#228

#228 INSTEK PSP-405 programmable power supply re-cap and repair
I thought I’d get away with just a re-cap as “it’s always the capacitors” and the “Good hearing Oz” would say. Bugger that should have been the “DefPom’s” channel
But it turned out that the switching controller let go at the same time "insert sad face here!"
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[@DigicoolThings]

Nice repair. Great idea using the hex stand-off as an accessible heatsink screw replacement!

[@TheEmbeddedHobbyist]

Thanks, it would have been better if I could have found the m3 spanner. :-)

[@DaftOldMan]

Nice repair. I would never have found the fault. Seems quite accurate now it's working.

[@TheEmbeddedHobbyist]

Took a lot longer to trace the circuit and then find a replacement chip than I had hoped. but got there in the end.

[@daveodessa]

Good work TEH, great result. Hope you many more years of use from the PSU.

[@TheEmbeddedHobbyist]

Thanks Dave, it's such a nice power supply I do use it every day. going to have a look at controlling it via RS232 as that might make it more useful in the future.

[@andymouse]

Good fix ! The ' White Gold ' meter was from our dearly beloved Maplin I think, I could be wrong, very unlikely but you never know, am I right please ? and will be good to see you doing COMM's with bits of test gear !.....cheersysqueak !!

[@TheEmbeddedHobbyist]

Showing signs of old age Mr Squeak, yes it's a 40 year old or so Maplin meter. Quite expensive at the time if I can remember. i think it was the second meter i got, the first being a moving coil one. Not sure what i'm going to do coms wise but it might be connected with my HP DMM.

[@davidv1289]

Well done, sir! I will have to try to remember that trick with the stand-off, clever solution. If you have to reverse engineer a double-sided board, use the same photography trick then stack the two photos in your editor, align them and use the opacity control on the top layer to shift from top to bottom - sort of like xray vision. Regards, David

[@TheEmbeddedHobbyist]

Thanks for the suggestion that sounds like a great idea. I'll give it a go next time.

[@davidv1289]

​@@TheEmbeddedHobbyist One detail, when you take each of the photos the board should be the same distance from the camera to avoid parallax errors. I use some long standoffs to support the component and non-component sides equal distance from the table top. Regards, David

[@TheEmbeddedHobbyist]

that's why i did them side by side as i just used screen grabs and changed the size in paint shop. I'll try your method next time thinks.@@davidv1289

[@hansregli8678]

Looks like a quite old design. Such boards I have seen in 1990..2000. Today they are made in SMD technology. Instead of LCDs they use LED displays. I guess you could buy a modern replacement for this device, which is much smaller also, for a quite low price (below 100$).

[@TheEmbeddedHobbyist]

Its quite old but they still sell this model. The problem with cheaper new designs is they have cut costs so they don't work In practice as good as they claim on paper. The current one cost about £225 so well worth saving.

[@hansregli8678]

@@TheEmbeddedHobbyist At least it's a taiwanese company and not chinese. I avoid any chinese stuff as much as possible to not support the nationalistic expanse and also the attack on Taiwan that China is planning. From this standpoint it's even better to repair. Repairing is better generally, to avoid senseless waste. I also repaired many of my stuff. Standard rule: A modern device is failing usually after 3..5 years to let you buy another one. A selling tactics called "Planned Obsolescence". If you repair the one location that is intended to break down in nearly all cases you get a device that works wonderfully for 10..20 years. Your device should now work for another 10..20 years while with a chinese one you could expect a maximum of 5 years. The only thing which would bother me is the size. It's quite big compared to modern ones. If you use it on a fixed bench, no problem. But if you travel with it, not so cool.

[@TheEmbeddedHobbyist]

@@hansregli8678 i prefer to repair my older equipment as it was made to better spec's etc. Plus i don't need to travel much with my kit. my main DMM's are HP bench meters, my frequency meters are all bench units so all about the same size. when i equipped the last electronics lab all the DMM's were mains powered bench units, just got two handhelds. this stops folk coming in and trying to borrow them all the time. Also never see the point in calibrating handhelds, just stick a "reference only" sticker on them. the same as i did with power supplies. Saves a lot of time and money. 🙂

[@FridayHouseXYZ]

The important thing is, the magic smoke is still inside.

[@TheEmbeddedHobbyist]

my thoughts exactly, bloody hard to get the smoke back in. 🙂

[@AJB2K3]

Normally they have goo or pads.

[@TheEmbeddedHobbyist]

one did show signs of starting to puff up. but at least it is now back up and running. i missed it as the current limit is so useful when playing with leds.

[@fredflintstone1]

So many drunk Capacitors, A good fix have you tried it under load????

[@TheEmbeddedHobbyist]

I've hooked it up to a few 12V car bulbs and it's happy up to 3A. They don't make caps like they use to, but I was spoilt by having a good supply of solid tant's they seemed to last forever.

[@fredflintstone1]

@@TheEmbeddedHobbyist they do make caps like they always have done in China🙂

[@TheEmbeddedHobbyist]

@@fredflintstone1 Next time I pop down to the local Chinese takeaway I'll pick up a side order of caps. 🙂

[@fredflintstone1]

@@TheEmbeddedHobbyist Okay don't forget the sweet and sour sauce 🙂

[@TheEmbeddedHobbyist]

quite like the idea of salt n pepper caps.