Denon DP45F; Tone Arm Return

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wolfie62
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Re: Denon DP45F; Tone Arm Return

Post by wolfie62 » 26 Jan 2017 17:05

Captmark,good info. I looked at the logic block diagram and the schematics several days ago. There is no direct adjustment for the arm return position, but, as you said, there are potentiometers (variable resisters)that can adjust the tonearm start positions. Also as you said, the return position is slaved from the "start" position of the tonearm for play. I followed the circuit input/outputs to/from the microprocessor and came to the same conclusion you did. (There is also a mechanical adjustment...That is a last resort for me.)

But, also looking at the logic and schematic, the red LED shines through 4 holes in the platter/mat, to tell the logic controller that either a 30 mm or 17 mm record is in place. There are both photo transisters (2)and CdS cells (3) under the platter; But these only get light from the "tower" LEDs when there is no record on the platter or a 17 mm (45) on it. The microprocessor uses that info to do the rest of the job. The return position of the arm is slaved from the down position (start)of the arm.

I have had to learn to distinguish preventive maintenance from troubleshooting, then assigning root cause failure analysis. Changing out caps might be a preventive measure; but that isn't troubleshooting. Also, in my line of work, if you start changing out parts before proper troubleshooting, then you may never know the root cause of a failure. Speculation is about the best you get.

captmark
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Re: Denon DP45F; Tone Arm Return

Post by captmark » 26 Jan 2017 20:38

wrote:WD40?
Anywhere NEAR a turntable?
I wouldn't hire ANYone who used that crap.
Amateurs.
My wife didn't run away with the WD-40 salesman (yet)so I don't have quite as much pure hatred as you do about it. I offered the OP several other better solutions before resorting to it than calling a guy who was trying to help him out an amateur. Unlike you he is probably only mortal and just wants to get his table back to working and that may be all he has.

I'm sure he appreciates your vast knowledge and insight to helping a fellow member out here as much as I do. I only hope such wisdom as this didn't make up your library of posts that somehow gained you senior member status...tell us you philosophical thoughts about margarine-it would be just as helpful and read-worthy...

captmark
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Re: Denon DP45F; Tone Arm Return

Post by captmark » 26 Jan 2017 21:05

IMG_3988.JPG
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wolfie62 wrote:Captmark,good info. I looked at the logic block diagram and the schematics several days ago. There is no direct adjustment for the arm return position, but, as you said, there are potentiometers (variable resisters)that can adjust the tonearm start positions. Also as you said, the return position is slaved from the "start" position of the tonearm for play. I followed the circuit input/outputs to/from the microprocessor and came to the same conclusion you did. (There is also a mechanical adjustment...That is a last resort for me.)

But, also looking at the logic and schematic, the red LED shines through 4 holes in the platter/mat, to tell the logic controller that either a 30 mm or 17 mm record is in place. There are both photo transisters (2)and CdS cells (3) under the platter; But these only get light from the "tower" LEDs when there is no record on the platter or a 17 mm (45) on it. The microprocessor uses that info to do the rest of the job. The return position of the arm is slaved from the down position (start)of the arm.

I have had to learn to distinguish preventive maintenance from troubleshooting, then assigning root cause failure analysis. Changing out caps might be a preventive measure; but that isn't troubleshooting. Also, in my line of work, if you start changing out parts before proper troubleshooting, then you may never know the root cause of a failure. Speculation is about the best you get.
Well, I come from the school that if you open your turntable up and see that your schematic is wrong (as many Denon one's are), then you have a lot more time in the day to enjoy the sunshine...

Attached here is a picture of the arm section of a 52f in real life. As you can see there is a direct adjustment for the arm return position-it moves the relationship of the CDS sensors to the shutters that trip them-it is not a VR. You can see how they routed the plinth to allow for the movement. You can also see the cam there and a bit of those LED you read about. Turn the screw and see if that fixes your problem. If it does, Bob's ur uncle. If it doesn't then troubleshooting circuits levels needed

wolfie62
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Re: Denon DP45F; Tone Arm Return

Post by wolfie62 » 26 Jan 2017 22:48

Since right now I'm still at work, I will have to let you know tomorrow. I suspect Bob's my uncle on this....everything else on the TT works as it's supposed to. My start positions, height, etc. are all spot on. So, I don't know if making pot adjustments is the way to go....Perhaps the mechanical adjustment you kindly showed is the way to go. Great visual aid! Also, if it sets everything to normal, credit goes to you!

Once I get this adjusted, I have the JVC QL-Y5F to deal with. That is going to be a complete restore job. OK...I'll do the recap on this job. #-o =D> But, unlike a car, it won't take up my whole garage......at least, that's what I told my wife... :^o [-X :lol:

captmark
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Re: Denon DP45F; Tone Arm Return

Post by captmark » 27 Jan 2017 00:27

Let me know how that works out with the wife...I know EXACTLY what you are saying! :-)My house turned into a CB repair shop but with turntables so I had to get out of this hobby for a couple of months over the holidays. I got sucked back in but the house isn't "quite" as bad-I found a buddy who loves the process as well-he is taking over the over-spill. I tell my wife at least we're drinking at home. Oddly enough that still didn't make everything sunshine and rainbows round here...

The Denon schematic on VE for this table (and several others here) is wrong, at least for the few 51/52's I've done. I get the impression that whenever they did revisions back in the day they probably sent out one sheet "bulletins" to their authorized repair stations that you were supposed to add to the binder, rather than printing a whole new V2.0 manual... 75% of the tables I open up have some kind of factory jumper or ceramic cap across the chip revision that isn't always in the VE version of the manual. If you want to PM me I can send you some scribble I did that has the correct values on a jpg or doc for the 51/52.

wolfie62
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Re: Denon DP45F; Tone Arm Return

Post by wolfie62 » 27 Jan 2017 00:54

A comrade in arms!! For me, this will be a hobby. Hopefully a labor of "love"! If I can keep my wife, anyway... It's the servo control features that have me sucked in...

wolfie62
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Re: Denon DP45F; Tone Arm Return

Post by wolfie62 » 01 Feb 2017 22:01

The mechanical procedure laid out in the service manual worked for getting the arm to return properly.

I put out a post about a DP15F.....used that one to practice on before I do anything major on this 45F, as far as reconditioning.

LN Cree
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Re: Denon DP45F; Tone Arm Return

Post by LN Cree » 12 Apr 2018 10:33

Guest wrote:WD40?
Anywhere NEAR a turntable?
I wouldn't hire ANYone who used that crap.
Amateurs.
Dear guest I would reckon most of the people on this forum are amateur vinyl and turntable lovers. WD40 is a water dispersion lubricant, and although it usually isn't the first choice for super fine mechanicals it also cannot do harm and most people have at least one can around that's handy. That being said, sparse use of any lubricant on any turntable is recommended and not just spraying and hoping for the best.
To all the rest, I've read the threads on the DP-45F after experiencing the same problems with mine. After first perusing the service manual, i've helped most of the problems by making small adjustments, but everyone's extra tips and own experiences are also very valuable. Thanks to all who've posted! Cheers

jkavguy
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Re: Denon DP45F; Tone Arm Return

Post by jkavguy » 07 May 2019 06:36

I will tell everyone anecdotally about my case. I rescued my DP-45F from the top of a trash can one night in the early 2000s. I used it for several years and hadn't touched it for a long time. Upon turning it on nothing happed unless I held down the 33 or 45 button. Out of desperation, I found this site. In another thread, someone said to change all the capacitors. It turns out there are 48 electrolytics on the main board of 6 different values. After 6 bags of capacitors from eBay totalling 20 bucks and soldering them in, I'm up and running for almost a year. After an install of a Denon DL-103, I'm quite pleased.