Casio SK-1 Repair

A story of repair by our member Jeffrey.

I do like the chance to repair things every now and again. It allows me to get away from coding and try something.

This Sunday I had a look at this broken Casio SK-1. A classic small sampling keyboard made by Casio from 1985.

https://en.wikipedia.org/wiki/Casio_SK-1

From the owner, they didn’t have a plug for it and it was no longer working with batteries and the last time they played it the sound was a bit off.

I got the unit to power up with an adjustable voltage supply but taking care of the odd centre pin negative configuration. It can certainly make noise.

Finding the service manual online, made opening it up fairly straightforward. I can see some type of liquid had stained the area around the battery compartment.
A good while cleaning contact points and spraying it with a load of compressed air it looked a lot better. Now testing with five AA batteries the unit came to life.

Now for the odd sound. It seems when the volume is about 40% and a few of the bass notes are played distortion comes to visit. Thinking it might be just the inbound speaker, a line out was plugged in and it had followed us there.


The demo mode and other instruments at higher volume seem to be free of this distortion. A visual inspection of the caps and parts on the board, I saw no immediate signs of damage.
I called it a day before reaching for the oscilloscope and began probing singles and that’s all the time on I had on a Sunday morning.  For more photos check out our gallery.

More Appliance Repairs

We are no stranger to appliance repairs at TOG. In the past we have taken part in Repair Cafe’s, and we’ve looked at things brought to us by members and visitors. This time it was a Beko DW600 dishwasher that kept burning out its water heater relay every few months. The heater should only be on when heating the water but it seemed to be on all the time, and the machine could be heard gurgling and hissing when filling. On investigation, the Omron G5 relay that powers the water heater had failed with visible burning on the case. The relay failed in the ON state.

This is a very cheap part…. less than 1 Euro. After replacing it several times a few months apart, a bigger and better relay was found after a rummage through our electronics room. A Crydom D2450 solid state relay rated at 45 Amps and zero-crossing switching no less! This should have no trouble handling the approx 7.5A that the heater draws.

What was causing the original relay to fail is not certain. It doesn’t have much air circulation where it is mounted, and the the location of the control PCB itself is very close to the hot inner door of the dishwasher. So time will tell if the new relay can handle the job.

Welder repair

An ancient proverb says that power tool failures occur in threes. During the same week that the lathe motor burned out and the compressor wire meltdown has turned it into a scary noise machine, we also had a mysterious malfunction in one of our welders. It didn’t release any smoke, didn’t make weird noises. It just didn’t weld. 0 volts across the output.

Inside of the welder (top view) before the repair attempt. Note that a large number of similar – but not identical – top boards can be found on Aliexpress.

This machine, a small 180A TIG/MMA inverter welder, has recently been repaired. It was not used heavily, as TOG has only so much use for welding. In fact, it was only used by a couple members to practise their welding skills.

On one hand, this machine was 5 year old, has been used extensively in the past and could have been written off as death of old age. The cost of a commercial repair would probably exceed the value of the welder. On the other hand – why not try to repair it ourselves before scrapping it?

Continue reading “Welder repair”

Sandymount Repair Cafe – CANCELLED

repaircafebanner

Repair Cafe  returns to Sandymount on Saturday 7th of March 2:00pm5:00pm. The event were expert volunteers help you repair everyday items and talk you through the process. The event is totally free.

Bring along your broken items and learn how to fix them alongside expert volunteers…. anything from stereos to suitcases, lamps to laptops, chairs to chinos and plates to parasols.

TOG will be making up part of the team of volunteers on the day. The event takes place in Christchurch Hall, Sandymount.

-Update- This is now cancelled. https://www.facebook.com/events/804078342975111/

 

TOG at Repair Cafe

repair_smallTOG will be at Sandymount Repair Cafe this coming Saturday (27th) 2pm – 5pm  in Christchurch Hall, Sandymount.

A repair cafe is where people come together and fix all sorts of things. Experts work along side the object’s owner and take a journey together to repair things. The hope is next time you will be able to fix something yourself .

If you have something that is in need of repair and want to know how to do it, drop by on Saturday.