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Small Design Error Saga

Hi to my many friends,

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this story involves local Sydney electronics maker Jands, a few years ago.

I know Jands quite well, been to their factory many times.

I know the particular amplifier, the SR3000, rated at 1500W per channel on music programme.

I know the designer, Doug Ford - he has since appeared on U-tube.

See pics of culprit amplifier:

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Doug appears here, the talkative one on the left:

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Story:

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An SR3000 turns up on my bench, just out of its one year warranty.

One channel has failed, many blown MJ15024/5 TO3 devices and TO220 drivers. I start removing the shorted BJTs and then stop - pick up the phone and dial Doug.

Me:

Hi Doug, tell me why are you using axel grease instead of thermal compound in the SR3000 ? The grease under your TO3s has boiled away and spread itself all over you nice red heatsinks.

Doug:

Bullshit !! We have been using the same *thermal grease* for years ( names local supplier ) we have a gallon can of it labelled thermal grease.

Me:

I don't think so, that is very thin clear Silicone with no filler, only used for lubricating bearings and such.

Doug:

No way, I will go get the can and call you back - OK ?

** 45 minutes later .....

Doug:(now much quieter)

Bloody heck, you were right Phil, the can is labelled Silicone Grease Lubricant. Fuck knows how we got supplied the wrong type, must have been years ago and the people here kept re-ordering it.

I checked with our service department, they have a private stash of heatsink grease with blue coloured filler used for repairs. First time I ever knew about that.

I can see how with no grease left, some devices would overheat and fail.

I already ordered genuine heatsink compound and should have it delivered tomorrow. Shit, we are gonna have to strip all the amps here now on soak and re-grease them.

Thanks for the information.

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FYI:

The red anodised heatsinks you see in the SR3000 pics are mounted on a PCB and operate live, with no insulators under the TO3s.

They are quite small and rely on powerful fan cooling.

The amp uses 4 x DC supply rails, +/-75V and +/- 150v so needs multiple heatsinks.

It took a while and some hot weather to remove the last vestiges of axel grease, so few came under the makers 1 year warranty.

That the service guys ( same building ) had a secret stash of the proper stuff is interesting.

FYI 2

I had been using normal, ZnO filled white grease for decades.

Jands never used it until after that phone conversation.

.... Phil

Reply to
Phil Allison
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Great story !

Reply to
boB

So, the company now KNEW they made a serious mistake with their product, that was going to needlessly cost their customers downtime and unnecessary repairs if they kept quiet about it.

Did they issue a recall or notify people of the problem? If yes, kudos to them for being an upright and honest company looking after the interests of their customers, they would have had many more loyal people after that admission.

If not, then they are not a company that I would want to deal with in the future.

John :-#(#

--
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Reply to
John Robertson

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** Yep.

** Jands have been out of the audio manufacturing business now for many years - cheap Chinese imports were the final nail in in the coffin.

Far as I know, their various service agents were told of the wrong grease issue, but there was no recall as such.

The SR3000 was by far NOT the worst design Jands ever made, the J1000CS takes the prize for that. Story for another day.

I tried to warn them of the bad mistakes in that model while still very early in it's production run and was shooed away with:

"... if *you* think you can design a better amp, why don't you go and do so ? " It nearly cost them their reputation and Doug came along afterwards to clean up the mess - he got hours of free advice from me. Some of which he took.

Doug later moved on several times, first to Rode Microphones then a mining survey company and other things.

He often sought comment from me over the phone and I reckon I saved him and the business he worked for a fair bit of grief and money over the years.

I did get a few spare parts donated once.

I was never a service agent for Jands, only authorised dealers got that privilege.

..... Phil

Reply to
Phil Allison

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