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View Full Version : Technics 1200/10 external PSU info needed please



Reid Malenfant
21-10-2010, 17:43
Hi people, would someone or should i say a few people (which would be better) please let me know a few things if possible. This is quite important as far as i'm concerned & may well be to those with external PSUs.

1. Can you please let me know the length of the cable that is feeding the Technics deck from the external PSU.

2. How much cable do you estimate that there is from where it enters the deck to the connections made internally.

3. Any idea what size area the conductors are in the cable feeding the deck itself? IE what is the cable cross sectional area (each wire not both added together) of the DC lead feeding the Technics deck?

4. Does anyone happen to know the average current drawn by a Technics 1210, peak current would also be very handy, so would minimum current. I doubt i'll find this out but it's worth asking :eyebrows:

Thanks very much in advance :)

jonners
21-10-2010, 20:11
4. Does anyone happen to know the average current drawn by a Technics 1210, peak current would also be very handy, so would minimum current. I doubt i'll find this out but it's worth asking :eyebrows:

Thanks very much in advance :)

I can answer that one, Mark: http://theartofsound.net/forum/showpost.php?p=20744&postcount=7

MartinT
21-10-2010, 21:43
1. Approximately 1m

2. Approximately 20cm

3. Hard to say for sure but probably 3A twin

4. About 0.8A peak

Reid Malenfant
22-10-2010, 10:23
Thanks for the replys guys :) Now we come to the interesting bit :eyebrows:

You see something occured to me when i was taking a look at a thread that Shuggie posted on how to wire up the 1210 for use with an external PSU. I hope he doesn't mind me swiping a couple of pictures to illustrate my point, thanks Hugo, i'll remove them if you'd like me to ;)

First up here is a picture of the standard Technics regulator in relation to the main motor PCB.

2874

Notice that it is fairly close to the motor board.

Here is the other picture i swiped, notice that the only decent sized low impedance capacitor is on the far side of the motor board from where the regulator is.

2875

There is no large capacitor on the PCB where you'd connect the external PSU to..

Now before anyone shoots me down let me tell you that i used to work as an electronics engineer on SMPS, i was even sent abroad by one firm to fix & modify a load of power supplies that were failing certain tests.

There really isn't a lot of difference between a switch mode power supply & a linear power supply apart from the frequencies involved. They both rely on feedback to maintain a regulated output.

So having said that lets get down to business.

Has anyone considered the effect of using an external PSU? Yes it may make the 1210 sound better but i have spotted a flaw that means you aren't getting the best performance from the external PSU as you could be getting :rolleyes:

Put quite simply the external PSU is doing a superb job of maintaining it's regulated output at the PSU itself. The 1210 will not be drawing pure DC current from the supply due to the nature of the motor, there will be significant AC current superimposed on the supply due to the current pulses being drawn by the motor.

Now look at where the external PSU is, about 1.5M from the motor board. If we factor in the probable type of wire being used to connect the external PSU to the motor board (in Martins case a max of 0.5mm^2) then there is a loop resistance of 0.108 ohms (3M of wire at 0.036 ohms/M). With a possible peak current of say 0.8Amps there will be nigh on 80mV of ripple superimposed on the DC at the input of the motor board :eek: Or if you like your nice clean 21V DC will be dropping down to 20.92V DC with a 0.08V AC component on top. That may not sound like a lot, but what we want is no ripple at all :)

So, what do we need to do to cure this :scratch: The answer is quite simple & is known as remote sensing ;) Effectively what needs to be done to get the very best out of the 1210 is to feed two more wires (though these can be much thinner) back to the PSU & sense the voltage directly at the motor board. This will totally eliminate any ripple where it really matters...


I believe someone on here mentioned helping me out with a PSU for my Aiwa AP2600, it's nice to know that i can help out you guys with the 1210 :eyebrows:

I'm just amazed that no-one noticed or ever considered what effect the remote PSU would have at the motor board itself, as i say i spotted it straight away as soon as i saw the above picture :mental:

vanwykca
22-10-2010, 11:15
Hi Mark, here's my attempt. Hexfred rectifiers with 18v 100VA transformer with 4700uf/0.47R CRCRC externally (BHC ALP30 caps) and using cable as R to turntable into another 4700uf BHC ALP30 internal to turntable and then to 21v Spower reg.

The reg uses the chassis of the turntable as heatsink as did the original reg. On the output of the regulator 1500uf Panasonic FM bypassed with 100nf Wima MKS. Also used Panasonic FM in various sizes to improve local decoupling of IC's. On the photo I've also done "motor dynamics mod" which I subsequently removed as it makes the turntable sound terrible to my ears.

I'm no expert, but this sounds better than my previous DIY LM317 external power supply. Maybe overkill though:-).

http://picasaweb.google.co.uk/lh/photo/Vr8wc0AB8uAnUig8Ip5sAw?feat=directlink

Reid Malenfant
22-10-2010, 11:26
Hi Cornelius, you'd better pop into the welcome area before the (forum) police arrive :eyebrows:

Just say hello, tell us a bit about your system & musical tastes etc.


Looks interesting, there are advantages to having the regulator right next to the motor board as i have just shown ;) There are advantages to having a damn good regulator & over size transformer etc as well though :doh:

anthonyTD
22-10-2010, 12:29
hi mark,
what you have discovered is very relevent hence why i have already been working on a design which uses remote sensing to compare against the standard aproach.
interesting times ahead i think!:)
Anthony,TD...

Techno Commander
22-10-2010, 12:32
Could you not mount transformer and smoothing caps off board and mount the regulator on the TT chassis?

Reid Malenfant
22-10-2010, 12:34
hi mark,
what you have discovered is very relevent hence why i have already been working on a design which uses remote sensing to compare against the standard aproach.
interesting times ahead i think!:)
Anthony,TD...
Indeed Anthony, it really shouldn't be too difficult to modify any of the existing PSUs to remote sense.

As you say though, a dedicated design might be the way to go & yes, i'd expect there would definately be audible improvements :eyebrows:

All the best with the design, i'll eventually get round to one for my own deck ;)

vanwykca
22-10-2010, 12:44
Could you not mount transformer and smoothing caps off board and mount the regulator on the TT chassis?

Hi Andy, that's precisely what I've done with my attempt:-). The trafo and first CRCRC is off board in aluminium case with 2 meters off DC cabling to cap in chassis. I get 32v DC with 5mV of ripple before the last reservoir cap and Spower reg.

Mark, I'll comply to rules asap:-).

Cornelius

Reid Malenfant
22-10-2010, 12:55
Could you not mount transformer and smoothing caps off board and mount the regulator on the TT chassis?
You could yes, but you could only really do it with a series regulator ;) There would more than likely be too much heat output with a shunt regulator for the Technics chassis to get rid of without upsetting a few things such as the quartz crystal oscillation frequency & probably other stuff to.

Hi Andy, that's precisely what I've done with my attempt:-). The trafo and first CRCRC is off board in aluminium case with 2 meters off DC cabling to cap in chassis. I get 32v DC with 5mV of ripple before the last reservoir cap and Spower reg.

Mark, I'll comply to rules asap:-).

Cornelius
That's not a lot of ripple for the regulator to deal with :eyebrows:

No worries on the rules, i don't make them :wave:

anthonyTD
22-10-2010, 14:35
Indeed Anthony, it really shouldn't be too difficult to modify any of the existing PSUs to remote sense.

As you say though, a dedicated design might be the way to go & yes, i'd expect there would definately be audible improvements :eyebrows:

All the best with the design, i'll eventually get round to one for my own deck ;)
hi mark,
thank you!:)
as with everything audio related what may look good on paper and test may turn out to not be the right solution as far sonic performance is concerned,:scratch: so i am optimistic at the moment but untill its been tried and tested in a real aplication, the jury is out!
Anthony,TD...

Reid Malenfant
22-10-2010, 14:48
If you want to see if it's likely to make a difference i'd suggest quickly fitting a decent sized electrolytic accross the input terminals of the motor PCB.

Now i know it's not ideal, but it should reduce the ripple voltage that'll most certainly be there ;) This is why i also mentioned the lack of a low impedance source & the fact that the only decent sized electrolytic is on the opposite side of the PCB, it wouldn't be in the modified circuit anyway.

It'd be a heck of a lot faster to do & might give you some pointers as to the efficacy of the remote sensed PSU.

You have probably considered this anyway :eyebrows:

leo
22-10-2010, 16:03
I'm just amazed that no-one noticed or ever considered what effect the remote PSU would have at the motor board itself, as i say i spotted it straight away as soon as i saw the above picture :mental:

Its not been missed by all of us, just not got around to sorting it just yet, it is in the works though ;)

Good thread though, look forward to see how it progresses :)

Paul Hynes
22-10-2010, 17:38
Hi Mark,

Whilst there are some good benefits to be had from using a high quality external power supply, I have already suggested further regulator application internally as phase two of the power supply upgrades I recommend for the SL1200/SL1210 for the reasons you are putting forward. There is nothing like regulating as close to the load as possible, and I much prefer doing this to remote sensing, particularly over long distances. With this in mind I have already designed the phase two regulator upgrades, and trials are currently in motion. The results will be posted when the trial is completed.

Regards
Paul

Reid Malenfant
22-10-2010, 17:51
Its not been missed by all of us, just not got around to sorting it just yet, it is in the works though ;)

Good thread though, look forward to see how it progresses :)
Cheers Leo, looks like no-one has really missed the blooper :)

Hi Mark,

Whilst there are some good benefits to be had from using a high quality external power supply, I have already suggested further regulator application internally as phase two of the power supply upgrades I recommend for the SL1200/SL1210 for the reasons you are putting forward. There is nothing like regulating as close to the load as possible, and I much prefer doing this to remote sensing, particularly over long distances. With this in mind I have already designed the phase two regulator upgrades, and trials are currently in motion. The results will be posted when the trial is completed.

Regards
Paul
:lolsign: Oh well i guess i can't be the first at everything ;) It'll be interesting to see how things sound once this is all done, another thought i had is that there is probably a better place to connect to the motor board that'll result in better overall regulation to the motor itself than where the standard regulator is connected. Finding the ideal + & - connections shouldn't be too difficult.

Just out of interest Paul, i know you designed the SR5, may i ask if you are planning to implement a series regulator for stage 2 or a low drop out shunt regulator?

All this came about as i'll be designing & building a PSU for a completely different deck, i just spotted what i could see would mess up the regulation :eyebrows: At least it has generated a few interesting posts if nothing else...

Bests

anthonyTD
22-10-2010, 19:03
hi mark,
as paul has already discussed there are indeed further gains to be made by stiff regulating at key areas on the deck itself and it is something that both paul and myself have discussed, and we are looking into things, hopefully we can share ideas on how best to impliment our findings, i think [hope] we are both mainly interested in coming up with the best amendment to finaly be able to offer a complete solution to replace some of the "sticking plaster" fixes that have been on offer to date.
Anthony,TD...

Paul Hynes
22-10-2010, 19:10
Hi Mark,

The control circuitry and the motor drive section are being separately regulated to reduce power supply inter-modulation between the control circuitry and the motor drive circuitry. I will be using the same discrete component regulator topology as used in the SR5 for the internal regulator modifications. This is a series regulator.

I do have a low noise discrete component shunt regulator that should work well electrically but the standing current would have to be set at more than the maximum peak current draw from the SL1200/SL1210 electronics. This would generate considerable heat under idle conditions, as the output stage would have to absorb the unused current. I donít think this would be good for thermal stability of the SL1200/SL1210 control circuitry, as the heat generated would vary depending on the load current changes.

The series regulator has already proved itís worth in the SR5 external supply. I have used these series regulators cascaded in many applications and it is all benefit with this particular regulator. Because of this the SR5 will not become redundant but will provide an extra layer of supply line rejection and provide a very quiet feed for the new internal regulators. The only change to the SR5 is the output voltage is adjusted to 27 volts to provide enough headroom for the internal regulators.

Unfortunately, due to the layout constraints of the SL1200 printed circuit board, some track surgery is required to implement the new regulation scheme. Some of the forum DIY enthusiasts will be able to accommodate this and details will be provided so they can, but for many the deck will have to be shipped for modification, unless I can find someone on the central mainland to provide this service.

Iím sorry this background activity has surprised you Mark, but please donít back off with your ideas. There is room for everybody with good ideas here and each individual has his own set of unique experiences and his own knowledge base. We just want better music. Itís a two-way thing and forming a think tank can produce great strides forward. Nobody knows everything no matter how much they stand on their orange box on Hyde Park Corner proclaiming they do.

Regards
Paul

Reid Malenfant
22-10-2010, 19:30
Cheers both Anthony & Paul :) This is now turning out to be even more interesting & i'm pleased i brought it up. It never occured to me that these lines were already being explored, in that respect i was a tad naive :eyebrows:

Good on both of you ;)


<snip> Hi Mark,

The control circuitry and the motor drive section are being separately regulated to reduce power supply inter-modulation between the control circuitry and the motor drive circuitry. I will be using the same discrete component regulator topology as used in the SR5 for the internal regulator modifications. This is a series regulator.

Iím sorry this background activity has surprised you Mark, but please donít back off with your ideas. There is room for everybody with good ideas here and each individual has his own set of unique experiences and his own knowledge base. We just want better music. Itís a two-way thing and forming a think tank can produce great strides forward. Nobody knows everything no matter how much they stand on their orange box on Hyde Park Corner proclaiming they do.

Regards
Paul
Hi Paul, very nice indeed, it makes even more sense to isolate the control circuitry from the motor itself ;)

Don't be sorry as i'm not in the least upset, in fact as i didn't know that this was on the agenda you could say that my own reasoning has been proved correct & i know what to do :) :lolsign:

Nice tip about control circuitry isolation :)

The very best of luck with your project & thanks for posting on here & letting me know what's going on!

I hope both you & Anthony have a good weekend :wave:

anthonyTD
22-10-2010, 20:12
Hi Mark,

The control circuitry and the motor drive section are being separately regulated to reduce power supply inter-modulation between the control circuitry and the motor drive circuitry. I will be using the same discrete component regulator topology as used in the SR5 for the internal regulator modifications. This is a series regulator.

I do have a low noise discrete component shunt regulator that should work well electrically but the standing current would have to be set at more than the maximum peak current draw from the SL1200/SL1210 electronics. This would generate considerable heat under idle conditions, as the output stage would have to absorb the unused current. I donít think this would be good for thermal stability of the SL1200/SL1210 control circuitry, as the heat generated would vary depending on the load current changes.

The series regulator has already proved itís worth in the SR5 external supply. I have used these series regulators cascaded in many applications and it is all benefit with this particular regulator. Because of this the SR5 will not become redundant but will provide an extra layer of supply line rejection and provide a very quiet feed for the new internal regulators. The only change to the SR5 is the output voltage is adjusted to 27 volts to provide enough headroom for the internal regulators.

Unfortunately, due to the layout constraints of the SL1200 printed circuit board, some track surgery is required to implement the new regulation scheme. Some of the forum DIY enthusiasts will be able to accommodate this and details will be provided so they can, but for many the deck will have to be shipped for modification, unless I can find someone on the central mainland to provide this service.

Iím sorry this background activity has surprised you Mark,
but please donít back off with your ideas. There is room for everybody with good ideas here and each individual has his own set of unique experiences and his own knowledge base. We just want better music. Itís a two-way thing and forming a think tank can produce great strides forward. Nobody knows everything no matter how much they stand on their orange box on Hyde Park Corner proclaiming they do.

Regards
Paul
totaly agree!
paul has already done most of the investigating of the innards of the techie electronics so far, so has a more indepth understanding of what is needed as far as descreet regulation is concerned, i will eventualy have more input to offer once i have conducted my own investigations and tests etc but i think this will indeed be quite an exciting exercise for all of us who are interested in coming up with the ideal solution for the 1210!
Anthony,TD...