EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: lazarusr on December 24, 2015, 09:48:11 am
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I have a vintage CRT monitor with a failed three pin positor/PTC for the degaussing coil. The part number of the positor (taken from the service manual) is 263100P2332T333. But I cannot find anything about this part number online.
I attach some pictures of the part. The markings on the part are “T 333”.
The monitor is a Microvitec Cub 1451MS monitor which was commonly used with BBC Computers in schools in the UK. It hails from around 1984.
It has a 14 inch colour Mitsubishi CRT (part number M34JBF02X01) with what appears to be an entirely unremarkable degaussing coil.
The CRT is somewhat different to that used in domestic TVs in that it has a higher resolution mask suitable for computer displays of 505 x 585.
I would be grateful for any assistance in selecting a suitable replacement. I am not fussed in finding anything that is original or of a suitable vintage. I just want one that works and ideally has a similar ‘footprint’ so as to easily fit on the PCB.
Any suggestions on a suitable replacement or where I could enquire would be greatly appreciated.
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I'd start by tracing the circuit to determine if the heating element for it is series or shunt. Apparently some 3 pin posistors use a NTC heating element in series with the PSU's main power feed that also provides inrush protection, and others have a shunt PTC heating element across the mains supply. Once you've confirmed the pinout, you might be able to cross-reference it to something else that's still available, maybe using the tables in this Vishay datasheet: http://pdf.datasheetcatalog.com/datasheet/vishay/23226629.pdf (http://pdf.datasheetcatalog.com/datasheet/vishay/23226629.pdf)
Worst case, if its got the usual shunt heating element, odds are most 3 pin posistors from similar screen size tube TVs would be compatible - but double check the pinout.
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It's a thermistor
http://www.cjemicros.co.uk/micros/individual/newprodpages/prodinfo.php?prodcode=MVT-PH9344 (http://www.cjemicros.co.uk/micros/individual/newprodpages/prodinfo.php?prodcode=MVT-PH9344)
http://stardot.org.uk/mirrors/www.bbcdocs.com/filebase/hardware/Microvitec%20Service%20Manual%20Series%203%20Colour%20Display%20Monitors.pdf (http://stardot.org.uk/mirrors/www.bbcdocs.com/filebase/hardware/Microvitec%20Service%20Manual%20Series%203%20Colour%20Display%20Monitors.pdf)
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Thanks. That's the part I am looking for. Indeed, the info in the link has allowed me to find suitable replacement for much cheaper than CJE are selling it. It turns out that it is just a standard generic positor/PTC.
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Positor replaced. Monitor working. Thanks for the help.