This reminds me of my childhood. Got a brandnew Amiga 500 but every once in a while it turned off and on again. So I had to bring it back to the shop, they sent it in, and I had to wait 8 weeks before I got it back. But they didn't repair anything, the failure was still there. Since I didn't wanna send it in again, I opened the power supply myself, saw a cable that was jammed in the case, rerouted it and all was working flawlessly again. Good old times (and the beginning of my better-do-it-myself career).
I find the easiest way to put on a UK mains plug is to first, make sure all the leads are the right length, then I remove the pins amd the strain relief from the plug and attach the pins to the wires, then starting with the neutral, then live, and finaly earth, re-insert them into the plug and put the strin relief back.
Thanks for a nice for a long repairaton/refurbaton. Those old caps were surprisingli good for their age. I looked up the 78540, which is in the C128 psu at 26:00 I was curious to if it was a step-down converter, seeing that large donut inductor, and yes 78540 is a switching regulator. That would help with efficiency.
Btw the KME Series are Chemicon ones, standard, 105 degrees. Not bad ones. Much better then the Frakos. Also, in general, in switch modes the primary caps arent usually aging very fast.All they see is nice, rectified AC. Its the secondary side ones that are tortured with high frequency pulses. Can be seen - the KME primary was just a standard type, while the secondary ones needed to be low esr types. I'd rather change them and leave the primary ones in.
I will cover that in a future video, TAED (Vanish Oxy Action in the UK) doesn't always clean up plastic yellowing - but it brought my PC Engine back to almost white, and some of these Amiga PSUs back to normal creme colour.
If possible please don't directly short the main filter cap as that is bad for the cap and can cause damage to your tool used to short it out (and sparks as well). Get a proper resistor to bleed down the charge in a controlled manner. If you don't have a resistor you can use yourn multimeter in ohm's mode to do the same thing but only if your meter is a good quality one. There is a video from eevblog on how to do it that way. Those wire loops in the C128 power supply may be current shunts but I could be wrong on that.
Thanks, totally aware - from my own experience it makes no difference to the capacitor or life of the capacitor. You do just risk damaging tools from the arc! Anyone I've worked with in the trade (and I did get to work with a lot of engineers - one that was head of repairs for Dixons UK - covering just about every brand of electronics). They all just took the short cut rather than bleed with a resistor. The exception was on higher voltage capacitors (eg. over 400V). It is best practice to bleed a capacitor, in reality - hardly anyone one does it as it takes some time. The multimeter idea is good, until it isn't - ie. where you forget to change the mode and that current causes some issue or blows fuse internal to the meter etc. I guess on a good multimeter that's definitely a nice quick practical solution!!
This reminds me of my childhood. Got a brandnew Amiga 500 but every once in a while it turned off and on again. So I had to bring it back to the shop, they sent it in, and I had to wait 8 weeks before I got it back. But they didn't repair anything, the failure was still there. Since I didn't wanna send it in again, I opened the power supply myself, saw a cable that was jammed in the case, rerouted it and all was working flawlessly again. Good old times (and the beginning of my better-do-it-myself career).
I enjoyed the video. After prying open my A1200 PSU and finding it full of resin, I didn't expect these to be serviceable.
That is the powersupply my a1200 came with. Granted, i bought it second hand. Remember the fist thing I thought was; “this is really light”
More of a maintenance vid than repair. Great find on the PSU's.
More actual repairs in following parts!
I've got one of those narrow 1200 supplies too.
I find the easiest way to put on a UK mains plug is to first, make sure all the leads are the right length, then I remove the pins amd the strain relief from the plug and attach the pins to the wires, then starting with the neutral, then live, and finaly earth, re-insert them into the plug and put the strin relief back.
Thanks for a nice for a long repairaton/refurbaton. Those old caps were surprisingli good for their age. I looked up the 78540, which is in the C128 psu at 26:00 I was curious to if it was a step-down converter, seeing that large donut inductor, and yes 78540 is a switching regulator. That would help with efficiency.
Thanks for the info! =D
I thought the C128 PSU was switching, but Ive never seen one? They did also put those stupid plugs over the screw holes on some of the Amiga PSUs.
you need to crimp ferrules on the flex ends these days mate
Btw the KME Series are Chemicon ones, standard, 105 degrees. Not bad ones. Much better then the Frakos. Also, in general, in switch modes the primary caps arent usually aging very fast.All they see is nice, rectified AC. Its the secondary side ones that are tortured with high frequency pulses. Can be seen - the KME primary was just a standard type, while the secondary ones needed to be low esr types. I'd rather change them and leave the primary ones in.
Btw, the symbol left to the KME marking is the chemicon (united, nippon etc) logo. ,)
I'd change the golden Frakos. They tend to go short.
When you said you can remove the yellowing by soaking it in boiling water, can you do a video or point me to one that does so?
I will cover that in a future video, TAED (Vanish Oxy Action in the UK) doesn't always clean up plastic yellowing - but it brought my PC Engine back to almost white, and some of these Amiga PSUs back to normal creme colour.
If possible please don't directly short the main filter cap as that is bad for the cap and can cause damage to your tool used to short it out (and sparks as well). Get a proper resistor to bleed down the charge in a controlled manner. If you don't have a resistor you can use yourn multimeter in ohm's mode to do the same thing but only if your meter is a good quality one. There is a video from eevblog on how to do it that way. Those wire loops in the C128 power supply may be current shunts but I could be wrong on that.
Thanks, totally aware - from my own experience it makes no difference to the capacitor or life of the capacitor. You do just risk damaging tools from the arc! Anyone I've worked with in the trade (and I did get to work with a lot of engineers - one that was head of repairs for Dixons UK - covering just about every brand of electronics). They all just took the short cut rather than bleed with a resistor. The exception was on higher voltage capacitors (eg. over 400V).
It is best practice to bleed a capacitor, in reality - hardly anyone one does it as it takes some time. The multimeter idea is good, until it isn't - ie. where you forget to change the mode and that current causes some issue or blows fuse internal to the meter etc. I guess on a good multimeter that's definitely a nice quick practical solution!!