HP531xx VLD display replacement source - what happened? - Page 1
Forum section: electronics / general

author: tkamiya
author_rank: Super Contributor
timestamp: April 25, 2021, 03:22:44 am
content: About two years back, ebay had plenty of replacement VLD displays for HP531xx series of frequency counters. Most of them were from China and they were sold as new. I picked up a few and yes, they were nice and bright. They didn't look like the original panel but I had no doubt they worked very well and acted like new.Then sometime last year, prices doubled and tripled, then all of them pretty much has gone away from market. A months or so ago, I noticed they started to appear on eBay again, but this time, they are sold USED or REFURBISHED. Price is around 160 to 2xx dollars a piece.I know there are few folks on here with intimate knowledge of Chinese market scene. What's going on? Is it even possible to refurbish VLD displays economically? At prices nearing $200 a piece now, I'm more reluctant to chance this. Even at these prices, supplies are low.My guess was, at some point, someone saw a market in these replacement VLDs and had some contract manufacturers make whole bunch of them. Now I guess the stock is depleted?

author: artag
author_rank: Super Contributor
timestamp: April 25, 2021, 11:27:53 am
content: I noticed the 34401A VFDs dropping in price until they were about $25. The 53131 displays were about $100 and dropped to about $75 but no lower. Hoping that both types had been remanufactured and dropped from an opportunist price to a stable one, I hung on - but as you say, the 53131 displays then dried up.I did read that a spare 34401 display from HP was only around $25 so I guess both could have been end-of-stock rather than remanufacture. I'm guessing there were a lot more 34401s made than 53131 and so more spares stock available.

author: tkamiya
author_rank: Super Contributor
timestamp: April 25, 2021, 11:34:21 pm
content: I wonder if I buy a few HP34401 ones for future use? I like that meter and they do wear out just the same way. Does anyone know if it is even possible to refurbish VLD? I know there are tricks to apply excesses voltage to heater to burn off impurities, but does anyone do this kind of thing in industrial quantity?

author: martinr33
author_rank: Frequent Contributor
timestamp: April 26, 2021, 05:32:20 am
content: https://item.taobao.com/item.htm?id=561447283234some of these displays are still out there. you can investigate that link, and will need an agent or friend in China or who can deal with the supplier. 53131 does appear to hve dried up.These parts are hard to find from a US location, I dig them up from old lnks.

author: tkamiya
author_rank: Super Contributor
timestamp: April 26, 2021, 06:07:27 pm
content: I can sort of read what it says....My needs are only few pieces that involving brokers and going through incorporation, etc, is not worth the trouble. It's amazing what can be found in Chinese market though. Thanks for the info.

author: floobydust
author_rank: Super Contributor
timestamp: April 26, 2021, 07:10:45 pm
content: You cannot refurb a VFD, the phosphor ages as well as the filament. Some people have success rejuvenating the filament (burning off contaminants) by over-voltaging it to moderate incandescence for a short period. There's a few threads here about doing that.The original fluorescent displays were made by Noritake. Samsung SSVD (Shanghai Samsung Vacuum Devices) made them next and I think there is no manufacturer ID on the replacements.

author: tkamiya
author_rank: Super Contributor
timestamp: April 26, 2021, 07:35:17 pm
content: One of the difficulty I get into often with sellers is that THEY don't seem to always know exactly what they are selling.... Vendors to them appear to tell them something but who knows if that's correct either. Very frustrating! What I bought about 2 years ago were neither Noritake nor Samsung. Very murky market....