UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

space_charged · 21st Sep 2019, 4:50 pm

I have just about finished with this restoration. One of the sets had a problem with intermittent changes of horizontal static convergence, H-STAT. With these early trinitron tubes, H-STAT is achieved by a variable voltage applied at almost the full EHT (nom 17.5KV). This is delivered by the "HV block" which houses the tripler. H-STAT comes from a pot with resistors either side across the final stage of the multiplier. Its all sealed, potted in epoxy so highly resistant to repair. The H-STAT voltage itself is delivered to the concentric final anode connector on the CRT. The EHT lead is co-axial with the H-STAT voltage the inner wire and the EHT the outer.

I found that just by running the set for a long time that this "jumping" of H-STAT gradually decreased and now seems to have gone. Possibly some residual moisture has been removed by heating and/or action of the EHT on it.

Ideally I'd replace the HV block, and web searches do show Sony parts coming up from time to time. The part number I searched for was Sony HV block 1-453-050-31. Nothing so far but I'll keep looking.

21st Sep 2019, 4:50 pm	#15
space_charged Hexode Join Date: Dec 2014 Location: West Midlands, UK. Posts: 315	Re: Restoring a Sony KV9000UB I have just about finished with this restoration. One of the sets had a problem with intermittent changes of horizontal static convergence, H-STAT. With these early trinitron tubes, H-STAT is achieved by a variable voltage applied at almost the full EHT (nom 17.5KV). This is delivered by the "HV block" which houses the tripler. H-STAT comes from a pot with resistors either side across the final stage of the multiplier. Its all sealed, potted in epoxy so highly resistant to repair. The H-STAT voltage itself is delivered to the concentric final anode connector on the CRT. The EHT lead is co-axial with the H-STAT voltage the inner wire and the EHT the outer. I found that just by running the set for a long time that this "jumping" of H-STAT gradually decreased and now seems to have gone. Possibly some residual moisture has been removed by heating and/or action of the EHT on it. Ideally I'd replace the HV block, and web searches do show Sony parts coming up from time to time. The part number I searched for was Sony HV block 1-453-050-31. Nothing so far but I'll keep looking.