Could someone explaine the working of the circuit that is connected to pins 21 en 20 of the SAA7010 on the decoder board.
I believe it 's a adjustable oscillator. Are there any modern products on the market to achieve the same thing?
I believe it 's a adjustable oscillator. Are there any modern products on the market to achieve the same thing?
It is a part of a PLL (phase locked loop) free running oscillator of approx 4.35Mhz and is part of the spindle motor servo.
The frequency is 'pulled' to the correct value for the actual disc playing (all discs vary a little) by means of the two varicap diodes. In other words it is a voltage controlled oscillator. The oscillator locks to the clock signal that is recovered from the data on the disc by comparison to the internal quartz controlled oscillator. The spindle servo then locks and runs at the correct speed which is not a constant but varies as the pickup tracks from inner to outer edge. The data rate is therefore fixed (CLV or constant linear velocity) unlike a vinyl disc (which is CAL or constant angular velocity).
The adjustment (if the coil is adjustable) is simply to get the free run frequency to approximately the correct value so that it is within range of the PLL to lock it exactly.
The frequency is 'pulled' to the correct value for the actual disc playing (all discs vary a little) by means of the two varicap diodes. In other words it is a voltage controlled oscillator. The oscillator locks to the clock signal that is recovered from the data on the disc by comparison to the internal quartz controlled oscillator. The spindle servo then locks and runs at the correct speed which is not a constant but varies as the pickup tracks from inner to outer edge. The data rate is therefore fixed (CLV or constant linear velocity) unlike a vinyl disc (which is CAL or constant angular velocity).
The adjustment (if the coil is adjustable) is simply to get the free run frequency to approximately the correct value so that it is within range of the PLL to lock it exactly.
Has anyone ever made a new decoder PCB? In order to have more place to place new caps, clocks, changing out a deteriorating board.
I made the schematic in KiCAD of the decoder (could use another check). No PCB layout because I don't know exactly what mods to implement. If anyone is interested we could work on it here.
I made the schematic in KiCAD of the decoder (could use another check). No PCB layout because I don't know exactly what mods to implement. If anyone is interested we could work on it here.
I would love to install a new decoder and audio section in my Nak OMS-7 that uses a Philips chip set. I don't have time to design one. Not liking the TDA1540 DAC chips. It needs Burr Brown inside and a SPDIF output.
PCM1702 or 1704. Others may work well. The PCM58 is another great chip. These are collinear DACs.
DF1700 Digital filter.
DF1700 Digital filter.
Why not? I've used it before (may have the exact part number wrong, working from memory here).
But it is a bit vanilla. I have it driving a pair of PCM63s. Not the most exciting thing I have which is why it is gathering dust in a corner somewhere.
YSF210B are plentiful available. If not from China, then from one of the many Yamaha expansion cards for the 01V mixers.
The digital filter doesn't affect sound quality that much between the better ones. The magic happens in the DAC and analogue stages following. The quality of the rest of your audio system swamps differences in the digital filter. I would not get overly picky between good digital filters.
Seems I also have one of the early CD-104 with the quasi CDM-0 transport.
On the CDM-1 there is a bearing with a screw that can be turned ever so slightly to adjust the turntable height.
I don't see this feature in the CDM-0 transport.
Is there such an adjustement?
I'm only asking because mine isn't reading the TOC.
Under warranty for those, we simply replaced the entire transport. I can't remember that far back. We had way more involvement with the CDM-1.
Maybe a simple noob question, but how do you make measurements on the Decoder PCB and Laser PCB. Can you lay the player upside down or do you have to put it upright and does the player work in that position.
Yes, I could have thought of that...😳
One more question. What is the fast way to see if the laser is working on a player that doesn't read the TOC?
If I put a cd in and it spins, does that mean the laser is working?
I read that you could measure it with a photodiode or a light dependent resistor, but that would mean you can insert a CD and then you can't get into service mode A.....
One more question. What is the fast way to see if the laser is working on a player that doesn't read the TOC?
If I put a cd in and it spins, does that mean the laser is working?
I read that you could measure it with a photodiode or a light dependent resistor, but that would mean you can insert a CD and then you can't get into service mode A.....
Players usually only spin when focus is found on the reflective disc and so if it spins with a disc present and doesn't with no disc present then at a basic level it suggests the laser is working. It doesn't tell you any more though such as quality of signal etc.
You can see the laser light during those few seconds when the lens performs the focus search routine. Look from above, look from at least 18 inches distant and look slightly off centre to the lens for safety. It is a dull red spot (sometimes very dull and hard to see) as all the energy is in the infra red which your eyes can not see. Do not stare into it at close range.
He had to buy and use a laser power meter. So this is what I use, also to check remotes. A jig was also made to check IR tape motion sensors and remote codes could be seen using it. You could check to see if a laser was working with it.
To set the laser power on Philips machine (earlier ones before garbage VAM types), you used a laser power meter to set power, or you must use Philips test CD 5 to set the RF level (meaning you have an accurate, calibrated oscilloscope - probe combination).
Some folks tell you to look down vertically into the laser. NO! It is a laser. Apparently you're "safe" a couple feet up. I only mention this as it is bad advice.
First check, a scope on the RFO pin from the head amp.
To set the laser power on Philips machine (earlier ones before garbage VAM types), you used a laser power meter to set power, or you must use Philips test CD 5 to set the RF level (meaning you have an accurate, calibrated oscilloscope - probe combination).
Some folks tell you to look down vertically into the laser. NO! It is a laser. Apparently you're "safe" a couple feet up. I only mention this as it is bad advice.
First check, a scope on the RFO pin from the head amp.