hybridfree/eevblog-posts huggingface dataset:
Low cost Logic Probe for Tek MSO4000? - Page 1
Forum section: electronics / repair

author: KM5TZ
author_rank: Newbie
timestamp: September 05, 2022, 05:26:18 pm
content: Prices on eBay for P6516 are a bit outrageous and doesn't look too difficult to cobble something together for a lot less $$.Has anyone done so and what was your solution?

author: okw
author_rank: Frequent Contributor
timestamp: July 15, 2025, 10:11:08 am
content: I'm also looking for this. Anyone?

author: tautech
author_rank: Super Contributor
timestamp: July 16, 2025, 07:51:53 am
content: How much is too much for a new one ?P6516 fits into a PCIe socket and is almost identical to SPL2016:https://siglentna.com/product/spl2016-16-channel-logic-probe-for-mso-option-sds2000x-oscilloscope-family/
low dropout regulator problem - Page 1
Forum section: electronics / repair

author: jmelson
author_rank: Super Contributor
timestamp: May 19, 2019, 03:09:53 am
content: Interesting issue. I make some gadgets that use either a Beagle Board (old) or Beagle Bone (newer) for a net interface. These run in a rack that supplies +6 V power, so I use an L4941 low dropout regulator to provide the +5 for the Beagles. These have run fine for several years. Now, a couple of them started crashing the Beagles every few minutes.Well, on some of these units I did not heat sink the regulators. The Beagles, when idling, draw 250 - 300 mA, with a 1 V drop from 6 V down to 5 V, that should be 250 - 300 mW. The L4941 is rated at 50 C/W junction to ambient in frree air, if I read the data sheet correctly. (Maybe they are playing with numbers in the datasheet and it really doesn't mean "free air".) Anyway, some checks I did when first setting these up seemed to indicate this was reasonable, as the regulators didn't get over about 40 C after a long run.Anyway, bolting the existing regulator to the aluminum equipment case fixed the issue. So, either the regulators got more sensitive to temperature, or the thermal conductivity changed, or something. I've never see this before.Jon

author: mariush
author_rank: Super Contributor
timestamp: May 19, 2019, 03:15:42 am
content: Could it be weak/cracked solder joints due to heat/cooling cycles over long time?maybe adding heatsink just put more pressure on joints or you resoldered and that actually fixed it.

author: Psi
author_rank: Super Contributor
timestamp: May 19, 2019, 03:19:36 am
content: The ones that started crashing, are they newly build units of exactly the same design, or old units that have been ruining fine for years?If newly build units i might suspect that your voltage regulators are fake. ie stamped with L4941 but actually some other reg.

author: jmelson
author_rank: Super Contributor
timestamp: May 19, 2019, 03:06:30 pm
content: Quote from: Psi on May 19, 2019, 03:19:36 amThe units had old Beagle BOARD computers from 2013. These are no longer made, they are replaced by the Beagle BONE. Yes, these units have been running in the field, on and off, for several years. They are not run 100% of real time, but may have to run for several months each time they are used.I buy all these parts from major franchised distributors like Digi-Key, Mouser, Newark, etc., so there should be just about zero chance of them being fakes.There's no way these got hot enough to deteriorate the solder on the regulators. For one thing, that leaves obvious darkening of the PC board.Jon
Low Frequency Continuity Beep for Fluke 8060A - Page 1
Forum section: electronics / repair

author: Dave Wise
author_rank: Regular Contributor
timestamp: April 24, 2024, 10:24:43 pm
content: I love my 8060A handheld DMM's instant continuity beep, except I can't hear it. It's approximately 2700Hz but I have a hearing loss that notches it out. I modified my 8060A to output a lower frequency that I can hear.The mod is a tiny daughterboard that mounts on the main board in place of Q6, a 2N3904 that drives piezo sounder LS1. We need one flying wire to pick up +5.2V Vdd to power the microcontroller.

author: Dave Wise
author_rank: Regular Contributor
timestamp: April 25, 2024, 07:22:27 pm
content: I just noticed that attach failed and only the pictures got uploaded. Here comes schematic, PCB layout, program, and assembly instructions.I figured out a trick for extending the frequency range on small PIC microcontrollers whose Numerically Controlled Oscillator has an undersize (16 bits) Increment register. It's in the program comments but I didn't test it as I'd already cut off the programming header. Affected parts are PIC10F320/2, 12F1501, 16F1503/7/8/9, 16F1713/6/7/8/9.
Low Voltage on 1997 AMH UltraMIG 200 Synergic Welder - Page 1
Forum section: electronics / repair

author: diablo9987
author_rank: Newbie
timestamp: March 10, 2022, 02:49:59 am
content: I have been trying to get my dads old MIG welder back up and running but could not get a good stable arc going (tons of sputtering even feels like it cuts out for a few ms. just guessing though)so started trouble shooting from the manual and came across the voltage stated in the manual that should be on the capacitor is not correct. it wants 14 - 26 VDC and I'm only getting 12 - 15.5. one of the thumbnails will have the section I'm talking about. so as usual it says to just replace the cap first but I pulled it out and tested it to the best of my ability's but it's a bit of a beast so made do with what I had and it seems fine. Measures 144000uf but that was done through an arduino, ESR of 0.14 and leakage was 6ma I think, it was a few days ago.so my question is should I replace the cap. if so will any of these workhttps://www.digikey.ca/en/products/detail/kemet/ALS70A134NF063/6928354- Same uf but will require work to get it to fit into the welder because they use bent aluminum plates for connections.Orhttps://www.digikey.ca/en/products/detail/kemet/ALS70A274NT063/6870548- Seems to be the same footprint size so should drop in just fine but is double the uf.If neither any you can recommend.If it's not the capacitor then it says to replace the circuit board but if I have to do that I might as well buy a new modern welder for the price they want for it $900 for the board plus $400 for micro processor.I'll upload some pics of the board also if any of you want to take look as I also found a blown tantalum cap. I tried replacing it with an equivalent ceramic I had on hand but it made no noticeable difference.if you need any other info let me know I'm trying to condense a weeks worth of trouble shooting into a small post.Thanks

author: diablo9987
author_rank: Newbie
timestamp: March 10, 2022, 03:02:31 am
content: Half my images are missing here are the rest hopefully*edit again its just picking random images too upload
Lowrance gps antenna repair - Page 1
Forum section: electronics / repair

author: sämäx
author_rank: Newbie
timestamp: July 26, 2019, 07:03:54 pm
content: Hello people!Me and my friend accidentally dropped our lowrance sonar. Yesterday I took it apart and did visual inspection to the pcb. While inspecting the pcb I saw two passive components had fallen off because of the impact. I tried to search for the components inside the case but didn't find them. I know that its quite far fetched to ask for the exact values for the missing components but is there some kind of rule of thumb that I could use to get the antenna working again? If not, does anyone possibly have any proposals how to proceed with this repair project?In attachments, first picture shows the gps circuit from the backside of the pcb. The next two show the antenna circuit from the front side missing the two passive components.Thanks for the help in advance! Hoping to get soon back to fishing

author: wraper
author_rank: Unknown
timestamp: July 26, 2019, 07:11:26 pm
content: Quote from: sämäx on July 26, 2019, 07:03:54 pmThere is only one component missing. Smaller footprint never had component populated.

author: ChuckDarwin
author_rank: Regular Contributor
timestamp: July 28, 2019, 11:49:06 pm
content: The missing part is probably a capacitor (C) somewhere in the 2.2-80pf range. The white smd part is an inductor (L) [I've seen white caps and resistors, but rarely]. Together they form the matching network (LC) for the antenna system. As @wraper said, the lower pads are unused. It is there to give the manufacturer flexibility in selecting and tuning an antenna system. Without a schematic or testing with a VNA, it will be hard to determine the value of the missing component.You could try emailing Lowrance and tell them you a have an out of wty device and you would like to repair it. Theymightbe willing to tell you the component specs. If it is in wty, have it repaired.See if someone on Lowrance forums knows or can measure the valueDo you have an external antenna port through which you rig an external antenna?If you are comfortable soldering, you could try 10, 4,7, 16, 2,2, 22, 47 pf caps and see how well the signal locks on. If something is close, then try closer values slightly up or down from that value. Brute force approach.

author: wraper
author_rank: Unknown
timestamp: July 29, 2019, 04:38:47 am
content: Quote from: ChuckDarwin on July 28, 2019, 11:49:06 pmIt's multilayer chip antenna, not inductor.

author: ChuckDarwin
author_rank: Regular Contributor
timestamp: July 29, 2019, 10:20:01 am
content: I was referring to the white (grey?) smd directly next to the missing part, not the chip antenna at the board edge.

author: wraper
author_rank: Unknown
timestamp: July 29, 2019, 10:53:53 am
content: Quote from: ChuckDarwin on July 29, 2019, 10:20:01 amIt's completely usual C0G MLCC cap. They usually are light grey or slightly pink. And yeah, it's grey, quite far from white.
LS7183 vs LS7083 QUADRATURE CLOCK CONVERTER - Page 1
Forum section: electronics / repair

author: kblue
author_rank: Regular Contributor
timestamp: April 04, 2025, 01:28:34 pm
content: Greetings!I was under the assumption (DIP) LS7083 can be used as a replacement for the (DIP) LS7183 but it seems not the case, right? Even if the pin-layout is identical, the block diagram seems to be a bit different. I need to replace a non working LS7183 (only gives UP-Clock but no Down-Clock). The replacement LS7083 does nothing, neither up nor down.Replacing the LS7183 with another one from the same equipment fixes the problem but stealing one IC from something else is not the solutionAre any special changes needed for the LS7083? The "output timing diagram" in the datasheet between the two is the same. Tow vs RBIAS seems the same too but still no luck.Best wishes!
LSI MUSE-B2B2-L hard drive controller (Hitachi Deskstar SATA drive failed) - Page 1
Forum section: electronics / repair

author: Unixon
author_rank: Frequent Contributor
timestamp: June 14, 2024, 10:54:49 am
content: Does anybody have datasheet for this SoC ?

author: fzabkar
author_rank: Super Contributor
timestamp: June 14, 2024, 02:31:09 pm
content: I doubt very much that you will find any data on HDD MCUs, even for those from the 1990s. If you have a repair question, perhaps I could help.

author: Unixon
author_rank: Frequent Contributor
timestamp: June 15, 2024, 09:58:41 am
content: Hitachi Deskstar HDS722020ALA330 2Tb mfg 09/2009 stopped responding on SATA without any obvious reason (other than working 24/7 for years without any issues). SATA controller on motherboard couldn't see the disk anymore but it was trying to do something and it took noticeable time during start up. The disk has been switched off for a week or so, then I plugged it into a dock station where it spun up and initialized but it was unreadable, reported some SATA errors and then has been stopped on controller command. After that I didn't hear a thing from this disk, no SATA errors, no spin-up. I hoped there's a debug UART or something to talk to MCU and at least get some information on what's going on.

author: fzabkar
author_rank: Super Contributor
timestamp: June 15, 2024, 04:23:11 pm
content: I'm not aware of a UART port on Hitachi HDD PCBs.The symptoms you describe are consistent with an internal fault, probably bad heads or media. When the drive starts up, it unpacks the PCB ROM code into RAM and transfers control to it. This RAM code then fetches more code overlays (discware) from the reserved System Area (SA) on the platters. The SA stores things like the LBA-to-CHS translator, defect lists and SMART. If the SA becomes inaccessible, or if one or more of the critical firmware modules cannot be read, then the drive remains busy or spins down.HDD - computer within computer:http://www.hddoracle.com/viewtopic.php?p=19087#p19087A no-spin condition usually points to a PCB fault, although a bad preamp on the headstack can also cause the MCU to decline spin-up.If you want to troubleshoot the PCB, please provide a detailed photo and I'll identify some test points for you.
LTC1151 EQUIVALENT SUBSTITUTE - Page 1
Forum section: electronics / repair

author: HUGOMAN
author_rank: Regular Contributor
timestamp: January 09, 2022, 06:22:41 pm
content: Hi everyonei am looking for LTC1151 dip equivalent ?Thanks

author: fzabkar
author_rank: Super Contributor
timestamp: January 09, 2022, 08:02:44 pm
content: Mouser has 1 left in stock:https://www.mouser.com/ProductDetail/Analog-Devices/LTC1151CN8PBF?qs=hVkxg5c3xu%2FoizGDP4GjPA%3D%3DCould you use an SOIC or SOP IC with this adaptor?https://www.ebay.com/itm/271524393797

author: whatboy
author_rank: Regular Contributor
timestamp: January 10, 2022, 01:40:25 am
content: OPAx189https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiL7ImFhqb1AhXUkWoFHW36BC4QFnoECCEQAQ&url=https%3A%2F%2Fwww.ti.com%2Flit%2Fgpn%2Fopa4189&usg=AOvVaw2W8GzpCC5AzScFFMyAIHhi
LTC3850 Step Down Regulator - Page 1
Forum section: electronics / repair

author: 2X
author_rank: Frequent Contributor
timestamp: July 23, 2024, 08:08:02 pm
content: Hi,I have a PCB from a custom inverter and the problem is that the step-down regulator (LTC3850) doesn’t enable the Vout1 of 5V and only enable the Vout2 of 3.3V. At pins “RUN1” & “RUN2” I have 4.7V. I believe that the IC is faulty but I found a connection to the Ground at pin 25 (FREQ/PLLFLTR) and I would like your opinion if this is a short or a normal connection (if it was a short, I believe that I wouldn’t have the 3.3V). I checked the mosfets and the components around the IC and I didn’t find any short, except from the pin 25.Because the PCB is over two layers (maybe I am missing something) I found that at the pin 25 is connected a ceramic SMD capacitor 1.5nF (measured value) with a parallel 0ohm resistor in parallel (picture 4). If I remove the resistor the connection to the ground is gone.Datasheet LTC3850:https://www.analog.com/media/en/technical-documentation/data-sheets/ltc3850-3850-1.pdf

author: fzabkar
author_rank: Super Contributor
timestamp: July 26, 2024, 06:56:58 pm
content: Are you sure there isn't a second capacitor between the zero-ohm resistor and ground? Otherwise it doesn't make sense to populate a capacitor if it is to be bypassed by a shorting link. :-?

author: 2X
author_rank: Frequent Contributor
timestamp: July 26, 2024, 07:00:20 pm
content: Quote from: fzabkar on July 26, 2024, 06:56:58 pmThe same thought I have too.. why to short a capacitor with a resistor? Any thoughts are welcomed.Finally, I replaced the chip LTC3850 and the PCB works ok.P.S. Thank you very much for yoru reply.
LTO drive head lubrication? - Page 1
Forum section: electronics / repair

author: guenthert
author_rank: Frequent Contributor
timestamp: May 04, 2020, 04:32:45 pm
content: Well, not to reduce the friction of the head against the tape of courseThe head rather rides (or is supposed to at least) on two shafts (in my HP LTO-2 drive those are some white plastic material, in newer ones they are made out of metal) along the width of the tape, driven I believe by a single coil on a 3rd shaft.When inserting a tape, the drive will move the head up and down once or twice (not sure, whether that is some kind of self-cleaning or self-calibration procedure). In the problematic drive it fails to do that, instead attempts some eight to ten times, thereby quite audibly knocking the head on the bottom, but not able to reach the full height. Turning the drive on the side, the knocking isn't quite so loud, but still the head moves only a fraction of the full width. Turning it up-side down yields similar results.http://sbfmdrv.blogspot.com/2018/11/disassembling-and-cleaning-lto-tape.htmldescribes the symptoms and cure and has some high resolution pictures.I attempted the same cleaning procedure, found indeed some residue, but not a whole lot and after cleaning those the symptoms remained. I then (foolishly, I knew, but desperately) cleaned the the shafts (and only those) with alcohol (70% isopropanol). In the beginning the head seemed to ride with more ease (when moved manually), but the drive still didn't succeed in moving it itself. Letting the alcohol evaporate over night, next day the symptoms remained and the head seems now to move even less freely. Not sure, whether the alcohol dissolved some not visible grease on the shafts or in the bearing of the rollers running on those.Now the question for you fellows: what oil or grease would be used in such a situation? Is the shaft being greased or just the rollers?(there's no rush really, as I just got on fleebay a *new* LTO-3 drive for a very reasonable price, which thankfully reads those old tapes of mine -- still, I'm curious)

author: coromonadalix
author_rank: Super Contributor
timestamp: May 06, 2020, 04:15:34 am
content: Well call me crazy, not for the faint of hearts WARNINGFor vcr video tapes, 8mm video heads, Dat mechanism, shafts, or the tape path i use acetone, its very strong and evaporate pretty fast, i never do / touch the plastic heads with acetone lollFor shaft lubrication i use teflon oil, a very small droplet. For gears i use molybdene grease or the graphite grease.And for the pinchrollers i use a plastic renew stuff specially made for that by Mg Chemicals or Chemtronics i think.
LTPPI non-inverted output distorted trash, fine on inverted output - Page 1
Forum section: electronics / repair

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: December 16, 2021, 09:17:45 pm
content: I am troubleshooting my amp and I have problems with fizzy distortion, I connected my signal tracer that I have going into my PC sound card and I have a scope program running, and found that the signal is fine on the inverted output of the PI, but trash on the non-inverted (cathode driven) side...I have scoped the signal on the grid, and if I crank the gain I get some AC there, nothing nice, but that might be just random capacitance leaking, or the ESR of the capacitor letting some of the signal trough. but nothing really alarming I think.I have attached the scope screenshots of the outputs of the PI, I didn't have a signal generator I just played one note on the guitarand also the schematic of the output stage of the amplifier...I scoped the power rail and there's no signal there.the amp has no NFBL
LW-K3010D Power Supply Failure - Page 1
Forum section: electronics / repair

author: IZ2KTE
author_rank: Newbie
timestamp: December 18, 2024, 10:56:53 pm
content: I am asking for advice regarding the "LW-3010D" power supply, as a scheme it is the same as the LW-305D, which for a few days has had a voltage regulation problem. Regardless of the setting of the current regulation potentiometer, by rotating the voltage potentiometer, from zero to eight volts the voltage respects the range of the multi-turn potentiometer, after eight volts the voltage, by rotating the "Voltage" potentiometer, begins to drop until it reaches zero, while the "CV" LED remains on and with the rotation, almost at the end of the stroke the ventilation is activated. I have checked the efficiency of the potentiometers which are regular. I measured the voltage of 12 V on the "TP" and it is regular. The "CC" LED remains off, it activates only when I bring the current regulation to zero, but this is regular.Thanks for your collaboration.
M328LCD Transistor Tester from Ebay not working as expected.. or at all - Page 1
Forum section: electronics / repair

author: applicanon
author_rank: Contributor
timestamp: January 06, 2022, 08:07:02 pm
content: Hello! So I ordered one of these units which claim to be able to give the pinouts for many different types of devices as well measure resistance, transistor gain, capacitance etc. Anyways, the one I ordered was a solder it up yourself type project which I did so with relative ease. This was not by any stretch of the imagination my first project of the sort, so I was dissapointed upon powering it up when it did not function as expected.The potentiometer / push button combo switch does not do anything except make the LED flash on and off when pressed. The first menu shows up on the screen, but you cannot switch between options. it automatically goes to the next screen which displays some information about the component connected to the test ports, but this information very quickly goes off screen and is replaced by a screen which says Timeout! then goes to a blank screen.Also to note: the kit seems to have come with an extra capacitor which I cannot for the life of me figure out where it is supposed to go if it is supposed to be a part of the circuit at all. Please watch the youtube video showing the device in action and let me know what I should do as far as getting this thing to work! Thanks guys!This is a link to youtube video:

author: madires
author_rank: Super Contributor
timestamp: January 06, 2022, 08:51:45 pm
content: There could be something wrong with the circuit around the rotary encoder/push button. The additional film cap is meant to be used for self-adjustment. Please seehttps://github.com/kubi48/TransistorTester-documentation/blob/main/pdftex/english/ttester.pdffor the original documentation of the OSHW transistortester.

author: bob91343
author_rank: Super Contributor
timestamp: January 06, 2022, 09:11:37 pm
content: The extra part is used when calibrating the unit. However there seems to be something wrong with yours and you probably should return it for credit or replacement.I have a similar unit that has been working great for years.
Mac Plus probing video signal help - Page 1
Forum section: electronics / repair

author: gkmaia
author_rank: Frequent Contributor
timestamp: January 09, 2020, 05:40:39 am
content: I am apparently with an issue on my Mac Plus video signal.Lifted R30 to isolate pin #20 (Video out) of BMU2 from the analog board and everything else. Nothing is damping it... it is pretty much weak on it's own. Also did some logic probing on the BMU2. All Is and I/Os are pulsing apart from I14 as it is nodded to OE.Anyone out there with one of this on the bench and could send me a scope plot of J8 pin1 or U2 pins 8,9 and 10?
MacBook A1989 missing rails PP3V3_S5 and PP1V8_S5 - Page 1
Forum section: electronics / repair

author: Nikan
author_rank: Regular Contributor
timestamp: December 04, 2023, 09:42:18 am
content: Greetings and Salutations,I have gotten an A1989 Macbook board number 820-00850-A which has two missing rails -> PP3V3_S5 and PP1V8_S5.PBUS is at 12.6V every other voltage made by the PMIC is just fine.Resistance to ground -> PP3V3_S5 ~ 220ΩResistance to ground -> PP1V8_S5 ~ 220ΩPP1V8_S5 and PP3V3_S5 are not shorted together.Voltages up to PP2V5_NAND_SSD0 seem to be fine.Can anyone confirm if these resistances are normal for this board?What could be causing this issue?Is there a way to rule out a defective PMIC without replacing it, as I do not have a donor.Thanks in advance and best regards from Germany,Nikan
MacBook A1989 repair no CPU Voltage no boot signs - Page 1
Forum section: electronics / repair

author: Nikan
author_rank: Regular Contributor
timestamp: November 24, 2023, 10:06:32 pm
content: Hello everyone.I have recently obtained a MacBook Pro A1989 model with a touch bar and Apple ID. Unfortunately, it does not want to start up.No CPU Voltage.U7800 Does produce voltages.T2 Chip warming up very very little.I do have voltages like 1.8, 0.9, 3.3, 2.5 volts, etc., present. All short circuits have been resolved. Unfortunately, the device has no touch ID/start button. So, I have used the debug jumper to put the device into DFU mode. - It is getting recognized as a Macintosh while not in DFU mode and as Apple (DFU) while in DFU mode.I thought to myself that it might need a BridgeOS revive. Unfortunately, I am not in possession of another Mac, so I have used VMware to set up a Mac Sonoma system. Apple Configurator does see the device in DFU mode. But whenever I try to revive it, it starts but unfortunately does not complete.I am wondering, do you need to have a Mac, or does the revive option also work in a virtual machine? What about the touch ID/start button? Does the Macbook need to have one installed to be able to revive it (does the T2 chip check if that module is installed) or can it be ignored for now to revive the T2 chip?Any help or what I should check would be appreciated.Thanks in advance and best regards from Germany,Nikan

author: kripton2035
author_rank: Super Contributor
timestamp: November 24, 2023, 10:11:50 pm
content: pressing cmd-alt-R at startup, and choosing a wifi connexion, does it boot completely ?if so it would only be a bad system in the drive problemif not, the T2 chip almost locks everything...

author: Nikan
author_rank: Regular Contributor
timestamp: November 24, 2023, 10:44:27 pm
content: I do not have CPU voltage at any given time.There is no startup/fanspin etc. There are no signs of life at all.The U7800 does produce voltages though.
Macbook Air 2014 (820-3437-B) liquid damage help (Repaired) - Page 1
Forum section: electronics / repair

author: poot36
author_rank: Frequent Contributor
timestamp: October 13, 2020, 02:37:47 am
content: I have a Macbook Air that I got in for repair that has had coffee spilled on it and no longer turns on. The charger light will change from green to orange and I can do a SMC reset with the keyboard combo and the light changes to indicate a reset. I have taken it apart and cleaned all the visible liquid damage off with a brush and then warm soapy water in a ultrasonic bath. It made no difference. I have confirmed that I am getting all the G3 Hot rails and that they are in spec. The PP1V2_S3 rail and the PP1V05_S0 briefly turn on when the charger is plugged in and the battery is disconnected (the battery is dead as the client left it in a closet for 1 year after the spill) and then turn off. When they do come up they are at the correct voltage (checked with a scope). What would be the next thing to start measuring?

author: coromonadalix
author_rank: Super Contributor
timestamp: October 13, 2020, 02:58:51 am
content: a complete visual inspection would be good, not just measuring stuff, you may have corroded parts or ic's etc ...

author: tooki
author_rank: Super Contributor
timestamp: October 13, 2020, 08:41:25 am
content: Left for a year after the spill? RUN. Coffee is acidic, and after a year, part of which was with residual battery power present, there is guaranteed to be corrosion damage.

author: poot36
author_rank: Frequent Contributor
timestamp: October 14, 2020, 12:24:06 am
content: I have given it a quick visual inspection and there are some laces that look questionable but test fine. I will have to clean the brown rust like substance off the inductors though.

author: tooki
author_rank: Super Contributor
timestamp: October 14, 2020, 12:30:57 am
content: A “quick” visual inspection isn’t going to show you the problem areas, which are where capillary action kept them wet longer, like under chips.

author: poot36
author_rank: Frequent Contributor
timestamp: October 14, 2020, 02:55:26 am
content: I have ordered one of the cheap usb microscopes so hopefully it will get here by the end of this month. I am a bit concerned because I did have some corrosion around the CPU vrm and the side of the CPU that has the PCH on it. Will take a closer look when I get the microscope.

author: poot36
author_rank: Frequent Contributor
timestamp: May 28, 2021, 02:06:37 am
content: I got it working after a good cleaning with hot soapy water in an ultrasonic cleaner. Thanks for the help.
Macbook Pro 15" 2011 late motherboard repair - Page 1
Forum section: electronics / repair

author: mateksz
author_rank: Newbie
timestamp: April 30, 2020, 12:43:59 am
content: Hi guys,I have a water damaged Macbook Pro 2011 15". I am a complete beginner. I’ve watched a couple of youtube videos, but I don’t know more, so I’m sorry if I’m writing nonsense.The problem: No power. Sometimes I have green charging led, sometimes not.I downloaded the board schematics and the .brd file and openboardviewer.I checked the 3.3v rails, It looks good. I have 5v on PP5V_S5, but no on P3V3S5. So I think the U7201 (TPS51980) chip is bad. I've checked the P3V3S5_EN enable signal, and it is good (3.x V).What do you think? U7201 (TPS51980) is faulty? Or it can be something else? What should I check?Thank you!

author: ivi_yak
author_rank: Regular Contributor
timestamp: April 30, 2020, 01:11:47 pm
content: hi, take a look around about corrosion its 90% of all cases

author: ivi_yak
author_rank: Regular Contributor
timestamp: April 30, 2020, 01:13:02 pm
content: check pgood state

author: kripton2035
author_rank: Super Contributor
timestamp: April 30, 2020, 01:55:32 pm
content: on these models you may also have a bad nvidia chip ... it doesn't prevent power on but you have to plan on buying a chip to disable the nvidia chip after this repair.

author: mateksz
author_rank: Newbie
timestamp: April 30, 2020, 04:55:39 pm
content: P5VS3_PGOOD is 0V, not shorted. What it means?

author: mateksz
author_rank: Newbie
timestamp: April 30, 2020, 04:57:11 pm
content: These models have amd gpu, but I thnik the water damage couses the problem not the GPU

author: ivi_yak
author_rank: Regular Contributor
timestamp: April 30, 2020, 09:42:35 pm
content: I guess some cap is shorted to groundso power up your board and palp all the caps around chip and you find the hottest one desolder it and power board again

author: mateksz
author_rank: Newbie
timestamp: May 06, 2020, 02:45:45 pm
content: So, some progress. I do not have PM_SLP_S4_L, which is necessary for the u7201 and come from U1800 chip. I checked U1800 ENs and I do not have SMC_ADAPTER_EN, that come from U4900 chip. But now I do not know what to do.Do you have any idea?

author: kripton2035
author_rank: Super Contributor
timestamp: May 06, 2020, 04:37:01 pm
content: I would bath the board in an ultrasonic cleaner, you may have some corrosion left.

author: MegaObi
author_rank: Newbie
timestamp: September 11, 2020, 02:48:48 am
content: hey bud - how did you go with this?
MacBook Pro 17' A1297 video - Page 1
Forum section: electronics / repair

author: djsp
author_rank: Newbie
timestamp: November 27, 2019, 06:32:13 pm
content: Hi thanks for accepting me in this blog. Video of problems at startup displays this problem how to proceed ?I wanted to try the GPU reflow

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 28, 2019, 03:15:11 pm
content: I cannot offer any help on re-flowing, and you probably already know of this guy, but:https://www.youtube.com/user/rossmanngroupdoes many videos on mac repair and may have some info for you.

author: andy2000
author_rank: Frequent Contributor
timestamp: November 28, 2019, 06:20:47 pm
content: Reflowing won't work, it's a defect in the GPU itself. I recently went through a pile of those laptops and only the ones that had the revised GPUs worked. All of the others were bad. If Apple installed a new GPU, there should be a small green sticker on the RAM slot. You can also tell based on the part number and date code on the GPU, but that requires totally disassembling the laptop.Having said that, your problem looks more like a bad LCD panel to me. Usually, a bad GPU causes no picture, random lines or blocks over an otherwise normal picture, or crashing during boot. Try it with an external monitor to be sure.

author: djsp
author_rank: Newbie
timestamp: November 29, 2019, 06:45:56 am
content: thanks for the answers I tried to connect an external monitor but there is no video signal, maybe because it is not enabled, someone has insinuated that it was the low resolution gpu, that is the one contained in the processor

author: andy2000
author_rank: Frequent Contributor
timestamp: November 29, 2019, 04:47:31 pm
content: Quote from: djsp on November 29, 2019, 06:45:56 amTry turning it on with a monitor connected, and immediately closing the lid. That should make it switch to the external display. Or, you can disconnect the LCD from the motherboard. Can you tell if it's booting? A bad GPU will usually prevent it from booting.

author: kripton2035
author_rank: Super Contributor
timestamp: November 29, 2019, 05:00:03 pm
content: what year/model is it ? what are the last 3 digits of the serial number ?it could be a gpu problem, but the picture makes me think like andy2000 of a bad lcd. if so you must have a picture on an external display.

author: kripton2035
author_rank: Super Contributor
timestamp: November 29, 2019, 05:03:30 pm
content: Quoteyou can make them work again ( the 2011 models 15" and 17") using this hack :http://www.cmizapper.com/products/tiresias-gpukiller.htmlI tried it with success. the only drawback is the video output is disabled (but not the other thunderbold features)
Macbook Pro 2015 13" power problem - Page 1
Forum section: electronics / repair

author: andy2000
author_rank: Frequent Contributor
timestamp: April 09, 2021, 07:39:09 pm
content: I'm working on a Macbook Pro 13" early 2015 A1502 model with a weird set of symptoms. I have already found the schematic and board view files, but before I spend hours on it, I'd like to hear any tips, or known faults.It was described as dead, no power, but that wasn't exactly true. With a charged battery, it will power on and work perfectly. I've had it running all day with no issues. It sleeps, and restarts fine. It passes all the diagnostics. It charges the battery, it runs from the battery or AC (a working battery seems to be required for this model, as it won't work at all with no battery connected).The problem is that if you turn it off, it goes almost completely dead. It won't power on, or charge the battery. The only sign of life is that the orange/green LED in the power connector does correctly indicate whether or not the battery is fully charged even though it won't charge the battery. Also, the SMC reset key combination results in the indicator LED briefly turning off. There is still a voltage across the power button, and I have confirmed that the keyboard power button works. I have tried clearing the PRAM with the key combination, but it didn't help.At this point, the only thing that will make it work again is to disconnect the battery and AC power for somewhere between 30 minuets and a few hours (I'm not sure what the exact threshold is). After I reconnect the battery, it will turn on as soon as I either hit the power button, or connect the power adapter. It then works again until it's shut down. Note that this model has no CMOS battery, so disconnecting the main battery is equivalent to removing the coin cell from a PC.The laptop is in immaculate condition with no signs of liquid damage, and no sign of prior repair attempts. I'm going to start by connecting the battery and checking all of the power supply rails before it has been turned on, then I'll turn it on and shut it down and recheck the power supplies. If that reveals nothing, I plan to start poking around the SMC chip. Does anyone have any other ideas?

author: CMIzapper
author_rank: Newbie
timestamp: November 03, 2021, 01:51:53 pm
content: That model will work without a battery. Except that it runs at about 1/3 of the speed without the battery.

author: BradC
author_rank: Super Contributor
timestamp: November 03, 2021, 02:24:31 pm
content: Quote from: andy2000 on April 09, 2021, 07:39:09 pmThis won't help, but I encountered exactly the same symptoms on a friends Macbook Air earlier this year. It was under extended Applecare so they had Apple replace the mainboard.On the other side of the coin I love my A1502s.
MacBook Pro A1502 Late 2013 battery not charging - Page 1
Forum section: electronics / repair

author: matthuszagh
author_rank: Frequent Contributor
timestamp: November 15, 2022, 10:42:45 pm
content: I've got an old MacBook pro that I dual boot Mac and Windows on and pull out when I need to use one of these OS's. It served me well for a number of years before the battery started to degrade. I replaced the battery with an A1493 battery I found on eBay. The battery worked fine for the first few uses, but now it shows as completely drained and won't charge (it's been probably 2 months since I installed it, but I don't use it often so I've probably only pulled it out 5 times so far). The battery health indicator says it's normal, but it won't charge. I tried resetting the SMC.Having gotten this on ebay I'm a bit skeptical that it's a proper Apple battery. Are these replacement batteries often problematic? Is the battery the likely culprit, or did I maybe mess something up during installation? I can return the battery, but if something else is at fault I'd rather not waste the time to return it and find out something else is at fault.Any ideas what might be wrong here? I can run any tests that people want and I also have equipment and can perform troubleshooting if needed. Thanks.

author: kripton2035
author_rank: Super Contributor
timestamp: November 15, 2022, 10:55:44 pm
content: I buy batteries for mac laptops only if the seller gives a one year warrantyevery other batteries are crap and last max a few months.every batteries you buy less than $50 are crap too.before I found such seller, I sometimes had to buy 5 batteries before getting a reasonnably good one.www.duracelldirect.comis an example of a good battery dealer in europe.
Macbook Pro fan runs for a few seconds and then stops - Page 1
Forum section: electronics / repair

author: Samer
author_rank: Newbie
timestamp: December 09, 2023, 01:44:50 pm
content: Hi all,I have a MacBook Pro model 1708The fan runs for a few seconds and then stopsThe device overheats and stopsI couldn't find a solution to this problemPlease helpThanks.
Macintosh Portable LCD repair - Page 1
Forum section: electronics / repair

author: Peacefrog
author_rank: Contributor
timestamp: June 24, 2022, 12:02:38 am
content: I have a backlit Macintosh Portable that I'm attempting to rescue and have recapped. Unfortunately, there appears to be a problem with the display, in that there's a constant vertical line present.I'm not sure how repairable this will be, as I'm unsure whether it's a problem with the connection between display and board or one of the driver chips itself. Any advice?

author: Peacefrog
author_rank: Contributor
timestamp: June 24, 2022, 01:00:06 am
content: By the way, this is a 30+ year old display, and I'm assuming that the panel connects to the PCB via zebra strips. I *could* take a pair of pliers and remove the metal frame (picture to come) then try cleaning them - but I'm afraid of inadequately replacing them and causing more damage.
Mackie 402VLZ4 mixer PSU - Page 1
Forum section: electronics / repair

author: RFmaster89
author_rank: Newbie
timestamp: August 18, 2024, 08:05:47 pm
content: Hello ForumBackground and DescriptionI've recently picked up a pair of faulty Mackie 402VLZ4 analog audio mixers. These are small units that are handy for small venues where one or two microphones and line audio can be used. These can be used for dance classes or a training room. Both units suffered from a failed PSU boards. PSU, part number CP2047468 (aka longjoin) takes +12V @ 2 Amps and converts it to +/- 15Vdc and -48V. A portion of the PCBA is not populated - my guess the PSU board is used in other products where additional DC rail is needed. PSU is based on DC-DC converter topology and employs LM5022. There are only two LM5022 on this PCBA and other DC-DC controllers present - however I might be wrong! One of the two LM5022 is used to generate -48V DC (phantom power) while the second iunit s used to generate +/- 15V rails. I don't know what trickery engineers used to use a single boost controller to generate +/-15 voltages! There are no schematics available and Mackie's help support is at best can be described as laughable.Problems statement:Both units exhibit no power symptom. PSU board is disconnected from analog PCBA for testing, no load. + 12 Vdc is applied from a lab supply, current limited. Visual inspection yielded no obvious signs of trauma.Unit # 1 +12V input is loaded (2.5V @1.8Amps) - shorted to ground. Utilizing IR camera I was able to ID Q2 as pass to ground - 85C hot spot. Q2 appears to be TSOP-6 device. It has marking ZU AC as shown in the photo. From TI's LM5022 data sheet Q2 should be a N-channel MOSFET, per application circuit. Pin 5 (OUT) ot LM5022 is coupled to Pin 3 of the transistor (gate). My search for ZU marking yielded nothing definitive except for Nexperia PMN27UP which is a 20V P-channel trench mosfet. No output voltages. +/-15 and -48Vdc are down.Unit #2 +12V input is at 0.056A - no +/- 15Vdc but -48Volt is alive. without schematic further troubleshooting is problematic at best. Any ideas or suggestions how to proceed further would be appreciated.Thanks in advance.

author: aeg
author_rank: Regular Contributor
timestamp: August 19, 2024, 12:09:50 am
content: Is the circuit similar to the DL806Mk2?http://bee.mif.pg.gda.pl/ciasteczkowypotwor/%23pro_audio/Mackie/Mackie_DL806,_DL1608_Main_MKII_Schematics.pdfPage 13 for the power supply.

author: RFmaster89
author_rank: Newbie
timestamp: August 19, 2024, 03:42:16 pm
content: Thanks aeg. Yes, PSU section for +/- 15Vdc is identical! Case closed!

author: RFmaster89
author_rank: Newbie
timestamp: August 20, 2024, 03:52:29 pm
content: Since I'm not an SMPS designer this app note covers use of generic boost converter to generate both positive and negative voltage rails.https://www.analog.com/en/resources/design-notes/generating-negative-output-voltage-from-positive-input-voltage.html
mackie mixer diode replacement - Page 1
Forum section: electronics / repair

author: samuel497
author_rank: Newbie
timestamp: May 25, 2020, 04:26:46 pm
content: Hi AllIm new to this forum so please be gentle lolI am attempting to repair a mackie audio mixer pro fx v2 as there is no input in channel 3I purchased a pair of smart tweezers for in circuit testing to save removing from pcb board although im not entirely sure I trust the readings.It is showing a short in some of the diodes DL4148 near the preamp so I have decided to order them and a pair of heated tweezers to make changing them as painless as possible.I contacted mackie and got the data sheet for the part number and it seems to be very difficult to get the exact spec of the diodes needed and wondered if someone could point me in the correct direction of the correct part or confirm the diodes I ordered will be ok.I have attached the diode spec I got sent from mackie and will post a link to the diodes ive ordered they are very similar in spec but thesurge currentis different they have the same reverse voltage etc.link to ordered diodeshttps://www.switchelectronics.co.uk/ll4148-switching-diode-150ma-100vAny help would be much appreciated.thanks in advance

author: floobydust
author_rank: Super Contributor
timestamp: May 25, 2020, 09:45:47 pm
content: They are the same, it's just the surge current spec either has a typo (Changzhou Changyuan Electronics "=1s") while otherreputable makesare 1usec, for IFSM of 2A. IFSM 500mA is under 1 sec.The diodes fail if there is a phantom power surge coming into that mic channel, best to not hot plug.If you find a diode instead went open-circuit due to the overload, it will damage the op-amp they are protecting.

author: TheMG
author_rank: Frequent Contributor
timestamp: May 26, 2020, 01:25:45 am
content: That diode is nothing special, just a MELF (surface mount) version of a 1N4148 which is a jelly bean part. While there might be some small variations in specs between manufacturers they should be quite similar. I doubt the exact specs matter much in this application, any 4148 diode from any manufacturer will probably work just fine.

author: samuel497
author_rank: Newbie
timestamp: May 26, 2020, 10:07:24 am
content: Thanks the main thing I was worried about was matching the reverse break voltage as if its exceeded then the diode becomes destroyed or at least that's what the told me on my HNC course.Thanks

author: samuel497
author_rank: Newbie
timestamp: May 29, 2020, 04:11:02 pm
content: Hi AgainI have replaced 5 faulty diodes and now channel 3 is back working so defo making progressI have one other issues to try and solve.Channel 1 is noisy when you move the fader up it sounds like an increasing loud static noise even if no mic connected.Any ideas?
[Solved] Mackie mixer with noise on two channels - Page 1
Forum section: electronics / repair

author: trondl
author_rank: Regular Contributor
timestamp: October 26, 2022, 08:00:08 am
content: Hi!I'm a bit stuck on fixing a noisy cheapo Mackie mixer.I've concluded that two of the channels with noise has a negative DC offset in the gain stage.There is a chance that something has gotten damaged due to phantom power hot plugging.See attachment for the circuit.What I've found so far is that there is a negative 12V DC present on the red line when it should be at 0V compared to the working channels without an incoming signal.I've swapped Q19 with Q18, no change.U15 has been replaced, no change.R228 doesn't measure 3k in circuit but closer to 2k, but R227 does.R228 measures correct out of circuit.Any hint is welcome.Thanks in advance!

author: wasedadoc
author_rank: Super Contributor
timestamp: October 26, 2022, 08:09:56 am
content: Try removing D27. If that restores proper dc conditions, the diode is faulty.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: October 26, 2022, 09:39:09 am
content: Yes, it's quite common for these protection diodes to go faulty, which either makes DC, or noise, or both.I usually change all 4, 1N4148 are very cheap.

author: trondl
author_rank: Regular Contributor
timestamp: October 26, 2022, 12:12:08 pm
content: Thanks a bunch to both of you for your knowledge!Immediately found one very broken (-12VDC) and one partially broken (leaky in circuit which gave about -1.5VDC on the second faulty channel) 4148 when desoldering.0VDC restored
Mackie SRM450V2 turns off wo. Any reason - Page 1
Forum section: electronics / repair

author: pienari
author_rank: Regular Contributor
timestamp: January 25, 2025, 10:15:19 am
content: I sold pair SRM450v2 pa speakers what i tested before as "workking "But after 6month buyer contacted me and told 1 of the speakers keeps turn off when plays music ab. 10minutes.I wanted to check what is wrong but i cant find anything wrong.Amp heatsink is not warm when powers off.If power level is low speaker works hours.Have anyone have this issue??.Edit.Psu is prot or down.Power need to switch off and back on psu is back on business.

author: m k
author_rank: Super Contributor
timestamp: January 30, 2025, 07:44:20 am
content: Since PSU goes to protected state there is something that defines it, right or wrong.PSU down can be also the switch itself.
Macrotest HT5030 - Resistor unknown - Page 1
Forum section: electronics / repair

author: carlitos
author_rank: Contributor
timestamp: July 23, 2021, 06:54:50 pm
content: Hi all,I have a meter Macrotest, model HT5030 that have a resistor burnt, position on PCB R70, i can't read its value.Anyone that have this meter or knows its value can help me, please.Thanks.Carlitos