BK Precision 885 886 lcr            Identify theses masked / buffed ic's ...   - Page 1
Forum section: electronics / repair

author: coromonadalix
author_rank: Super Contributor
timestamp: July 29, 2019, 11:57:04 pm
content: I want to repair an "Bk precision 886 lcr meter" around year 2000-2001 handheld lcr, did not receive full permission to show the full schematic here, (waiting for an answer) but allowed to do some search.All majors ic's are buffered, no saliva work,and believe me i searched tons of info's/photos/markings on the webEDIT: Just found out pictures (google will show you theses on a model search) and a manual / schematics and calibration, possibly / surely converted in jpegs pagesBasically i need to id the chips insideMore photos to come ... maybe not ?Identified so far (Warning : errors may be still possible in the parts identification)u101 = Holtek HT1621b RAM Mapping 32x4 LCD Controller for I/O MCUu102 = HSDL-3610 IRDA emitter / receiveru106 = HSDL-7001 IR 3/16 Encode/Decode ICu107 = could be an AT89C52 CMOS 8-bit microcomputer thks @fzabkaru108 = SN54LS373 / SN74LS373 Octal latch thks @fzabkaru109 = AM39SF010 / AM29C010 / AM29F010 1 Megabit (131,072 x 8-Bit) CMOS thks @shakalnokturnu110 = MCM6264C 8K x 8 Bit Fast Static RAM thks @fzabkaru111 = LT1302 thks @fzabkaru112 = LM393u113 = AIC1117cy 800ma Low Dropout Positive Adjustable Regulator sot-223 caseu201 = TMS320C203 or TM320LC203 (100 pins) Digital signal processor thks @fzabkaru202 = 82C55 plcc44 pinsu203 = 74ls138u204 = similar to IDT71016S (CMOS Static RAM 1 Meg, 64K x 16-Bit) but with shuffled address bits thks @fzabkaru205 = AT27C1024 / AT29C1024u208 = Maxim MX7524, AD AD7524, TI TLC7524 thks @Macboyu212 = AD9832 DDS thks @fzabkaru215 = TPS76501D thks @Macboyu315 = 4051 8:1 analog multiplexer thks @turbotom

author: coromonadalix
author_rank: Super Contributor
timestamp: July 30, 2019, 12:09:53 am
content: Still has some intermittant supply problems it seems, maybe cold solders ?Sorry wasn't clear enough

author: fzabkar
author_rank: Super Contributor
timestamp: July 30, 2019, 01:19:06 am
content: The pinout of U205 (64K x 16 OTPROM) issimilarto an Atmel AT27C4096 (pin 43 differs):http://ww1.microchip.com/downloads/en/DeviceDoc/doc0311.pdfEdit:http://ww1.microchip.com/downloads/en/DeviceDoc/doc0019.pdf(AT27C1024, 1Mbit, 64K x 16, pin 43 differs)U204 is similar to IDT71016S (CMOS Static RAM 1 Meg, 64K x 16-Bit) but with shuffled address bits:https://www.idt.com/document/dst/71016-data-sheetI guess it's obvious to all, but U215 is a power supply supervisor IC in an SO-8 package. The FB pin appears to sense the target voltage.The potential divider would suggest that the FB reference voltage is 1.24V.165K / (165K + 499K) x 5V = 1.24VFWIW, if the FB pin were set to trigger when it drops below an internal reference voltage of 1.2V, then the output voltage would need to drop to 4.83V.(165K + 499K) / 165K x 1.2V = 4.83VI haven't checked all the pins, but U201 could be a TMS320C209:http://www.ti.com/lit/ds/symlink/tms320c203.pdf

author: coromonadalix
author_rank: Super Contributor
timestamp: July 30, 2019, 01:48:42 am
content: @joeqsmithNothing signed, but discussed in email only ..... they told me no parts available ... and please dont show the full schematic, keep it a mystery untill i receive the permission to tell the model ??The dds chip is already an information giver ...I asked: do you have an crossover part list, response was nada, niet ?

author: fzabkar
author_rank: Super Contributor
timestamp: July 30, 2019, 02:02:27 am
content: Quote from: coromonadalix on July 30, 2019, 01:48:42 am"Port A" is not a port, AISI. Those are the address bits. In any case, it doesn't matter if you shuffle the address bits. It only matters when you try to make sense of the dump.

author: coppercone2
author_rank: Super Contributor
timestamp: July 30, 2019, 02:04:44 am
content: we had a similar case to this back in the 80's, people started going missing...

author: coromonadalix
author_rank: Super Contributor
timestamp: July 30, 2019, 02:07:18 am
content: Quote from: fzabkar on July 30, 2019, 02:02:27 amYes my bad, adress bit thksthks @fzabkar very good detective workEDITu215 could be in theTPS7101Q, TPS7133Q, TPS7148Q, TPS7150QTPS7101Y, TPS7133Y, TPS7148Y, TPS7150Yfamily

author: fzabkar
author_rank: Super Contributor
timestamp: July 30, 2019, 04:34:03 am
content: U108 is an octal latch -- eg 74373, 74374https://www.onsemi.com/pub/Collateral/SN74LS373-D.PDFU110 looks like an 8K x 8 static RAM eg 6264.http://users.ece.utexas.edu/~valvano/Datasheets/MCM6264.pdfU109 = 128K x 8 SRAM, verysimilarto V62C5181024, but slight pinout differences.http://pdf.datasheetcatalog.com/datasheet/mosel/V62C5181024.pdfU111 appears to be regulating a 5V supply. If so, then the voltage on its FB pin would be ...56.2K / (56.2K + 169K) x 5V = 1.248So we need to look for a PWM regulator with an internal 1.25V reference voltage.U111 lookssimilarto the LT1305, but it is NOT compatible (it differs in pins 2 and 5, but FB = 1.24V).https://www.analog.com/media/en/technical-documentation/data-sheets/lt1305.pdfEdit: U111 could be an LT1302.https://www.analog.com/media/en/technical-documentation/data-sheets/lt1302.pdfU113 appears to be a standard 3-terminal regulator. If the voltage differential between its Vout and Adj pins is 1.25V, then it is configured as a 154mA current source, probably to trickle charge the battery.1.25 Volts / 8.1 Ohms = 154mAU107 looks very similar to several ICs like this one, but the pin count is different:https://doc.lagout.org/electronics/doc/ic_various/at89c52.pdf

author: fzabkar
author_rank: Super Contributor
timestamp: July 30, 2019, 07:04:55 am
content: Quote from: coromonadalix on July 30, 2019, 02:07:18 amhttp://www.ti.com/lit/ds/symlink/tps71.pdfThe pinout is wrong, although the pin names are a match, but even so, the device in the circuit diagram appears to have the same input and output voltage (?), so I'm having a hard time believing that it could be a linear regulator of any kind. I was sure that the device had to be a supervisor IC, but now I'm starting to feel stupid.

author: shakalnokturn
author_rank: Super Contributor
timestamp: July 30, 2019, 07:48:10 am
content: For U109 maybe more like a 128k x8 flash "ROM" the "LCC32" points more that way. Code for the DSP?39SF01029C01029F010

author: coromonadalix
author_rank: Super Contributor
timestamp: July 30, 2019, 07:54:21 am
content: Quote from: fzabkar on July 30, 2019, 07:04:55 amDont say that, i just searched app notes for the TMS320 DSP chip, and theses numbers appeared, they do seem similar, but your first assumtion may be good.U113 appears to be a standard 3-terminal regulator. If the voltage differential between its Vout and Adj pins is 1.25V, then it is configured as a 154mA current source, probably to trickle charge the battery.1.25 Volts / 8.1 Ohms = 154mAA warning has been issued with the switch (s103 dc-dc converter section), if its not in the right position, an ordinary battery can or could ne wrongly chanrged and could burst ?

author: fzabkar
author_rank: Super Contributor
timestamp: July 30, 2019, 07:57:08 am
content: Quote from: shakalnokturn on July 30, 2019, 07:48:10 amDoh! You're right.http://noel.feld.cvut.cz/hw/amd/16736f1.pdf

author: CJay
author_rank: Super Contributor
timestamp: July 30, 2019, 08:37:54 am
content: As FZabkar has stated, U107 is some variant of the venerable 80c5x microcontroller.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 30, 2019, 09:00:23 am
content: u113 = AIC1117cy 800ma Low Dropout Positive Adjustable Regulator sot-223 case

author: coromonadalix
author_rank: Super Contributor
timestamp: July 30, 2019, 09:33:04 am
content: Managed to get this from a web site with a link to an other one for the images ...BK Precision 885 886 Originally known as Motech MT 4080A (100khz version)And i got an Part list with calibration procedures AND the schematics ?? seems the same has the one provided to me year 2001 ...BUT they are jpegs images and i removed the website markers in the lower right corners imagesThey did not had any confidential warnings, but they may have been edited prior meTheses images show on some google image search ... just checkedMy 886 is in the same shape for the buffered chips, all major ones, even u101 the holtek display driver.

author: TurboTom
author_rank: Super Contributor
timestamp: July 30, 2019, 09:47:43 am
content: U315 =40518:1 analog multiplexer

author: coromonadalix
author_rank: Super Contributor
timestamp: July 30, 2019, 09:51:08 am
content: thksthat leaves the 2 final onesu208 supervisor ic or an voltage regulator ..... something lollu215 its a dac for sure

author: TurboTom
author_rank: Super Contributor
timestamp: July 30, 2019, 10:00:57 am
content: U215=TLC7524multiplying DAC... I mean U208 of course...

author: CJay
author_rank: Super Contributor
timestamp: July 30, 2019, 10:03:13 am
content: U208, MAX7253

author: macboy
author_rank: Super Contributor
timestamp: July 30, 2019, 07:18:01 pm
content: U215 is a an LDO with enable input and power-good output.Example is TPS76501D which matches both function and pinout exactly (except for unknown design current or power dissipation).

author: macboy
author_rank: Super Contributor
timestamp: July 30, 2019, 07:26:45 pm
content: Quote from: CJay on July 30, 2019, 10:03:13 amI think you mean the Maxim MX7523 (note: MX not MAX). This is equivalent to Analog Devices AD7523. But that can't be it, because both pins 12 and 13 are connected, but are N/C on those devices. The 7524 is a match (Pin 13 is /WR and pin 12 is /CS). So it could be Maxim MX7524, AD AD7524, TI TLC7524.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 30, 2019, 08:24:19 pm
content: And now the calibration procedures ( thoses aren't restricted ) for the BK Precision 885 886 lcr meter ... attached photosHaven't received a response to show the schematics ....Thks to all the detective(s) work, hope it help for future calibrations and or repairs if neededWill upload these image to K04BBAs i see it the 10khz model (885) and the 100khz (886) share the same identical design (i dont know for the 100khz info in the 885 lcd ??), must be a firmware restriction, dont want to damage mine trying to make a firmware dump ... but would have been nice to try a 885 ---> to 886 conversion ??

author: coromonadalix
author_rank: Super Contributor
timestamp: July 31, 2019, 09:23:46 am
content: Everything upped to K04BB in the Recent uploadsContains the schematics / calibration (from a chineese link) / part numbers and added the first thread part numbers equivalents, no firmware.BK Precision 885 - 886 BK Precision 885 886 lcr meter aka Motech 4080 Service Manual-886 calib31072019.zip ------ 11 megsthks to all who helped me here.I think mine is repaired, redone a few solders in the psu section, seems to hold.

author: lzqing
author_rank: Contributor
timestamp: May 12, 2020, 03:50:30 am
content: Thank you Coromonadalix!Nice shareing for the k04bb.I just want share communication process for serial ports of a working machine here .By the way, There are a lot of cases seem firmware locked or damage the flash , anybody have idea for fixed this issue ?

author: MarkL
author_rank: Unknown
timestamp: May 12, 2020, 04:51:19 pm
content: I wanted to share another version of the schematic for the 885/886, below.I didn't do a detailed comparison to the schematics that have already been posted to this thread and uploaded to KO4BB, but it appears to be a more recent version.One thing I did notice is a little section labeled "USB PORT". I have an 886 and it's not spec'd to have a USB port, but it's there! It's well hidden under a bar-code sticker, which is on top of a thin gray piece of stick-on plastic that exactly matches the case color, which is on top of a small piece of stick-on rubber. See photo.Plugging in the USB, from linux dmesg:usb 1-4.1: new full speed USB device number 13 using ehci_hcdusb 1-4.1: New USB device found, idVendor=10c4, idProduct=ea60usb 1-4.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3usb 1-4.1: Product: CP2102 USB to UART Bridge Controllerusb 1-4.1: Manufacturer: Silicon Labsusb 1-4.1: SerialNumber: 4080IJ1140usb 1-4.1: configuration #1 chosen from 1 choiceUSB Serial support registered for cp210xcp210x 1-4.1:1.0: cp210x converter detectedusb 1-4.1: reset full speed USB device number 13 using ehci_hcdusb 1-4.1: cp210x converter now attached to ttyUSB0usbcore: registered new interface driver cp210xcp210x: v0.09:Silicon Labs CP210x RS232 serial adaptor driverThe USB port works (9600/8/N). It appears to operate the same as their benchtop version of this meter, the 889B. You can find the commands and data formats documented in the 889B manual.I never really thought much about the "Remote" label on the front of the meter. Maybe there's a problem with USB and they withdrew support for it, or maybe they didn't want it to encroach on 889B sales. Maybe it's not on all versions of the 886.