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Help identifying Apple Monitor H-card components


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I recently had one of my Apple Color High-Resolution Monitor Video Color Board ‘B-board’ re-capped. One of the large capacitors  (22 µf 250 V ) had started to erode. The video was slightly improved, and the occasional shutting down issue seems to be gone. However, the H-board has a broken dial, and it is hopelessly awkward to adjust the horizontal centering ‘H.CENT’.

 

So where can I buy this little dial (marked with magenta in the picture) and what is it called?

 

Thanks!

/ktkm

 

ACHD-BC-Card.thumb.jpg.d506782b9edb5831b4c568c13aae444f.jpg

Edited by ktkm
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Looks like a low profile potentiometer.  If you can determine the value in ohms and the lead spacing, you should be able to select and buy a replacement from an electronic parts supplier.  If you have the schematic and know the part identifier you should be able to figure what value is needed.

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4 hours ago, cruff said:

low profile potentiometer

Thank you! It is a ‘trim potentiometer.’ But how can I determine the resistance value? The ‘trimpot’ says: ‘102’ – is that a value? The size is approximate 7 mm.

Edited by ktkm
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That is likely to be a 1K ohm linear taper.  10 followed by 2 zeros.  If the only issue is that the adjustment dial fell off, then you could remove the pot from the board and measure across the two legs that aren't connected to the wiper, which will be the pair on the flat side.  That is an odd mounting method in the picture.

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6 hours ago, cruff said:

That is likely to be a 1K ohm linear taper.  10 followed by 2 zeros.  If the only issue is that the adjustment dial fell off, then you could remove the pot from the board and measure across the two legs that aren't connected to the wiper, which will be the pair on the flat side.  That is an odd mounting method in the picture.

I measured the pot in place, with the monitor turned off, to 1.078 kΩ, and with the monitor on, to 11.32 V DC.

Later I found this one, could it be what I’m looking for in this case? When it comes to down to effect, the spec says 100mW, how do I measure that?

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