Need help to identify a diode.  Not SMD. - Page 1
Forum section: electronics / repair

author: 4thDoctorWhoFan
author_rank: Regular Contributor
timestamp: July 08, 2018, 10:10:05 pm
content: I have an open diode on a piece of equipment and I'm not sure of the type of diode.It looks like your standard DO-35 clear glass case.It has three groupings of numbers under each other:1074728My best guess is a 1N747 but I'm really not sure.The diode is from an old HP 8560E spectrum analyzer, the YTO to be exact. Of course there is no schematic or parts list for the YTO.Did they use 10 for a 1N back in the day?Any input would be appreciated.Thanks!Edit to add a picture:

author: rf+tech
author_rank: Frequent Contributor
timestamp: July 09, 2018, 01:44:57 am
content: Hi 4th,Knowing this diode came from an HP Spec An, provides the clue to reading the numbers correctly.One comes up with 2810 as the part number suffix and 747 as the date code.Again, knowing the equipment manufacturer is HP, it would be a safe bet the manufacturer prefix ahead of 2810 is 5082, HP in this case.Take a look at 5082-2810 datasheet:http://www.datasheetcatalog.com/datasheets_pdf/5/0/8/2/5082-2810.shtmlRF+ Tech

author: modrobert
author_rank: Regular Contributor
timestamp: July 09, 2018, 02:57:37 am
content: The 1N747 is listed as a "Zener Voltage Regulator Diode" in the technical data list attached.I did find schematics for HP 8590A (link below), but maybe that model differs a lot compared to HP 8560E?ftp://ftp.agilent.com/manuals/5963-2591%208590A%20Series%20Component%20Level%20Info%20Package%20July97.pdf

author: 4thDoctorWhoFan
author_rank: Regular Contributor
timestamp: July 09, 2018, 10:32:47 am
content: Quote from: modrobert on July 09, 2018, 02:57:37 amThanks for the link but I already have the CLIP info for the 8560E. Unfortunately, they do not break down the YTO.

author: 4thDoctorWhoFan
author_rank: Regular Contributor
timestamp: July 09, 2018, 10:36:26 am
content: Quote from: rf+tech on July 09, 2018, 01:44:57 amThanks for the great info.Your breakdown of the part number is helpful and I think correct.Someone else posted the breakdown as a HP 1901-0747 which = 5082-5232. However, I cannot find any info on this number.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 09, 2018, 10:41:03 am
content: can it be 2810-747Is it located on supply rails / near regulators ?that would be similar to thishttps://www.rf-microwave.com/en/hewlett-packard/5082-2810/schottky-diode/5082-2810/at first i would have said germanium diodes ... in the past ...

author: 4thDoctorWhoFan
author_rank: Regular Contributor
timestamp: July 10, 2018, 10:21:49 pm
content: Quote from: rf+tech on July 09, 2018, 01:44:57 amI have come to the conclusion that your decode of the diode numbers are correct.Of course, these parts are obsolete and very pricey when you do find them. I found some people selling them for $20, $26 & $50 for one piece.However, surprisingly the 5082-2810 does cross reference to a NTE584. The specs are practically exactly the same. I found some of these cheap so I will try them out. If it works, perhaps I might think of getting some better quality parts but for now, I'll give them a try.The JANTX1N5712 is also a direct replacement for the 5082-2810. Mouser does have some in stock and they are $13 each.

author: rf+tech
author_rank: Frequent Contributor
timestamp: July 11, 2018, 03:15:07 am
content: Hi 4th,Thanks for the vote of confidence. I've spent several decades servicing HP gear and sorting their part numbers.Both 1N5712 and 1N5711 share the same datasheet, as they are of the same family.Subtle differences are minimum breakdown voltage of 20 Vdc versus 70 Vdc, respectively; and maximum reverse leakage of 150 nA @ 15 Vdc versus 200 nA @ 50 Vdc.1N5711 are readily available from Digikey for 40 cents in single quantity. I wouldn't even think twice about substituting 1N5711 for 1N5712.I doubt the YTO will even notice.RF+ Tech

author: 4thDoctorWhoFan
author_rank: Regular Contributor
timestamp: July 22, 2018, 12:58:15 pm
content: After replacing the diode, the YIG still was not functioning. The problem has to be on the inside of the YIG where all that VooDoo RF stuff is taking place.I bought a new YIG. I put in a ridiculously low "make an offer" on the auction site and to my surprise, the seller agreed. I was not about to pay the crazy prices they are asking for a new YIG. I would have parted out the analyzer first.Anyway, after installing the newly acquired YIG, that part of the RF section is now working. YAY!Unfortunately, I'm still not seeing my input signal being displayed. **SIGH**After more troubleshooting, I determined that I am not getting output from the A13 second converter. There are only two RF inputs to A13. One is from the YIG, which is now working. The other input is a 600Mhz, -5dbm signal. Now, the problem is that the 600Mhz signal going into A13 is way low. Instead of -5dbm, I'm getting about -25.I tracked the problem down to a faulty RF amp in the 600Mhz section. However, the part is obsolete and not readily available from the usual sources. It's a MSA-0505, HP# 1826-2421. I found some NOS parts on the auction site but they are coming from Israel. Now I'm just waiting for these parts to arrive. Should take no longer than two weeks.Now I know why I got this dirt cheap from the auction site. This unit is filled with bad boards. LOL I did not mention that when I first received it, it would not power up. I had to fix the power supply first. I am now repairing the third failure. It went from the power supply, to the YIG and now the RF amp. It's fun though.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: July 22, 2018, 01:52:33 pm
content: It's fun up just to the point, where failing old brand devices block the everydays work pile down. As soon as you repair the scope or the spa more often than getting forward on your regular task, it just sucks; this is why I sold all those old nice beauties and got new ones. It took a while to get used to the imagination working with a DSO instead of a crt scope, but in the meantime, I wouldn't like to miss it.