HP 8647 VFD Display - Page 1
Forum section: electronics / testgear

author: kiheiman
author_rank: Contributor
timestamp: January 29, 2016, 08:48:14 pm
content: The VFD display on my HP 8647 signal generator is dim, but still usable. Does anyone know where I can get a replacement? There are some on eBay, but the part number does not quite match. I need a Noritake Itron CU40025SCPB-U3J. That number gets the circuit board and the VFD display. I would not be opposed to just getting the VFD display and soldering it to the existing circuit board. The good thing about this is that it is very easy to replace the display - takes no more than 30 minutes.RegardsClint

author: Muxr
author_rank: Super Contributor
timestamp: January 29, 2016, 08:53:08 pm
content: You could try contacting the Noritake Itron, I've had good luck with them in the past:https://www.noritake-elec.com/

author: michaeliv
author_rank: Frequent Contributor
timestamp: January 29, 2016, 09:52:32 pm
content: You can also try reviving it:https://xdevs.com/fix/kei2000/#vfd_rejuvhttps://www.eevblog.com/forum/chat/vacuum-fluorescent-display-rejuvenation/

author: kiheiman
author_rank: Contributor
timestamp: January 29, 2016, 09:57:48 pm
content: Thanks for the feedback. I did just send an email to Noritake Itron. On eBay, I found a display that appears to be almost identical and the price is right. The circuit boards are different, but if the VFD display is the same, then I can remove it from the board and install it on my existing board. I wish that I could find a data sheet for my board - I have a datasheet for the eBay unit.

author: michaeliv
author_rank: Frequent Contributor
timestamp: January 29, 2016, 09:59:59 pm
content: Is the eBay one new ? If only the VFD + board are being sold (presumably from a used unit ), are you sure that it's any brighter than yours ?

author: kiheiman
author_rank: Contributor
timestamp: February 01, 2016, 04:01:34 am
content: The eBay add said it was a brand new unit. The circuit boards appear to be different but I am hoping that the actual VFD display will be the same as what I have. Will not know for sure about the brightness until I install the new unit. On my current display, not all the dots in each character are dim - some are very bright - the ones that never get used.

author: kiheiman
author_rank: Contributor
timestamp: February 02, 2016, 12:48:22 am
content: I received the eBay VFD unit. It will not work. The display was about 1.5" too wide.

author: michaeliv
author_rank: Frequent Contributor
timestamp: February 02, 2016, 12:53:31 am
content: Quote from: kiheiman on February 02, 2016, 12:48:22 amIf you post pics of both the displays(along with pinout) that would help in identifying them.By pinout I mean view of the pins from the side.

author: kiheiman
author_rank: Contributor
timestamp: February 02, 2016, 10:44:49 pm
content: Noritake tells me that the VFD was custom made for HP and they have no specs. However, they said that the VFD glass on the circuit board is a DN4025C and it is still used on a number of Itron displays such as the CU40025-UW6J. Noritake says that the cost of the glass is about $70, but they currently have no units in stock. Here is a link to the specs for the DN4025C:http://www.noritake-itron.com/NewWeb/Glass/specs/DN4025C.pdfI think that I can get the complete UW6J assembly from Digikey for about $90. Interesting statement in the spec sheet for the DN4025C "prolonged on time of the same digits will cause the digits to dim.

author: macboy
author_rank: Super Contributor
timestamp: February 03, 2016, 03:00:37 am
content: Quote from: kiheiman on February 02, 2016, 10:44:49 pmNot so interesting really, this is a fact of life for every VFD display.

author: kiheiman
author_rank: Contributor
timestamp: February 12, 2016, 08:25:17 pm
content: I received the DN4025C VFD glass from Noritake. It took about 30 minutes to change out the part, but I could have done it quicker if I had just cut off the leads on the old VFD glass. Once I had the old VFD out, I could see the DN4025C part number of the backside of the glass. The display is now nice and bright. Upon a very close look at the old part, I could see the burned in dots - especially "dBm" and "OFF", plus others.Repair is finished.