My LPT has died

tim_bissell · Post by **tim_bissell** » 10 Dec 2017 22:53

Inspirational, Abril! I Have a similar black-topped LPT with a dead PSU so will be looking to do a similar transplant next year,when the garage gets a bit warmer.

In the meantime I had better start looking for a cheapish FG-servo donor.

-- Tim

abril · Post by **abril** » 11 Dec 2017 08:43

Thanks,and here is the damage.
50k trimmers £2.49
3p 4w switch Lorlin £2.29
Knob £1.49
Technics SL-BD22D £29.25
Plugtop transformer 12V AC 500mA £6.81
Socket connectors (to mate with transformer plug) £2.79
Black paint £1.79
Belt 408mm £14.12
DC conversion at a fraction of the cost of a commercial kit,and it sounds stunning :D

Knowing what I know now I would be quite happy to pay double for the donor Technics.
https://www.ebay.co.uk/itm/TECHNICS-SL- ... SwbihaKU2P

abril · Post by **abril** » 12 Dec 2017 11:49

Remove the mains input socket by slicing off that portion
of the PCB.
Remove the transformer and connect two wires to the
secondary side of the PCB,these will be your connection to
the external transformer.
Remove strobe lens from main PCB.
Desolder and remove the fine speed adjust potentiometer
and it's mini PCB,this will leave 2 solder points on the
main PCB.
Trim off completely one pin of the 50k trimmer and set it
to approx 32-33k,solder the two pins to the solder points
on the main PCB.
Set the rotary switch to use 3 positions only,the mid point
will be off and either side will be 33 and 45.
Remove the speed select slide switch from the PCB,the
centre connection is common and the ones either side are
33 and 45,connect as appropriate to one pole of the
rotary switch.
Remove the leaf switch from the 12V power supply lead
and connect to another pole of the rotary switch using a
jumper lead to connect two of the pins so that power is
fed only when 33 and 45 is selected.
Bingo! :D

tim_bissell · Post by **tim_bissell** » 16 Dec 2017 15:10

I'm sold! Can't have too many PTs... I'll let you know how it goes.

abril · Post by **abril** » 17 Dec 2017 08:07

Good luck.
Just be aware that the rotational position of the magnetic sensor on the motor is necessary otherwise it will catch on the platter,and to drill 2 holes through the underside of the base to line up with the adjust trimmers.
Now updating it :roll:
Using a Velleman K1823 regulator kit taking a feed from the transformer to provide dc to a bi-colour led on the front panel,switched via another pole on the switch.
Early days yet,just put the Velleman kit together last night :D
Argghhhh - 2200mfd capacitor is too tall #-o

abril · Post by **abril** » 29 Dec 2017 20:01

Lorlin switch
speed A
1=33
3=45
2=off
power B
4=12V
6=12V
5=off
LED power C
7=9Vdc yellow
9=9Vdc green
8=off

abril · Post by **abril** » 08 Jan 2018 16:07

Here it is ---final---final setup.
9 months in the making :lol:
2200mfd on the PSU was replaced with 470mfd to make it lower so it will fit :roll:
Been the biggest problem from the start-very little height available.

End of story =D> - a working LPT again,better than original to my ears,for a bargain price.

Tonybro · Post by **Tonybro** » 09 Jan 2018 06:44

Great work, Abril.

abril · Post by **abril** » 15 Jan 2018 16:37

Oh forgot the LED,little PCB made up of a pair of 390ohm current limiting resistors,one for each colour,off 9VDC ------ too bright #-o

abril · Post by **abril** » 11 Mar 2018 17:35

The LED is a 2 colour common cathode 3 wire 5mm LED.
The cathode returns directly to the K1823 PSU
The anodes are fed from the switch by separate 9V supplies through separate 10k resistors which gives a much more sensible brightness 8)

My LPT has died

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