BBC Micro Master 128 - High Quality Advanced Power Supply Capacitor Kit
Now with Wurth "RedExpert" C9, rated to +125 Degrees
Contains ALL electrolytic caps on the board, as well as the X2 supression caps and two balance resistors
This is a Buy-It-Now sale for a set of twelve capacitors, and two resistors, used to refurbish the ACORN and HITRON type Switch Mode Power Supplies found in the BBC Master 128. This kit is NOT suitable for the Model B Power Supply, or the later type ASTEC PSU found in some Masters. If you have any of those, please contact me for further assistance.
Turned your BBC Master on after 30 years being in the loft, only for it to go bang in a puff of smoke? Bought your latest "untested" machine off eBay, only to find it doesn't turn on? You've got the standard power supply issues that are common to all these machines, and it just needs a little TLC.
It is said on the internet, and in other listings you may see on eBay, that most issues with any BBC Micro power supply can be resolved by changing three capacitors in the circuit, C1, C2, and C9. However a lot of BBC power supplies are coming through my workshop now with overheated caps in the output section. The problems with these can manifest themselves as a bad smell after the PSU has been on for a little while, or failure to regulate properly and not supply a stable voltage to the motherboard. It can also affect using the AUX power port, with a weak PSU shutting down if you plug a disk drive or other accessory into it. After 35 years of use, this is only to be expected - can you imagine your iPhone lasting that long! For this reason I do not recommend just changing the "basic 3", as you will not be able to guarantee reliability going forward, for the sake of saving a few pounds.
This kit allows you give your power supply a complete recap of all the electrolytic capacitors, as well as the usual X2 caps that can fail in a slightly more dramatic fashion! Once changed, your PSU should be good to go for many more years to come.
This advanced kit comes with twelve capacitors:
- C2 - 100nF X2 RIFA KEMET
- C1 - 10nF X2 RIFA KEMET
- C7 and C8 - 100uF 250v - Panasonic or Rubycon
- C9 - 220uF 25v - Wurth "RedExpert" +125 Degrees
- C12 and C13 - 220uF 35v - Panasonic
- C14 - 470uF 35v - Panasonic
- C15 - 2200uF 35v - Panasonic
- C18, C19 and C20 - 2200uF 16v - Panasonic
The X2 capacitors are RIFA brand, made now by KEMET, C9 is by Wurth, and the others are all Panasonic, with the exception of the 100uF / 250v, which may be Panasonic or Rubycon, due to supplier stocks. The RIFA KEMET caps manufactured now are made to a better standard than the ones 30+ years ago, and are not prone to the same failures as the earlier ones. The new ones now have a temperature rating of 105 degrees Celsius, whereas the original ones fitted were usually only 85 degrees. The new, more expensive C9 supplied with this kit is also rated to +125 degrees. This is to help even further the longevity and reliability of the part, as it is mounted very close to hot components. All the capacitors are the exact correct lead spacing for the PCB to fit without having to splay the leads out to force them to fit.
Two resistors are also supplied, 180k 2W. These are used to balance the two 100uF 250v capacitors in the high voltage section. Occasionally one or both can fail open circuit, which causes the power supply to not want to turn back on again straight away, after being switched off.
The components supplied are high quality, and high temperature graded components. They are also the exact correct lead spacing for the PCB to fit correctly without having to splay the leads out to force them to fit. Other kits you may see being sold on eBay and elsewhere may supply cheaper low grade Chinese capacitors. They won't last as long as the genuine high quality ones supplied here.
The kit also comes with an 8 page printed fitting guide, and two cable ties for reassembly of the cables on the outside of the metal cage. Remember this kit is for the HITRON or ACORN type PSU, as shown in the listing photos. Please email me with a photo of your PSU if you're not sure.
If you prefer not to do the work yourself, I can either refurbish your power supply, or supply you with an outright replacement, if I have stock. Note the pictures of the caps installed into the power supply do not show the upgraded C9 fitted - I will update these photos when I get chance to take new ones.
IMPORTANT: You will need to be able to solder and de-solder competently in order to fit these components. Servicing a Master 128 PSU is more involved than a Model B PSU. You also need to be aware that mains power supplies contain dangerous voltages, even for a while after they've been disconnected from the mains. and should be worked on with care.
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** You will not be disappointed! **
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** Worldwide shipping by the eBay Global Shipping Program **
We also supply GOTEK USB drives for the BBC Micro, as well as Raspberry Pi multi-core Second processors in internal and external versions.
As well as 1770 Disk Upgrade kits, 4 way switchable OSs for the Master 128 and 2 way for the B+, we can supply other refurbished BBC Model Bs and Master 128s to your specification.
Please check my other items for sale, or if they've sold out on my listings, please contact me for details.