45 years worth of replaced API 2520's!

[Walrus]

Why do we keep stuff that is broken?
This is 45 years collection of 115 faulty 2520's and 15 2551B VCA blocks.

 

[dmp]

Mount them on something you can hang on the wall - it would be a sweet piece of art for a studio space

 

[sahib]

I think API supplies replacement 2520 on the condition that you return the faulty one.

 

[JohnRoberts]

maybe you could arrange them to make a chess board?

JR

 

[Walrus]

maybe you could arrange them to make a chess board?

JR

Can’t play Chess, will have to be a Draughts board,

 

[Walrus]

I think API supplies replacement 2520 on the condition that you return the faulty one.

”Dear Sirs, could i have 115 replacements please?”

 

[Tubetec]

They dont supply new parts for free , you still have to pay
A buddy has a 4:2 Api rack , he's managed to blow several 2520's
Im sure the 2520 has been back engineered a million times over by now , its probably heat that causes these things to die ,which in turn is related to how the component is potted up . This idea that you have offer up a broken 2520 to be able to buy a new part is most likely illegal under European law also . Its like having the worst kept secret , which really isnt secret anymore ,but everyone including the end users willingly buy into the BS .
Send all those dead DOA's to companies is China and have them make modern clones for 50 cents each .
At least if they werent potted up you could repair them for next to nothing instead of having to make them into a monument to stupidity .

 

[pucho812]

The 2520 is designed to fail. It’s not an if but when. A former api worker told me you could get the epoxy removed but I forget which chemical bath they used. In short they are repairable but I forget the details. Field service is, replace with a known good one

 

[Tubetec]

Four of the six original 2520's on my buddies unit died over the years , thats a fairly appauling failure rate , so its like a golden goose that keeps on laying for API
Apparently paint stripper will soften epoxy ,never tried it though ,sounds messy

 

[sahib]

I think I should have said " I think API still supplies replacement ....." as some years ago a gentleman from another forum had kindly sent me six broken ones and I had purchased new ones form API under that condition.

However, it seems it is still the case.

https://studiocare.com/products/api-2520-opamp

 

[Walrus]

Yes, I know you have to pay for replacements, I was just joking.
Tubetec, were your buddies ones new versions? They seem to be a bit less reliable, as I have changed a few of those for people.
The ones in our desks are mainly old ones, in the 17 years I've been here I've probably changed less than 10. (That's done it now.....)

MEK (Methyl Ethyl Ketone) will disolve the potting epoxy, but it is a serious carcinogenic so I wouldn't recommend it! It also strips off the resistor paint.

 

[Tubetec]

Yes the guys unit is around 10 years old at this stage , so relatively new ,and I think a couple of the replacement DOA's have blown now too.

I guess you could cut all the components off ,then x-ray the pcb to find the board layout , then disolve the plastic and potting compound away and try and identify what remains .

 

[Youngwhisk]

If you have a few dead ones to spare, this might work, just don't let your wife catch you using her good pans.

 

[Tubetec]

Thanks for that Whisk ,
boiling water is much more preferable to nasty chemicals , and the board comes out nice and clean ,ready to get repaired

 

[Youngwhisk]

Of course it may turn out to not come out that easily. The softening temperature could be higher than the boiling point. Also you may have to boil it more than once.

 

[Tubetec]

Walrus ,
I noticed in your pile of dead DOA's , various labels relating to the fault condition ,
DC ,frying etc some with burnt pins , would be interesting to take a closer look at the cause of death of the various eras of 2520 ,
maybe even try and re-construct a few working modules from the various leftover parts , of course they wouldnt need to be repotted in epoxy either,
If you want you could send me a handfull and I'll workout how to get rid of the potting compound .
If 100C or 212F isnt sufficient I could always try using 'er indoor's pressure cooker , hot DOA chowder ,MMMMMMMM

 

[Youngwhisk]

Here is another video showing the boiling method on a larger item.

 

[Walrus]

Walrus ,
I noticed in your pile of dead DOA's , various labels relating to the fault condition ,
DC ,frying etc some with burnt pins , would be interesting to take a closer look at the cause of death of the various eras of 2520 ,
maybe even try and re-construct a few working modules from the various leftover parts , of course they wouldnt need to be repotted in epoxy either,

Yes, I had a bored day once and went through a lot of them to see why they'd failed. DC offset on the output is
quite a common failure, usually denoted by no output because the 47 Ohm resistor commonly used on the output has
burnt out!
I think the 'burnt" pins is just tarnish.

If you want you could send me a handfull and I'll workout how to get rid of the potting compound .
If 100C or 212F isnt sufficient I could always try using 'er indoor's pressure cooker , hot DOA chowder ,MMMMMMMM

PM me and see what can be arranged.

 

[Golgoth]

@Walrus Digging that thread up, have you been able to have some of them "unpotted" and fixed? What did you do with the remaining bunch? I would buy a couple to try and do it myself!

 

[Walrus]

Yes, I did unpot a few but the chemical necessary to dissolve the potting compound destroys the resistors and circuit board, so I never bothered to attempt a repair.
I retired last year so now do not have access to them. It’s possible my replacement may have disposed of them.