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Systemdek IIX UK power supply help please.

Posted: 28 Jan 2019 23:40
by rossman
Hi folks, I could use some advice regarding the power supply for my IIX.

After the motor stopped working, I thought that I would try and repair it myself. First job was to replace the 6K8R resistor which superficially solved the issue. however from the info that I managed to glean from various sources including VE I thought that the Systemdek power supply should give readings of about 90V from both the grey/red and grey/blue outputs. I have 90V at the red connection but only 56 or so at the blue. The motor is working at these voltages but the replacement resistor that I had sourced was 14W and got warm quite quickly. From the size of the previous resistor I believe it was 10W but as the markings were unreadable it was difficult to tell exactly, although it is worrying if it was a 10W resistor that has burnt out.

I have read that the 0.82uF and 1uF caps might not be the best values for this power supply but if not what would improve on them and if necessary get the lower voltage closer to 90V.

I'm also getting a loud thump through the system when switching on and off. Where and what value cap would be the best place to put something to stop this.

Thanks in advance for any help. I look forward to you replies.

Re: Systemdek IIX UK power supply help please.

Posted: 30 Jan 2019 09:21
by abril
Hi and welcome.

Firstly 90 and 56V are are well out of balance and although you will never get exactly the same I would expect significantly closer values.
It would be very useful to know exactly which motor you have,there should be a label on the bottom of the motor,also useful to know which PSU with current component values - there were multiple variants - pics?
As for switch on thump - Systemdek fitted if I remember 10nf capacitors across each pole of the switch precisely to stop that - one or both may have gone.

Hope you can get it sorted - well worth it as a turntable.

Re: Systemdek IIX UK power supply help please.

Posted: 30 Jan 2019 11:16
by abril
Read this - it might help
Knew had seen something similar recently

Re: Systemdek IIX UK power supply help please.

Posted: 31 Jan 2019 17:29
by rossman
Hi Abril,

thanks for the replies. Yes I was expecting closer values too. Time constraints mean that work on the 'Dek will always be intermittent for me but the PS/circuit board looks to be a later one than the one in the link you supplied. It doesn't have the 10nF caps mentioned at all. I'll try and get a picture of the PS and try and find out which version of the motor it is.

Re: Systemdek IIX UK power supply help please.

Posted: 01 Feb 2019 10:50
by abril
On some the switch capacitors are soldered actually on the switch and not on the PSU board.