Hi, Steve. For anyone who has one of these, this video will be like the holy grail of how to fix them. I bet the views go through the roof. Anyway, thanks for sharing.
We use to include a small internal fan, just to stir up the air inside our radar receivers. This was very effective in preventing hotspots. Might help here to keep this lovely unit running well into the future. BTW nice clear video :)
I was thinking exactly the same - might be worth modifying the case such that some air cooling (just a weak draught is better than nothing) can drift across those components. I would imagine the cumulative effect of those quite hot components would contribute towards a little oven inside that case! Definitely room for improvement.
Great job, I'm amazed a faulty cap could make noise like that. The wall wart PSU was recalled by Cambridge audio as the plastic case can fail exposing live parts.
A couple of cautions on use of ceramic capacitors: (my first time here, apologies if these have been discussed before) Some of the dielectrics used in modern ceramic caps result in appallingly high magnitude negative voltage coefficient of capacitance. A capacitor operated at anything near its rated voltage may be down to 20% or less of its nominal capacitance. What I typically found is that by the time you derate the working voltage adequately to maintain some semblance of decent capacitance you are better off with a cap with a better dielectric and lower nominal capacitance, thought typically at slightly higher cost. When used in LC filters, the ESR of an electrolytic cap can sometimes prevent extremely high filter gain around resonance. The very low ESR of ceramic caps can actually make the performance of a filter problematic because of this gain peak. (This is similar to the problem you get with ceramic caps used on the output of some low-dropout linear regulators - ESR must be not greater than some value but also not less than some value.) When designing a circuit you can deal with this by use of a discrete resistance to dampen the peak or choosing an inductor that has sufficient series resistance. If you plunk in a ceramic cap where there was an electrolytic, you may make a mess of things.
Soldering surface-mount ceramic caps with an iron is something that should be done only in desperation. The thermal shock can cause cracking of the dielectric. All of the major ceramic cap manufactures discuss this in ap notes.
Excellent job. Is this a job you would recommend doing on a working unit as a preventative measure. By the way I had some blue LED's fail on mine but I replaced those some years ago.
@@mikepxg6406 I would leave it until you have issues. The surface mount electrolytic capacitors can be difficult to remove without the right tools and risks damaging a unit that's still ok
very nice one, just a one think, is it really ok replace electrolitics for ceramics? im worry as electrolitics when get bad they tend to be open or as high resistor but ceramics they get faulty as shortage and it couild do some damages. the same with tantalum they tent to be shorted as well. is it not to much risky?
Ceramic capacitors are fine in this particular application, but there are many cases where they can cause more issues - I think I did a video several years ago about ceramic capacitors. It's fairly rare for them to go short circuit like a tantalum capacitor.
Very impressive work and beautiful narration. Liked and subscribed. As a man that clearly knows his onions, can you recommend any particular brands / models for a great HD dac at a reasonable price. I was considering both Cambridge audio and the topping. Any thoughts?
That brought back some hi-fi development memories ! It still irritates though that Cambridge Audio has nothing to do with Cambridge. My designed-in-Waterbeach Arcam rDac engineering sample is still going strong and I must say it has a much more compact design. Single DAC IC but the WM8741 which does sound noticeably better. And I always ended up melting something when replacing caps during development listening sessions!
Nice to hear from you Matt. I have a couple of Arcam amps for repair, but it looks like Arcam dissolved in 2019, so they are gone now from Cambridge along with any kind of customer service. Harman (Samsung!) seem to own the brand and probably lost the essence of the original products!
@@sdgelectronics the algorithm sent me a few of your videos recently, good stuff. I knew Harman bought Arcam and they left the original Waterbeach factory site, but I thought there were still a handful of engineers on the newish business park across the road. Might have to ping a contact to find out!
Wolfson was absorbed into Cirrus Logic I think (or similar larger semi co) that later dissolved the site and now I have ended up with a manager who used to work there, as Kandou have a semiconductor manufacturing operations team in Scotland.
Usually adding zoom lens makes temperature readings somewhat higher if there is no correction in menu for that (Noticed this when I made E4 hacks and menu in EEVblog)
I could be wrong but are the relays at the outpus just a delayed connect so you don''t get a pop on switch on. As well as the reasons you gave Edit: You mentioned stopping speaker pop later, I just hadn't got there in the video yet
I’d like to learn more about the charge pump section: ICs, filtering & noise. I’d use external 12v AC PSU instead (a transformer) and no charge pumps. But maybe their way is better overall.
@@sdgelectronics Designing a circuit where an opamp runs about 40°C above ambient seems a bit strange. is there another fault or just bad design.(IMHO)
@@TheEmbeddedHobbyist Under no load, they're dissipating around 0.5W, so you'd expect the temperature to be raised to some extent. The OP275 used at the last stage use less power and correspondingly have a reduced temperature, so I think it lines up.
Great job with the repair! Bad design though from Cambridge Audio. No proper heat management on the linear regulators that are probably driven so close to max current.
Always makes me roll my eyes how those with golden ears think butchering something designed by people who know what they're doing with mods recommended by those without a clue will improve a product. I'm surprised you didn't take the opportunity to fit a gold-plated mains plug, as these have been "proven" to improve the sound so many times in the audiophool world...
@@sdgelectronics Good choice. When I design switching regs i NEVER use electrolytic for input or output primary caps, You can always do ripple reduction with MLCC's then stack electrolytic for bulk capacitance but even with 3-4 MLCC's you can get output ripple 1mV ptp with 4 22uF MLCC caps and those are cheap and easy to package.
PCBWay 3D Printing and Fabrication: www.pcbway.com/rapid-prototyping/
Hi, Steve. For anyone who has one of these, this video will be like the holy grail of how to fix them. I bet the views go through the roof. Anyway, thanks for sharing.
I really enjoyed this. The example of a noisy power rail and the scope work was great. I learned something new.
I wonder if the "Cambridge Butcher" is watching.......what a mess! Nice repair Steve.
'mess' is an understatement 🤣. An apprentice bricky with a trowel and some mortar would have done a cleaner job.
@IanScottJohnston - The original 'mod' job made me sad. :(
most professional repair job i watched on youtube
Almost looks like "Factory", after your rework, Steve. NICE!
We use to include a small internal fan, just to stir up the air inside our radar receivers. This was very effective in preventing hotspots. Might help here to keep this lovely unit running well into the future. BTW nice clear video :)
I was thinking exactly the same - might be worth modifying the case such that some air cooling (just a weak draught is better than nothing) can drift across those components. I would imagine the cumulative effect of those quite hot components would contribute towards a little oven inside that case! Definitely room for improvement.
Awesome work, really nice job to do as you found the fault and then cleaned up the mess. Very satisfying !
What a horrible butchered hack job you started out with - but a great repair, leaving it in a vastly improved state. Nice Nichicon Muse bipolars too!
Wow great, glad I found your channel. You’ll definitely keep me going between mend it Mark’s video releases
Great job, I'm amazed a faulty cap could make noise like that. The wall wart PSU was recalled by Cambridge audio as the plastic case can fail exposing live parts.
A couple of cautions on use of ceramic capacitors: (my first time here, apologies if these have been discussed before)
Some of the dielectrics used in modern ceramic caps result in appallingly high magnitude negative voltage coefficient of capacitance. A capacitor operated at anything near its rated voltage may be down to 20% or less of its nominal capacitance. What I typically found is that by the time you derate the working voltage adequately to maintain some semblance of decent capacitance you are better off with a cap with a better dielectric and lower nominal capacitance, thought typically at slightly higher cost.
When used in LC filters, the ESR of an electrolytic cap can sometimes prevent extremely high filter gain around resonance. The very low ESR of ceramic caps can actually make the performance of a filter problematic because of this gain peak. (This is similar to the problem you get with ceramic caps used on the output of some low-dropout linear regulators - ESR must be not greater than some value but also not less than some value.) When designing a circuit you can deal with this by use of a discrete resistance to dampen the peak or choosing an inductor that has sufficient series resistance. If you plunk in a ceramic cap where there was an electrolytic, you may make a mess of things.
Oh boy, this poor Cambridge DAC was badly butchered... Nice repair job you've done...
Cool video. I had to do the same repair to a DADMagic plus I just bought, that the seller sold as "flawless".
Excellent, analysis, repair and info! Thank you very much.
A quality repair. Good to see how it should be done properly too following the hack job that had happened prior.
Soldering surface-mount ceramic caps with an iron is something that should be done only in desperation. The thermal shock can cause cracking of the dielectric. All of the major ceramic cap manufactures discuss this in ap notes.
Excellent job. Is this a job you would recommend doing on a working unit as a preventative measure. By the way I had some blue LED's fail on mine but I replaced those some years ago.
@@mikepxg6406 I would leave it until you have issues. The surface mount electrolytic capacitors can be difficult to remove without the right tools and risks damaging a unit that's still ok
Thanks for the repair video 👍.
very nice one, just a one think, is it really ok replace electrolitics for ceramics? im worry as electrolitics when get bad they tend to be open or as high resistor but ceramics they get faulty as shortage and it couild do some damages. the same with tantalum they tent to be shorted as well. is it not to much risky?
Ceramic capacitors are fine in this particular application, but there are many cases where they can cause more issues - I think I did a video several years ago about ceramic capacitors. It's fairly rare for them to go short circuit like a tantalum capacitor.
fist time I see SMT film in product, and ofc it is audiofillery.
keep up🤘
Great job, nice professional video.👍
Very impressive work and beautiful narration. Liked and subscribed. As a man that clearly knows his onions, can you recommend any particular brands / models for a great HD dac at a reasonable price. I was considering both Cambridge audio and the topping. Any thoughts?
Would you be able to modify the dac to have an even cleaner voltage reference in for even less signal distortion?
That brought back some hi-fi development memories ! It still irritates though that Cambridge Audio has nothing to do with Cambridge. My designed-in-Waterbeach Arcam rDac engineering sample is still going strong and I must say it has a much more compact design. Single DAC IC but the WM8741 which does sound noticeably better.
And I always ended up melting something when replacing caps during development listening sessions!
That was where in the founders in the 1960s, Cambridge Audio began life as a division of Cambridge Consultants in 1968 were educated.
Nice to hear from you Matt. I have a couple of Arcam amps for repair, but it looks like Arcam dissolved in 2019, so they are gone now from Cambridge along with any kind of customer service. Harman (Samsung!) seem to own the brand and probably lost the essence of the original products!
@@sdgelectronics the algorithm sent me a few of your videos recently, good stuff.
I knew Harman bought Arcam and they left the original Waterbeach factory site, but I thought there were still a handful of engineers on the newish business park across the road. Might have to ping a contact to find out!
Wolfson was absorbed into Cirrus Logic I think (or similar larger semi co) that later dissolved the site and now I have ended up with a manager who used to work there, as Kandou have a semiconductor manufacturing operations team in Scotland.
Usually adding zoom lens makes temperature readings somewhat higher if there is no correction in menu for that (Noticed this when I made E4 hacks and menu in EEVblog)
I'll have to check this, it didn't seem too far off with/without the lens.
Do you know the reason why?
OpAmps running on 60C??? Why such big heat dissipation?
I could be wrong but are the relays at the outpus just a delayed connect so you don''t get a pop on switch on. As well as the reasons you gave
Edit: You mentioned stopping speaker pop later, I just hadn't got there in the video yet
Opamps running that hot? Aren't they oscillating at few MHz?
They're running close to 0.5W based on their supply voltages, so the temperature is probably quite representative of that.
Great work
Nice di you want to sell it? Whereabouts are you based in the UK
@10:43 That Wurth capacitor seems to be loose, it moves quiet a bit when you bumped it :)
That's the one with the lifted pad. All sorted now though!
@@sdgelectronics Yeah I saw it. and furthermore, nice job!
I’d like to learn more about the charge pump section: ICs, filtering & noise. I’d use external 12v AC PSU instead (a transformer) and no charge pumps. But maybe their way is better overall.
I suspect it's something to do with energy requirements - transformer-based power adaptors are pretty much gone from new equipment.
Hey Steve, by chance would you have a recommendation for a repair tech in California, USA? My Cambridge 851N is giving me trouble.
What's your room temperature 60°c seems a bit excessive for an opamp.
That room is usually intolerably hot (30*C)
@davadoff that explains it, the chip is only 30°C above ambient. In 😀
Air conditioning was on, so it should have been around 21C
@@sdgelectronics Designing a circuit where an opamp runs about 40°C above ambient seems a bit strange. is there another fault or just bad design.(IMHO)
@@TheEmbeddedHobbyist Under no load, they're dissipating around 0.5W, so you'd expect the temperature to be raised to some extent. The OP275 used at the last stage use less power and correspondingly have a reduced temperature, so I think it lines up.
more repair videos specifically on complex equipment
I’d love to see more analysis & reverse engineering & teaching too. I didn’t even know about those sensitive SMD caps 🤔
@@davadoff me neither now i get it why i destroyed a few , i had a hunch they could not stand the head but did not knew exactly what type they where
I would've super glued that pad down because there is not much holding the cap on one side, ie, don't drop it - lol -.
was the feed of the bclk than cause issues in ppl thanks
Great job with the repair! Bad design though from Cambridge Audio. No proper heat management on the linear regulators that are probably driven so close to max current.
I repaired a bunch of those a few years back, every one of them had failed blue LEDS. Must've been a bad batch of LEDS or they were overdriven.
I have one of this DAC, the only issue is the LEDs for sample rate are all dead.
Cool channel. Not sure I’m on board with the cheap Chinese PCB way advert. Patron would be better but mans gotta eat I guess
Nice video, of course muted as "music" but still.
I would also put some glue at base of that cap with the loose pad.
Yeah I was expecting him to do that instead of the wire. Superglue would be ok?
Before putting it back together, I put a blob of glue between the capacitor case and the edge of that IDC connector.
Always makes me roll my eyes how those with golden ears think butchering something designed by people who know what they're doing with mods recommended by those without a clue will improve a product. I'm surprised you didn't take the opportunity to fit a gold-plated mains plug, as these have been "proven" to improve the sound so many times in the audiophool world...
Thanks for sharing the video, I've fixed mine by replacing the small 10uF capacitor
@@michelaarssen1520 great to hear!
This DAC is a really high-cost product.
Why not just replace em with MLCC's? the 1206 MLCC"S fit perfectly in that footprint haha
Went for 1210's in the end!
@@sdgelectronics Good choice. When I design switching regs i NEVER use electrolytic for input or output primary caps, You can always do ripple reduction with MLCC's then stack electrolytic for bulk capacitance but even with 3-4 MLCC's you can get output ripple 1mV ptp with 4 22uF MLCC caps and those are cheap and easy to package.
Ohhh. You using Peak ESR. I'm using Hantek. For really tiny stuff NanoVNA H4. I know industry standard is DE-5000.
@@codernov the ESR70 works really well. Jez does a great job at Peak.
A great video, but if you must run background music, please run it at a low level.
Agreed! Although no music would be better, with ASMR style repair noises instead.
brilliant work, but its probably not worth it, at least subjectively the sound from CA dacs would be described as "sterile"
What’s the point of repairing it, you can buy one for £50 that would perform better.
i have 3 replaced because of the front leds, now years later got same issue with noise
fixed my one with same issue by just changing few smds