, regardless of whether the laser had started to try to focus or a disc was inserted.
Does this info help any conclusions, or is it all still an uncertainty?
On SK204 (note that the DAC board was NOT plugged in when measuring these voltages due to access problems):
P18V was 17.3V
N18V was 17.7V
P5VDAC no reading
P5V was 5.1V
P11V was 18.4V
Couldn't work out what RLYV is, and couldn't locate it on the board.
On Z206 I measured 1.2V and 11.4V between adjust and I or O. Can't remember which was I or O. SW201C is the power switch.
Measuring FOK on SK201, pin 18 and using pin 1 as ground - the reading was 4.8V from the instant power was on, regardless of whether the laser had started to try to focus or a disc was inserted.
Does this info help any conclusions, or is it all still an uncertainty?
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Whether or not the player should run without the DAC supply, you're gonna need it to get any audio out of the thing. Should fix that first. Is Z207 cold? Voltage on pin 1?
The FOK logic signalling could be normally inverted, going low during lock. Seems odd but may not mean much yet.
The FOK logic signalling could be normally inverted, going low during lock. Seems odd but may not mean much yet.
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P11 at 18 volts sounds OK.
So if there is no P5DAC voltage that looks like R64 or R65 might be open circuit... so measure the voltage on them ! Check on each end of each resistor and then to the input of that 5 volt reg.
A supply (P11VCLK) is taken from the midpoint of those resistors.
Also recheck the readings on Z206 regulator. The easiest way to measure safely is just go on the anode of diode D13 (non stripy end) and see what voltage is... should be 7 volts to the pickup.
So if there is no P5DAC voltage that looks like R64 or R65 might be open circuit... so measure the voltage on them ! Check on each end of each resistor and then to the input of that 5 volt reg.
A supply (P11VCLK) is taken from the midpoint of those resistors.
Also recheck the readings on Z206 regulator. The easiest way to measure safely is just go on the anode of diode D13 (non stripy end) and see what voltage is... should be 7 volts to the pickup.
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So that's OK... where next then... pickup ?
Is there anything lost in tweaking the pots on the pickup ?
Laser power is factory adjusted... do you think any of these have been twiddled. From what you say it has been "got at" a bit.
Focus and tracking could be set mid point for starters... laser power hmmm, you really need to monitor the supply to it (measure current in 5 volt line to the pickup) all trial and error if you are not used to it.
Is there anything lost in tweaking the pots on the pickup ?
Laser power is factory adjusted... do you think any of these have been twiddled. From what you say it has been "got at" a bit.
Focus and tracking could be set mid point for starters... laser power hmmm, you really need to monitor the supply to it (measure current in 5 volt line to the pickup) all trial and error if you are not used to it.
Burned PCB because of local Overheating
Such thinking errors by PCB design and heatsink management unfortunately are not the exception but rather the rule in the high price range of audio components. Even by Krell (KBL + PS) and Mark Levinson (e. g. ML23 No.23 Power Amplifier) there is to find the same situation.
This means in case of necessary service working, that a lot of additional work must be carried out.
What do have the so-called highly qualified development engineers in their heads while developing of such designs ?
Actually, the manufacturer would have to return a purchase price of such audio components, even after a use of 20 years.
But then most of these manufacturers would probably go to bankruptcy.
How to avoid such design errors and as consequence burned PCB aeras (and thus dried electrolytic caps) shows LINN by their products (except first generation devices LK1/LK2). All voltage regulators are mounted on an aluminum block, that serves as sub-heatsink, which in turn is mounted on the bottom side from the main envelope (housing, cabinet, enclosure or what ever the right english term therefore must be - check therefore the atteched jpg files). Now the metal housing is the main heatsink and local overheating isn't longer an issue.
Even after a long time of use the PCBs keeps always its new condition.
Such thinking errors by PCB design and heatsink management unfortunately are not the exception but rather the rule in the high price range of audio components. Even by Krell (KBL + PS) and Mark Levinson (e. g. ML23 No.23 Power Amplifier) there is to find the same situation.
This means in case of necessary service working, that a lot of additional work must be carried out.
What do have the so-called highly qualified development engineers in their heads while developing of such designs ?
Actually, the manufacturer would have to return a purchase price of such audio components, even after a use of 20 years.
But then most of these manufacturers would probably go to bankruptcy.
How to avoid such design errors and as consequence burned PCB aeras (and thus dried electrolytic caps) shows LINN by their products (except first generation devices LK1/LK2). All voltage regulators are mounted on an aluminum block, that serves as sub-heatsink, which in turn is mounted on the bottom side from the main envelope (housing, cabinet, enclosure or what ever the right english term therefore must be - check therefore the atteched jpg files). Now the metal housing is the main heatsink and local overheating isn't longer an issue.
Even after a long time of use the PCBs keeps always its new condition.
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