I have an old Yamaha CDC-745 that I'm trying to upgrade. I ordered two AD826 opamps and then discovered that there are two more opamps in the signal path, presumably for the volume control. Do I need to upgrade those as well? I have a very limited understanding of all this and would appreciate any advice.
Can you get the schematics? This will help greatly, and give you clues about what to do in other places other than just op-amp rolling. Plus, as a learing experience it is hard to beat.
One place that has the service manual is here:
http://tigerdirect.partsearch.com/ProductDetail.aspx?ProductSKU=6726585&ProductType=ACCS
For $10 it is money well spent.
One place that has the service manual is here:
http://tigerdirect.partsearch.com/ProductDetail.aspx?ProductSKU=6726585&ProductType=ACCS
For $10 it is money well spent.
Thanks for the replies! I need to get a schematic but here's what I know so far:
1) There are two JRC 55320 8-pin chips and two JRC 2068DD 8-pin chips that all use +/- 5v.
2) I have a sales brochure that gives a sketch of the DAC and output circuit. It shows a YAC514LSI chip which contains Pro-Bit, S-Bit Plus, etc. Then there is a "Twin Balanced Processing Circuit", followed by a 3rd order LPF, followed by an output buffer amp, for each channel. The brochure states that in the Twin Balanced Processing Circuit, "The normal (+) and reverse (-) phase signals from the left and right channel DAC outputs are combined before passing through the filters."
I'm fairly sure that the 2068DD's are the "Twin Balanced Processing Circuit" and the 55320's are the output buffer amps. Any thoughts on how critical the 2068DD's are? Any idea where I can find specs for both opamps?
1) There are two JRC 55320 8-pin chips and two JRC 2068DD 8-pin chips that all use +/- 5v.
2) I have a sales brochure that gives a sketch of the DAC and output circuit. It shows a YAC514LSI chip which contains Pro-Bit, S-Bit Plus, etc. Then there is a "Twin Balanced Processing Circuit", followed by a 3rd order LPF, followed by an output buffer amp, for each channel. The brochure states that in the Twin Balanced Processing Circuit, "The normal (+) and reverse (-) phase signals from the left and right channel DAC outputs are combined before passing through the filters."
I'm fairly sure that the 2068DD's are the "Twin Balanced Processing Circuit" and the 55320's are the output buffer amps. Any thoughts on how critical the 2068DD's are? Any idea where I can find specs for both opamps?
Don't worry, that JRC 5532 is well known about these parts, and a liitle typo won't disguse him for long.
Datasheets. Easy answer is www.datasheetarchives.com for most things.
http://www.datasheetarchive.com/semiconductors/pdfdatasheet.php?Datasheet=1559987
Google is also often your friend. But the YAC514LSI is a Yamaha proprietory part and information doesn't seem to have leaked out about it. But it is a single bit DAC, so most of what you need to know is already known, for better or worse.
I'm going to bet that the 2068DD (which is a dual op-amp) implements two transimedance amplfiers - one each for the + and - DAC outputs. These two signals then pass to the first of the op-amps in the 5532 which implements a simple balanced to single ended conversion, thence to the second op-amp in the package which buffers it to the output. If there is a volume control - it would sit before the output buffer.
This is a very generic circuit. Much fun, and probably some significant gains should be realised by op-amp rolling. The 5532 garners some pretty vitriolic opinions, despite its ubiquity in hifi gear. The 2068DD is not all that shabby a device, and having a bipolar input has nice low noise. But other specs are beaten by the AD826, noteably gain bandwidth and slew rate - things that are important for the transimpedance amp. But nothing is ever clear cut. That is why it is fun
Datasheets. Easy answer is www.datasheetarchives.com for most things.
http://www.datasheetarchive.com/semiconductors/pdfdatasheet.php?Datasheet=1559987
Google is also often your friend. But the YAC514LSI is a Yamaha proprietory part and information doesn't seem to have leaked out about it. But it is a single bit DAC, so most of what you need to know is already known, for better or worse.
I'm going to bet that the 2068DD (which is a dual op-amp) implements two transimedance amplfiers - one each for the + and - DAC outputs. These two signals then pass to the first of the op-amps in the 5532 which implements a simple balanced to single ended conversion, thence to the second op-amp in the package which buffers it to the output. If there is a volume control - it would sit before the output buffer.
This is a very generic circuit. Much fun, and probably some significant gains should be realised by op-amp rolling. The 5532 garners some pretty vitriolic opinions, despite its ubiquity in hifi gear. The 2068DD is not all that shabby a device, and having a bipolar input has nice low noise. But other specs are beaten by the AD826, noteably gain bandwidth and slew rate - things that are important for the transimpedance amp. But nothing is ever clear cut. That is why it is fun
Francis - Thanks for all your help! This will be fun; much more so with your good advice! I think I'll try four AD826's. I also need sockets. I'm looking at the following 8-pin, open frame, 30ì gold plated DIP sockets with solder tails:
Assmann AR08-HZL/07-TT .93/ea Digikey# AE7313-ND
Mill-Max 110-93-308-41-001000 .42/ea Digikey# ED3308-ND
Are these good choices or would you recommend something else?
Assmann AR08-HZL/07-TT .93/ea Digikey# AE7313-ND
Mill-Max 110-93-308-41-001000 .42/ea Digikey# ED3308-ND
Are these good choices or would you recommend something else?
AD826's Installed
Hey Francis - Four sockets and AD826's are installed. Sounds great! Much cleaner, more open, and more detailed - top to bottom. The only complaints I found when researching the AD826 were that some found it too bright and/or the midband too recessed. My system needed the additional brightness and vocals were in your face. Now it sounds much better and vocals are back on stage with the rest of the band. Thanks again for the help!
Hey Francis - Four sockets and AD826's are installed. Sounds great! Much cleaner, more open, and more detailed - top to bottom. The only complaints I found when researching the AD826 were that some found it too bright and/or the midband too recessed. My system needed the additional brightness and vocals were in your face. Now it sounds much better and vocals are back on stage with the rest of the band. Thanks again for the help!
Yamaha cdc-635 opamp question
Hi,
I'm new here. I have a Yamaha CDC-635, and would like to improve its sound and dynamics. In the output stage there are four 2068JRC's (I don't have any schematic)
After looking through some threads, it seems like the OP275 or the OPA2134 are "safe" replacement opamps. The AD826 seems a bit more risky, regarding oscillation.
I would appreciate any help on this.
Best regards
Sunyata
Hi,
I'm new here. I have a Yamaha CDC-635, and would like to improve its sound and dynamics. In the output stage there are four 2068JRC's (I don't have any schematic)
After looking through some threads, it seems like the OP275 or the OPA2134 are "safe" replacement opamps. The AD826 seems a bit more risky, regarding oscillation.
I would appreciate any help on this.
Best regards
Sunyata
Sunyata - There are many on here that could provide a much better answer than me but I'll give it a shot. The I/V is the current to voltage converter immediately following the Digital to Analog Converter (DAC). The output buffer is the last stage in the analog section. If I understand correctly, it acts as a small line level amplifier and allows the components behind it to see a constant load. In my CD player, there is a low pass filter in between. If I botched that up, anyone feel free to correct or better explain.
Alesis ADAT AI3 replacement opamps
Hi,
Thanks for all your help with the CD player.
My new project is to replace these surface mount 4560 JRC ops, in my ADAT interface. What would be a good choice. There are 2 in each channel. There are 8 channel in and 8 output channels (that eqals 32 ops). I was thinking of trying out by modding 2 input channels and 2 output channels, to see the result first. Then i would have two '"super channels". I don't have a schematic, so it might be some guesswork here...
I'm a total newbie to soldering surface mount chips. I watched some instructions on youtube:http://www.youtube.com/watch?v=e5qYG95bbz8
I have good soldering skills though, since I used to work full time with electronics years ago. So I think I can manage. Do you have any experience in this field?
Best regards
Sunyata
Hi,
Thanks for all your help with the CD player.
My new project is to replace these surface mount 4560 JRC ops, in my ADAT interface. What would be a good choice. There are 2 in each channel. There are 8 channel in and 8 output channels (that eqals 32 ops). I was thinking of trying out by modding 2 input channels and 2 output channels, to see the result first. Then i would have two '"super channels". I don't have a schematic, so it might be some guesswork here...
I'm a total newbie to soldering surface mount chips. I watched some instructions on youtube:http://www.youtube.com/watch?v=e5qYG95bbz8
I have good soldering skills though, since I used to work full time with electronics years ago. So I think I can manage. Do you have any experience in this field?
Best regards
Sunyata
Attachments
Yamaha CDC-635
Hi everyone,
I am posting here because my search for "Yamaha CDC-635" directed me to Sunyata's post.
My CDC-635 5-CD changer recently lost the ability to open the carousel without an assist (slight tug with fingers). I removed the cover and it looks like the drive motor turns alright when I press the open/close button. The belt, however, looks loose. The "rails" that guide the carousel in and out are well coated with the electrical grease and I did not feel any noticeable resistance when manually pulling the door open (with the unit unplugged). I guess that the least expensive item to try might be the rubber drive belt. Any good suggestions for ordering that item or a dependable generic substitute?
If there are other possibilities, please let me know as this old player is otherwise working well.
thanks, bernball
Hi everyone,
I am posting here because my search for "Yamaha CDC-635" directed me to Sunyata's post.
My CDC-635 5-CD changer recently lost the ability to open the carousel without an assist (slight tug with fingers). I removed the cover and it looks like the drive motor turns alright when I press the open/close button. The belt, however, looks loose. The "rails" that guide the carousel in and out are well coated with the electrical grease and I did not feel any noticeable resistance when manually pulling the door open (with the unit unplugged). I guess that the least expensive item to try might be the rubber drive belt. Any good suggestions for ordering that item or a dependable generic substitute?
If there are other possibilities, please let me know as this old player is otherwise working well.
thanks, bernball
I had the same problem some time ago. I found there is a metal bracket that holds the carousel in place. After adjusting the tension of it, the problem disappeared.
I also cleaned away dirt in the plastic gear in the laser tracking mechanism, since the disc slipped/lost tracking. Now it works perfectly.
btw, it sounds great after changing the opamps.
/Sunyata
I also cleaned away dirt in the plastic gear in the laser tracking mechanism, since the disc slipped/lost tracking. Now it works perfectly.
btw, it sounds great after changing the opamps.
/Sunyata
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