How to repair failing Dynamiks

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Linntek
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How to repair failing Dynamiks

Post by Linntek » 2019-09-07 18:48

Some time ago my M4100/D began to make funny clicking noise (mechanical/relay). Soon after it died completely.
The power supply was out of business. I was trying to find another power supply without luck.
Now - I don't give up so easily. I found out the standby power supply didn't work.
It is a smal SMPS build around af TopSwitch 223 from Power Integrators.
It should be 12 Volt DC to power other circuits.
I started out replacing the TopSwith since it is obsolete and hard to find (it is always these failing...).
It didn't help so i started to see if I could find other failing components around the TopSwitch, but no success.
I even meassured capacitors but all was fine.
I tried a external 12V power supply and it worked fine - but not practical with an external LAB supply.... wires all around.
The project stalled until earlier this year and I gave it another shot.
I started replacing the most critical capacitor and believe or not - it worked!

The standby power supply is basicly like in the datasheet.

https://ac-dc.power.com/sites/default/f ... 21-227.pdf

The failing capacitor is C5 on page 6 in the datasheet.

It is a 22uF/16V SMD

Remember - I have allready tested the cap and the capacity I meassured was fine - around 22uF.
So I guess it is ESR related but my capacitor tester can't meassure ESR.

Why I post this now?? My M-DSI just did the same (it just died) a few days ago. I replaced the cap and we're playing again.
That's why I think I'm not the only one out there and this might help you.
Both are facing their 10 year birthday.

If your dynamik is constantly powered it will continue to work. You will only see it fail if you switch it off (and on...).
Mine is always powered.

If your'e interested I can send some pictures with instructions.

Good luck

Disclaimer :
The normal stuff - own risk - high voltage - don't kill yourself etc.

Defender
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Re: How to repair failing Dynamiks

Post by Defender » 2019-09-07 19:15

measuring caps while still in the circuit can give misleading results - did the cap measured the same o.k. value after you taken him out?
you are right thermal cycles/power on and of cycles usually kill the components in the long run


congratulations for being successful

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lejonklou
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Re: How to repair failing Dynamiks

Post by lejonklou » 2019-09-07 19:38

Wonderfully helpful, Linntek! Thanks for posting.

I think it's more likely leakage current related than ESR.

Defender: I'd go a bit further than 'misleading' and say that it's pointless to try measuring a cap in circuit.

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Linntek
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Re: How to repair failing Dynamiks

Post by Linntek » 2019-09-07 20:05

Defender wrote:
2019-09-07 19:15
measuring caps while still in the circuit can give misleading results - did the cap measured the same o.k. value after you taken him out?
you are right thermal cycles/power on and of cycles usually kill the components in the long run


congratulations for being successful
They were out - of course.

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Briain
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Re: How to repair failing Dynamiks

Post by Briain » 2019-09-09 13:55

Hi

One of my friends (who now owns my old Klout/Keltik system) had a problem with his MDSi and before trying to diagnose it, he did some wed dredging and found an entertaining video of someone fixing one (without any diagrams; he figured out and described its 'modus operandi', on the fly) and in that case, the low power (standby) section of the SMPS had expired due to a duff capacitor.

Having fitted a few Dynamik's over the years, whilst watching it I noticed that he'd put the heat sink back the wrong way around (and I added a comment on same, about 7 months ago) and he responded that he'd noticed that before finishing the job, but he'd not bothered to re-shoot that part of the video. Great effort in fixing the SMPS without any diagrams, though; hats off to Mr 12voltvids, I say!

https://www.youtube.com/watch?v=Cz9VYWRzIMw

Bri

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Linntek
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Re: How to repair failing Dynamiks

Post by Linntek » 2019-09-09 18:50

OMG.
That is the one. That is the cap failing.
The cap i pulled out (of the DSI) meassured 18.8uF . Not alarming . Within +- 20%
But proberbly ESR related.

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Re: How to repair failing Dynamiks

Post by vicdiaz » 2019-10-02 01:01

Hi,

ESR meters are relatively cheap and can measure ESR without removing caps from the board.
Vic
Ivor's "Tune-Method Seminar" Alumni

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