Can anyone help me with circuits digrams for either of these?
I am having problems getting mine to use the Sync Lock between the DisMagic transport and the DAC. The relay in the trasnport seems to be swicthing in and out intermittently and the DAC will not lock on to the signal.
Any suggestions?
Kind regards,
Jonathan
I am having problems getting mine to use the Sync Lock between the DisMagic transport and the DAC. The relay in the trasnport seems to be swicthing in and out intermittently and the DAC will not lock on to the signal.
Any suggestions?
Kind regards,
Jonathan
The most likely problem will be with the optical RX / TX modules on the clock-lock / SPDIF lines - these are very easily damaged by physical stress to there housings (during production or servicing). When physically stressed - the internal detector or transmitter diodes are displaced, causing the problems you described
John
John
jdunham said:
I have circuits drawings for the DiscMagic and some stuff on the clock link. Email me and I'll send them to you.
Dan - Many thanks for the diagrams for the DiscMagic, that's a great help!
JohnW - having done some searches before I posted this, I realise who you are - the designer himself!!
I really appreciate you taking time to respond directly to my post. Many thanks for the suggestion, I will look into this one first, and see if I can find some new TX/RX modules.
You don't happen to have a circuit diagram for the Isomagic do you?
With kind regards,
Jonathan
JohnW - having done some searches before I posted this, I realise who you are - the designer himself!!
I really appreciate you taking time to respond directly to my post. Many thanks for the suggestion, I will look into this one first, and see if I can find some new TX/RX modules.
You don't happen to have a circuit diagram for the Isomagic do you?
With kind regards,
Jonathan
Jonathan,
Sorry over the years & the many changes in computer systems, I no longer have the circuits for the Isomagic. In fact I ask Dan to forward me the DiscMagic Circuits for my referance. If you like, once I get back to Europe (end of Oct) I can send you an old Digitial OP board from a Discmagic - could be good for spare parts - or replacement (with some work).
If you have no luck in fault-finding your unit, I will soon be launching a CD transport with Clock-Lock, which will also be compatiable with older Cambridge Audio designs.
Dan - thanks for the Circuits. As for your Drop-out problems due to external induced RF from mains and heating system, are you sure the units are correctly grounded? I understand parts of US & Canada often don't have Ground connected... You could also try optical link for SPDIF.
If you use Clock-Lock, then I recommend to use optical for both Clock (no Choice) & SPDIF - this helps Isolate RF between the units.
John
Sorry over the years & the many changes in computer systems, I no longer have the circuits for the Isomagic. In fact I ask Dan to forward me the DiscMagic Circuits for my referance. If you like, once I get back to Europe (end of Oct) I can send you an old Digitial OP board from a Discmagic - could be good for spare parts - or replacement (with some work).
If you have no luck in fault-finding your unit, I will soon be launching a CD transport with Clock-Lock, which will also be compatiable with older Cambridge Audio designs.
Dan - thanks for the Circuits. As for your Drop-out problems due to external induced RF from mains and heating system, are you sure the units are correctly grounded? I understand parts of US & Canada often don't have Ground connected... You could also try optical link for SPDIF.
If you use Clock-Lock, then I recommend to use optical for both Clock (no Choice) & SPDIF - this helps Isolate RF between the units.
John
JohnW said:
That's great news. The IsoMagic truly is magic when clock-synched. As I told you via email, I compared the DiscMagic/IsoMagic to a new Classe CDP-10 and there was really very little difference in sound.
Dan - thanks for the Circuits. As for your Drop-out problems due to external induced RF from mains and heating system, are you sure the units are correctly grounded? I understand parts of US & Canada often don't have Ground connected... You could also try optical link for SPDIF.
Thank you for the great design.
My stereo system is grounded, but I suspect my main house ground needs some cleaning up where it connects to the plumbing. I've been meaning to get an electrician in to fix that. I guess now's a good a time.
If you use Clock-Lock, then I recommend to use optical for both Clock (no Choice) & SPDIF - this helps Isolate RF between the units.
I tried that just now, and I dimmed the halogen lights. No dropouts, problem solved. Thank you! The optical connection doesn't sound exactly the same as the coax, so I'll have to see how I like it long-term.
BTW, I bought the DiscMagic before I bought the IsoMagic. I was very disappointed to find the Iso had no XLR connectors for data connection to the supposedly matching transport. What happened, did Cambridge cut your budget? And why was the DiscMagic discontinued at the same time as the IsoMagic was finally released in North America? That was very strange, considering what a fantastic value they were together. An IsoMagic without the clock link is rather ordinary sounding. With the clock-lock it's extraordinary.
I have a circuit diagram for the Isomagic - I'll just have to find it (it's on paper) 
The diagrams which I got from Cambridge were completely wrong in some places, so I had to buzz out parts of the circuit and correct the diagram.
I made some mods to the clock circuitry too, which really improved the sound.
-Mark.
The diagrams which I got from Cambridge were completely wrong in some places, so I had to buzz out parts of the circuit and correct the diagram.
I made some mods to the clock circuitry too, which really improved the sound.
-Mark.
This thread has getting better by the minute, thanks guys!
Brussell Sprout - it would be great if you could scan and email this - there are three of us here that I'm sure would bite your hand off for a copy!!
JohnW - many thanks for the offer of the Digital OP board, that would be great to have. Do you want me to email you in early November on this? Are you coming to the UK at all?
Regarding the fault on my units, a friend is actually doing the fault finding so perhaps Tom, you might post with more details on what you have found so far? And maybe you or others might be able to shed some further light on things.
With kind regards,
Jonathan
Brussell Sprout - it would be great if you could scan and email this - there are three of us here that I'm sure would bite your hand off for a copy!!
JohnW - many thanks for the offer of the Digital OP board, that would be great to have. Do you want me to email you in early November on this? Are you coming to the UK at all?
Regarding the fault on my units, a friend is actually doing the fault finding so perhaps Tom, you might post with more details on what you have found so far? And maybe you or others might be able to shed some further light on things.
With kind regards,
Jonathan
I'll do that, and I'll be sure to wear my chail mail gloves... I've moved house since I last saw the papers, but I have a pretty good idea where they are Give me a couple of days though.
The Isomagic really is rather nice once it's been tweeked a bit.
-Mark.
Give me a couple of days though.The Isomagic really is rather nice once it's been tweeked a bit.
-Mark.
Troubleshooting the Discmagic
Hi all,
I've been trying to get my Discmagic to work in clock locked mode so that Jonathan can use it with the Isomagic he recently acquired... that is due to undergo some... shall we say, substantial modifications. 🙂
John - I tried replacing the RX176 optical block, but to no avail. I've also tested the removed unit, and it appears to be in perfect working order - connecting my frequency counter to the output pin gave a stable 5.644673MHz (or thereabouts), so the Isomagic appears to be outputting a decent clock, and is also being received okay.
I tried connecting the frequency counter to R11 (which should be giving the tripled clock, AFAIK), but I was just getting rubbish, regardless of whether the clock was connected to the receiver block or not.. jumped from an average of around 300kHz to around 1MHz when the lead was plugged in, but no stability at all.
So I disconnected the coupling cap C34, so the relay/LED driver circuitry was taken out of the equation... this made R11 show a clock of around 16.3MHz when the clock from the Isomagic was fed in... not rock solid, but not terrible either.
I thought C34 might be dodgy, even though my DMM measured it as around 120nF out of circuit, so put in a nice 100nF C0G. Unfortunately, this had no effect on the intermittent relay problem.
The relay/LED circuit is something I find quite peculiar... I was wondering whether it would be feasible to replace it with a different circuit using a HC126 chip, LP cap, gain stage, and an NPN transistor to drive the relay. My best guess right now is that some of the gates of the HCU04 are damaged (U6: D in particular), but it is proving hard to make sure of this without a scope...
I have ordered a replacement HCU04 in case it is broken, but I don't understand how such a thing could occur (VCC is fine). R13 and R16 both measure around 10K in circuit. What about C46? Or am I clutching at straws?
One thing I haven't tried yet is removing D5 and seeing whether it's already messed up at pin 12, but as it already seems to be messed up at pin 13 when it is in circuit... hmm...
Beyond trying to figure out what is wrong with the unit, I saw something that struck me as odd in the power schematic... the centre tap of the transformer is shown as being connected to common ground... as is the -12V (which becomes ground for lower common mode noise after the CM choke, it seems)...
I would have thought the centre TX tap would be only connected to the pre-regulators and decoupling before L2? I'm not claiming to know, being a relative novice, but I just thought better CMRR would be obtained that way...
Audiobomber - I've also had trouble with losing S/PDIF lock over the coaxial output of the Discmagic. When I brought in a AT PC PSU and plugged it into the same power strip to demo the problem, the salesman in the Richer Sounds listening room seemed unphased... even though my JE510 was losing lock several times a second...
With clock lock, the optical should (in theory!) be fine, but there may be other factors at work. You might want to try using the positive pin and ground (pins 3 and 1) of the XLR to an unbalanced plug - I used this for a while, and never suffered a music glitch when I switched a light on or some such thing...
One major reason why the Isomagic doesn't have an AES/EBU input is probably because the connector would be physically too big to fit on the back panel! Besides which, it is not regarded as a particularly good connector from a HF impedance POV.
- Tom.
Hi all,
I've been trying to get my Discmagic to work in clock locked mode so that Jonathan can use it with the Isomagic he recently acquired... that is due to undergo some... shall we say, substantial modifications. 🙂
John - I tried replacing the RX176 optical block, but to no avail. I've also tested the removed unit, and it appears to be in perfect working order - connecting my frequency counter to the output pin gave a stable 5.644673MHz (or thereabouts), so the Isomagic appears to be outputting a decent clock, and is also being received okay.
I tried connecting the frequency counter to R11 (which should be giving the tripled clock, AFAIK), but I was just getting rubbish, regardless of whether the clock was connected to the receiver block or not.. jumped from an average of around 300kHz to around 1MHz when the lead was plugged in, but no stability at all.
So I disconnected the coupling cap C34, so the relay/LED driver circuitry was taken out of the equation... this made R11 show a clock of around 16.3MHz when the clock from the Isomagic was fed in... not rock solid, but not terrible either.
I thought C34 might be dodgy, even though my DMM measured it as around 120nF out of circuit, so put in a nice 100nF C0G. Unfortunately, this had no effect on the intermittent relay problem.
The relay/LED circuit is something I find quite peculiar... I was wondering whether it would be feasible to replace it with a different circuit using a HC126 chip, LP cap, gain stage, and an NPN transistor to drive the relay. My best guess right now is that some of the gates of the HCU04 are damaged (U6: D in particular), but it is proving hard to make sure of this without a scope...
I have ordered a replacement HCU04 in case it is broken, but I don't understand how such a thing could occur (VCC is fine). R13 and R16 both measure around 10K in circuit. What about C46? Or am I clutching at straws?
One thing I haven't tried yet is removing D5 and seeing whether it's already messed up at pin 12, but as it already seems to be messed up at pin 13 when it is in circuit... hmm...
Beyond trying to figure out what is wrong with the unit, I saw something that struck me as odd in the power schematic... the centre tap of the transformer is shown as being connected to common ground... as is the -12V (which becomes ground for lower common mode noise after the CM choke, it seems)...
I would have thought the centre TX tap would be only connected to the pre-regulators and decoupling before L2? I'm not claiming to know, being a relative novice, but I just thought better CMRR would be obtained that way...
Audiobomber - I've also had trouble with losing S/PDIF lock over the coaxial output of the Discmagic. When I brought in a AT PC PSU and plugged it into the same power strip to demo the problem, the salesman in the Richer Sounds listening room seemed unphased... even though my JE510 was losing lock several times a second...
With clock lock, the optical should (in theory!) be fine, but there may be other factors at work. You might want to try using the positive pin and ground (pins 3 and 1) of the XLR to an unbalanced plug - I used this for a while, and never suffered a music glitch when I switched a light on or some such thing...
One major reason why the Isomagic doesn't have an AES/EBU input is probably because the connector would be physically too big to fit on the back panel! Besides which, it is not regarded as a particularly good connector from a HF impedance POV.
- Tom.
Re: Troubleshooting the Discmagic
Optical definitely sounds a little different than the coax connection. I've switched to optical and I'm hearing a little more low-level detail now, but when the music gets loud and busy, it's a little splashy (loses focus, gets slightly edgy). These are very subtle differences and I'm happy with the optical connection, especially since I'm having no more trouble. At first I tried a good quality plastic toslink wire (Kimber OPT-1) for the data and a Sound Professional glass toslink for the clock. Reversing them was a definite improvement. Possibly an even better toslink would be better than coax all around.
If I did as you suggest with the XLR cable, wouldn't that result in a sub-optimum impedance?
Another idea I had was to float the ground on the DiscMagic and use the coax connector.
tbrowne said:
Optical definitely sounds a little different than the coax connection. I've switched to optical and I'm hearing a little more low-level detail now, but when the music gets loud and busy, it's a little splashy (loses focus, gets slightly edgy). These are very subtle differences and I'm happy with the optical connection, especially since I'm having no more trouble. At first I tried a good quality plastic toslink wire (Kimber OPT-1) for the data and a Sound Professional glass toslink for the clock. Reversing them was a definite improvement. Possibly an even better toslink would be better than coax all around.
If I did as you suggest with the XLR cable, wouldn't that result in a sub-optimum impedance?
Another idea I had was to float the ground on the DiscMagic and use the coax connector.
Yes, but the connector is sub-optimal anyway. Speaking of which, the BNC socket on both units looks like a 50 ohm type instead of a 75 ohm (?).
One thing might be to try making a 50 ohm high-level output on the Discmagic via. the BNC, and then use an old-style "thin ethernet" 50 ohm network cable to link the two devices.
I'd change R19 to 10 ohm (giving approx. 55 ohm series termination in combination with the HC logic output impedance), remove R20, and connect the BNC ground to PCB ground instead of inverted output.
... but I lack the scope to verify whether in reality this is an improvement or not!
- Tom.
Re: Re: Troubleshooting the Discmagic
I hate to break the news, but Kimber did a lousy job on that one...
Arne K
audiobomber said:
I hate to break the news, but Kimber did a lousy job on that one...
Arne K
Re: Re: Re: Troubleshooting the Discmagic
The OPT1 is advertised as medical grade plastic. It was judged superior to other plastic toslinks by one of the Brit hi-fi mags (I believe it was Hi-Fi Choice). I compared it as a clock link to an Ultralink cable at about half the price, and an Audioquest Optilink-1 at around the same price as the Kimber, and the Kimber came out on top.
Clearly a clock-link isn't the most demanding application. because I couldn't hear any difference between the OPT1 and the Sound Professional glass toslink. When I tried them both as data cables, the glass cable was clearly better.
That's my experience but I'm no expert on optical cables, what have you found?
Cobra2 said:
The OPT1 is advertised as medical grade plastic. It was judged superior to other plastic toslinks by one of the Brit hi-fi mags (I believe it was Hi-Fi Choice). I compared it as a clock link to an Ultralink cable at about half the price, and an Audioquest Optilink-1 at around the same price as the Kimber, and the Kimber came out on top.
Clearly a clock-link isn't the most demanding application. because I couldn't hear any difference between the OPT1 and the Sound Professional glass toslink. When I tried them both as data cables, the glass cable was clearly better.
That's my experience but I'm no expert on optical cables, what have you found?
Hi Tom,
You’re pretty much correct with all you said,
There’s and error on the Cambridge Audio power schematic, "Ground" for the DOTX board is taken AFTER the CM choke - the Ground connection shown on the transformer Centre Tap is incorrect.
From your diagnostics, the fault would appear to be around the LC clock x3 circuit. When clock-locked you should see a very steady 16.9344MHz. I would probe each LC section (there are 2 sections cascaded to reduce jitter) and confirm that each section outputs 16.9344MHz when functioning correctly. The first section should output 16.9344MHz however, with higher cycle to cycle jitter, the second stage LC should clean this up, and cycle to cycle will be about 1nS or less (this does not effect the operation of the CD transport).
I would check all the components around the LC x3 circuit, check both inductors (remove each and perform a DC resistance check if you don’t have an inductance meter - if you have a way to measure inductance, then they should both be 3.3uH). As you suspect, I would be very surprised if the HCU04 has failed...
Best of luck with finding the fault,
John
You’re pretty much correct with all you said,
There’s and error on the Cambridge Audio power schematic, "Ground" for the DOTX board is taken AFTER the CM choke - the Ground connection shown on the transformer Centre Tap is incorrect.
From your diagnostics, the fault would appear to be around the LC clock x3 circuit. When clock-locked you should see a very steady 16.9344MHz. I would probe each LC section (there are 2 sections cascaded to reduce jitter) and confirm that each section outputs 16.9344MHz when functioning correctly. The first section should output 16.9344MHz however, with higher cycle to cycle jitter, the second stage LC should clean this up, and cycle to cycle will be about 1nS or less (this does not effect the operation of the CD transport).
I would check all the components around the LC x3 circuit, check both inductors (remove each and perform a DC resistance check if you don’t have an inductance meter - if you have a way to measure inductance, then they should both be 3.3uH). As you suspect, I would be very surprised if the HCU04 has failed...
Best of luck with finding the fault,
John
Hi John,
Many thanks for your advice... much appreciated. I do recognise it's probably a while since you've looked at this stuff!
Ah... okay, good! I didn't bother to check the PCB itself.
I'm just wondering... is the Isomagic the right thing to use as a clock source for diagnostics? Because it only outputs clock when an S/PDIF signal is fed in... and with the coupling cap disconnected that usually joins to the LED/relay select circuitry (to try and eliminate one factor - just in case), the Discmagic is sending S/PDIF on its own clock rather than based on the Isomagic clock... or would this not affect the quality of what was seen at R11?
If the Isomagic is just dividing the local oscillator output by three and sending it out when the CS8412 indicates lock, then it wouldn't matter, but without seeing the schematic, I'm not sure of what it does.
If you can confirm that with the coupling cap disconnected to the relay/LED circuit, I should definitely be getting a clean 16.9344MHz after the first and second LC filters, then I'll certainly test the DCR of the inductors and replace the caps if possible.
Unfortunately as I am quite recent to electronics, I'm missing the tools to do pF and uH measurements... so the caps would simply have to be replaced. I should have a few 22pF C0Gs lying around.
Thanks again for your help. I wasn't going to bother with troubleshooting it today... was getting fed up with it, and wanted to get my teeth into the Isomagic (half the PCB is going to be made redundant - sorry!), but should really listen to it in clock locked mode before making changes that will be hard to undo. If there isn't a *big* difference in performance, I might have to rethink what I was going to do...
- Tom.
Many thanks for your advice... much appreciated. I do recognise it's probably a while since you've looked at this stuff!
Ah... okay, good! I didn't bother to check the PCB itself.
I'm just wondering... is the Isomagic the right thing to use as a clock source for diagnostics? Because it only outputs clock when an S/PDIF signal is fed in... and with the coupling cap disconnected that usually joins to the LED/relay select circuitry (to try and eliminate one factor - just in case), the Discmagic is sending S/PDIF on its own clock rather than based on the Isomagic clock... or would this not affect the quality of what was seen at R11?
If the Isomagic is just dividing the local oscillator output by three and sending it out when the CS8412 indicates lock, then it wouldn't matter, but without seeing the schematic, I'm not sure of what it does.
If you can confirm that with the coupling cap disconnected to the relay/LED circuit, I should definitely be getting a clean 16.9344MHz after the first and second LC filters, then I'll certainly test the DCR of the inductors and replace the caps if possible.
Unfortunately as I am quite recent to electronics, I'm missing the tools to do pF and uH measurements... so the caps would simply have to be replaced. I should have a few 22pF C0Gs lying around.
Thanks again for your help. I wasn't going to bother with troubleshooting it today... was getting fed up with it, and wanted to get my teeth into the Isomagic (half the PCB is going to be made redundant - sorry!), but should really listen to it in clock locked mode before making changes that will be hard to undo. If there isn't a *big* difference in performance, I might have to rethink what I was going to do...
- Tom.
Tom,
The IsoMagic should output a continues clock - even when unlocked.
The LED & Relay circuit should have no effect on the operation of the LC x3 circuit, check if you have a ~ 5.6448MHz Clock (when Clock-Locked from the IsoMagic) at the junction of R8 / R9 - from your description it sounds like the clock signal is missing at this Node.
John
The IsoMagic should output a continues clock - even when unlocked.
The LED & Relay circuit should have no effect on the operation of the LC x3 circuit, check if you have a ~ 5.6448MHz Clock (when Clock-Locked from the IsoMagic) at the junction of R8 / R9 - from your description it sounds like the clock signal is missing at this Node.
John
The Iso here doesn't, unfortunately... I'd thought so far that it was in perfect working order... you don't think so?
I've the RX176 removed from the Discmagic hooked up to a test 5V DC supply (Elektor SCMS stripper), with the output hooked up to the frequency counter. When the S/PDIF cable is connected between the Discmagic and the Iso, the RX176 shows 5.6446MHz from the Iso clock output... when it is disconnected, there is nothing. The red light stays on, but no clock is present.
Interestingly, there are brief glitches in the count from time to time with this extracted RX176 (so, say, stable for a few seconds, then a brief change, then stable again) - this is with only 10cm of 22swg wire with no local decoupling - the RX173 on the Elektor board itself with local decoupling right next to the module shows no such glitches, so it seems to be very critical for these parts.
When S/PDIF is fed to the Isomagic (as above - this is currently needed for clock from the Iso), and the C34 is removed, there is the 5.6446MHz at the R8/R9 junction. Now getting a stable 16.93404,3,4,3, etc. from R11.
So can I say with some certainty that the LC x3 is working right?
If I remove the S/PDIF link, no clock from the Iso is obtained, so nothing at R8/R9 or R11. When C34 is present, it looks like a problem with the relay circuit (perhaps U6 pin 13 pulling down hard or intermittently to ground?) causes the S/PDIF output of the Discmagic to become intermittent, which in turn stops the clock from being sent by the Iso!
Either that or the Iso should indeed be outputting clock all the time, and I need to figure out why it isn't doing that... which I wouldn't have a clue about...
Shall I try feeding the Iso with a different S/PDIF source, like my Cambridge Audio D500, and see if the clock outputs inside the Discmagic at R8/R9 and R11 are still okay with C34 present? But I don't understand what the Iso is actually doing if you say it's meant to be continuous clock output...
- Tom.
Tom,
100% certain the IsoMagic should output a clock under all Lock conditions (as long as the clock lock switch is enabled). I cannot understand how SPDIF lock is effecting the clock - something very stange is going on with your IsoMagic.
If the LC x3 circuit works correctly with C34 removed - then it would appear that theres a problem with the clock detect circuit, is C34 not gone short? - if not then it will most likely be the HCU04...
John
100% certain the IsoMagic should output a clock under all Lock conditions (as long as the clock lock switch is enabled). I cannot understand how SPDIF lock is effecting the clock - something very stange is going on with your IsoMagic.
If the LC x3 circuit works correctly with C34 removed - then it would appear that theres a problem with the clock detect circuit, is C34 not gone short? - if not then it will most likely be the HCU04...
John
Hi John,
Uh-oh...
I've just verified it again. Unplug all I/O from the unit, power the unit up, flick the clock switch down... and... nothing from the clock output. Plug the S/PDIF in, and the clock output immediately lights up!
To me, that sounds like a circuit is wired wrong or not at all in the Iso, rather than a bad logic part. It's a Rev.2.1 board if that triggers any memories.
If you think that's weird, get this - wired a twisted pair lead from the TX176 connections in the Iso to my frequency counter (so standard unbalanced 5V), with the Discmagic S/PDIF connected to the Iso coaxially. No optical or otherwise dedicated clock connection between Discmagic and Iso.
This *somehow* corrupts the clock in the Discmagic - the disc starts spinning backwards at high speed! Disconnect the frequency counter from the twisted pair link, and it is fine...
I've already replaced C34 with a shiny new C0G... no luck.
I've arranged to have one delivered today, so I can substitute that.
Unfortunately, this leaves us no closer to figuring out WTH is going on with the Isomagic. I've inspected the Iso PCB, but cannot see any blobs of solder or bad connections - very clean.
The only idea that came to mind is that power wasn't getting to one of the ICs, and that it was drawing power from the S/PDIF input signal... but the S/PDIF output of the Discmagic is very low and not capable of delivering much current.
Really need the schematic, methinks.
- Tom.
Uh-oh...
I've just verified it again. Unplug all I/O from the unit, power the unit up, flick the clock switch down... and... nothing from the clock output. Plug the S/PDIF in, and the clock output immediately lights up!
To me, that sounds like a circuit is wired wrong or not at all in the Iso, rather than a bad logic part. It's a Rev.2.1 board if that triggers any memories.
If you think that's weird, get this - wired a twisted pair lead from the TX176 connections in the Iso to my frequency counter (so standard unbalanced 5V), with the Discmagic S/PDIF connected to the Iso coaxially. No optical or otherwise dedicated clock connection between Discmagic and Iso.
This *somehow* corrupts the clock in the Discmagic - the disc starts spinning backwards at high speed! Disconnect the frequency counter from the twisted pair link, and it is fine...
I've already replaced C34 with a shiny new C0G... no luck.
I've arranged to have one delivered today, so I can substitute that.
Unfortunately, this leaves us no closer to figuring out WTH is going on with the Isomagic. I've inspected the Iso PCB, but cannot see any blobs of solder or bad connections - very clean.
The only idea that came to mind is that power wasn't getting to one of the ICs, and that it was drawing power from the S/PDIF input signal... but the S/PDIF output of the Discmagic is very low and not capable of delivering much current.
Really need the schematic, methinks.
- Tom.