Hello again Simon,
This might be a silly question, but I assume you have checked that you do in fact have +5V at one end and –5V at the other end of the 22K track on the trimpot?
Joe
Hello Joe,
Thanks for your suggestions. It struck me last night that I needed to check this. Well spotted. I made a note at midnight to check this morning, in case I forgot 🙂
I'm glad the laser was ok, that saves me money. The Alpha laser is playing merrily right now in a lightly tweaked CD52. Nice enough but there's no weight or treble quality at all by comparison!
edit: I did wonder about adjustments. I may have to do an interesting mounting!
Thanks for your suggestions. It struck me last night that I needed to check this. Well spotted. I made a note at midnight to check this morning, in case I forgot 🙂
I'm glad the laser was ok, that saves me money. The Alpha laser is playing merrily right now in a lightly tweaked CD52. Nice enough but there's no weight or treble quality at all by comparison!
edit: I did wonder about adjustments. I may have to do an interesting mounting!
I checked the +-5V and they are ok. The pot is also 100% fine when tested out of circuit.
Today I've re-soldered the focus and radial driver op-amp pins and the TDA8808 and TDA8809 servo chips. I've spent a while cleaning with IPA and cotton buds to get it all tip-top neat under there. I've also re-done some PSU wires that were only 90%.
I think all I can do now is to put it back together and see if it works any better.
Today I've re-soldered the focus and radial driver op-amp pins and the TDA8808 and TDA8809 servo chips. I've spent a while cleaning with IPA and cotton buds to get it all tip-top neat under there. I've also re-done some PSU wires that were only 90%.
I think all I can do now is to put it back together and see if it works any better.
Good luck with that.
I am now out of my depth and can't offer any suggestions, except perhaps checking the connector for the laser unit.
Joe
I am now out of my depth and can't offer any suggestions, except perhaps checking the connector for the laser unit.
Joe
Woohoo, it's working again! 😀
The cleaning up of joints and wiring has worked. I had a slight scare when I knocked my decoder regulator input wire off (it's a stumpy pin) and saw sparks... and the disc first span at light speed due to no clock power - oops....
After all that commotion the disc read and every time. I checked the focus and laser voltages and they were very close to spot-on this time. I just adjusted them a little and have put it back together - with the 250pF mica cap on COsc finally lol
Just having a little listen now.
Simon
The cleaning up of joints and wiring has worked. I had a slight scare when I knocked my decoder regulator input wire off (it's a stumpy pin) and saw sparks... and the disc first span at light speed due to no clock power - oops....
After all that commotion the disc read and every time. I checked the focus and laser voltages and they were very close to spot-on this time. I just adjusted them a little and have put it back together - with the 250pF mica cap on COsc finally lol
Just having a little listen now.
Simon
Congratulations. But isn'y it a frustration when you fix something and don't know exactly what it was that did it?
Anyway, happy listening.
I am still waiting for Farnell to deliver a 4.0000mHz XO to replace the resonator on the microprocessor. I have given up on RS. At times like this it is drummed home just how isolated Perth in Western Australia is. Farnell (Element 14 in Australia) is bringing the XO from Singapore and it should be delivered on Tuesday next week. I hope to be able to report on it's effectiveness next week.
Joe
Anyway, happy listening.
I am still waiting for Farnell to deliver a 4.0000mHz XO to replace the resonator on the microprocessor. I have given up on RS. At times like this it is drummed home just how isolated Perth in Western Australia is. Farnell (Element 14 in Australia) is bringing the XO from Singapore and it should be delivered on Tuesday next week. I hope to be able to report on it's effectiveness next week.
Joe
It is indeed frustrating but I'll happily settle for it working at this stage! It sounds great but it's been too long to report on the 250pF COsc cap in isolation, impossible to say what it did for me. The sound is so much huger and weightier than the CD52 I briefly listened to, I have been missing this. It is quite dark though, I always notice that. The bass depth and definition is surprising after time-off.
I'd love to know how you get on with the 4.00Mhz crystal upgrade. I have a Fidelity Audio C1 clock with attached Super Regulator that is spare ready for this job. I have to admit that taking the whole thing apart wasn't quite as traumatic as expected. I could do that again to make it a little better. I also noticed the TDA8808/8809 look rather important and might benefit from +-5V super regs. Furthermore, if one was to go all-out then perhaps the two caps in-line with the HF signal could be swapped for silvered mica, though they appear to be decent caps already. Likewise, there are some servo resistors that could be changed for tight tolerance / low noise types, though I suspect we're talking the last tiny, tiny degrees of improvement... and of course there are the signals that travel from digital filter to DAC via long unshielded wires. Perhaps mini coax would be a better fit, if very fiddly.
I'd love to know how you get on with the 4.00Mhz crystal upgrade. I have a Fidelity Audio C1 clock with attached Super Regulator that is spare ready for this job. I have to admit that taking the whole thing apart wasn't quite as traumatic as expected. I could do that again to make it a little better. I also noticed the TDA8808/8809 look rather important and might benefit from +-5V super regs. Furthermore, if one was to go all-out then perhaps the two caps in-line with the HF signal could be swapped for silvered mica, though they appear to be decent caps already. Likewise, there are some servo resistors that could be changed for tight tolerance / low noise types, though I suspect we're talking the last tiny, tiny degrees of improvement... and of course there are the signals that travel from digital filter to DAC via long unshielded wires. Perhaps mini coax would be a better fit, if very fiddly.
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Glad to see it's working simon, congrats on getting it going again.
Adding low-noise regs to those ic's will improve things a bit more I'm sure.
Lee.
Adding low-noise regs to those ic's will improve things a bit more I'm sure.
Lee.
Well done Simon - I was about to offer you a spare main board too.
You don't need it now - bravo.
You don't need it now - bravo.
After I put the + and – 9V regs on the servo chips and listened for a while, I then put some + and – 9V 7805/7905 regs on the TDA8808/8809 chips. But I could discern any improvement at all, let alone a difference. My wife, who is quite sensitive to the effects of different mods didn't hear any difference either. Perhaps some lower noise regs might bring an improvement, but I am not inclined to persevere with these chips.
Andrew - you're a kind soul. Thanks again for that mica, I'm happy to say it's in use now and sounding superb. Sadly I'm away from home for a week so not enjoying the player. I'll have to have a good old listen when I return.
Joe, perhaps the regs you added were not enough of an improvement on the existing supplies to draw out any improvements, whether they're available or not. Those rails are already running off regulators which, after much modding, are probably almost dedicated to those chips. Still, I would have expected some gains on individual 7805/7905s if any were ever to be seen.
Simon
Joe, perhaps the regs you added were not enough of an improvement on the existing supplies to draw out any improvements, whether they're available or not. Those rails are already running off regulators which, after much modding, are probably almost dedicated to those chips. Still, I would have expected some gains on individual 7805/7905s if any were ever to be seen.
Simon
I am glad you will get to hear the Mica on the DEM. Given the state of art of your machine it will be interesting to hear your impressions once you get a good listening.
Simon,
I have just installed the new XO clock on the uprocessor. It is functional at least but I can't say I hear any improvement. Perhaps it's too late. I will listen again tomorrow.
I have attached a URl for a discrete i/v stage being produced by Greg Ball here in Australia which may be of interest to those with the Arcam CDP. I don't need an i/v stage because the Rotel DAC is voltage out.
SKA sponsored Audio Forum - Discrete Stereo I-V with Onboard Discrete Regs
The thread is not too long and there are several reports from people who have used it on TDA1541 DACs with impressive results. On the website there is also a thread on very low noise and low impedance discrete regulators - the Minireg. Noise less than 1uV, which is very impressive when the best 780X regs are about 40uV. I am using these on my DAC chip and the analog out. However. max current is 50mA or 100mA depending on the transistor used.
Minireg: SKA sponsored Audio Forum - MiniReg discrete low noise Regulator
Joe
I have just installed the new XO clock on the uprocessor. It is functional at least but I can't say I hear any improvement. Perhaps it's too late. I will listen again tomorrow.
I have attached a URl for a discrete i/v stage being produced by Greg Ball here in Australia which may be of interest to those with the Arcam CDP. I don't need an i/v stage because the Rotel DAC is voltage out.
SKA sponsored Audio Forum - Discrete Stereo I-V with Onboard Discrete Regs
The thread is not too long and there are several reports from people who have used it on TDA1541 DACs with impressive results. On the website there is also a thread on very low noise and low impedance discrete regulators - the Minireg. Noise less than 1uV, which is very impressive when the best 780X regs are about 40uV. I am using these on my DAC chip and the analog out. However. max current is 50mA or 100mA depending on the transistor used.
Minireg: SKA sponsored Audio Forum - MiniReg discrete low noise Regulator
Joe
Last night I thought I had wasted my time with replacing the 4mHz clock on the microprocessor. Today I am not so sure. I think what I am hearing is slightly more definition. Nothing jumps out at me an improvement in any specific area, just an overall sense that the musicians and singers are slightly more present in the room than before. It is very subtle, as most of the mods are when you get to this stage, and I am prepared to accept that it is just my wishful thinking rather a real improvement, and yet....
Perhaps your superclock will bring a greater improvement than the 3.3V driven XO that I used.
Perhaps your superclock will bring a greater improvement than the 3.3V driven XO that I used.
Here's my "Practice" machine, a CD-65 II. Usual Philips PCB and A/B/C chips. I've just finished it, not had a chance to listen to it for extended periods.
Mods are:
- Cut out plastic base and replace with 18mm MDF
- Blu-tack on the underside of the disc clamp
- Removed the voltage selector
- Polypropelene output caps
- Polystyrene filter caps (waiting on the last ones to arrive)
- 2 additional transformers (30VA 6-0-6 toroid and 30VA 15-0-15 sealed)
- Os-con/Silmic/Cerafine coupling caps on the board
- LME49720 op-amps
- "Q-mini" 15V/-15V regs fo analogue state
- "Q-mini" 5V reg for SAA7220
- "Q-mini" 5V reg for SAA7210
- "Q-mini" 5V reg for TDA5708 and clock circuit
- "Q-mini" 5V/-5V/-15V regs for TDA1451
- Full DEM reclock using 0.3ppm TCXO
- 220nF decoupling caps on the divider
In the Arcam I plan to use a discrete output stage, but there isn't much room left in this Marantz case for a different I/V stage.
I plan to perform very similar mods to the Arcam but plan on using Salas shunt regs. Are there any other mods people would recommend?
Today I will be replacing the phono sockets.
Mods are:
- Cut out plastic base and replace with 18mm MDF
- Blu-tack on the underside of the disc clamp
- Removed the voltage selector
- Polypropelene output caps
- Polystyrene filter caps (waiting on the last ones to arrive)
- 2 additional transformers (30VA 6-0-6 toroid and 30VA 15-0-15 sealed)
- Os-con/Silmic/Cerafine coupling caps on the board
- LME49720 op-amps
- "Q-mini" 15V/-15V regs fo analogue state
- "Q-mini" 5V reg for SAA7220
- "Q-mini" 5V reg for SAA7210
- "Q-mini" 5V reg for TDA5708 and clock circuit
- "Q-mini" 5V/-5V/-15V regs for TDA1451
- Full DEM reclock using 0.3ppm TCXO
- 220nF decoupling caps on the divider
In the Arcam I plan to use a discrete output stage, but there isn't much room left in this Marantz case for a different I/V stage.
I plan to perform very similar mods to the Arcam but plan on using Salas shunt regs. Are there any other mods people would recommend?
Today I will be replacing the phono sockets.
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I have no experience of the "Q-mini" regulators. What is their current capacity? I ask because the SAA7220 is a current hog and sucks about 200mA, which means that all three leg chip regulators need a very hefty heatsink. How is the temperature of the Q-mini feeding the 7220?
For completeness, you could separate the digital and analog rails and give them their own PSU's (and a separate regulator for each power pin of each chip).
For the CD65II, the LME49720 dual op-amp is a very nice but I have found that the LME49720HA, in a metal can, has better focus and bass slam and clarity. Subtle but discernible.
The transport in the photo looks like the CDM4/19, the same as the Arcam transport, so it will probably have two TCA0732 servo chips. These are fed by and unregulated nominal + and – 10V, but closer to 12V when measured. A useful mod is to add –ve and +ve regulators to each chip. I have used 7906/7805 fed from the raw supply and it makes a discernible improvement in base clarity and in focus.
Joe
Thanks Joe, all of the regs are capable of around 800mA apparently. In this player I installed a metal bracket/heatsink and the output transistors on each reg are attached to that. The heatsink gets only warm to the touch. The regs supplying +/-5V have their own 30VA 6-0-6 toroid and the +/-15V regs have their own 30VA 15-0-15 potted transformer. The toroid and another dual reg board are hidden on the right hand side. The SAA7220 and SAA710 have dedicated regs on their 5V rails, the TDA1541A has three dedicated for 5/-5/-15V. Another is for the clock circuit and the TDA5708, and the last dual reg is for the op-amps, so 8 regs in total.
I'll have a look at the servo chip, thanks. I'm just starting to bed the player in, with so many new parts it will probably take a while...!
The DEM clock made a massive difference, this was one of the first mods I did (I wanted to get this working before I added all the regs)
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