Daiwa PS-30XM . 30 amp linear power supply, very intermittent fault, sorted .

One to watch out for when dealing with an intermittent fault on any type of equipment not just this power supply.
Michael Dranfield.
4-11-2024.

[@aroundthebush8514]

Excellent work!

[@walker55able]

Great work Michael

[@RPike-bq3xm]

Nice find. High five! Love your content. I'm restoring a Pioneer sx-1500TD that has similar trimmers in the amp assembly and they were toast as well.

[@mosfettg6857]

Good detective work, great lesson learned, thanks

[@chrissmith7655]

Hi, very good info, many thanks.

[@johnrudd9550]

Nice find Michael…thanks for the video.

[@michaeldranfield7140]

No problem m

[@alanclark5264]

Well done Michael, much appreciated, you are the top electronics Wizard! 👏👏

[@michaeldranfield7140]

No need for me to ring you up now Al !!!!!!!

[@tubeDude48]

That must have been driving that Op-Amp crazy!

[@crr8297]

Good job, those faults are really hard to find plus it's unusual for a trimmer to act up that way, maybe it's an intermittent contact on the rivets to the conductive part

[@petervideos8699]

Hi well done good find

[@t1d100]

👍👍👍👍👍

[@matthewgriffin4761]

Another great video Michael. Very strange. Good find.

[@michaeldranfield7140]

Many thanks .

[@dalerobinsuk]

One big issue with a lot of these high current linear PSU's is there is no overvoltage protection. Adding a crowbar is cheap insurance as if any of those series pass transistors go short (And they can and will) you will end up with quite a bit of voltage going in to the device that's connected to it. And one or more transceivers and accessories can cost several thousand pounds.

[@user-rf9me7xm1w]

Definitely, always suspect the presets and the bits which get hot ! Very interesting presentation Michael, just one point though, wavy lines for resistors went out with the arc. Sorry, I used to be a City and Guilds external verifier, old habits die hard.

[@michaeldranfield7140]

showing my age .

[@sw6188]

I've encountered this many times with trimpots and ordinary pots. The carbon track loses connectivity with the terminals. Causes all sorts of interesting faults!

[@Barbarapape]

Under a microscope you might find a hairline crack where the tags are riveted to the resistive track. The sort of fault that drives you nuts until you find it.

[@michaeldranfield7140]

Thats what it must be , you will notice I fitted a decent quality pot .

[@Barbarapape]

@@michaeldranfield7140 I noticed that you had fitted an enclosed pot. I have seen this fault a few times on so called prestige Hi-Fi that is made with cheap parts.

[@someone7648]

Anyone know what causes the variable resistor to fail like that ?, top video as usual !

[@peterhancox6962]

cool!

[@wisher21uk]

Wow who would of thought it was that! How strange great tip thanks Michael 😊

[@FariSamSoli]

you can use that as random number generator

[@harryshector]

Quite often, things lose something in the transition from paper to hardware. This can usually be attributed to the meddling of bean counters, who are dedicated to producing something at the lowest possible cost. Sure, it’ll work for awhile. But, how long that while is going to be is a crap-shoot. This was definitely not lab grade equipment. Your ham operator just reached the end of his ‘while.’

[@pi6706]

Daiwa? I thought they made fishing gear.

[@leplum2001]

Linear PSU? Looks nire likr a switched mode supply...

[@michaeldranfield7140]

Give you a clue , big transformer connected straight to the mains .