Changing a sm op amp.

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Paul Barker
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#1 Changing a sm op amp.

Post by Paul Barker »

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My Firestone dac (not a mkII) has a dual op amp sm package. I’d like to try something better ie the Muse so2 or a Burson Audio V6 dual Classic.

1/ if I use desoldering braid is it likely the sm devise would come off easily. Wont matter if it’s dead after!

2/ what’s best way to solder adapt to a plug in package?

3/ any pointers about the role of the single op amp? Is it input op amp before a stero decoder ? As such how much would it’s quality matter?
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#2 Re: Changing a sm op amp.

Post by Nick »

No idea about the single, may be part of the power supply. The best way I find is to cut the legs of the original part as they exit the epoxy case with a craft knife, then using an iron and braid clean up the pads, then solder the new part in.
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#3 Re: Changing a sm op amp.

Post by Paul Barker »

thanks nick and yes single opamp near power in. I see utilising the old legs would help the soldering process.
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#4 Re: Changing a sm op amp.

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Paul Barker wrote: Sun Apr 17, 2022 12:53 pm thanks nick and yes single opamp near power in. I see utilising the old legs would help the soldering process.
I might have to order a finer Weller tip.
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#5 Re: Changing a sm op amp.

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No, you remove the old legs as part of the cleaning up part to just leave the solder pads.
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#6 Re: Changing a sm op amp.

Post by Paul Barker »

I see, in order to allow you to get the old pins off the sm pads doing them individually.
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#7 Re: Changing a sm op amp.

Post by Ray P »

Agree with Nick's suggestion, it's likely to end in tears if you try to unsolder the package in one go.
Sorry, I couldn't resist!
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#8 Re: Changing a sm op amp.

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I’m sure of that. My tactile skills are vanishing fast.
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#9 Re: Changing a sm op amp.

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Ray P wrote: Sun Apr 17, 2022 1:40 pm Agree with Nick's suggestion, it's likely to end in tears if you try to unsolder the package in one go.
Unless you use a air rework station. Just saying.
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#10 Re: Changing a sm op amp.

Post by Ray P »

Yep, but it appears that Paul doesn't have one.
Sorry, I couldn't resist!
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#11 Re: Changing a sm op amp.

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Not heard of them, never been involved in flow soldering. I have an electronics friend in a near village who does some surface mount soldering but he’s s hiv positive so haven’t wanted to see him and kill him with a disease. He’s haemofiliac of my generation so has zero immunity from us convicts blood transfusions in the ‘70’s, which they’re still fighting the government for compensation. But I’ll not be the first one to visit him at this time in our evolution.

I’ll manage.
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#12 Re: Changing a sm op amp.

Post by Nick »

It's not flow soldering. That was generally for through hole parts. Again just saying.
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#13 Re: Changing a sm op amp.

Post by ed »

If you're still doing work in Hull you're welcome to drop in and borrow mine. It doesn't get that much use these days.
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#14 Re: Changing a sm op amp.

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That would be great Ed. Im starting contracting to BG again mid May, it can wait.
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#15 Re: Changing a sm op amp.

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OH What a ballsup! I was all set up to fit a new socket for testing dacs easily. As I cant bear no music, I put my Bushmaster (the first Bushmaster dac.) Stan had kindly updated the chip which locks onto the signal free of charge, by finding my post on a forum, might have been here? So he voluteered himself to fix it foc. What a gent!

So Ive plugged it in in order to update the Spitfire, which from reviews should wipe the floor with everything at or under its price level.

Well guess what? The Bushmaster wipes the floor, the sounds I felt could sound more analogue (being the reason for opamp journey) are great analogue. The week bass of the speakers is suported and stronger. The voicing is right, the drum skins and cymbols are better. Everything better soundstage imaging darkness, whatever you want to call it is better.

Id better check what the opamp is, might only be that. Its another sm but after reading the number I did nothing about it, thinking, “Ill upgrade my best dac first then see if I can do anything with this old thing! The arogance of it. I prefusely apologise Stan if youre looking in! Pride before a fall.

Dang, Now I have to switch back and open up my best dac so far instead. Unable to run to that v6 classic / vivid, I ordered one $20 discreat dual opamp, but with no info so probably bjt pair at front end. But also ordered 3 to 4 opamps I discovered have fet inputs. Cant recall if 3 or 4 of them, well it is 4 when the two single opamps OPA445BM arrive and Ive converted to dual opamp.

And ordered a few non fet input opamps highly recommended.

so the journey met a fork in the road, as they do, and ive had sufficient intelligence to adjust.

Still listening and man, this dac with whatever its surface mount opamp is. When Ive seen the number again Ill get the datasheet, might be another fet input?

But cant stop listening! My prayers were answered already!
Last edited by Paul Barker on Sat May 07, 2022 7:04 pm, edited 1 time in total.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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