LeCroy WavePro 7200 input module failure, HSMS-2828 replacement - Page 1
Forum section: electronics / testgear

author: dgo_42
author_rank: Newbie
timestamp: December 26, 2019, 06:02:20 pm
content: Hello all,I've found what is wrong with my input module! I guess I've correct found the type (SOT143 code C8B). It is quad diode bridge, HSMS-2828 (Broadcom/Avago/HP).With this part same signal on two channels looks like this:After I short this bridge:I get normal signal for both channels:HSMS-2828 is obsolete and do not exist anymore by digikey or mouser...Question, can somebody suggest some replacement for HSMS-2828?Best regards,Dimitrij

author: shakalnokturn
author_rank: Super Contributor
timestamp: December 26, 2019, 08:49:43 pm
content: Couldn't find a drop-in equivalent, how about a couple of the right flavour of BAS69?

author: madao
author_rank: Frequent Contributor
timestamp: December 26, 2019, 08:57:21 pm
content: https://www.ebay.de/itm/Diode-Gleichrichterdiode-Schottky-SMD-15V-10mA-Ufmax-0-5V-HSMS-2828-BLKG-Schot/383196147685?hash=item5938452fe5:m:mzn8uQHU0tuxkyHNNp_Y69wYou need only one, i think, price should not a problem for you.regardsmatt

author: dgo_42
author_rank: Newbie
timestamp: December 28, 2019, 06:19:54 pm
content: BAS69 might be alternative, but there is no bridge and it is also obsolete...I've already ordered by this ebay seller,.. but it get deliver the parts first in November 2020Sad, that such good parts are not more produced...

author: nctnico
author_rank: Super Contributor
timestamp: December 28, 2019, 06:50:57 pm
content: Delivery in November 2020? I'd cancel that order! It is a major PITA that Broadcom has obsoleted all the nice HP/Agilent/Avago semiconductor parts. Lots of people are pulling their hairs over that. But there has to be an alternative supplier by now. I wouldn't replace this diode with a jelly-bean part but very carefully match the specifications. Perhaps Nexperia (formerly Philips / NXP) has a replacement. They make lots of RF parts as well.

author: xemax
author_rank: Contributor
timestamp: March 06, 2020, 09:22:47 am
content: I bought a WavePro 7100A from India. On 4 frontend the HSMS-2828 was broken. After replacing it all channels are fine.I ordered the HSMS-2828 here:https://www.ebay.com/itm/Avago-RF-Schottky-Bridge-Quad-Diode-HSMS-2828-SOT-143-10pcs/402027292164

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 06, 2020, 07:24:37 pm
content: Considering location and other items sold there are fair chances it is a genuine part.Did you try measuring the diode capacitance before fitting the parts?

author: xemax
author_rank: Contributor
timestamp: March 07, 2020, 08:02:46 pm
content: How do i measure it? With a LCR meter i got 1,5nF at 1kHz.Not genuine?

author: perdrix
author_rank: Frequent Contributor
timestamp: March 08, 2020, 03:31:28 am
content: Skyworks Solutions SMS3923 range may offer a part that will do the jobDavid

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 08, 2020, 04:19:03 pm
content: is it possible with this HMS-2828 damaged we get this kind of distorted signal? (CH4 green)fromhttps://www.eevblog.com/forum/repair/gaining-access-to-the-acquisition-board-on-a-lecroy-wavepro-7200/msg2376651/#msg2376651the AFE is below, from the picture (April 2019), i can see it almost exactly in the location like in OP (nearest to ADC (black heatsink), but the marking is like C81

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 08, 2020, 11:39:33 pm
content: Quote from: xemax on March 07, 2020, 08:02:46 pmYes LCR with special attention to zeroing / subtracting leads capacitance.You did mean 1.5pF didn't you?That sounds reasonable without paying special attention to the measurement setup.@ Mechatrommer: That could look like a bad AC/DC coupling relay.

author: nctnico
author_rank: Super Contributor
timestamp: March 08, 2020, 11:55:45 pm
content: Quote from: shakalnokturn on March 08, 2020, 11:39:33 pmNo. The channel is set to AC coupling. Look at the screen!

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 09, 2020, 12:24:11 am
content: Quote from: shakalnokturn on March 08, 2020, 11:39:33 pmis it one of the 2 white relays in the picture?

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 09, 2020, 08:18:44 am
content: Quote from: nctnico on March 08, 2020, 11:55:45 pmTrue, I spotted that after... It is quite unlikely an open relay would be showing closed intermittently, at first I thought a reed type may do that but RL1 is on the HF path...Anyway considering the displayed defect I'd still be looking for a poor contact around a capacitor. How about BWL switching?

author: nctnico
author_rank: Super Contributor
timestamp: March 09, 2020, 09:25:17 am
content: Can you show the same signal with the input set to DC1M first?

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 09, 2020, 09:57:14 am
content: I cant right now. Its hidden somewhere and my bench is full.. i'll get back to this later. I thought if its confirmed hsms2828 is broken, i might want to make an order now, so when i get to repair it again, i already have the part ready..