Denon DP-80 blowing fuses

[patslice]

Hey guys!
I'm helping a friend repairing his beautiful Denon DP-80.
About a week ago, he turned it on without using the step-down transformer; so our denon got a 220V charge instead of a 100V. The plate spinned a few seconds then stopped.
The 1.6A 30mm fuse was blown, we tried to swap it with a few 1.6A smaller slow-burning fuses (20mm) but they kept blowing as soon as the device was powered.
There's no sign of warn out components, no smoke, no burned parts, no leaking or curved caps...
Where could the problem be most likely?
I don't have a multimeter right now but hopefully soon, which component is the main suspect? (service manual attached)

Thanks for your help!

 

[w1jim]

My suspicion is that you've destroyed the primary circuit of the transformer.
Disconnect the transformer (looks like a connector) and measure the resistance across the primary - I'm betting it's going to be very low.

 

[tnsilver]

I don't have a multimeter right now but hopefully soon

That's alright, I can teach you how to measure voltage with a ball point pen refill, a cigarette filter and a banana peel.

 

[revox-b77]

I can teach you how to measure voltage with a ball point pen refill, a cigarette filter and a banana peel.

Ok, I'm game.

 

[petehall347]

. plenty of stuff after that fuse to go shorted . transistors diodes etc . i would unplug everything that unplugs and trace the short circuits .

 

[Freddymac2]

Do us all a favor and take it to a knowledgable denon qualified tech. That unit is very complex and you are just going to destroy it. Maybe I am blunt, but that is a fine piece of equipment, that you will have to sell for parts.

 

[patslice]

Do us all a favor and take it to a knowledgable denon qualified tech. That unit is very complex and you are just going to destroy it. Maybe I am blunt, but that is a fine piece of equipment, that you will have to sell for parts.

Thanks for the (useless and arrogant) advice guys, with a new transformer everything works fine!

 

[fiddlefye]

Thanks for the (useless and arrogant) advice guys, with a new transformer everything works fine!

Glad to hear you got things back up and running with the change of transformer. In this case I'm not entirely surprised as my tech mentioned to me that the circuitry after the power supply is pretty well isolated.

 

[Freddymac2]

Maybe we are all useless and arrogant, but the fact that you didn't have a meter made me think that you did not belong inside that piece of equipment. I believe the second post pointed you in the right direction, so all of us are not useless. We all try to keep AKers from destroying equipment with our best guess due to our experience. Sorry!

 

[tnsilver]

Seriously? You nincompoops fry a turntable in such a stupid way, come to us for advice on electronics without even having a meter and you dare complain?

 

[bimasta]

Thanks for the (useless and arrogant) advice guys, with a new transformer everything works fine!

I hesitate to comment, as I had no role in the main conversation. But you need an attitude transformer, Patrick. Strangers who don't even know you try to help you with good advice and their reward is extreme rudeness. Is the friend you were trying to help your only friend? Your arrogance is quite something — you started by posting the service manual and asking us to go through it for you, and solve your problem for you. Why on earth would we when you're such a c--t?

 

[fiddlefye]

In all seriousness - the DP-80 is very serious piece of kit and was made in truly tiny numbers, I gather just a bit over 1,600 in total. I wouldn't take any unnecessary risks with one.

 

[bimasta]

the DP-80 is very serious piece of kit and was made in truly tiny numbers, I gather just a bit over 1,600 in total. I wouldn't take any unnecessary risks with one.

Only 1600? Do you think that's a reliable number, Fiddlefye? I ask because I have a DP80, and I treat it with kid-gloves because it's so good, and I'd feel awful if I damaged it. But I had no idea it was so rare — it's not reflected in the current resale prices, which are less than a new crap Project.

 

[majick47]

I'v done quite a bit of reading and talked with a number of owners re the DP-80, I never ran across any production figures and "assumed" they were fairly common as far as high end tables go with a fair amount of use in broadcast and recording along with sales to serious audiophiles. I'v read that the flagship Denon DP-100 only numbered about 400. Due to all the fake news from the British audio press the top tier direct drive tables like the DP-80 were ignored and were available to those that could appreciate them at reasonably low prices. As a couple members have mentioned the DP-80 has fairly complicated circuitry and any repairs should be left to a professional, if anyplace has skilled professionals it should be Switzerland.

 

[bimasta]

I'v done quite a bit of reading and talked with a number of owners re the DP-80

So you must have learned a lot, Majick, besides production numbers. Why the interest? Do you have one?

From all that research, you may be able to help me. I haven't used my DP80 is about 5 years. It worked perfectly then, but I'm paranoid about powering it up after a 5-year slumber, having heard horror tales of old caps destroying all the unobtainum chips. The "Doorstop" theory. I will use a Variac to bring it up slowly, but still I worry — a cap may fail later. As Freddymac said above, it's too good to risk damaging it. But the cost of shipping it back and forth to a pro, plus his charges, is prohibitive.

"Full recap" of everything seems to be a core belief here at AK, and I have enough skill to replace caps (if I can find them) — but is that overkill? And in my experience, old circuits boards can be very fragile, with thin copper traces coming lose and breaking. If I eff it up, I'll be bummed out for months.

Any guidance you can offer will be very welcome.

 

[fiddlefye]

So you must have learned a lot, Majick, besides production numbers. Why the interest? Do you have one?

From all that research, you may be able to help me. I haven't used my DP80 is about 5 years. It worked perfectly then, but I'm paranoid about powering it up after a 5-year slumber, having heard horror tales of old caps destroying all the unobtainum chips. The "Doorstop" theory. I will use a Variac to bring it up slowly, but still I worry — a cap may fail later. As Freddymac said above, it's too good to risk damaging it. But the cost of shipping it back and forth to a pro, plus his charges, is prohibitive.

"Full recap" of everything seems to be a core belief here at AK, and I have enough skill to replace caps (if I can find them) — but is that overkill? And in my experience, old circuits boards can be very fragile, with thin copper traces coming lose and breaking. If I eff it up, I'll be bummed out for months.

Any guidance you can offer will be very welcome.

As you probably noted my DP-80 proved to be a doorstop when it arrived and my tech fired up for the first time. It is indeed a very complex circuit. According to my tech (who researched a whole raft of the Denon DD drives in the process of trying to get it running) it is much more complex than even the DP-75 to which it is superficially similar and uses completely different chips. As to the caps - I understand that (unlike many tables) most of those used are metal film and have long lifespans. Even with all of the research he did my tech still didn't have enough information to get the drive running, but I have found someone who works with them all the time and confidently tells me he will get it up to snuff. I will have to ship it a long way, but in the case of a DP-80 it is well worth it!

As to the production numbers; I forget now where I encountered them, but I believe they were accurate - 1,691 or 1,695 (I forget which). The DP-75 was made in much greater numbers, relatively speaking.

 

[majick47]

Since the DP-80 has sat idle for 5 years using a Variac to bring it up slowly is a wise move and if I was to bet it will work perfectly as before. Unless there is any obvious signs of bulging caps etc I would leave well enough alone and not follow the AK core belief to replace all the caps. God knows how many perfectly good low hour excellent quality stylus have been tossed due to another AK core belief. It really depends on the history/ownership of the table, if it lived its entire life in the US/Canada since the early 1980s in a loving audiophile home I'd say you are on solid ground for many more years of reliable use. I assume you have a decent quality step down transformer of adequate rating preferably one made in Japan. Once up and running use it on a regular basis, they were built for years of reliable use in a broadcast setting and your use wont make a dent. Like Mr Pig I own a DP-75 in a VPI plinth with the exception of having a Technics EPA-100 tonearm. Fiddlefye as per your production numbers for the DP-80 of 1,600 that is very possibly correct. This is going by memory from reading years ago about the market shares of the big three, Denon, Technics, Sony and JVC tables that were used by pros in broadcast and recording. Denon did well in Japan with what appeared to be a contract with NHK. Technics managed to vastly outsell Denon on a world wide basis due to excellent marketing, Sony and JVC to even a lesser degree dropped the ball completely. The individual tables were very competitive but the companies weren't equally as good marketing their top tier professional tables. I did a search at HiFido going back as far as it allowed and the number of DP-80 tables they sold wasn't all that many. Sales of the DP-80 to audiophiles in the US/Canada was probably fairly low in number.

 

[fiddlefye]

Since the DP-80 has sat idle for 5 years using a Variac to bring it up slowly is a wise move and if I was to bet it will work perfectly as before. Unless there is any obvious signs of bulging caps etc I would leave well enough alone and not follow the AK core belief to replace all the caps. God knows how many perfectly good low hour excellent quality stylus have been tossed due to another AK core belief. It really depends on the history/ownership of the table, if it lived its entire life in the US/Canada since the early 1980s in a loving audiophile home I'd say you are on solid ground for many more years of reliable use. I assume you have a decent quality step down transformer of adequate rating preferably one made in Japan. Once up and running use it on a regular basis, they were built for years of reliable use in a broadcast setting and your use wont make a dent. Like Mr Pig I own a DP-75 in a VPI plinth with the exception of having a Technics EPA-100 tonearm.

I would agree wholeheartedly with this assessment. I would also add that according to my tech the actual "working" circuitry in the DP-80 is unusually well isolated by the power supply from the "outside world". I also agree that simply dumping any stylus that comes through the door without a good inspection first is a horrendous waste. I have had countless carts arrive with a perfectly good stylus that I got very long "afterlife" from.

It will probably take a few more weeks, but I have to say I am really looking forward to getting my DP-80 up and running finally. I suppose one must learn patience and good things come to those who have it - something like that!

 

[bimasta]

It really depends on the history/ownership of the table, if it lived its entire life in the US/Canada since the early 1980s in a loving audiophile home I'd say you are on solid ground for many more years of reliable use. I assume you have a decent quality step down transformer of adequate rating preferably one made in Japan.

Thanks so much, Fiddlefye and Majick. Very reassuring, especially the long-lasting nature of the original caps. Really sets my mind at rest. I will examine whatever 'lytics it contains, as I have to go inside anyway to clean/relube the bearing.

I'm second owner, or so I was told by the dealer, whom I know well and trust completely — and it came in the VPI plinth, suggesting the first owner was serious about his audio. Oddly, it came with a Linn Basik Plus arm and Blue Point Special cart (bent cantilever), many steps down in quality from the TT — maybe the owner removed a better arm and added the Basik just so it was "complete". I sold the arm for more than the entire system cost me.

I have a stepdown I used with it previously. Chinese, but seems very solid. Tests at 100.9V with no load, and it's fused for further protection — not your average cheap stepdown. Rated for 100W so no concerns there, as I think the TT draws 14V.

As for the stylus question, I refurbished a very shabby Thorens TD150 for a client awhile back. It had a Stanton 881S. He said "Just toss that shitty old cartridge." I gave him an OM10 in its place and he was delighted (I regret that now because the OM's are pretty good, and he'd have been delighted with anything). The Stanton's stylus had so much hardened crud I couldn't even see a stylus, and thought it really might be useless — but after a very thorough clean, using every technique I know, including a scalpel, the Stereohedron was shining in the dark. And amazingly, it showed almost no wear under 150X. My first 881 — what a fine cartridge. So I'll never "just toss" any styus. Diamonds last so much longer than they were rated for (just to make you buy a new one).

Thanks again gentlemen, for the good news on the DP80 — and I know it has a solid basis, not just AK hearsay.

 

[fiddlefye]

Thanks so much, Fiddlefye and Majick. Very reassuring, especially the long-lasting nature of the original caps. Really sets my mind at rest. I will examine whatever 'lytics it contains, as I have to go inside anyway to clean/relube the bearing.

I'm second owner, or so I was told by the dealer, whom I know well and trust completely — and it came in the VPI plinth, suggesting the first owner was serious about his audio. Oddly, it came with a Linn Basik Plus arm and Blue Point Special cart (bent cantilever), many steps down in quality from the TT — maybe the owner removed a better arm and added the Basik just so it was "complete". I sold the arm for more than the entire system cost me.

I have a stepdown I used with it previously. Chinese, but seems very solid. Tests at 100.9V with no load, and it's fused for further protection — not your average cheap stepdown. Rated for 100W so no concerns there, as I think the TT draws 14V.

As for the stylus question, I refurbished a very shabby Thorens TD150 for a client awhile back. It had a Stanton 881S. He said "Just toss that shitty old cartridge." I gave him an OM10 in its place and he was delighted (I regret that now because the OM's are pretty good, and he'd have been delighted with anything). The Stanton's stylus had so much hardened crud I couldn't even see a stylus, and thought it really might be useless — but after a very thorough clean, using every technique I know, including a scalpel, the Stereohedron was shining in the dark. And amazingly, it showed almost no wear under 150X. My first 881 — what a fine cartridge. So I'll never "just toss" any styus. Diamonds last so much longer than they were rated for (just to make you buy a new one).

Thanks again gentlemen, for the good news on the DP80 — and I know it has a solid basis, not just AK hearsay.

I love that tale of the 881S. I've never owned one, though I've heard a couple. They were definitely something a bit special.

As the there being a Basik on there when you got the table - back when these were new the selection of arms wasn't as vast as what we have to work with these days. The Basik was a pretty highly regarded arm at the time as far as I can tell. I'm not sure what else might have been in that location at the same spindle to pivot in those days? If you got more for the Basik when you sold it than you paid for the whole shootin' match then you got one whale of a deal!