I often forget this was my most viewed thread with good contribution from others:
https://www.diyaudio.com/community/...-switch-for-audio-signals-logic-drive.325663/
Yet I failed to see a drop in readily available replacement.I need yo reread that thread myself.
https://www.diyaudio.com/community/...-switch-for-audio-signals-logic-drive.325663/
Yet I failed to see a drop in readily available replacement.I need yo reread that thread myself.
There's even one more positiv thing about these drm decks.They have shielding for the fluorescent display and many good decks suffer of the noise induced by the display while only the top of the top models from other manufacturers were provided with a shield for that. All in all I think it has true potential for additional improvement because all main key aspects have been adressed properly.Wll...a needle meter might have been noiseless and better looking 🙂
Some decks need the erase oscillator to be shielded as well.Not this one.Its ground is almost a perfect star ground spreading to each stage from the middle of the board unlike my Pioneers who provide shielding for the oscillator only in the top models.While I have a deep respect for some Pioneers, the Denon is infinitely easier to work on.
Some decks need the erase oscillator to be shielded as well.Not this one.Its ground is almost a perfect star ground spreading to each stage from the middle of the board unlike my Pioneers who provide shielding for the oscillator only in the top models.While I have a deep respect for some Pioneers, the Denon is infinitely easier to work on.
As yet said, the DRM-800 worked to my pleasure until 2017 
. Initially, I also owned a Denon DCD-1500. Connecting both allowed me to start both the cassette and the CD simultaneously for recording.
Best regards!
. Initially, I also owned a Denon DCD-1500. Connecting both allowed me to start both the cassette and the CD simultaneously for recording.Best regards!
I have a Denon DCD 1560 myself.A friend gave me a pcm1792 kit to replace the whole digital section in Denon, but I also need to convert the eiaj to i2s.
Hopefully in this life...
I did use the pioneer ct777 in a loop after denon...one of the best sounding experiment.
Hopefully in this life...
I did use the pioneer ct777 in a loop after denon...one of the best sounding experiment.
You might like drm700a manual more cause it's print is better.
Looking to replace the 47uf base caps in the cap multiplier with 220u òscons I'm looking at 4 times longer startup and the 5 v rail and reset for the microcontroller is made by an aditional 5 v single trz refferenced with a zenner from the 8 v cap multiplier..I have no ideea if the microcontroller will like the 1 second long startup...Should I use a 7805 for the microcontroller straight from main 12v line?It might also improve the +8v line ripple.
Finally put it together and it plays really well , but I saw a problem after removing one filter cap that I have placed wrongly with its pins reversed.The IC902 driving the take up reels gets very hot and I feel it's not normal.I'd really need some feedback on that in your deck.Is it operating cold or hot?The capstan motor identicsl drive chip is cold, but they are not supplied in the same way.
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I'd have to recover it from my shelves. As said yet, it is waiting there for more than five years now and I really can't be sure if it is still operating at all (think of decomposing belts etc., a phenomenon that I observed so many times...).
Anyway, why, for heaven's sake, did you do these mods at all? Did your unit refuse to play? Did you notice any difference that can be verified objectively? Don't you trust the engineers that designed the deck? After all, and as you indeed encountered, there's always some danger threatening in procedures like these.
Best regards!
Anyway, why, for heaven's sake, did you do these mods at all? Did your unit refuse to play? Did you notice any difference that can be verified objectively? Don't you trust the engineers that designed the deck? After all, and as you indeed encountered, there's always some danger threatening in procedures like these.
Best regards!
I did such things for way too many times to have a count...Usually I'm pretty confident in what I do.I'll solve this problem eventually .It would be just a really helpful feedback to find if that particular driver runs hot or cold, so that I can do something about it.
I'll do what I can...
Anyway, I've always been scratching my head about the power consumption of the DRM-800. Where do these 19 watts go to in a plain cassette deck? Hence, and without having opened mine, I suspect I'd find the same as you.
Best regards!
Btw, I think it might be preferable for you to proceed in another thread with appropriate theme...
Anyway, I've always been scratching my head about the power consumption of the DRM-800. Where do these 19 watts go to in a plain cassette deck? Hence, and without having opened mine, I suspect I'd find the same as you.
Best regards!
Btw, I think it might be preferable for you to proceed in another thread with appropriate theme...
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I might have found the problem...anyway the real trouble is that my power supply is not respecting any of the schematics found in drm800 and drm 700 SM.
Diodes d922 and d927 to drivers totally missing strapped with a wire...some more transistors missing and strapped.I see this recurrent trouble every now and then with different versions of electronic equipment not just audio where you have no true version in front of your eyes...I'll do it as cold and efficient as can possibly be!
Diodes d922 and d927 to drivers totally missing strapped with a wire...some more transistors missing and strapped.I see this recurrent trouble every now and then with different versions of electronic equipment not just audio where you have no true version in front of your eyes...I'll do it as cold and efficient as can possibly be!
Was too tired yesterday to replace the power filter capacitors ...that is why i just paralleled some of them over the older ones .Now I'm probably going to replace some diodes too 🙂 Measured them...the usual -10% loss due to shelf life in a good Nippon Chemicon capacitor.SME caps were very good .
As long as we are the only participants in this thread it doesn't matter what is all about...I could change the first post and title , but it's started with lots of Telefunken photos...Highjacking my own thread should be allowed as time as the original theme is kinda dead...The search function and Google can send anyone interested here...
I'll just post everything about my findings and trials on this Denon and it will probably be easier for you to make your own mods.The sound is really good already.In the past I also tried replacing the first input op amp inside the cxa20188 Dolby chip but the difference was just theoretical because tqpe distortion and noise is about 2 or 3 orders of magnitude higher than that of any op amp .Old op amps sound very good on tape as at milivolt level their distortions are way too low to make a difference. The only true gain with newer opamps in cassette decks are the lower noise which is swallowed by the tape noise anyway and maybe in the headphones drive department, but I found m5218 or ba15218 being really good for headphones drive.Somehow I like it more than njm4556 on high impedance headphones.The lower noise m5220 which was made for phono and tape preamps is theoretically better on headphones than m5218 due to thd, lower noise and higher slew rate, but I never tried it yet, which I will do on this deck later.For now I used opa2228P as I have some and I'm ok with it especially now that I modified that into a 5x gain inverted stage.
There's one essential difference btw drm800 and drm700 in the motor drive section.Drm700 uses the plus 12v rail and the ground for the capstan motor nulling the S9 pin commend on microcontroller and tr914 which can't do the job now while your drm800 uses both S9 and tr914 to connect the capstan motor between ground and minus 12v rail.Thus in my drm700a the capstan works all the time unconditioned by the microcontroller.
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I didn't notice yet that the capstan stopped spinning with the deck in STOP-position 🤔.
Btw, can't disclose where TR914's base is connected to in your DRM-700?
Best regards!
Btw, can't disclose where TR914's base is connected to in your DRM-700?
Best regards!
Nowhere because none of the tr914/915 are on the board.The capstan motor spins all the time until power off as its permanently wired .Actually that's better because it prevents some accidents with the tape.Seen it in many decks.
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Finally made some first recordings on 90 min Sony Metal XR and 60 min Basf chrome maxima 2.For some reason the quality on the sony metal tape was worse, much worse than on basf chrome.I suspect the tape itself was used and abused but it can't take the bass on Coldplay Magic while Basf Chrome maxima 2 still is my best tape.I need to put back together my Pioneer cause I think it still has an edge over this Denon while this deck is not callibrated yet, but I remember the Pioneer didn't perform well on a Fuji metal tape either...It might be that I need better metal tape.
It performs pretty well on dolby C as well but not on the metal tape I could find and afford unfortunately.I have tons of good chrome tape but only 3 metal cassettes and they're not really the best.
The hot driver is still hot...I added a heatsink and it still gets hot but only when it works.I have no ideea how it should be .Maybe I need to clean and oil the transport..
I'll look for a new chip , maybe it's just bad.I could replace it with the cam driver as the cam driver takes a lot less current and see if it makes a difference.
It performs pretty well on dolby C as well but not on the metal tape I could find and afford unfortunately.I have tons of good chrome tape but only 3 metal cassettes and they're not really the best.
The hot driver is still hot...I added a heatsink and it still gets hot but only when it works.I have no ideea how it should be .Maybe I need to clean and oil the transport..
I'll look for a new chip , maybe it's just bad.I could replace it with the cam driver as the cam driver takes a lot less current and see if it makes a difference.
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Maybe the »Metal« setting doesn't work at all? Check the switch and the related components.
Best regards!
Best regards!