Hi,
Someone kindly gave me a Marantz CD42, which has a broken drawer gear and a mediocre but not terrible sound quality.
For the fun of it I thought I'd modify and sell it on.
The player uses the SAA7310 decoder, SAA7350 DAC fed from the SM5840 digital filter. I read in another thread that this IC is used to up-sample the signal to 20bits. The disc mechanism is a CDM4.
Output is the typical NE5532 running on +-15V. Most caps are tiny 47uF/25V parts. DC blocking electrolytics and SMT muting transistors are employed.
My aim was to get a very substantial improvement from mainly unremarkable parts.
I've spent the evening with the soldering iron and appear to have achieved that goal.
Simon
Someone kindly gave me a Marantz CD42, which has a broken drawer gear and a mediocre but not terrible sound quality.
For the fun of it I thought I'd modify and sell it on.
The player uses the SAA7310 decoder, SAA7350 DAC fed from the SM5840 digital filter. I read in another thread that this IC is used to up-sample the signal to 20bits. The disc mechanism is a CDM4.
Output is the typical NE5532 running on +-15V. Most caps are tiny 47uF/25V parts. DC blocking electrolytics and SMT muting transistors are employed.
My aim was to get a very substantial improvement from mainly unremarkable parts.
I've spent the evening with the soldering iron and appear to have achieved that goal.
Simon
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I did the obvious and tackled the cheap decoupling capacitors first:
* PCF3523P (unknown IC) [2673] - 68uF os-con
* MN4264P (RAM chip I think) [2602] - 68uF os-con
* X24C16P (might not be important but why not..) [2612] - 68uF os-con
* SAA7350 (DAC pin 12 / VDDD) [2615] - 68uF os-con
* SAA7350 (DAC pin 18 / VDDAR) [2819] - 100uF Elna Cerafine
* SAA7350 (DAC pin 39 / VDDAL) [2818] - 100uF Elna Cerafine
* SM5840 (digital filter pin 14 / VDD) [2611] - 68uF os-con
I also dealt with the basic 5V feed:
* 10V smoothing cap [2678] - 4700uF / 25V Panasonic FC (was a small 3300uF cap)
* 5V regulator output cap [2680] - 4700uF / 6.3V Panasonic FC (replaced a tiny cap)
And a couple of changes to the output section:
* Op-amps swapped for Burr Brown OPA2132PA [6611] & [6612]
* DC blockers [2665] & [2666] were shorted out with a wire link
Unfortunately one channel gives 125mV (other just 23mV) of DC offset so I may put some caps back in there.
* PCF3523P (unknown IC) [2673] - 68uF os-con
* MN4264P (RAM chip I think) [2602] - 68uF os-con
* X24C16P (might not be important but why not..) [2612] - 68uF os-con
* SAA7350 (DAC pin 12 / VDDD) [2615] - 68uF os-con
* SAA7350 (DAC pin 18 / VDDAR) [2819] - 100uF Elna Cerafine
* SAA7350 (DAC pin 39 / VDDAL) [2818] - 100uF Elna Cerafine
* SM5840 (digital filter pin 14 / VDD) [2611] - 68uF os-con
I also dealt with the basic 5V feed:
* 10V smoothing cap [2678] - 4700uF / 25V Panasonic FC (was a small 3300uF cap)
* 5V regulator output cap [2680] - 4700uF / 6.3V Panasonic FC (replaced a tiny cap)
And a couple of changes to the output section:
* Op-amps swapped for Burr Brown OPA2132PA [6611] & [6612]
* DC blockers [2665] & [2666] were shorted out with a wire link
Unfortunately one channel gives 125mV (other just 23mV) of DC offset so I may put some caps back in there.
The sound has opened up quite nicely and now has a fairly sweet midband. Detail has increased and the treble isn't too shabby now. Pretty good sound for an evening's work and parts that I had lying around.
I think I would need to put some of those chips on separate regulators to get much more detail from this machine now, as too many share the same voltage rail. Some cheap 11.2MHz clock option appeals too.
I'm also going to try some different op-amp decoupling caps. Instead of the usual favourites (Black Gate or Rubycon ZA) I'm going to try some cheap 1000uF jobs. The standard caps are 1000uF but TINY!
It's worth noting just how nice this machine is to work on. The bottom panel unscrews and you have near full access to the PCB's underside. No risky PCB removal! Easy to put the player on its side and get at it from top and bottom - ideal!
Also, the player is rather tall and if desired I think there's room for additional transformers on top of the funny plastic cage.
Be aware that you need a small torx driver for the bottom screws.
Simon
I think I would need to put some of those chips on separate regulators to get much more detail from this machine now, as too many share the same voltage rail. Some cheap 11.2MHz clock option appeals too.
I'm also going to try some different op-amp decoupling caps. Instead of the usual favourites (Black Gate or Rubycon ZA) I'm going to try some cheap 1000uF jobs. The standard caps are 1000uF but TINY!
It's worth noting just how nice this machine is to work on. The bottom panel unscrews and you have near full access to the PCB's underside. No risky PCB removal! Easy to put the player on its side and get at it from top and bottom - ideal!
Also, the player is rather tall and if desired I think there's room for additional transformers on top of the funny plastic cage.
Be aware that you need a small torx driver for the bottom screws.
Simon
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It looks like a replacement for the dodgy cog can be sourced on Ebay, e.g.:
Philips CDM4 CDM-4 cd player tray gear with belt on eBay (end time 22-Oct-09 20:27:11 BST)
I just need to check if that's universal to all CDM4 mechs, as I realise there are various types.
Philips CDM4 CDM-4 cd player tray gear with belt on eBay (end time 22-Oct-09 20:27:11 BST)
I just need to check if that's universal to all CDM4 mechs, as I realise there are various types.
I ordered that cog from the Ebay seller, and had a little listen after leaving the player on repeat all day whilst I was at work.
The sound is very smooth and enjoyable with a sweet midrange.
I've now put 2 x 7805 on the DAC analogue left and right 5 volt supplies. I used the plastic cross-bracing to screw the regulators in place, as this looks tidy and is secure.
It's too early to say what this modification has done but a quick listen suggests things have opened up a little more.
edit: there's also more impact and the sound is more interesting, very good.
Simon
The sound is very smooth and enjoyable with a sweet midrange.
I've now put 2 x 7805 on the DAC analogue left and right 5 volt supplies. I used the plastic cross-bracing to screw the regulators in place, as this looks tidy and is secure.
It's too early to say what this modification has done but a quick listen suggests things have opened up a little more.
edit: there's also more impact and the sound is more interesting, very good.
Simon
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Nasty ceramic caps
My next mod is inspired by this web page:
CD-player mods
That person removed the 39pF ceramics from after the DAC (2622, 2623, 2624 & 2625) and said he got a rather large improvement in SQ.
I will do that one tomorrow I think, it's getting late.
Simon
My next mod is inspired by this web page:
CD-player mods
That person removed the 39pF ceramics from after the DAC (2622, 2623, 2624 & 2625) and said he got a rather large improvement in SQ.
I will do that one tomorrow I think, it's getting late.
Simon
Ah ha! Here you are!
Yep that cog is a common problem on the CDM 4/19 deck. I got mine from the same place. It certainly fits a Marant CD50 and philips cd850. The chassis are almost identical for 40,42,50,52..... and CD850MkII so you'll be fine!
I didn't do an awfull lot to my player by my standards today but then I didn't know as much!
1st in was a Trichord Clock 4. This made a huge difference. Much more than in any other player where I've upgraded the clock (until I put the C2 in my CD960!). No PSU mods and the clock was just fed from the main +12v reg. A couple of years later, in went AD825 (from memory!) on Brown Dog adapters. This cleaned the sound up again but wasn't a massive change by comparrison. Next came LM4562's and a play with ZA's and SilmicII's on the op amp decoupling. These op amps and caps lifted the player again.
There are a few old photo's on the old pages of my website here. I had planned more but never got round to it.
Then I started on the 63's and put it back as std poss to sell!
I'd def be interested in what you can acheive compared to the other players we have.
Yep that cog is a common problem on the CDM 4/19 deck. I got mine from the same place. It certainly fits a Marant CD50 and philips cd850. The chassis are almost identical for 40,42,50,52..... and CD850MkII so you'll be fine!
I didn't do an awfull lot to my player by my standards today but then I didn't know as much!
1st in was a Trichord Clock 4. This made a huge difference. Much more than in any other player where I've upgraded the clock (until I put the C2 in my CD960!). No PSU mods and the clock was just fed from the main +12v reg. A couple of years later, in went AD825 (from memory!) on Brown Dog adapters. This cleaned the sound up again but wasn't a massive change by comparrison. Next came LM4562's and a play with ZA's and SilmicII's on the op amp decoupling. These op amps and caps lifted the player again.
There are a few old photo's on the old pages of my website here. I had planned more but never got round to it.
Then I started on the 63's and put it back as std poss to sell!
I'd def be interested in what you can acheive compared to the other players we have.
Hi Ian,
It sounds like you covered some of the key basics on your CD850. I read in another thread that a good clock makes a huge difference on these DAC chips. I'm in two minds about whether to install one on this as I'm going to chuck it on Ebay and hope it sells. If buyers can't hear how amazing it is, it won't command decent money, so it might as well be good value with cheap modifications. It's really not bad now actually!
Another thing I've considered is transformer-coupled outputs as the SAA7350 has built-in op-amps so should be happy driving this kind of output, which will do away with the standard external op-amps and filtering. I may try it with some spare 120VAC psu transformers I have lying around.
Simon
It sounds like you covered some of the key basics on your CD850. I read in another thread that a good clock makes a huge difference on these DAC chips. I'm in two minds about whether to install one on this as I'm going to chuck it on Ebay and hope it sells. If buyers can't hear how amazing it is, it won't command decent money, so it might as well be good value with cheap modifications. It's really not bad now actually!
Another thing I've considered is transformer-coupled outputs as the SAA7350 has built-in op-amps so should be happy driving this kind of output, which will do away with the standard external op-amps and filtering. I may try it with some spare 120VAC psu transformers I have lying around.
Simon
Hi,
As a cheaper alternative to a cheap clock.....
I've found good improvements on some players just by disconnecting the clock out feed from the chip to the std crystal and feeding a clean isolated power supply to the crystal instead. I guess by the time the standard 5v feed (or whatever is used) is routed through and out of the chip it's pretty polluted. With a cheap lm317 reg you get quite an improvement for next to nothing.
Regards
Pete
As a cheaper alternative to a cheap clock.....
I've found good improvements on some players just by disconnecting the clock out feed from the chip to the std crystal and feeding a clean isolated power supply to the crystal instead. I guess by the time the standard 5v feed (or whatever is used) is routed through and out of the chip it's pretty polluted. With a cheap lm317 reg you get quite an improvement for next to nothing.
Regards
Pete
Hi Pete,
So I can just disconnect the xtal from pin 15 (XOUT) and connect a 5V feed to the 1K resistor which connects to the xtal?
Sounds intriguing!
Simon
Hi Martin,
Marantz have put 10uF & 47nF here. I'll replace the 10uF with a 68uF os-con - will that do or should I push the boat out and go for 470uF os-con SEPC (7mR)? That's another fiver on the cost of this work so far, and I'm worried nobody will want it
At least I'm learning and having fun
Simon
Yes, try the oscon; 10-68uF is quite large enough - it has to charge-up through the chips internal divider, so you don't want too long a start-up time. If the 47nF thingy is SMT, leave it in place too.
This dac was used in a lot of good equipment. DPA used it in various PDM1 / Little/Bigger Bit designs. They used an active, low-noise 2.5v voltage reference with buffer to drive these pins, so if you want to really experiment...
The full Philips 'CD7' chipset is to use the SAA7350 to generate the bitsream, and the TDA1547 solely to decode it. It's a pairing capable of stunning sound.
This dac was used in a lot of good equipment. DPA used it in various PDM1 / Little/Bigger Bit designs. They used an active, low-noise 2.5v voltage reference with buffer to drive these pins, so if you want to really experiment...
The full Philips 'CD7' chipset is to use the SAA7350 to generate the bitsream, and the TDA1547 solely to decode it. It's a pairing capable of stunning sound.
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Not sure about the 5v. The ones I've done have had about 2, 2.5v out. Best to measure with a meter first.
Understood, thanks. I'll measure it before and after the resistor. I have some LM317 so I could configure one to run at these sorts of voltage levels. I don't want to sell this player until it sounds good enough, and currently the treble isn't clean enough for my liking. There's a murky haze over cymbals, brushed ones are particularly hopeless.
I know this is partly due to the OPA2132 op-amps which, although better than average, do make a blurred top end compared to good ones (LM4562).
I know this is partly due to the OPA2132 op-amps which, although better than average, do make a blurred top end compared to good ones (LM4562).
Hi Simon, I tried 4562's in there and although it lifted, I don't think that will give you what you want on its own. Seeing as you're also addressing the power supply(s) in the chip, you may have better results than I did. Not sure if you're layout is similar but my phones amp was on a sub board so that came out too!
With respect to the cheap clock mod Pete, I assume you mean measure the xtal supply pin and then create a seperate supply to drive the existing xtal? This would work on all players then! Another 'almost' freebie mod!
I'm now sort of wishing i'd persevered a bit more with this player now! The final straw was the loading cog (ate istself like they all do) and thats replaced now anyway! You never know, I might give it all another go! Not sure I need another CD project on the go at the moment tho' (CD960,CD50,2xCD63's!) although the 850MKII is sitting on the stand with the rest! the misses might
With respect to the cheap clock mod Pete, I assume you mean measure the xtal supply pin and then create a seperate supply to drive the existing xtal? This would work on all players then! Another 'almost' freebie mod!
I'm now sort of wishing i'd persevered a bit more with this player now! The final straw was the loading cog (ate istself like they all do) and thats replaced now anyway! You never know, I might give it all another go! Not sure I need another CD project on the go at the moment tho' (CD960,CD50,2xCD63's!) although the 850MKII is sitting on the stand with the rest! the misses might
Hahaha, you can never have too many projects Ian! As long as each one gets a bit of love 
It seems most cd players are broadly similar. Below an outrageous price-point a lot of work is needed to make them detailed and fluid.
There's a broken CD52 MkII SE on Ebay right now. I may put a low bid on that as it may not need more than the cog and a lens clean. If not then never mind, it's still good for some spares and/or to sell on again.
Simon
It seems most cd players are broadly similar. Below an outrageous price-point a lot of work is needed to make them detailed and fluid.
There's a broken CD52 MkII SE on Ebay right now. I may put a low bid on that as it may not need more than the cog and a lens clean. If not then never mind, it's still good for some spares and/or to sell on again.
Simon
Exactly.
It's not as good as an aftermarket clock but it is better than the standard setup. I'd be interested in your impressions. Obviously the results will depend to a certain extent on the accuracy of the std crystal, some will be better than others.
Pete
Thats it! The CD850's gonna get the Xtal mod as soon as I get the lid back on the 63 i'm messing with right now!
Also, I'll use 1 of those Low noise LDO regs I was talking about on the 63/7 thread. I ordered enough to build 25! Gonna be a fiddle tho'
Edit: Actually I've got the original 16mhz Trichord 4 pin xtal. The clock 4 now on my project DAC with an 11mhz xtal. I might try that as well!
Look what you guys have started.........
......again! lol
Also, I'll use 1 of those Low noise LDO regs I was talking about on the 63/7 thread. I ordered enough to build 25! Gonna be a fiddle tho'
Edit: Actually I've got the original 16mhz Trichord 4 pin xtal. The clock 4 now on my project DAC with an 11mhz xtal. I might try that as well!
Look what you guys have started.........
......again! lol
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