Hi Shawn,
What would be nice would be to replace these things with a relay contact. Those would be T109 through T112. You just need to short the positions at T111 and T112. The contacts (N.C.) replace the E-C leads of those transistors. Simply pull T109 and T110. It appears that the de-emphasis occurs in the DSP chip or you would have another pair of transistors to replace with a relay.
-Chris
I did. They are normally 2SC2878, in a TO-92 case. Those are special parts with a high reverse E-B breakdown voltage. Yours are BC338-40 in this machine. Interesting, as they are not spec'd with high reverse E-B breakdown voltage.
What would be nice would be to replace these things with a relay contact. Those would be T109 through T112. You just need to short the positions at T111 and T112. The contacts (N.C.) replace the E-C leads of those transistors. Simply pull T109 and T110. It appears that the de-emphasis occurs in the DSP chip or you would have another pair of transistors to replace with a relay.
-Chris
Hi Shawn, I found this posting on Google as I did a search for Mods on my RCD 865. Then I joined and I am now a DIYer. What have you done on your RCD 865? How does it sound and do you recommend any of the Mods you completed? I also posted a question about AD847 op amps vs OPA627 op amps this morning. Rotel recommends the AD847 op amps and replacing 4 resistors with jumpers! Thanks!
Regards//Keith
Regards//Keith
KP11520 said:What have you done on your RCD 865? How does it sound and do you recommend any of the Mods you completed? I also posted a question about AD847 op amps vs OPA627 op amps this morning. Rotel recommends the AD847 op amps and replacing 4 resistors with jumpers! Thanks!
Regards//Keith
Welcome to the DIY Keith!
I put some new parts in that were sent to me from Rotel's service people but the laser still needs adjustment. I have a couple other CD players and one of them is a Rotel RCD-855 so I'm not in a big rush to fix it now. Also, I'm strapped for time lately. It would be interesting to see what you do to yours. Keep us in the loop.
Cheers,
Shawn.
I will certainly follow up with the decisions and results. If I get no feedback about which way to go, I will move forward with the Rotel advice and then listen.
In my opinion the stock 865 sounds significantly better than the 855. This is based on many hours of listening over several days at the dealer when purchased (early 90s). Hopefully you will mod both but if I had to pick one, it would be the 865! Over the years the stock 865 when in the right system would amaze me with both excellent produced music and the forgiveness on the poorly produced stuff converted from analog tto digital and not remixed! It does alright on both sides ofthe fence! I'll stay in touch!
Regards//Keith
In my opinion the stock 865 sounds significantly better than the 855. This is based on many hours of listening over several days at the dealer when purchased (early 90s). Hopefully you will mod both but if I had to pick one, it would be the 865! Over the years the stock 865 when in the right system would amaze me with both excellent produced music and the forgiveness on the poorly produced stuff converted from analog tto digital and not remixed! It does alright on both sides ofthe fence! I'll stay in touch!
Regards//Keith
(aussie version)
awpagan said:
ok not quite, the same cd850 uses 2 SAA7321's
slightly different values around the 3rd order filters.
TomWaits said:
Cheers,
Shawn.
yes, I agree
Chris has always been very helpful in any thread he's in.
thank you Chris
allan
ps buy him a beer for me
pps Still havn't found the saa7321 datasheet yet.
I want to find out about the internal opamps used for the 3rd order filter.
Here is a link to the datasheet for SAA7322/7323. It is virtually the same as SAA7321.
SAA7322/7323 datasheet
SAA7322/7323 datasheet
Fin
Do you have the cd850 sm? (not MKII)
It shows the 3rd order filter opamp as a separate opamp with filter components around it.
It still is incorporated in the dac though.
The different values may be relevent to the difference between the 7321 and the 7322/3
Or someone preferred a different rolloff.
allan
Ps have you tried oscon's, FC's and/or x7r's around the dac?
Do you have the cd850 sm? (not MKII)
It shows the 3rd order filter opamp as a separate opamp with filter components around it.
It still is incorporated in the dac though.
The different values may be relevent to the difference between the 7321 and the 7322/3
Or someone preferred a different rolloff.
allan
Ps have you tried oscon's, FC's and/or x7r's around the dac?
Hi Allan
The CD624 pcb (I assume that CD614 was a typo) is not the same as the Rotel RCD865 pcb.
The Rotel's pcb looks much better to me. It is neater and more compact and seems like it was designed specifically for this purpose.
The CD624's pcb looks like it was an adaptation from the pcb used in earlier models like the CD630 etc. The analogue stage is more spread out and bit messy.
The CD850 uses the same pcb as the CD624 for servo and decoder etc. However, it has a separate audioboard that looks neater than the layout of the CD624.
The main pcb of most of the Philips machines in the era from the CD630 to the CD850Mk2 and Marantz machines from the CD40 to the CD62 are very similar. The power supply and servos are just about the same. The layout just changed a bit as different filters and dacs were introduced.
The CD624 pcb (I assume that CD614 was a typo) is not the same as the Rotel RCD865 pcb.
The Rotel's pcb looks much better to me. It is neater and more compact and seems like it was designed specifically for this purpose.
The CD624's pcb looks like it was an adaptation from the pcb used in earlier models like the CD630 etc. The analogue stage is more spread out and bit messy.
The CD850 uses the same pcb as the CD624 for servo and decoder etc. However, it has a separate audioboard that looks neater than the layout of the CD624.
The main pcb of most of the Philips machines in the era from the CD630 to the CD850Mk2 and Marantz machines from the CD40 to the CD62 are very similar. The power supply and servos are just about the same. The layout just changed a bit as different filters and dacs were introduced.
Hi Fin
yah! oops typo
I like the look of the rotel pcb too..
It would be expensive for a company to make a specific pcb.
we need someone with a Rotel to do a quick check for us
Please
just for comparison's..
or reference
Changing the filter rolloff should affect the sound of the player.
allan
yah! oops typo
I like the look of the rotel pcb too..
It would be expensive for a company to make a specific pcb.
we need someone with a Rotel to do a quick check for us
Please
just for comparison's..
or reference
Changing the filter rolloff should affect the sound of the player.
allan
Below is a link to a TNT-Audio article on modding the RCD865/965.
http://www.tnt-audio.com/sorgenti/chevin_cdmods2_e.html
http://www.tnt-audio.com/sorgenti/chevin_cdmods2_e.html
Rotel's DRAM
In my 865BX CD player there is a piece of DRAM marked MN4264P-15 or on the service manual noted as UPD41416-20.
I thought this would be an easy upgrade to a -12 (or 120 nano second part). Any thoughts? These old IC's can still be had NOS or as pulls from old gear for cheap $$.
Cheers,
Shawn.
In my 865BX CD player there is a piece of DRAM marked MN4264P-15 or on the service manual noted as UPD41416-20.
I thought this would be an easy upgrade to a -12 (or 120 nano second part). Any thoughts? These old IC's can still be had NOS or as pulls from old gear for cheap $$.
Cheers,
Shawn.
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