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Old 1st Aug 2022, 8:26 am   #1
percival007
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Default Philips ISP IS5021

Hi All,

I have been asked to look at a Philips ISP IS5021...............
( https://www.dutchaudioclassics.nl/Fo...ound-enhancer/ )

It has failed on one channel and I have discovered it is the Right channel Volume Control which has physically broken and failed at zero Volume.
The tiny spiggot which should protrude from the actual knob and mate with the Resistor actuator has snapped. I have attempted a repair and have been slightly successful but it is not as 'smooth' any longer, in feel and operation.

I can find no service manual, Hi-Fi Engine etc etc.
I have approached Dutch Audio Classics (see above) but as yet no reply.

The control is an ALPS unit. 5 Pins and not a conventional Variable Resistor.
It operates in the Digital Domain, I think, and varies a Voltage or Current. I think maybe Current as I can see nothing changing when 'scoping the Pins (on the good channel).
One Pin sits at 5V, constantly and the rest appear 0V, constantly but the control is doing what it should on the good channel.

I wonder, does anyone have a service manual for this and can give me the part number? Who knows, I may be able to find one somewhere.
(Picture of disassembled control attached but not great quality, sorry. The long silver coloured protrusion is my 'fix' cut to a more appropriate length.)

Thanks,

James.
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Last edited by percival007; 1st Aug 2022 at 8:28 am. Reason: Added clarification
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Old 1st Aug 2022, 10:05 am   #2
Analogue man
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Default Re: Philips ISP IS5021

if it works in the digital domain then it sounds like a rotary encoder rather than a potentiometer to me.
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Old 1st Aug 2022, 10:11 am   #3
pointsman
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Default Re: Philips ISP IS5021

Hi percival007,

CPC Farnell page, may help.

https://cpc.farnell.com/c/electronic...otary-encoders
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Old 6th Aug 2022, 6:23 am   #4
percival007
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Default Re: Philips ISP IS5021

That makes perfect sense that it is an encoder.
I haven't 'scoped any pulses on it, but i am sure that'll be what it is.

Unfortunately I can't find the exact one at CPC/Farnel or RS.
I shall have to scour eBay.

Thanks for the pointers though.

No-One got a schematic?

James
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Old 6th Aug 2022, 9:58 am   #5
G6ONEDave
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Default Re: Philips ISP IS5021

Is the model number from the front or rear of the unit, as I don't recognise it as a Philips model. Most of the Philips model numbers start with 2 or 3 numbers followed by a couple of letters and then another few numbers, such as 22DC561 etc.

Dave
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Old 6th Aug 2022, 8:56 pm   #6
percival007
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Default Re: Philips ISP IS5021

Quote:
Originally Posted by G6ONEDave View Post
Is the model number from the front or rear of the unit, as I don't recognise it as a Philips model. Most of the Philips model numbers start with 2 or 3 numbers followed by a couple of letters and then another few numbers, such as 22DC561 etc.

Dave
Hello,
it's what's on both the front and rear panels.

See the pictures in the link in my first post (the Dutch Audio Classics link)

James.
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