White noise and PCB flux cleaner.

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matabhaine
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White noise and PCB flux cleaner.

Post by matabhaine » Sat Nov 26, 2016 1:29 pm

I have just bought a BBC Micro Model B from EBAY, it makes a hiss sound (white noise) when I switch it on. I was wondering if this is normal.
I have bought some PCB flux cleaner from Maplins, after some thought, would this be the correct stuff to clean the inside of the machine, I just want to give it some TLC.

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CMcDougall
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Re: White noise and PCB flux cleaner.

Post by CMcDougall » Sat Nov 26, 2016 1:39 pm

Normal, its less noisy once it's heated up.

Dishwasher comes to mind :lol:
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JudgeBeeb
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Re: White noise and PCB flux cleaner.

Post by JudgeBeeb » Sat Nov 26, 2016 2:56 pm

Maplin PCB flux cleaner is useless. I would strongly suggest you don't use it unless you want the PCB covered in a sticky film which then attracts dust.

I use '100%' IPA which is available cheaply on eBay. There are other more reputable branded flux cleaners which people far more experienced than me report are more effective than IPA.
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matabhaine
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Re: White noise and PCB flux cleaner.

Post by matabhaine » Sat Nov 26, 2016 9:37 pm

Great answers, quick response as well, what a great site and thanx for the advice.

Just one more thing: I have bought a PSU capacitor replacement kit. Should I go ahead and replace the capacitors? Any thoughts.

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1024MAK
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Re: White noise and PCB flux cleaner.

Post by 1024MAK » Sat Nov 26, 2016 9:44 pm

matabhaine wrote:Great answers, quick response as well, what a great site and thanx for the advice.

Just one more thing: I have bought a PSU capacitor replacement kit. Should I go ahead and replace the capacitors? Any thoughts.
If C1, C2 etc are the old originals, yes, replace them as soon as you can.

Mark

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1024MAK
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Re: White noise and PCB flux cleaner.

Post by 1024MAK » Sat Nov 26, 2016 9:48 pm

1024MAK wrote:
matabhaine wrote:Great answers, quick response as well, what a great site and thanx for the advice.

Just one more thing: I have bought a PSU capacitor replacement kit. Should I go ahead and replace the capacitors? Any thoughts.
If C1, C2 etc are the old originals, yes, replace them as soon as you can.

Mark
Unless you like magic smoke...

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JudgeBeeb
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Re: White noise and PCB flux cleaner.

Post by JudgeBeeb » Sat Nov 26, 2016 10:22 pm

matabhaine wrote:Just one more thing: I have bought a PSU capacitor replacement kit. Should I go ahead and replace the capacitors? Any thoughts.
Assuming the kit is from a reputable supplier. :shock:
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1024MAK
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Re: White noise and PCB flux cleaner.

Post by 1024MAK » Sat Nov 26, 2016 10:50 pm

lazarusr wrote:
matabhaine wrote:Just one more thing: I have bought a PSU capacitor replacement kit. Should I go ahead and replace the capacitors? Any thoughts.
Assuming the kit is from a reputable supplier. :shock:
Yes, keep away from some kits, like this one :lol:

Mark

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Re: White noise and PCB flux cleaner.

Post by JudgeBeeb » Sat Nov 26, 2016 10:55 pm

1024MAK wrote:
lazarusr wrote:
matabhaine wrote:Just one more thing: I have bought a PSU capacitor replacement kit. Should I go ahead and replace the capacitors? Any thoughts.
Assuming the kit is from a reputable supplier. :shock:
Yes, keep away from some kits, like this one :lol:

Mark
To be fair, those are genuine RIFA parts. :?
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1024MAK
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Re: White noise and PCB flux cleaner.

Post by 1024MAK » Sat Nov 26, 2016 11:00 pm

lazarusr wrote:
1024MAK wrote:
lazarusr wrote: Assuming the kit is from a reputable supplier. :shock:
Yes, keep away from some kits, like this one :lol:

Mark
To be fair, those are genuine RIFA parts. :?
And if anyone does want some genuine used RIFA parts (that have some missing magic smoke), I may still have some. Yours for only the cost of postage :lol:

Alternatively, you may want to get some that have not lost any magic smoke. They are available from RS and Farnell. Or from RetroClinic.

Mark

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Re: White noise and PCB flux cleaner.

Post by matabhaine » Sat Nov 26, 2016 11:42 pm

I bought the kit from here: http://www.ebay.co.uk/itm/391168606844
Please let me know what you think. Even if you think I should buy them elsewhere or any links to better kits.

Thanx for all the help.

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Re: White noise and PCB flux cleaner.

Post by JudgeBeeb » Sat Nov 26, 2016 11:48 pm

You're probably alright with that, but if you want to be confident, try this: http://www.ebay.co.uk/itm/262735633849. He supplies RIFA branded X2 caps and a low ESR electrolytic.
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1024MAK
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Re: White noise and PCB flux cleaner.

Post by 1024MAK » Sun Nov 27, 2016 12:16 am

matabhaine wrote:I bought the kit from here: http://www.ebay.co.uk/itm/391168606844
Those are okay for a BBC model A, B or B+. C9 does not have to be a low ESR type, it just needs to be a 105oC rated type. C1 and C2 need to be X2 275Vac rated (or better), they do not have to be made by Rifa. The parts in the kit meet those criteria. cool-novelties are UK based and are a major supplier of SCART, video and other cables to the retro computer hobbyists, so are established and known.

However, some people like to fit parts as close to the original as possible, hence Rifa capacitors are preferred. In which case, buy from RetroClinic. Also the parts he supplies also fit in Master 128 and 512 machines. This seller is very well known in the Acorn 8 bit world (he's a member of the forum).

I should perhaps say that I have bought cables from cool-novelties and various items, including capacitors from RetroClinic.

Mark

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Re: White noise and PCB flux cleaner.

Post by matabhaine » Sun Nov 27, 2016 12:55 am

Right, I've just ordered the RetroClinic kit, thanx to everyone for all the speedy help. :D

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Re: White noise and PCB flux cleaner.

Post by matabhaine » Sun Dec 04, 2016 6:24 pm

I have replaced the capacitors on the PSU and even bleached her back to the light cream colour that I remember but the hiss appears to be coming from the speaker (I was brave enough to put my ear close to the speaker). On wikipedia it says that some Model B Micro computers shipped with this problem, something needs to be soldered across something in order to fix it. That's when the brain fog took over me. :D
I don't mind soldering, so I might try to fix it, if anyone has any pointers (Please though, keep it relatively simple) :D

Kind regards
Matt.

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Re: White noise and PCB flux cleaner.

Post by hoglet » Sun Dec 04, 2016 6:44 pm

matabhaine wrote:I have replaced the capacitors on the PSU and even bleached her back to the light cream colour that I remember but the hiss appears to be coming from the speaker (I was brave enough to put my ear close to the speaker).
Every Beeb I have used has some background noise coming from the speaker.

Unless it's excessive, I wouldn't worry.

How loud is it compared to Ctrl-G?

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1024MAK
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Re: White noise and PCB flux cleaner.

Post by 1024MAK » Sun Dec 04, 2016 8:32 pm

All Beeb's hiss.... :D

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Re: White noise and PCB flux cleaner.

Post by matabhaine » Sun Dec 04, 2016 8:57 pm

Maybe hiss is the wrong word, it makes a sort of hiss with a very light rasp and also the sort of interference whine you would get on a radio but this only lasts a short while. Having nothing to compare it to makes it difficult to determine. Maybe there is a youtube link to a similar sound. Just want to be sure all is well.

Kind regards.
Matt.

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1024MAK
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Re: White noise and PCB flux cleaner.

Post by 1024MAK » Sun Dec 04, 2016 9:23 pm

However, the level of hiss may be reduced by renew the following capacitors:
C2 (4.7uF), C5 (10uF), C9 (10uF)
Check the solder joints for the speaker connector on the PCB. Also other joints in the same area.

On issue 3 and below boards, there is also a simple modification. Connect a 10k ohms resistor between pin 8 of IC20 and the plated-through hole just south of pin 8. If there is green solder resist, this needs to be scratched away before the solder will take.

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Re: White noise and PCB flux cleaner.

Post by matabhaine » Sun Dec 04, 2016 10:13 pm

I changed c1 c2 and c9, c5 I am not sure about.
The second thing, I saw on Sprow's webpages, Quote:- crosstalk from the processor data and address lines to the sound amplifier on the 1MHz bus connector where the two signals run in parallel. For the BBC B it can be solved by soldering a 10k resistor from the 'AIn' pin of the 1MHz bus to ground.

I would need some small photo tutorial for this, I changed the capacitors (which was fun) done some mods on a speccy and an C64 but this I would need to see a vid or something first.

I changed modes and the sound doesn't change.

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Matt.

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1024MAK
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Re: White noise and PCB flux cleaner.

Post by 1024MAK » Sun Dec 04, 2016 10:23 pm

When I say C2 (4.7uF), C5 (10uF), C9 (10uF), I mean on the Beeb main PCB.

It's also worthwhile doing C16 (47uF) at the same time.

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Re: White noise and PCB flux cleaner.

Post by matabhaine » Sun Dec 04, 2016 10:42 pm

I see.

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Re: White noise and PCB flux cleaner.

Post by matabhaine » Sun Dec 04, 2016 10:46 pm

Managed to find a schematic of the BBC Micro online but the print is rather ropey in places will need to open the Micro up later, going to bleach the base tomorrow anyway.

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Re: White noise and PCB flux cleaner.

Post by matabhaine » Sun Dec 04, 2016 10:48 pm

@mark: Love the link at the base or your post, just what I was looking for when trying to choose my software.

Kind regards.
Matt.

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1024MAK
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Re: White noise and PCB flux cleaner.

Post by 1024MAK » Sun Dec 04, 2016 10:51 pm

See here for schematics ;-)

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matabhaine
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Re: White noise and PCB flux cleaner.

Post by matabhaine » Sun Dec 04, 2016 11:05 pm

That's the one I am using. Sadly, some of the print is a little faded.
Thanx for the reply.

Kind regards
Matt.

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Re: White noise and PCB flux cleaner.

Post by MartinB » Mon Dec 05, 2016 7:38 am

Matt wrote:Sadly, some of the print is a little faded.
Here's a re-worked version...
BBC B.png

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Re: White noise and PCB flux cleaner.

Post by flynnjs » Mon Dec 05, 2016 8:01 pm

Martin, nice addition to my various other "cleaned up" schecmatics. Did you do that?
Do you know if is it raster only, or is it in vector or CAD format?

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Re: White noise and PCB flux cleaner.

Post by matabhaine » Mon Dec 05, 2016 9:49 pm

@MartinB thanx, that's great.

Kind regards
Matt.

matabhaine
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Re: White noise and PCB flux cleaner.

Post by matabhaine » Tue Dec 06, 2016 5:20 am

Can these capacitors be had from retroclinic? Thanx.

Kind regards.
Matt.

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