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

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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.
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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.
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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.
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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.
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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.
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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.
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