Stocking parts... ? - Page 1
Forum section: electronics / repair

author: Saddle
author_rank: Newbie
timestamp: January 14, 2021, 07:25:29 pm
content: I seem to be doing more and more old receiver and amp repairs. I'm talking all discrete component types from the late 70's and early 80's. SAE, Sansui, Onkyo, etc. Problem is... all of the transistors are obsolete and unobtainium. Which leads me to two basic questions:1. NTE doesn't seem to get much love as a replacement transistor line, any others? Sometimes NTE is the only thing I can get that matches what I need.2. I don't stock many transistors. It's seems that every time I open up a receiver I'm presented with new (but obsolete) transistors. Does anyone have a list of recommended transistors to just have on hand?With regard to the second question, I have some basics: 2N3904, 3906, 2222, C945, stuff like that. But rarely do those fit what I need.Also, do you know of a place that caters to small orders without a minimum or high shipping charges?ThanksSaddle

author: bdunham7
author_rank: Super Contributor
timestamp: January 15, 2021, 01:24:35 am
content: NTE may say they are a match, but that is often questionable. The two 'brands' that I've found to be mostly a random collection of remarked (if that) parts are NTE and MultiComp Pro from Newark/Farnell.Cross-referencing replacements is an art and if you do repairs on that stuff, the fun will never end.I can't tell you what to stock, but try to buy more than you need when you do get stuff--the individual parts prices are usually pretty low and you often get a break at volumes as low as 10.As far as where and what to buy, Mouser has $3.49 shipping and Digi-Key is free if you mail them a check. I stick with ONSemi, STM or Central Semiconductor when I can. Central Semi has a lot of older part numbers or good replacements for them. Don't be too afraid to go to eBay or AliExpress as long as you aren't buying rare, in-demand things that are likely to be faked. I found these complementary transistors on AliExpress that were originally used in audio and (I think) horizontal drive circuits in Korean CRT television sets. The work well in certain audio amps found in many of those older receivers. I'd buy a bag just to have them--look up and keep the data sheet with them. Beyond that, it's hard to make a list because my list might not work for you.https://www.aliexpress.com/item/32888616476.html?spm=a2g0s.12269583.0.0.22371e1fLP6zTO

author: bob91343
author_rank: Super Contributor
timestamp: January 15, 2021, 05:47:20 am
content: I get my parts from scavenging obsolete gear. Monitors, stereos, you name it. I have amassed an amazing collection of 2S and 2N transistors, lots of ICs, diodes, rectifiers, some originally expensive. Voltage regulators, zener diodes, LEDs, capacitors, resistors.If I need something, it's often in the drawers somewhere. If it's a good part I won't throw it away. Sometimes the leads are short but if it's good electrically I will keep it.Having something in stock beats placing expensive orders.

author: Saddle
author_rank: Newbie
timestamp: January 16, 2021, 01:47:31 pm
content: Thanks for your inputs everyone. Great information! Haven't scrounged any parts from old monitors for a while. Need to do that. Didn't know about the shipping from mouser and digikey either.

author: SilverSolder
author_rank: Super Contributor
timestamp: January 16, 2021, 05:06:00 pm
content: I'm so cheap I even strip old computer motherboards of their MOSFETs, inductors, etc. - surprisingly often, these things are usable in other projects/prototypes.Might be worth keeping a lookout for electronic equipment from the same era that you are interested in (thrift shops, junk yard, etc.) and strip them for "period parts" that may be in common with stuff that you repair?

author: bob91343
author_rank: Super Contributor
timestamp: January 16, 2021, 06:56:31 pm
content: I don't think so. There are too many freebies on Craigslist to pay anything for a broken unit. I admit storage space has become a serious problem so now I am more selective and have been throwing out stuff that otherwise I might have saved.A few years ago a friend died and her son gave me all the parts drawers, a treasure trove of old stuff I often tap for immediate needs.