I piked up an old silver-faced Luxman D-405 at Goodwill the other day for $5. It's a pretty neat player and doesn't sound too bad despite the old 16-bit DAC. I've got to replace a little belt that opens the transport and figure while I'm in there I might as well do some low-cost mods by replacing some of the caps and opamps. I'm running into an issue with the latter. Looks like it uses two JRC opamps, a 4037 and a 4020. Can't find a thing on these guys. Any suggestions what might be good replacements? Also, I'm a beginner at this, but I'd take any other suggestions for easy mods.
The manufacturer, JRC, is Japan Radio Company. I believe it's now called NJR, New Japan Radio. Printing on the parts are: 072DH JRC 4037 and 072DG JRC 4020. This player was introduced back in 1984 so has been out of production for a long time. I doubt there is much info out there but I'm keeping my fingers crossed.
Those are TL072 dual opamps, standard issue. Just from JRC instead of TI. The other #'s are just batch #'s. I'd replace them with OPA2134.
I know that, just they didn't have those part numbers on their database. After your posting, I saw that you read them wrong, in the first post you give us the batch numbers instead of the part number.
OPA2134 should be more that ok, they replace well the old 072.
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Hey guys. I'm looking for another dual opamp substitute whose package only has one row of legs: TA75458S. I found NTE1529 for about $12. That seems steep, and since there are four on the board, I'm wondering if there is something else (more up-to-date) I can try. Ideas?
You are referring to a "SIP" package, "single inline pins", and there are no really great opamps available in that form. When I need to deal with this, I use a surfacemount OPA2134UA on an SOIC-8 to SIP adapter board. If it's a 9pin SIP, you have to shift the 8-pin adapter to account for the redundant B+ pin, i.e., pins 1 and 9 are both B+, with B- on middle #5 pin. As for actual SIP chips, the best you can do is an NEC uPC4570S, which is not a lot better than a regular 4558/5532 type.
Yeah, I was thinking about something like that. Got a good source for SIP adapter boards? Google doesn't turn up much...Here's a crazy question: Would it be possible to make my own from PC board and run leads from the pins into the old through-holes? If so, would I have to worry about resistance and voltage drop along the leads? Stupid idea?
Brown Dog adaptors.
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Hi fmjunkie,
Try the NJM2041L, NJM2043L or NJM2068L. The latter is the better part. Besides that, they even fit the PCB!
These parts deserve some respect to be honest with you. In many audio applications, the slew rate isn't too demanding at all. Many of the "best" op amps may not function well in the particular circuit. To add, I have no love for the TL07* series IC's either. They were quite something when they first came out, but that was then. In contrast, the old reliable 5532A and 5534A perform extremely well. In some circumstances, they can't be beat - especially once you begin to consider price! These were very expensive in the first few years of production. So, time for a reality check to see what they are actually doing in these locations.
Another member came up with a cool way to replace the SIP package without adapters. I forget who it was, but they offered up a great solution. Take a quad DIP package and install it on one side. The other side points up. The other power lead needs to be connected, and all the unused inputs should be grounded. I can't remember the exact configuration, but I do recall it wasn't a brain buster to figure out. I've been dying to try this out ever since.
In general, I like to replace JFet types with same, and Bipolar types with same. You do need to look at things like common mode range and supply current (the '07* series draws about 1/2 the current of most other for example).
I'm going to try to attach these data sheets for you (the ones I suggested you look at).
I used to be authorized warranty for Luxman and saw these machines when new. You do not want to mess with the loading gear timing - it's a pain to deal with. The first thing you should really be checking is the disc motor and the eye pattern. There isn't any point in throwing money into an almost dead horse! I think this one is a magnetic clamp system, so no top chuck bearing (ha ha - right) to worry about. If it does have a mechanical pressure system for clamping the CD, then you probably have to clean, resurface, clean and lubricate it. Watch your tolerances here.
-Chris
Try the NJM2041L, NJM2043L or NJM2068L. The latter is the better part. Besides that, they even fit the PCB!
These parts deserve some respect to be honest with you. In many audio applications, the slew rate isn't too demanding at all. Many of the "best" op amps may not function well in the particular circuit. To add, I have no love for the TL07* series IC's either. They were quite something when they first came out, but that was then. In contrast, the old reliable 5532A and 5534A perform extremely well. In some circumstances, they can't be beat - especially once you begin to consider price! These were very expensive in the first few years of production. So, time for a reality check to see what they are actually doing in these locations.
Another member came up with a cool way to replace the SIP package without adapters. I forget who it was, but they offered up a great solution. Take a quad DIP package and install it on one side. The other side points up. The other power lead needs to be connected, and all the unused inputs should be grounded. I can't remember the exact configuration, but I do recall it wasn't a brain buster to figure out. I've been dying to try this out ever since.
In general, I like to replace JFet types with same, and Bipolar types with same. You do need to look at things like common mode range and supply current (the '07* series draws about 1/2 the current of most other for example).
I'm going to try to attach these data sheets for you (the ones I suggested you look at).
I used to be authorized warranty for Luxman and saw these machines when new. You do not want to mess with the loading gear timing - it's a pain to deal with. The first thing you should really be checking is the disc motor and the eye pattern. There isn't any point in throwing money into an almost dead horse! I think this one is a magnetic clamp system, so no top chuck bearing (ha ha - right) to worry about. If it does have a mechanical pressure system for clamping the CD, then you probably have to clean, resurface, clean and lubricate it. Watch your tolerances here.
-Chris
Hi fmjunkie,
Now for the other news. The audio section in this machine uses a real relay for muting (yahoo!), but J-Fets for the pre-emphasis selection. More importantly, it uses a couple of AFL89GB as low pass filters. A dedicated part for HF reduction instead of a discrete 7th order filter. The D/A is a Toshiba TD6705AP, I don't have any info on that one. The only Op Amp in that area is a TL071 type. That should go, but that's it. You're out of options.
Not a real problem though. The one thing I know does improve the sound quality is making sure the CD Player is properly aligned. That can be a bit of work to get right, and you need the proper bench setup.
-Chris
Now for the other news. The audio section in this machine uses a real relay for muting (yahoo!), but J-Fets for the pre-emphasis selection. More importantly, it uses a couple of AFL89GB as low pass filters. A dedicated part for HF reduction instead of a discrete 7th order filter. The D/A is a Toshiba TD6705AP, I don't have any info on that one. The only Op Amp in that area is a TL071 type. That should go, but that's it. You're out of options.
Not a real problem though. The one thing I know does improve the sound quality is making sure the CD Player is properly aligned. That can be a bit of work to get right, and you need the proper bench setup.
-Chris
I have tried NJM2068 (bjt) before and does not perform as well as OPA2134 (jfet) or LM4562, AD8599 (bjt).
Plus is not a j-fet OpAmp, it might have issues replacing those TL072 (or TL071).
The adaptor that I posted on the other page is USD3.50 a pice. Not really cheap, but either are the the PIL versions of the circuits.
Plus is not a j-fet OpAmp, it might have issues replacing those TL072 (or TL071).
The adaptor that I posted on the other page is USD3.50 a pice. Not really cheap, but either are the the PIL versions of the circuits.
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Hi SoNic_real_one,
-Chris
Depends greatly on the exact circuit as well. The NJM2068 is an excellent little op amp, and cheap!!
-Chris
True, NJM2068 is better than the average OpAmp. I like it better than a regular 5532 and did try it in several places before I found out the LM4562 (DIP capsule too)...
Hi SoNic_real_one,
Yes, but again it depends on the actual circuit. Some op amps don't like common mode signals at all, and some have a restricted allowable input voltage range. Then of course there are those circuits where a better op amp will not change the performance one little bit. Output current is another possible gotcha.
The NJM2068 is a low noise part, and it's price is more than reasonable. Dropping the newer parts into some units is simply painful to watch. It can be such a waste. Also, the fact that you can get the NJM2068 in a SIP can make all the difference in the world.
The LME49710 / LME49720 and LME49740 can be a life saver, but those and the LM4562 (no surprise here) can really misbehave due to their very high slew rates. Just had to back out of one upgrade path for that reason.
Just like always, there are no "best parts". Just parts that suit an application well.
-Chris
Yes, but again it depends on the actual circuit. Some op amps don't like common mode signals at all, and some have a restricted allowable input voltage range. Then of course there are those circuits where a better op amp will not change the performance one little bit. Output current is another possible gotcha.
The NJM2068 is a low noise part, and it's price is more than reasonable. Dropping the newer parts into some units is simply painful to watch. It can be such a waste. Also, the fact that you can get the NJM2068 in a SIP can make all the difference in the world.
The LME49710 / LME49720 and LME49740 can be a life saver, but those and the LM4562 (no surprise here) can really misbehave due to their very high slew rates. Just had to back out of one upgrade path for that reason.
Just like always, there are no "best parts". Just parts that suit an application well.
-Chris
I always add some capacitors between the rails and ground (if they are not close enough). That's the only reason IMO why a faster OpAmp (but unity gain stable) would not behave as drop-in.
But true, some DAC's really don't need good OpAmps, it would be just a waste of time. TDA1543 is one example.
But true, some DAC's really don't need good OpAmps, it would be just a waste of time. TDA1543 is one example.
I used to have an Aiwa cassette deck (ADF770) that I seem to remember used SIL 2068's... not 100% sure now. I used to pull a lot off scrap music centre CD boards too but tbh I never really liked them.
I'm surprised so many have fallen out of favour with the TLO71/2/4 as they are extremely capable audio performers and pretty docile too. Their real limitation is limited output drive capability but used correctly and within their capabilities and they are very transparent. Yes they have been surpassed but non the less for a beginner wanting something stable and good sounding...
And just to show how opamp swapping can turn around and bite the unwary,
http://www.diyaudio.com/forums/anal...u-have-checked-see-its-stable-havent-you.html
I wish I could find the article that mentioned low level hf noise from DAC's as being a possible reason for "poor" subjective sound quality when using the NE5532/4 type devices as the diodes on the input could be demodulating the HF and causing non linearity.
I'm surprised so many have fallen out of favour with the TLO71/2/4 as they are extremely capable audio performers and pretty docile too. Their real limitation is limited output drive capability but used correctly and within their capabilities and they are very transparent. Yes they have been surpassed but non the less for a beginner wanting something stable and good sounding...
And just to show how opamp swapping can turn around and bite the unwary,
http://www.diyaudio.com/forums/anal...u-have-checked-see-its-stable-havent-you.html
I wish I could find the article that mentioned low level hf noise from DAC's as being a possible reason for "poor" subjective sound quality when using the NE5532/4 type devices as the diodes on the input could be demodulating the HF and causing non linearity.
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