Need help for NEC IC data - Page 1
Forum section: electronics / repair

author: Roman oh
author_rank: Regular Contributor
timestamp: July 12, 2023, 02:20:47 am
content: Hi guys,I am trying to fix a YEW type 3132 DC isolation amplifier. I’m guessing that finding a schematic for it is just too improbable, so I am trying to trace the circuit. It has this NEC IC uPC614D, one on each side of the isolation barrier. I have searched a couple of NEC catalogs of that vintage (late 70’s) and there is no mention of it. It’s an 18-pin ceramic DIP, which is a little unusual.Can anyone help identify what this chip is? Any help at all would be appreciated.Roman

author: srb1954
author_rank: Super Contributor
timestamp: July 12, 2023, 02:46:21 am
content: Best of luck on sourcing information for this chip.Finding information on NEC chips can often be difficult. I used to work as a design engineer for the Australian branch of NEC and even working inside the company it was often frustrating trying to get information on their chips.

author: fzabkar
author_rank: Super Contributor
timestamp: July 12, 2023, 03:27:17 am
content: I remember that during the 1980s I always had great difficulty getting datasheets from Japanese IC manufacturers. At that time NEC claimed to be the world's largest IC maker, but they may as well have been invisible to anyone in the design or service game. Support from the Japanese was sh1t in those days.

author: floobydust
author_rank: Super Contributor
timestamp: July 12, 2023, 03:47:26 am
content: I found nothing about it beyond mention of an app note: “Application Information for uPC614D” Provides application hints and parameters for a pulse width modulation converter in a digital multimeter application. NEC America (6 pg.)'

author: Roman oh
author_rank: Regular Contributor
timestamp: July 12, 2023, 09:52:45 am
content: Thanks guys. Floobydust, your comment especially - I suspected that it might be some sort of PWM or V/F device because of the nature of the amplifier (and the fact that there is a TP on the PCB marked “PWM”!). The comments about NEC ICs are also interesting..this device doesn’t even get a mention in a couple of very thick NEC catalogs I found on line. I will uncross my fingers….As an aside, can’t get over how many Aussies lurk here!

author: coromonadalix
author_rank: Super Contributor
timestamp: July 12, 2023, 12:23:34 pm
content: only place ive seen a mentionhttps://www.togotech.co.kr/index.php/ADCuPC614D 8-bit ADC, Yokogawa 2533 AC power meter, A/D converter board

author: fzabkar
author_rank: Super Contributor
timestamp: July 12, 2023, 05:36:47 pm
content: In light of new info, it seems I was way off the mark. Please ignore what follows.FWIW ...uPC603 = PMI DAC01CuPC610 = PMI DAC02CuPC624 = PMI DAC08ADC-908, PMI, 8-bit ADC, replaces AD7574, 18-pin CerDIP:https://pdf.dzsc.com/20090227/200902050038066354.pdfAD7574, Analog Devices, 8-bit ADC, 18-pin DIP:https://www.buchty.net/ensoniq/files/ad7574.pdfPMI's ADC-8208 (18-pin CERDIP) was an improved second source for the AD7574.https://mirrorservice.org/sites/www.bitsavers.org/components/pmi/_dataBooks/1986_PMI_Linear_and_Conversion_Products_Data_Book.pdf(page 717)AD7575 and AD7576 appear to be more modern 8-bit ADCs with the same package and pinout.

author: aeg
author_rank: Regular Contributor
timestamp: July 12, 2023, 10:04:33 pm
content: Application diagram from Yokogawa 2533 service manual:

author: Roman oh
author_rank: Regular Contributor
timestamp: July 13, 2023, 12:49:51 am
content: Thanks, aeg, that diagram will be very helpful.Long shot…..since you reference a Yokogawa service manual (haven’t seen any of them in the usual sites for manuals). You don’t happen to have a manual for the 3132 DC Amplifier? (Branded YEW which I understand is Yokogawa Electrical Works)As I said, lo-o-o-o-ng shot!Roman

author: aeg
author_rank: Regular Contributor
timestamp: July 13, 2023, 08:24:16 pm
content: Quote from: Roman oh on July 13, 2023, 12:49:51 amSorry, I don't have it.