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Old 22nd Sep 2018, 8:41 am   #59
Heatercathodeshort
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Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
Default Re: Help needed restoring a Murphy V310

I doubt if anything has been damaged. I suspect that the EHT is low, probably around 9-10KV. This will put the focus magnets out of range preventing correct focusing.

Unfortunately an EHT meter or probe is required to confirm this. The raster should be oversize if the EHT is low. I am not familiar with your test card being weaned on Test Card C so cannot judge this.

If the EHT is low it may well be the oil filled LOPT.

Another possibility is that decades ago the LOPT may have failed and the customer decided to purchase a new model. The repair shop may have salvaged the good CRM172 substituting a low emission one into the chassis without tightening anything. This was quite a common occurrence. We can only guess.

It should still focus OK even if low. John.
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