Transistor IC replacement suggestions [Solved] - Page 1
Forum section: electronics / repair

author: Gip-Gip
author_rank: Contributor
timestamp: May 07, 2017, 01:19:26 am
content: I'm repairing an old Tektronix OS-245(P)/U and while going through the scope I found a transistor array IC with the mark of death given by a previous repairman. The guy that had it last says it worked fine, but I'd like to investigate anyways. I have a few questions:* How should I test the IC?* If it is bad, how should I go about replacing it? Should I just choose transistors with the right voltage ratings(which I would have to guess), or is there more to it? Nothing could be found online; I only have the schematic for reference.

author: Trooper_Dan
author_rank: Newbie
timestamp: May 07, 2017, 01:25:07 am
content: Transistor ic? If it an ic u can't test it u have to change it if it a transistor u can test it the reading should be 0.5 to 0.8 once u have the schematic u can get it fix.can u upload a pic so I can see exactly what ur talking aboutSent from my SM-N920T using Tapatalk

author: Gip-Gip
author_rank: Contributor
timestamp: May 07, 2017, 01:43:48 am
content: It's an IC that contains an array of transistors. I've attached a few images that'll hopefully clear everything up

author: theatrus
author_rank: Frequent Contributor
timestamp: May 07, 2017, 02:21:34 am
content: There was a 5 array transistor made by Intersil (CA3083), but it's not a pinout match.Is there any marking left?Since it looks socketed, just pull it and use a standard diode check or even a test circuit.The transistor pairs are likely matched and replacing it with discretes would require some binning.

author: amspire
author_rank: Super Contributor
timestamp: May 07, 2017, 03:34:51 am
content: It is almost certainly a CA3046 transistor array.https://www.bucek.name/pdf/ca3046.pdfCan be hard to get from Digikey, Mouser, etc in the dual-in-line package but they are still readily available from ebay and Aliexpress.

author: whitevamp
author_rank: Regular Contributor
timestamp: May 07, 2017, 04:04:40 am
content: this looks like it..http://datasheet.datasheetarchive.com/originals/distributors/Datasheets-30/DSA-595398.pdfIC. NPN Transistor array, monolithic. Three isolated transistors and one differentially connected transistor pair. Package: 14 Cdip. Note: Silicon.Harris Corp - CA3045F - IC. Transistor array, NPN.then that crosses to mc3346 then that crosses to lm3045 and that is identical to the lm3086nhttp://www.digchip.com/datasheets/parts/datasheet/321/LM3086N.phphttp://store.americanmicrosemiconductor.com/lm3046n.htmlif i was looking at it all correctly...

author: tautech
author_rank: Super Contributor
timestamp: May 07, 2017, 04:23:57 am
content: Go to this page and scroll to the bottom where there's a 27 Mb zip file with a full Tek X-reference list.Do not link it as requested by Sphere.http://www.sphere.bc.ca/test/tekequiv.html

author: Kleinstein
author_rank: Super Contributor
timestamp: May 07, 2017, 07:44:13 am
content: The shown circuit suggest this a voltage regulator for a rather high voltage. Two of the transistors seem to be for a current limit and thus not that critical in matching. Depending on the use of the voltage the other pair might not be that critical too. So it might be feasible to replace them with just normal small NPNs, with maybe one pair matched.

author: Gip-Gip
author_rank: Contributor
timestamp: May 07, 2017, 04:30:45 pm
content: Good news:I finally got around to testing the IC and it looks to be in working condition.I'd like to thank those who contributed, even though it went no-where

author: David Hess
author_rank: Super Contributor
timestamp: May 08, 2017, 02:33:33 am
content: I know it is academic now but if the transistor array was bad, the differential pairs could be replaced with discrete transistors matched for Vbe. The differential pairs in this case are used for the error amplifier and foldback current limit amplifier and the offset voltage demands are not super critical.