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Old 9th Apr 2019, 7:02 am   #21
AD360 Rob
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Default Re: Dansette Major seems a bit quiet.

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That HT voltage reading is a bit strange - is something dragging it down?

You do realise that you MUST completely disconnect the old rectifier when 'tacking' in a diode. Fitting it it series or paralleling it across the old rectifier should NOT be done. The old rectifier as well as having increasing forward resistance due to age, may also have some reverse leakage.

I suspect a cartridge problem. The old SX5H will likely be lower on output due to its age and the SC12H is basically equivalent to a medium output cartridge, regardless of it having the 'H' suffix.

I would also agree with others regarding checking such things as the cathode bypass capacitor etc.

Of course I disconnected the original rectifier completely when trying the silicon one, the job will be made permanent once the relevant parts arrive from the suppliers. I do intend to check all the capacitors in the smoothing can as I agree, there does seem to be a higher than I would expect drain on the HT supply once the valve has warmed up.
In reality, the level of output isn't that concerning, there's enough not to warrant trying to find an even higher output cart than the SX6H currently fitted (which is only 100mv lower than the TC8H. If in time it does become an issue then I can always fit a preamp. Currently cleaning up the cabinet and hardware and debating whether to spend the £38 asked by a supplier for new bronze fittings. . . probably won't as I'm not recovering it and the tarnished originals are part of the player's history.
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Old 9th Apr 2019, 8:17 am   #22
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Default Re: Dansette Major seems a bit quiet.

From my own experimentation, an SC12H can give just about adequate listening volume with a single stage amplifier (EL84). A Chinesium red-stylus special was not quite loud enough.
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Old 9th Apr 2019, 8:44 am   #23
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Default Re: Dansette Major seems a bit quiet.

The readings for this particular circuit is typically around 210VDC @ 40mA, measured at the output of the rectifier. Any slight variation from this will not make much difference to the volume.
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Old 9th Apr 2019, 10:02 am   #24
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Default Re: Dansette Major seems a bit quiet.

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Originally Posted by julie_m View Post
From my own experimentation, an SC12H can give just about adequate listening volume with a single stage amplifier (EL84). A Chinesium red-stylus special was not quite loud enough.
Yes, it can give an adequate output from 78s and most 45s (not so much on EPs) but when playing less heavily modulated LPs, the output will be lacking. And by running those EL84-only amps at full volume makes one more aware of the hum and noise levels when playing these basic amplifiers at maximum.
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Old 14th Apr 2019, 5:21 pm   #25
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Default Re: Dansette Major seems a bit quiet.

Afternoon all, back on the electronics side of things after cleaning up the cabinet (not replacing the hardware with new as the "patina" is part of the players history). Diode and surge resistor fitted to a little tag strip. Am I correct in assuming the resistor should be fitted to the output of the rectifier? (never done this before). I also removed and tested the main smoothing can, all sections measured over value for capacitance but not alarmingly so, no leakage on the avo but on the Chinese multi magic tester, the esr was higher than I would expect for the values of electrolytics in the can. In particular the 25uf cathode cap measured over 90 ohms esr. Is the capacitance of this particular cap critical? Which way should I go with a replacement? 22uf or 33uf? I've never had to replace one before without having the exact value to hand (thanks to M. O. D. bulk purchasing)
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Old 14th Apr 2019, 5:28 pm   #26
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Default Re: Dansette Major seems a bit quiet.

The resistor and diode are in series and nothing else is connected to the junction between them, so it literally makes no difference which way around you connect them. By the Principle of Equivalence, nothing you could connect to the two terminals could determine whether the resistor was connected to the anode or the cathode, or if two separate resistors each of half that value were in series with each lead. The resistor will slow the passage of the electrons a bit; the diode will block them altogether if they are trying to go the wrong way; and the overall effect will be the same, whichever one the electrons encounter first.

22µF would be fine if you didn't have a 33µF capacitor to hand; but anything up to 100µF will do really. The idea is for this capacitor to be as large as possible, so that the voltage change due to it charging and discharging is not enough to upset the cathode bias voltage and therefore the amplifier's DC operating point. Otherwise, it would have a much lower gain.
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Old 18th Apr 2019, 9:20 am   #27
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Default Re: Dansette Major seems a bit quiet.

Morning all, a further little update on the Dansette.
The new electrolytics arrived and have been fitted along with appropriate insulated wire links for the negative connections, the 1N4007 and 220 ohm resistor have been permanently fitted on their new tagstrip. a quick test using my phone as a source revealed no massive increase in max volume BUT a marked reduction in hum level (which was low before) so a worthwhile exercise. Now I'm waiting for new motor mounting grommets to arrive, the old ones look to be in good condition and are still pliable but seem to have sagged a little meaning the idler tends to run on the very edge of each step on the motor shaft resulting in a reduction of torque.
One question I do have relates to earthing. Currently, the player has no mains earth. I'd like to add this but am a little confused as all the metalwork (amp chassis and deck chassis) is connected to HT and signal negative. I wouldn't have thought it acceptable to connect mains earth to the metalwork in its current configuration. It's easy enough to isolate the deck from the chassis, I just disconnect the link on the tagstrip that carries the signal wires but the amp has several points connected to the metal chassis (p.c. board riveted in place) Your sage advice would be much appreciated.

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Old 18th Apr 2019, 12:48 pm   #28
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Default Re: Dansette Major seems a bit quiet.

IF the Major has an isolating transformer feeding the amplifier then you can simply earth the deck and chassis as the HT- and signal -ve will be isolated from the mains anyway. If it doesn't then earthing anything is bad news. Simply make sure that NEUTRAL is connected to amp chassis and ideally fit an RCD type mains plug. Any cartridge isolating capacitors should be Y-rated type(s).
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Old 18th Apr 2019, 7:00 pm   #29
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Default Re: Dansette Major seems a bit quiet.

The Dansette Major has an EL84 valve supplied by a proper power transformer and early semiconductor rectifier, but only a 2-core power lead. The amplifier chassis should not be connected to the mains.

Earthing the changer metalwork will be fine. Test it with a rechargeable battery to make sure your earth connection will withstand enough current to blow a 3A fuse.
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Old 18th Apr 2019, 10:57 pm   #30
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Default Re: Dansette Major seems a bit quiet.

Hi Rob,

I'm doing one of these for my daughter.
Single EL84 and "proper" transformer with metal rectifier(half wave).
HT in my case is 237 volts. EL84 cathode volts 4.5 across 102 ohms( approx. 45mA then, so not too bad. Check screen volts (fed by big 10K resistor on mine, but some have 47K) as well. It should be nearly HT.
Haven't had it running for a while but as I remember volume was adequate. If you need the volume at "11" then you could always modify it to use an ECL82.
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Old 19th Apr 2019, 8:45 am   #31
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Default Re: Dansette Major seems a bit quiet.

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Originally Posted by julie_m View Post
The Dansette Major has an EL84 valve supplied by a proper power transformer and early semiconductor rectifier, but only a 2-core power lead. The amplifier chassis should not be connected to the mains.

Earthing the changer metalwork will be fine. Test it with a rechargeable battery to make sure your earth connection will withstand enough current to blow a 3A fuse.
That was my thought, isolate the deck metalwork from the signal and HT negative and earth it leaving the amp chassis at HT neg as there's no exposed metalwork (unless knobs are pulled off)
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Old 19th Apr 2019, 8:51 am   #32
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Default Re: Dansette Major seems a bit quiet.

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Originally Posted by Tim View Post
Hi Rob,

I'm doing one of these for my daughter.
Single EL84 and "proper" transformer with metal rectifier(half wave).
HT in my case is 237 volts. EL84 cathode volts 4.5 across 102 ohms( approx. 45mA then, so not too bad. Check screen volts (fed by big 10K resistor on mine, but some have 47K) as well. It should be nearly HT.
Haven't had it running for a while but as I remember volume was adequate. If you need the volume at "11" then you could always modify it to use an ECL82.
My HT is still lowish at about 187 volts (with 1n4007 and 220 Ohm resistor) mine has 2 small carbon resistors both of which checked ok. Amp works fine (no distortion or funny smells/noises/hum) Volume is OK except on newish LPs where it has to be flat out. I have my eye on a universal mono preamp kit that I could fit but need to explore one or two other avenues first . Honestly, not sure why I'm bothering as the sound quality is not that good. Hard to see what all the fuss is about dansette players.
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Old 19th Apr 2019, 10:16 pm   #33
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Default Re: Dansette Major seems a bit quiet.

Checked cathode volts, getting a smidge over 4 volts via 100 ohms, screen volts are just a bit lower than the HT.(mine has 47K) I did consider modding it to use an ecl 82 but really can't be bothered as to my ears the overall sound quality is actually quite poor. I had an old fidelity player that knocked spots off it.
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Old 20th Apr 2019, 1:03 am   #34
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Default Re: Dansette Major seems a bit quiet.

I had a similar record player in the 60s, not Dansette though. It was fitted with a red BSR TC8H high output cartridge and used a UL84 for audio output, with a UY85 rectifier valve. It was fine playing 45s but some LPs were too quiet. I spent ages rewiring the amp circuit to take a UCL82 triode pentode. The result was accoustic feedback when the volume was turned up on quiet records. As you say, the sound quality from most of these vintage record players is dreadful.

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Old 20th Apr 2019, 11:42 pm   #35
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Default Re: Dansette Major seems a bit quiet.

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Honestly, not sure why I'm bothering as the sound quality is not that good. Hard to see what all the fuss is about dansette players.
Ah, you're missing the point!
The whole purpose of the Dansette and similar players was to extract maximum racket from a record for minimum cost!

Without such machines, the pop explosion of the '60's could never have happened- they enabled the teenager to have their own player on which to listen to the latest Beatles '45.

Said teenager would have been quite oblivious to the 50% distortion after playing the single 50 times with a blunt Sapphire stylus! It wasn't about sound quality:- it was about the music!

So they are now seen as an object that represents the excitement of the 1960's. If you want good sound quality, there are probably very few worse ways of getting it!

The current incarnations of nasty record players such as the Crosley, achieve exactly the same as their Dansette forebears. Without the Crosley, the current 'Vinyl revival' would never have happened. It's been driven by young people- not old men with HiFi buying Dark Side of the Moon!

All the best
Nick
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Old 21st Apr 2019, 7:53 am   #36
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Default Re: Dansette Major seems a bit quiet.

Fair point Nick,
My family didn't have any form of record player until the late 70s when my dad bought a cheapish marconiphone radiogram which wasn't too awful sound wise so as a teenager I had no idea about Dansette players as they'd all but vanished. In fact suitcase style players were getting really scarce by the time I could afford to buy my own and for an extra few quid I could get a Van Der Molen stereo player with separate speakers (and I did)

Anyway, back to the Dansette in question. It's more or less finished, I've decided that it will have to live with the lower output of the ceramic cartridge so as to at least be able to play stereo records without damaging them.
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Old 30th May 2019, 8:38 pm   #37
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Default Re: Dansette Major seems a bit quiet.

A final update on the Dansette Major. It is now finished, I managed to find a higher output cartridge for it in a box of carts I bought some time ago and had all but forgotten about! It's an old Acos 101, not the absolute best cartridge available but at least it is Stereo compatible (I'm not going to be playing much other than singles on it so record wear isn't really an issue) it does go quite loud with that cart fitted and doesn't sound completely awful. You never know, I might experiment with an external loudspeaker as I have a random JVC 3 way one knocking about somewhere.

Thanks for all your input chaps.
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Old 31st May 2019, 8:57 am   #38
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Default Re: Dansette Major seems a bit quiet.

I'm quite surprised that an Acos 101 give's that much output. Connecting an external loudspeaker will not affect the volume. If you connect the JVC unit, which is likely to be an 8 ohm unit, which will give even less volume given the Dansette's 3 ohm output.
A replacement mono only BSR TC8H cartridge (now sold as an BSR HTC8) is the answer if all you really want to do is to play 45s.
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