Denon DP45F; Tone Arm Return

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Denon DP45F; Tone Arm Return

Post by wolfie62 » 16 Jan 2017 23:17

I bought this turntable in 1989 from the Navy Exchange when I was stationed in Bermuda. It was a return to the store, missing pieces. I sent it to a Denon factory repair center and they repaired everything, including a new dust cover and headshell for free. (Guess I can't get that kind of service anymore!)They replaced the bearings in the tonearm, gave it a tune-up.

I have been using this TT ever since. My parents used to work for Columbia Records out in California, and they brought home records that were returns from the Columbia Record Club (Anyone remember that?) So, I inherited the collection of over 4,300 lps; I have yet to listen to them all, (still have 71 boxes that have not been opened, most records are still sealed) from years 1957-1967. (From the dawn of the stereo lp in November 1957.)

Anyway, my problem now is that the tone arm does not always return at the finish of playing. Anyone know how to make the adjustment? Yes, I downloaded the Service Manual, but have little time with my job.....Was hoping I could tap into some experience on this. This has been a good turntable for me over the years, just about 6 years ago it started doing this.

Unlike many in here, I have never had a big budget for my audio system. I still use my Sherwood S9600CP receiver....it still works as good as the day I bought it in 1981. I use a Shure V15RS that I bought in 1997 along with 10 styli (my buddy worked at the Shack, told me to buy his stock since they were being discontinued), so they still have the beryllium cantilevers.

I am getting off point here.....a newbie to the group.... :roll:

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Re: Denon DP45F; Tone Arm Return

Post by Freddymac1 » 18 Jan 2017 01:47

I am new to the Denon 52F but I am sure they are similar. Does the arm fail to return more after being on for an hour. It is triggered by a LED light changing the the resistance of a small photo resistor, there isn't any adjustment that I can see. I know that the cells age they are less sensitive. Also the LED's become less bright with age. There are many here with more knowledge than I have. If Captain Mark is around he has the cell to replace the originals with.

Freddymac1

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Re: Denon DP45F; Tone Arm Return

Post by wolfie62 » 18 Jan 2017 16:36

Appreciate the response, Freddymac1! But, the LED light has nothing to do with the autoreturn of the tonearm. The LED is used to verify size of the vinyl placed on the platter mat, and to ensure the tonearm does not move from the rest position unless there is a vinyl record on the mat. The LED has no way of knowing the position of the tonearm on the record, as there are no sensors on top of the record. The servocontrol system DOES know the position of the tonearm, however. So there must be a position indicator that lets the logic circuitry know the tonearm is in a position in which it needs to be returned to rest (end of record), move the tonearm, and turn off the platter drive.

The problem I am having is hit-and-miss, or intermittent. The problem will show up on the first LP played, even after days of being off. Other times, it works perfectly for several LPs, then fails to return on the same LP played the second time. Apparently there is a minimum diameter of the lead out groove at which the tonearm will return, and my TT is not adjusted properly. In other words, the adjustment on my TT is set just a smidgeon too small; it is looking for a position just inside of where many LPs have the last and final groove. I can move it manually toward record center and it will return on its own from there.

I think the DP52F is about identical to the 45F, just a few years newer. All the controls are identical, as are the displays on the front of the plinth.

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Re: Denon DP45F; Tone Arm Return

Post by tuber » 24 Jan 2017 12:32

I am by no means an expert here. Far from it, but I do have a dp-47f. It will occasionally need a little nudge to get the tonarm to move over to the record when I hit the start button. From reading other posts here on VE, I am leaning towards a recap. Sounds like it may be the fix for yours as well. I have had other components recapped, and i can say your Denon will benefit even if it doesnt fix that particular problem. Old capacitors often need replacing after 30 years or so.

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Re: Denon DP45F; Tone Arm Return

Post by wolfie62 » 24 Jan 2017 15:49

This recap idea is overblown, in my opinion. I have been building electronic circuits since I was 8 years old. I still have most of those circuits; They are now 47 years old with no problems with the electrolytic filter/bypass caps. I also have vintage tube radios from the 20s and 30s; they still work perfectly with very old caps original to the radio. Mind you, a good inspection is called for. If the caps are swollen, leaking, etc., replace them of course.

This problem I am having is an adjustment problem. So far, everything works, and logically "answers the call". Yours may be as well.

I have set up my electronic lab in my garage (vacuum tube O'scopes, powersupplies, soldering station, cabinets full of electronic components), after years of having my stuff in storage. I plan to study the servo circuitry closely; apparently there are lots of folks that experience problems with both the Denon TTs, as well as with the JVC servo TTs. I just bought a non-working Denon DP15F to "play" with off of EBay. Also, I just bought a 1980 JVC QL-Y5F that needs to be repaired (beautiful unit, but not working properly). I may not be able to get replacement Integrated Circuits; I may have to use Arduino boards to replace the logic to get the tables up and running. But, if I do that, I have to be sure I am making real, certifiable, improvements to the TTs, or I will never be able to resell them as "serviced" and working "properly".

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Re: Denon DP45F; Tone Arm Return

Post by EdAInWestOC » 24 Jan 2017 20:12

I have owned a DP-62L since I bought it new in 1983. I took superb care of that turntable and it still came up with an intermittent speed control issue. It would periodically lose servo lock and you could here the effects as the tone wavered.

In spite of what you think, electrolytic capacitors do have a finite lifespan. The electrolyte in the capacitor loses its capacitance (or whatever) and it goes out of spec. It has nothing to do with the cap swelling (that happens in power supply circuitry) and the capacitance of the capacitor can be critical depending on the type of circuit and the job the cap is doing.

I should not be surprised. If you look on the internet there will be people who dismiss anything as overblown. Unfortunately the idea of recapping a Denon turntable is not a hoax. It is important to get the turntable to perform reliably. The other thing required is to replace the main bearing and the tonearm bearings (no, they do not last forever).

This is not a crazy statement. Old gear will not last forever. Everything requires maintenance, including electronic components. Old, romantic sounding gear is all too often an indication of old out of spec coupling caps. Having to wait until components have warmed up for an extended period of time is usually an indication of old, out of spec filter caps.

They really do not sound great that way, please fix them. Great old gear deserves to be restored.

Ed

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Re: Denon DP45F; Tone Arm Return

Post by tuber » 24 Jan 2017 21:19

Ed, did the recap fix the speed control issue on the dp62? Just curious.

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Re: Denon DP45F; Tone Arm Return

Post by wolfie62 » 24 Jan 2017 22:05

I'm sure there are times when replacing electrolytic caps helps a situation in an electronic circuit.

I am a maintenance/reliability engineer by profession. I graduated from the Naval Academy in '84, minored in electrical engineering, majored in mechanical. Living near OC Maryland, I know that you know where that is. I design and specify both electrical/mechanical/electronic equipment and machinery, and write manuals and procedures on how best to keep the equipment running efficiently and economically.

First, let me say there is a wealth of knowledge on this site. Lots of great factual information and resources, and folks who really know their stuff about spinning vinyl, the mechanics/physics/results. When I was in "college", all I really knew was that most of the equipment was out of my price range. I had a simple NAD 5025 TT and the NAD 9200 cartridge. I had the Sherwood receiver, my roommate had the Boston Acoustics speakers and Tecnics DBX cassette deck. Enjoyed my/our music. After all these years, and exploring my inherited vinyl collection, I have a renewed interest in playing vinyl as do so many on this site.

Back to capacitors. Electrolytic caps are notoriously non-precise devices when brand new. +/- 20%, or more, tolerance from nominal value is normal. They are used in the circuits where large size (capacitance) and tolerance is not an issue, such as in power supplies. They are used for filters, mostly, an applications where exact value doesn't matter. They are SELDOM used in any critical signal path. Standard electrolytics are made from an aluminum can (outer) and spiral-wound foil sheets separated by (in many cases) waxed paper or plastic film. A non-corrosive electrolytic paste is used on the insulator between the aluminum sheets. So, the electrolyte paste does not lose its "capacitance".

In almost any use of electrolytics, look at any circuit board, (especially pre-1992), and the use of an electrolytic cap means there is a power supply section present; either main supply or sub-supply (bias circuit for example). I have dealt with many circuit failures over the last 33 years, in military aircraft avionics to industrial equipment; electrolytic cap failure is not the first place I look for root cause on a circuit board or system. Probing with an O'scope or meter and looking for voltage (or lack of)is far easier than replacing perfectly good caps. Usually diode failure or resister failure is the root symptom; root cause is badly spec'ed diodes or resistors (not spec'd for enough heat dissipation).

I think treating electrolytic caps as a precision device is foolhardy. Much faster just to probe the voltage from the power supply and look for deviations there. Shoot, if anyone is going to replace caps at a glance, in order to "improve" their device or equipment due its age, go ahead and replace the rectifier diodes too! And where do we stop? Start replacing worn out transistors while we're at it, why don't we?

Part of the love of playing vinyl is that it is very "hands on". Lots of satisfaction to be had from choosing equipment, setting it up, alignment, interconnects, cleaning, etc. Lots of subjective stuff to do.

But replacing capacitors as a "norm" on vintage equipment just doesn't work for me, until I have proven they are bad. And in all my years, and equipment over 90 years old, I haven't witnessed the justification for replacing electrolytic caps just because they are "there".

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Re: Denon DP45F; Tone Arm Return

Post by EdAInWestOC » 25 Jan 2017 20:24

tuber wrote:Ed, did the recap fix the speed control issue on the dp62? Just curious.
Yes it did.

Ed

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Re: Denon DP45F; Tone Arm Return

Post by EdAInWestOC » 25 Jan 2017 20:34

wolfie62 wrote:I'm sure there are times when replacing electrolytic caps helps a situation in an electronic circuit.

I am a maintenance/reliability engineer by profession. I graduated from the Naval Academy in '84, minored in electrical engineering, majored in mechanical. Living near OC Maryland, I know that you know where that is. I design and specify both electrical/mechanical/electronic equipment and machinery, and write manuals and procedures on how best to keep the equipment running efficiently and economically.

First, let me say there is a wealth of knowledge on this site. Lots of great factual information and resources, and folks who really know their stuff about spinning vinyl, the mechanics/physics/results. When I was in "college", all I really knew was that most of the equipment was out of my price range. I had a simple NAD 5025 TT and the NAD 9200 cartridge. I had the Sherwood receiver, my roommate had the Boston Acoustics speakers and Tecnics DBX cassette deck. Enjoyed my/our music. After all these years, and exploring my inherited vinyl collection, I have a renewed interest in playing vinyl as do so many on this site.

Back to capacitors. Electrolytic caps are notoriously non-precise devices when brand new. +/- 20%, or more, tolerance from nominal value is normal. They are used in the circuits where large size (capacitance) and tolerance is not an issue, such as in power supplies. They are used for filters, mostly, an applications where exact value doesn't matter. They are SELDOM used in any critical signal path. Standard electrolytics are made from an aluminum can (outer) and spiral-wound foil sheets separated by (in many cases) waxed paper or plastic film. A non-corrosive electrolytic paste is used on the insulator between the aluminum sheets. So, the electrolyte paste does not lose its "capacitance".

In almost any use of electrolytics, look at any circuit board, (especially pre-1992), and the use of an electrolytic cap means there is a power supply section present; either main supply or sub-supply (bias circuit for example). I have dealt with many circuit failures over the last 33 years, in military aircraft avionics to industrial equipment; electrolytic cap failure is not the first place I look for root cause on a circuit board or system. Probing with an O'scope or meter and looking for voltage (or lack of)is far easier than replacing perfectly good caps. Usually diode failure or resister failure is the root symptom; root cause is badly spec'ed diodes or resistors (not spec'd for enough heat dissipation).

I think treating electrolytic caps as a precision device is foolhardy. Much faster just to probe the voltage from the power supply and look for deviations there. Shoot, if anyone is going to replace caps at a glance, in order to "improve" their device or equipment due its age, go ahead and replace the rectifier diodes too! And where do we stop? Start replacing worn out transistors while we're at it, why don't we?

Part of the love of playing vinyl is that it is very "hands on". Lots of satisfaction to be had from choosing equipment, setting it up, alignment, interconnects, cleaning, etc. Lots of subjective stuff to do.

But replacing capacitors as a "norm" on vintage equipment just doesn't work for me, until I have proven they are bad. And in all my years, and equipment over 90 years old, I haven't witnessed the justification for replacing electrolytic caps just because they are "there".
That is not the point. You do not replace them because they are there. You replace them because they are old, out of spec devices that do not add one thing to the reliability of the device. Considering the low cost of an electrolytic cap and the high cost of dealing with unreliable components (the cost being your time), replacing an old cap is always a good idea.

Yes, you might save $0.15 to $0.85 by agonizing over the fact it may still work in its current application. Personally my time is worth more than that. I err on the side of reliability and replace all of them. I do not see the argument to not do it.

I'd rather know for sure that my turntable is good to go for another 20+ years. My DP-62L is.

Ed

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Re: Denon DP45F; Tone Arm Return

Post by wolfie62 » 25 Jan 2017 20:40

But, of course.

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Re: Denon DP45F; Tone Arm Return

Post by wolfie62 » 25 Jan 2017 20:46

Tell you what.....I'll make a video of me replacing the caps. First, I'll video the current working condition. Then, I'll video using my meter on the voltages at the power supply. Next, I'll replace the caps. Finally, video the end result....see if it fixes the problem. That way, success or failure, we can see what works and what doesn't. Most likely, I'll wind up making the adjustment on the variable resistor to fix the problem.

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Re: Denon DP45F; Tone Arm Return

Post by captmark » 26 Jan 2017 07:00

You can do all of that...and you'll still have the same problem with your Denon. If you can read a schematic (and it sure sounds like you can) you'll see where the LED someone else was talking about is not the platter sensor LED, but the one's that trigger the CDS sensors at the arm.

I was going to bust your butt a bit and let you trace that, but I'm guessing your post really wasn't as mean-spirited as it felt like on the first read. Plus I'm having a bad hair day and feel bloated-it must be that time of the month for me...

On page 8 of the owners manual and 11 of the service available here you'll see the set screw to adjust the arm drop position, which in turn adjusts the end position as the distance between is fixed. I'm betting you could tweak that a hair and fix your issue for now.

With the amount of time you spent explaining what caps do you could've done the recap! :-) But you are correct in that in this instance the recap would probably not fix your issue...replacing your CDS sensors and cleaning any gunk off those LED's that energize it is another story. The whole cap debate is for another time and a few more drinks, but if I had the skill set (wait... I do!) I would do the recap just because and then scope the VR settings afterwards.

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Re: Denon DP45F; Tone Arm Return

Post by captmark » 26 Jan 2017 07:21

tuber wrote:I am by no means an expert here. Far from it, but I do have a dp-47f. It will occasionally need a little nudge to get the tonarm to move over to the record when I hit the start button. From reading other posts here on VE, I am leaning towards a recap. Sounds like it may be the fix for yours as well. I have had other components recapped, and i can say your Denon will benefit even if it doesnt fix that particular problem. Old capacitors often need replacing after 30 years or so.
Tuber- there are 2-3 things you need to do to fix your issue-none of which involve a recap, though as I just mentioned in another post I am a firm believer in the benefits of clean living and a fresh upgrade in any non-audio path circuit...OK at least the upgrade...

Things to do/check:

1) There is a small rod with a nylon tip on the end of it next to your arm that rides a semi-circle strip around the back of your arm. Wipe/degrease that strip down clean of any dirt or gunk on it, as well as the nylon tip. If it still sticks you can put a fine coat of oil/lube on it, but do this 2nd thing next.

2) Look to see how high your arm lifts when cueing/moving-I'm guessing it is all the way up. That set screw on the opposite end of the nylon tip adjusts how high the arm lifts, and hence how much pressure is pushing on the nylon tip. If you can adjust that down just a bit you will notice an improvement.

3) This is in lieu of you not feeling you can do #4 below... Remove your headshell, and quickly flip your tonearm back and forth across all of it's travel, end to end but especially near the rest position several times. Reinstall your headshell and rebalance the arm just in case the flipping moved the counterweight. The oil on the bearings dries and gums up at the rest position and this should loosen it up.

4) Remove the bottom (pull the platter and remove the headshell) You will see the bearings right at the end of the threads that mount the arm to the base. I use some fancy synthetic shite but 3 in one or even WD-40 sprayed in there and do #3 above will get you back to good.

Now let me take a few paragraphs to explain how variable resistors work... DOH I am an a-hole tonight!! :twisted:

Guest

Re: Denon DP45F; Tone Arm Return

Post by Guest » 26 Jan 2017 08:59

WD40?
Anywhere NEAR a turntable?
I wouldn't hire ANYone who used that crap.
Amateurs.

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