Where to buy 750kOhm 2W metal oxide(?) resistor in Australia - Page 1
Forum section: electronics / repair

author: Lorenzo_1
author_rank: Regular Contributor
timestamp: August 31, 2017, 01:13:38 pm
content: Hi. I need one of these for the primary side of a LeCroy power supply. Been looking at RS Components, Radio Parts and Element-14/Farnell without success. I think the one installed is perhaps metal oxide/flameproof type - green body & matt finish. From the size I think 2W (it's 9mm x 3mm in the body) Any suggestions? I can find them online in US/Canada but postage is high. Also ex China/Hong Kong with free postage but unknown quality. Grateful tips as to what to avoid/prefer.

author: Rbastler
author_rank: Frequent Contributor
timestamp: August 31, 2017, 02:05:57 pm
content: You could use two 1.5M in parallel, say 1W each, if there is enough space.Sent from my A0001 using Tapatalk

author: David_AVD
author_rank: Super Contributor
timestamp: August 31, 2017, 09:16:48 pm
content: How much of a hurry are you in and where are you located?Digikey has750K 2W onesand I could add a couple to my next order.

author: xavier60
author_rank: Super Contributor
timestamp: August 31, 2017, 10:24:28 pm
content: Over the years I have had trouble finding resistors that are reliable at high voltages. I take notice of a resistor's voltage rating instead of just its wattage. In recent years I have been using High Voltage Thick Film Resistors, usually Welwyn brand.

author: Lorenzo_1
author_rank: Regular Contributor
timestamp: September 01, 2017, 11:38:04 pm
content: Thks for the replies. I'm not in a great hurry as the PS is currently working fine with 2x1W 1.5M carbon composition resistors in parallel (all I could get locally) - Cairns is not an easy place to do these sorts of repairs as Jaycar's about the only supplier. Before deciding whether to take up David_AVD's kind offer, I could use some advice on what's recommended for primary side of this SMPS. The dead one I removed is 9mm x 3mm and matt light green finish - sits across 340V DC rail behind bridge rectifier with primary side ground at 170VDC (schematic & photo attached). I've taken it to be 1W and presumed it should be capable of handling at least 200V.I figured it might be metal oxide type - hence I was looking for those. Would an HV thick film resistor substitute OK or should I stick closer to a like-for-like replacement? Are there generic recommendations for appropriate composition of this type of SMPS resistor? I presume some fire/transient resistant type is recommended - does it matter if you put in something with kV volt rating if that's readily available here?For David_AVD - perhaps you can PM me to advise when you'd need a decision from me about adding one/some to your next order.

author: David_AVD
author_rank: Super Contributor
timestamp: September 02, 2017, 03:07:06 am
content: I order from Digikey or Mouser every week or two, so give me a yell when you need them. Should be able to pop them in an envelope so only a couple of bucks all up.

author: Lorenzo_1
author_rank: Regular Contributor
timestamp: September 02, 2017, 09:54:07 am
content: Thanks David. Will do. I'll PM you if that's OK.

author: David_AVD
author_rank: Super Contributor
timestamp: September 02, 2017, 11:25:03 am
content: No problem.

author: David_AVD
author_rank: Super Contributor
timestamp: September 13, 2017, 05:06:49 am
content: I have your resistors ready to send. Just need to double check address and give you PayPal details.

author: Lorenzo_1
author_rank: Regular Contributor
timestamp: September 13, 2017, 10:04:34 am
content: Thks David. I've PM'd you.