the home of the turntable

Anyone out there who know the Denon DP-80/75 Really well?

deeply dp

Anyone out there who know the Denon DP-80/75 REALLY well?

Postby fiddlefye » 06 Jan 2018 04:53

A couple of months back I picked up a Denon DP-80 with a nice two-arm plinth. It was sold by a reputable audio seller as "functions perfectly, strobe burned out". I took it to my tech to go through and he immediately found that while the lights came on there was no function at all. After some investigation it was found that the control chip was dead. My tech tracked down a new replacement (a considerable feat) which arrived recently and it was hoped that replacing the dead chip would get things back up and running.

This is where it becomes mysterious. The new chip seems to be doing what it is supposed to and producing what appears to be an appropriate signal. The "comparators" in the circuit both seem to be functioning. The components in the passive circuitry all individually test perfectly, but for some reason the signal gets stopped at each of the stages. Bypass a sector of the passive circuit and the signal continues on only to be stopped at the next location in the chain. We have the service manual with the circuit diagrams etc. but it doesn't say anything about what the circuits actually do. My tech is an extremely bright and experienced guy, but without knowing what is supposed to happen he is stumped at this point.

Are there any techs out there anywhere who know how these circuits actually work and could either advise or take on getting things up and running? Apart from the electronic issues (whatever they might be) the drive is in terrific cosmetic condition etc. The seller swears on a stack of Bibles that the deck was running correctly when sold and isn't backing off on that. I've bought other items from him in past and they were always exactly as presented. I could probably really pressure him for a refund, but to be quite honest I would much rather have a functional DP-80.

If anyone has any ideas I can scan copies of the circuit diagram with the problem areas highlighted.
fiddlefye
member
member
 
Posts: 45
Images: 3
Joined: 06 Feb 2009 05:00
Location: Windsor, Ontario

Canada

Re: Anyone out there who know the Denon DP-80/75 REALLY well

Postby Spinner45 » 06 Jan 2018 06:53

I would tend to think that since you admitted to having replaced parts in this unit, that asking for a refund is now out of the question.
In other words, "voiding the warranty" as such.
Better to have discussed returning it immediately if a problem was noticed.

A lot of techs are not versed on every possible repair, so perhaps finding someone who's worked on those before is the answer.
Also, since parts have been replaced, other issues may have cropped up, making troubleshooting more difficult.
Spinner45
long player
long player
 
Posts: 1918
Joined: 01 Mar 2017 18:21

United States of America

Re: Anyone out there who know the Denon DP-80/75 REALLY well

Postby sivagriva » 06 Jan 2018 09:52

I'm no expert at all, but found some useful info (for my DP60L) here. It's a Japanese site, but on my mac is translated automatically.
sivagriva
member
member
 
Posts: 80
Images: 10
Joined: 26 Dec 2014 01:18

Slovenia

Re: Anyone out there who know the Denon DP-80/75 REALLY well

Postby fiddlefye » 06 Jan 2018 16:47

Spinner45 wrote:I would tend to think that since you admitted to having replaced parts in this unit, that asking for a refund is now out of the question.
In other words, "voiding the warranty" as such.
Better to have discussed returning it immediately if a problem was noticed.

A lot of techs are not versed on every possible repair, so perhaps finding someone who's worked on those before is the answer.
Also, since parts have been replaced, other issues may have cropped up, making troubleshooting more difficult.

I actually did discuss the situation immediately and extensively with the seller and he was quite adamant that the table was running properly before it shipped. All of the discussion was in writing so there is a complete record of it all. The replacement chip was a result of that discussion and the sole part change made. The new chip runs whereas the old one did outputted nothing. Given there was no physical damage involved at all there was no possibility of that being a cause for the problem.

The point is that there really must be a solution to the issues, if only we knew the drive better. My tech is highly experienced, but with no definite knowledge of how the circuit is supposed to operate he has hit a dead end in terms of time investment. He would be happy to do some more work if he were not groping in the dark quite so much.

Finding someone who has worked on these drives is exactly the point to this posting, actually.
fiddlefye
member
member
 
Posts: 45
Images: 3
Joined: 06 Feb 2009 05:00
Location: Windsor, Ontario

Canada

Re: Anyone out there who know the Denon DP-80/75 REALLY well

Postby Spinner45 » 06 Jan 2018 19:58

fiddlefye wrote:
Spinner45 wrote:I would tend to think that since you admitted to having replaced parts in this unit, that asking for a refund is now out of the question.
In other words, "voiding the warranty" as such.
Better to have discussed returning it immediately if a problem was noticed.

A lot of techs are not versed on every possible repair, so perhaps finding someone who's worked on those before is the answer.
Also, since parts have been replaced, other issues may have cropped up, making troubleshooting more difficult.

I actually did discuss the situation immediately and extensively with the seller and he was quite adamant that the table was running properly before it shipped. All of the discussion was in writing so there is a complete record of it all. The replacement chip was a result of that discussion and the sole part change made. The new chip runs whereas the old one did outputted nothing. Given there was no physical damage involved at all there was no possibility of that being a cause for the problem.

The point is that there really must be a solution to the issues, if only we knew the drive better. My tech is highly experienced, but with no definite knowledge of how the circuit is supposed to operate he has hit a dead end in terms of time investment. He would be happy to do some more work if he were not groping in the dark quite so much.

Finding someone who has worked on these drives is exactly the point to this posting, actually.


Indeed, the design of this unit is quite complex, so yes even experienced techs have a problem with it.
Hopefully you'll locate one that's had the needed experience to troubleshoot it.
Of course it would have to be a "hands on" situation, it's the only way.

And I'd shy away from that seller from now on, no matter what their ratings are.
Some "ratings" I know are fake, and that's the beauty of being "annonomous online sellers" - they can always get away with having false claims.
Spinner45
long player
long player
 
Posts: 1918
Joined: 01 Mar 2017 18:21

United States of America

Re: Anyone out there who know the Denon DP-80/75 REALLY well

Postby fiddlefye » 06 Jan 2018 21:08

In the case of this particular seller I had bought a number of items from him previously. All had been precisely as described and nicely packed when shipped. He isn't exactly anonymous as I actually know where he lives, though I have not been to his house. He has been in the business quite a long time and usually has some very nice things for sale.

So yes, hoping someone turns up here or elsewhere who actually knows these drives and can troubleshoot it. I'd be more than happy to ship it to wherever it needs to go or put my tech (who is highly knowledgeable, just not with this drive) in touch if that seems an easier path.
fiddlefye
member
member
 
Posts: 45
Images: 3
Joined: 06 Feb 2009 05:00
Location: Windsor, Ontario

Canada

Re: Anyone out there who know the Denon DP-80/75 Really well

Postby fiddlefye » 02 Feb 2018 06:06

The drive is heading out west to California to Peter Noerbaek to get restored. He knows the drives really well and assures me he definitely can put it in first class shape. So the project will be much longer coming to fruition than planned and at considerably greater expense, but I think it will all be worth it in the end.
fiddlefye
member
member
 
Posts: 45
Images: 3
Joined: 06 Feb 2009 05:00
Location: Windsor, Ontario

Canada

Re: Anyone out there who know the Denon DP-80/75 Really well

Postby EdAInWestOC » 06 Feb 2018 16:05

Contact Peter Noerbeck at PBN Audio http://www.pbnaudio.com/.

Peter rebuilds Denon turntables and places them in custom plinths. It may not end up being cheap but you will end up with a turntable that you will treasure for the rest of your life.

Ed
EdAInWestOC
long player
long player
contributor
 
Posts: 1284
Images: 73
Joined: 03 Feb 2004 02:39
Location: Glen Burine, MD USA

United States of America

Re: Anyone out there who know the Denon DP-80/75 Really well

Postby fiddlefye » 10 Feb 2018 17:16

EdAInWestOC wrote:Contact Peter Noerbeck at PBN Audio http://www.pbnaudio.com/.

Peter rebuilds Denon turntables and places them in custom plinths. It may not end up being cheap but you will end up with a turntable that you will treasure for the rest of your life.

Ed
Ed, that is exactly what I did! Wonderful fellow to deal with. The drive will be heading home Monday with a new main chip, all caps and transistors replaced, the bearing serviced and new foam between the platters - basically as close to a brand new machine as one could find. The cosmetics on the unit as as-new so it really is like getting a new deck.

I didn't think the cost was at all unreasonable for the work done and given I got the table for a really good price in the first place the overall cost will still be less than a lot of unrestored units are selling for these days. Peter's reimagined Denon-based tables are gorgeous and I'd love to see (and hear) one "in the flesh".
fiddlefye
member
member
 
Posts: 45
Images: 3
Joined: 06 Feb 2009 05:00
Location: Windsor, Ontario

Canada

Re: Anyone out there who know the Denon DP-80/75 Really well

Postby EdAInWestOC » 13 Feb 2018 20:54

fiddlefye wrote:
EdAInWestOC wrote:Contact Peter Noerbeck at PBN Audio http://www.pbnaudio.com/.

Peter rebuilds Denon turntables and places them in custom plinths. It may not end up being cheap but you will end up with a turntable that you will treasure for the rest of your life.

Ed
Ed, that is exactly what I did! Wonderful fellow to deal with. The drive will be heading home Monday with a new main chip, all caps and transistors replaced, the bearing serviced and new foam between the platters - basically as close to a brand new machine as one could find. The cosmetics on the unit as as-new so it really is like getting a new deck.

I didn't think the cost was at all unreasonable for the work done and given I got the table for a really good price in the first place the overall cost will still be less than a lot of unrestored units are selling for these days. Peter's reimagined Denon-based tables are gorgeous and I'd love to see (and hear) one "in the flesh".


I'm glad it worked out for you...

If you don't mind another recommendation. Peter makes a phono preamp that is outstanding. He makes very expensive ones and then one that is more reasonable and direct to buyer pricing.

The phono preamp is the Liberty Audio B2B-1. If you like Peter's work on your turntable, you will adore his phono preamp. I have owned the B2B-1 for 2 years now and it is the quietest phono preamp I have ever heard.

Quiet is the name of the game in phono preamps and Peter's B2B-1 is an all class A, all FET preamp that is outstanding from every aspect. It is quiet, neutral, extremely dynamic and stunning.

The B2B-1 would demande over $5000 if it were sold through normal channels but it is sold direct to consumers. Michael Fremer has it listed as one of the best phono preamps in its class. Very, very highly recommended.

Peter is justifiably proud of the B2B-1. If you are in the market for a phono preamp it is more than worth your time. Don't let the $2000 price tag cloud your thinking. It is much, much better than its asking price.

Ed
EdAInWestOC
long player
long player
contributor
 
Posts: 1284
Images: 73
Joined: 03 Feb 2004 02:39
Location: Glen Burine, MD USA

United States of America

Re: Anyone out there who know the Denon DP-80/75 Really well

Postby fiddlefye » 19 Feb 2018 06:38

I have a friend who has Peter's phono pre and loves it. On my list after a few other things get dealt with.

The DP-80 is back home and running perfectly. What a magnificent beast it is! I have a bit of work to finish on the plinth and a couple of arms to get mounted yet. With a bit of luck I will be listening to it all by next weekend.
fiddlefye
member
member
 
Posts: 45
Images: 3
Joined: 06 Feb 2009 05:00
Location: Windsor, Ontario

Canada

Re: Anyone out there who know the Denon DP-80/75 Really well

Postby Legrace » 19 Feb 2018 13:36

Some great info in here for owners of these drives. And rather timely, as in a few days I'll be powering up a new to me DP-80, when the voltage transformer I ordered is delivered. The ad also said in perfect working order but nevertheless I know with vintage gear you always hold your breath on first turning things on. I hope its as described, but at least I know where to go if I find a glitch.

Glad you got yours working, hope you share some pics as sounds like it will be an impressive setup.
Legrace
long player
long player
 
Posts: 1272
Joined: 23 Nov 2015 21:17

Canada

Re: Anyone out there who know the Denon DP-80/75 Really well

Postby fiddlefye » 19 Feb 2018 17:03

Seeing as how you too are in Canada I wonder if you didn't get your DP-80 from the same chap? He had a few and a DP-75 at one point.

BTW - though at this point we will never know why the drive didn't fire up for my tech, Peter said the initial chip was actually viable except for the lead-out for the strobe having failed. Exactly the issue the seller mentioned in the listing. He just wasn't aware that it was an issue on the chip rather than a burned out bulb.

Yes, I will post some pics when it all comes together. Initially I was rather upset with all of the issues I had with my DP-80, but in the end I am viewing them more as a blessing as everything that could be serviced now has been. Not what I planned, and if I had paid "top dollar" in the first place I might have been a bit ticked - or not.

The thing with units like the DP-80 is that once one gets to that level (regardless of drive type preference) one is pretty much in an "end game" scenario for most of us. Installed in a good plinth with a fine arm it is going to be very hard (and expensive) to improve on the possibilities. Some of these drives really represent a major bargain in terms of price vs. performance. We shall see how long that holds up I guess!

It really is something starting up the DP-80. Press a button, the strobe comes on and it is turning up to speed instantly, but in stately majesty. No fuss, no bother. Chances are that the only sound you hear until the diamond hits the groove is a little hum from the transformer.

I have a two-armed plinth to work with (came with the drive) and will mount a NOS Audio Craft AC-400C (12" unipivot) in No.1 spot and a Sumiko MMT out back. I would eventually like something better on the rear board, but for starters the MMT will be fine. Easy to set up and work with and fairly flexible in terms of cart possibilities.
fiddlefye
member
member
 
Posts: 45
Images: 3
Joined: 06 Feb 2009 05:00
Location: Windsor, Ontario

Canada

Re: Anyone out there who know the Denon DP-80/75 Really well

Postby Legrace » 19 Feb 2018 19:09

Wow, I'm guessing you must have some pretty sweet cartridges lined up as well given that lot. :shock:

Separately I have a DK-110 plinth coming from Japan. Arm and cartridge will be transplanted from table 1 in my sig. The cartridge was actually a primary motivation for this purchase, and so the never ending upgrade cycle continues.
Legrace
long player
long player
 
Posts: 1272
Joined: 23 Nov 2015 21:17

Canada

Re: Anyone out there who know the Denon DP-80/75 Really well

Postby Spinner45 » 19 Feb 2018 20:47

fiddlefye wrote:It really is something starting up the DP-80. Press a button, the strobe comes on and it is turning up to speed instantly, but in stately majesty. No fuss, no bother. Chances are that the only sound you hear until the diamond hits the groove is a little hum from the transformer.


In the "better" designs, power transformers are shock-mounted, usually with some type of rubber/neoprene grommets or casing.
This will effectively silence any residual buzzing.
Spinner45
long player
long player
 
Posts: 1918
Joined: 01 Mar 2017 18:21

United States of America

Next

Return to Denon