hybridfree/eevblog-posts huggingface dataset:
Schematics for Boss ST-2 effect pedal ? - Page 1
Forum section: electronics / repair

author: carl_lab
author_rank: Frequent Contributor
timestamp: December 03, 2017, 07:51:29 pm
content: Did a google search without success...Can anybody help?https://www.boss.info/us/products/st-2/

author: Neganur
author_rank: Unknown
timestamp: December 03, 2017, 08:15:09 pm
content: it's probably too new.

author: carl_lab
author_rank: Frequent Contributor
timestamp: December 04, 2017, 06:25:39 pm
content: Is it a digitizer effect pedal or just good old analog technology?

author: Armadillo
author_rank: Super Contributor
timestamp: December 04, 2017, 06:36:49 pm
content: Just look at the locking nut and the knob, the paint type labelling, the rough paint surface and pocky-dot finish, definitely old technology.off course, due to my lack of experience with this sound effect thing, I could be wrong.

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: December 04, 2017, 06:48:29 pm
content: You should ask over atdiystompboxes.com- more specific audience there

author: Neganur
author_rank: Unknown
timestamp: December 04, 2017, 09:01:03 pm
content: Quote from: carl_lab on December 04, 2017, 06:25:39 pmWell it looks to me like it's just another flavour of op-amp distortion pedal like the OD1 (1977) or MT2 (1991) * etc but I don't recall the 'power stack' (whatever that means lol I played in a live band at motorcycle clubs) so it's probably newer than 15 years. But who knows with today's DSP technology it's entirely possible that they have a small blob in there to model the 'full stack crunch' and whatnot.I had a quick look athttps://www.hobby-hour.com/electronics/s/guitar-effect-schematics.phpwhich used to be a cool repository but they don't have it.*:http://bossarea.com/default.asp(unofficial)

author: carl_lab
author_rank: Frequent Contributor
timestamp: December 04, 2017, 11:13:25 pm
content: Quote from: Neganur on December 04, 2017, 09:01:03 pmI already found that page before, thank you.And yes, it's probably newer than 15 years, but it must be at least 7 years old (the video below is dated from 2010).I like the wide range of that pedal from slight overdrive to heavy distortion...

author: carl_lab
author_rank: Frequent Contributor
timestamp: December 05, 2017, 08:58:49 pm
content: I got a reply from BOSS: it is a digital signal processor.So I can forget my plan to build a clone...
Fluke 12 Multimeter Help  - Page 1
Forum section: electronics / repair

author: Dave_L
author_rank: Newbie
timestamp: December 01, 2017, 01:35:06 pm
content: Hi All,New to this site,so forgive me if I am doing this incorrectly.Ok, so I purchased a Fuke 12 multimeter from a car booty (knowing it didnt work) but the price was right and I thought what the heck. However, I am not the first person to open it up and it is missing a couple of parts (for a start). I have attached a picture and circled the missing parts and I wondered if anyone could let me know the value of the resistor as well as the value of the pot and what the pot is set to (i know they will all be different, but it will give me an idea where to start. Also does anyone know where i can buy a schematic or any repair guides to this meter if so could you email me the details please. Any help will be greatly appreciated.Dave

author: noidea
author_rank: Unknown
timestamp: December 01, 2017, 02:39:23 pm
content: Hi Dave_LI've put a copy of the service manual on Drobox for you, schemaitcs and component list are at the back.https://www.dropbox.com/s/o2lompuuoh1wqmv/FLUKE%2010%2C%2011%2C%2012%20Service.pdf?dl=0I'm not sure if mine is at work or not, if I can find it I'll open it up and try to take a few pics over the weekend

author: Dave_L
author_rank: Newbie
timestamp: December 01, 2017, 06:31:22 pm
content: Thnak you so much for this.

author: nicalitz
author_rank: Regular Contributor
timestamp: December 02, 2017, 11:23:45 am
content: I haven't checked the service manual myself, but I measured the pot at 8.5kOhm.If you end up having trouble with some of the buttons not working, which is common on the Fluke 12, you might also want to check the elastomeric strip that connects the keypad to the PCB. They do wear out over time, don't make decent contact anymore. I just added a bit of solder to the pads, easier than getting a new strip. Might also help to clean the button contacts.Best of luck with the repair!

author: Dave_L
author_rank: Newbie
timestamp: December 02, 2017, 11:41:05 am
content: Hi,Thanks for the information. This site is brilliant as the response I have received by people has been so helpful..Dave

author: noidea
author_rank: Unknown
timestamp: December 05, 2017, 07:38:26 am
content: Quote from: nicalitz on December 02, 2017, 11:23:45 amHow were you measuring that, from where to where?For what its worth the VR4 on mine is set to a similar physical position but I'm not going to mess with it as I don't have any sort of DC source to use as a reference to calibrate it again.
Fitbit Charge 2 charger - SMD transistor ID needed - Page 1
Forum section: electronics / repair

author: grumpydoc
author_rank: Super Contributor
timestamp: December 11, 2017, 09:14:40 pm
content: No1 son has a Fitbit ,like most of his friends.He handed me the USB charge cable last night saying that "it didn't work" - easy to see why, he had pulled the USB plug off the small circuit board inside.Not repairable but I thought I could at least hook it up for one last use, unfortunately the PCB is "potted" in a hot glue like material (but tougher) and I managed to pull a resistor off the board so no dice. I'd connect the wire ends to the bench supply but am not totally confident that the Fitbit is designed to get the full 5V from the USB (I think it is but it is an expensive mistake to make for the sake of waiting for Amazon to deliver a replacement).Anyway the reason for the post is I got curious as to what the circuit does - I guess it is just over voltage/over current protection (probably by crowbaring the supply) but I can't figure out what the two devices arePics of the boardR1 is missing. Power goes via the via to one side of the polyfuse and then via R1 to the output - I presume that it is for current sense.I can't quite figure out what the transistors are, one marked XN (2SJ626 ??) and one marked ND4 (??)Anyone got any ideas?
Repairing a drill battery charger. - Page 1
Forum section: electronics / repair

author: Bashstreet
author_rank: Frequent Contributor
timestamp: December 03, 2017, 01:00:05 am
content: Hallo allo.My battery charger has gone kaput it shows 5.2 volts when it should give 15.6 dc 500 mA 7.5VAI cracked it open and suspect the filter cap is goneChecked diodes etc .Question is it has 100uf 35v cap. (output)As i do not have 100uf caps at that voltage atm but larger ones 1000 uf. Can i use one of those ?

author: MomirPeh
author_rank: Newbie
timestamp: December 03, 2017, 08:30:40 pm
content: Hi there,Any pictures? That would help a lot to figure out what kind of power supply we have there. Is it switching power supply or a linear one. Does it have any charging control circuit (dedicated or MCU based). After we found out that, we can try to troubleshoot it step by step.

author: grifftech
author_rank: Frequent Contributor
timestamp: December 04, 2017, 07:02:20 pm
content: What type of battery does it use?

author: Bashstreet
author_rank: Frequent Contributor
timestamp: December 04, 2017, 09:07:40 pm
content: Quote from: grifftech on December 04, 2017, 07:02:20 pmThank you for answering.I am now using another power supply as i found out the linear transformer was the issueI discarded it as non feasible repair.
Metrix MX202B - Page 1
Forum section: electronics / repair

author: nicalitz
author_rank: Regular Contributor
timestamp: December 04, 2017, 08:17:22 am
content: Hi All,Would someone be able to help me with a service manual for the Metrix MX202B? I can't seem to find any documentation in English, apart from from a one pager on Electrotanya.

author: retiredcaps
author_rank: Super Contributor
timestamp: December 04, 2017, 06:43:08 pm
content: If you need a schematic, a search for MX202B pictures showshttp://radioman64.e-monsite.com/medias/images/schema.mx202b.jpg
Anyone here have experience with McIntosh solid state audio amps? - Page 1
Forum section: electronics / repair

author: cvanc
author_rank: Frequent Contributor
timestamp: December 04, 2017, 02:06:36 pm
content: ...You know, the ones that have an autoformer at the output.I've got one on the bench right now and I would love to hear what a reasonable reading might be for the autoformer winding resistance. I assume they've got pretty beefy windings (this one is 300W per channel), so nominal winding resistance would be quite low. But does that mean a couple ohms is normal, or a couple tenths of an ohm, or what?This one reads lower than I think is correct (unfortunately). All input welcome, thank you.

author: MomirPeh
author_rank: Newbie
timestamp: December 04, 2017, 02:45:19 pm
content: Hello,Well, if that amplifier is a stereo, then you should have two of them (one per channel), right?You could measure the known good one and compare, unless both have shorted windings.
What is the difference between two relays? - Page 1
Forum section: electronics / repair

author: panoss
author_rank: Frequent Contributor
timestamp: December 03, 2017, 10:44:17 am
content: Recently I repaired a Bosch PCB (from a Bosch - Junkers Eurosmart natural gas Boiler).A relay had blown.The problem was that it was a hard to find relay.It 's a 'slim' type relay and I had to find a replacement with the same dimensions or it wouldn't fit on the PCB.Anyway, I managed to use a 'normal' relay, doing some mods, and works fine.The hard-to-find relay is theSchrack v23092-a1024-a802.I found the Schrack v23092-a1024-a302. (but I didn't buy it because I didn't know if it's equivalent to the a802)So what 's the difference between these two?Can the a302 replace the a802?Thisis the datasheet about the slim line relays of Schrack.

author: SMdude
author_rank: Frequent Contributor
timestamp: December 03, 2017, 11:28:32 am
content: It really depends if the NC(pin 12) is used. If it is not used then the 302 should work fine.

author: panoss
author_rank: Frequent Contributor
timestamp: December 03, 2017, 12:25:18 pm
content: On a802 there are 4 pins only, A1, A2, 11 and 14. (pin 12 does not exist)In thepictureof the a302, I see it has the same pins as a802.So, they are identical?

author: rbm
author_rank: Regular Contributor
timestamp: December 03, 2017, 12:31:06 pm
content: Decoding the part number on page 3 says the difference is in the contact material. Otherwise, they are mechanically and electrically the same. Possibly the lifetime of the relay may be compromised by using the a302 (Silver/Tin) instead of the a802 (Silver/Nickel).

author: floobydust
author_rank: Super Contributor
timestamp: December 03, 2017, 08:44:02 pm
content: It would be trouble if the relay got stuck on.The relay in a burner controller has a functional safety requirement to meet (typically) IEC 60730-2-14.That standard has a (product) endurance/lifetime spec and test conditions are different than other standards, so special relay contact material and possibly other differences.
Onkyo SR606 help with schematics - Page 1
Forum section: electronics / repair

author: motorhomer
author_rank: Contributor
timestamp: December 02, 2017, 11:04:34 am
content: I am working on an Onkyo SR606 amp which has problems with going into protection mode. I have isolated one channel due to shorts on the output transistors but it is still doing it. To make it harder it only does it intermittently, sometime can go 15 min with no issues, other times straight away. This happens with no inputs or speakers connected.So, I am working through the schematics and have come across something I have not seen before so would like your advice. I am looking at the power supply circuit which I have attached. The voltage from the transformer between the yellow and green cables is 87 Vac and at plug J6952 is 43 Vac. Looking at the drawing both these supply’s go into bridge rectifiers and they are then connected in parallel on the output. So, I was expecting about approximately 87 Vdc on the output, but I am getting 110 Vdc on both rectifier outputs.Am I missing something? Also, it has a ground amp which looks like it is connected to the center capacitor network on the bridge inputs. I have not seen this before and cannot find much on the net to understand what this is for. Can anyone give so advice on this part of the circuit please.The service manual you should be able to get from herehttps://drive.google.com/file/d/1kxS6ENy_YlEnOL3qdcJmHhKllQ5JEvUd/view?usp=sharing

author: motorhomer
author_rank: Contributor
timestamp: December 03, 2017, 10:32:57 am
content: I got an answer from Mooly on a different forum which I thought I would post here in case any one is interested. i forgot I was measuring in RMS value with the fluke meter below is Mooly's quoteQuote
Schematic for Analogue Trio CS1575 Dual Trace  5mHz range - Page 1
Forum section: electronics / repair

author: kaborex
author_rank: Newbie
timestamp: December 01, 2017, 02:40:15 pm
content: Hi all,Does anyone know where I can find a schematic for the following:Analogue Trio CS1575 Dual Trace 5mHz rangeI believe they are Kenwood but cannot find a schematic anywhere for it.regards

author: Agent24
author_rank: Regular Contributor
timestamp: December 02, 2017, 11:29:46 pm
content: http://www.owner-manuals.com/CS1575-service-manual-TRIO.htmlclaim to be able to sell you a copy.You can probably find it for free if you search around enough though. There are lots of websites selling manuals which can be found on other, free sites.
BGA rework station machine advice - Page 1
Forum section: electronics / repair

author: asliyucegsm
author_rank: Contributor
timestamp: December 02, 2017, 10:15:45 pm
content: my friendBGA rework station machine advice1.jovy re-75002.Shuttle star RW-SP360C BGA Rework stationnotes.I would recommend another BGA rework machine and what features you need to pay attention tothanks
Faulty multimeter recycling - Page 1
Forum section: electronics / repair

author: rodolfok
author_rank: Contributor
timestamp: December 05, 2017, 04:44:19 pm
content: Hello,I have a digital multimeter of an Italian brand, Nimex NI2100, that was working ok until it suddenly gave erroneous readings, like 140V/AC instead of 220V/AC. I most pobably did something wrong that damaged it, because I can recall that I changed a blown fuse (200mA) with one I had as spare, but improperly of a higher current rating.I would like to know if there is some troubleshooting that can be done to possibly try a repair, to find out which could be the broken part, or if it's not worth the time. In the latter case, would there be some part of it to recycle, like e.g. the display, or just use the DC voltage measurement, maybe attempting a calibration.regardsrodolfok

author: Kleinstein
author_rank: Super Contributor
timestamp: December 05, 2017, 05:08:51 pm
content: With handheld meters a repair can be rather difficult. One problem is that the calibration procedures are often nor known and a professional calibration might cost more than many handheld meters.There are a few chances if the damage is visible (e.g. blown fuse / PTC ...) and not a critical part that effects the calibration.With handheld DMMs there are not that many parts worth to recycle: maybe the shunts. Using as DC only or Voltage only might be an option.

author: james_s
author_rank: Super Contributor
timestamp: December 05, 2017, 08:21:00 pm
content: Try poking around in the front end circuits, look for resistors that have gone open or changed in value, MOVs that have been damaged by surges and such. Also check the range selection switch for damaged or oxidized contacts. Otherwise it's pretty hard to offer much specific advice unless a schematic is available.

author: CJay
author_rank: Super Contributor
timestamp: December 05, 2017, 09:25:56 pm
content: Check the battery.

author: retiredcaps
author_rank: Super Contributor
timestamp: December 05, 2017, 09:49:54 pm
content: If it is this meter shown, any number of generic 830 multimeter schematics will give you a close approximation.This meter is sold under various brands.

author: rodolfok
author_rank: Contributor
timestamp: December 06, 2017, 07:39:41 am
content: Quote from: retiredcaps on December 05, 2017, 09:49:54 pmYes, mine it's a previous version because I only have 200uA.thanks
hp 1741a repair - Page 1
Forum section: electronics / repair

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: December 02, 2017, 05:13:02 am
content: Chapter 2 in the saga:I just found the reason the delayed sweep wouldn't run.A resistor that feeds the Miller Integrator went open. Easy fix and I'll have to recal the board. Might as well try to recal all of the instrument, anyway.However, I also decided to disassemble the time/div switches and clean the gunk from the contacts. These switches are constructed as two pancake molded wafers, one on each side of each of the two sweep PCB with the switch shaft running through them. The shaft is at right angles to the PCB. Each of the wafers have a few tiny spring contacts embedded to them and they wipe printed contacts on the board. I was so full of myself for finding the integrator fault that I accidentally wiped one of these spring contacts a little too energetically with a Kleenex and it broke off.Now I gotta either find some way to fabricate a new tiny embedded spring contact or get a new pancake switch.So here's my question:Does anybody have an HP 1741A you are using for parts only and that you could find it in your heart to sell me the pancake switch wafers for the MAIN sweep assembly. That's all I need. If you don't want to disassemble the switch from the PCB then I'll take the whole PCB with switches mounted.
onkyo SR606 going into protection mode - Page 1
Forum section: electronics / repair

author: motorhomer
author_rank: Contributor
timestamp: December 05, 2017, 01:00:23 am
content: I was wondering if anyone could help with a problem I have on my Onkyo 606. I have two of these one with a HDMI problem and one which is going into protection mode intermittently. I am trying to fix the intermittent protection one first. Sometimes it will run for 20 min playing music and some time it will go straight into protection mode. This happened even with all input and outputs disconnected.I have checked all power transistors and found one channel open shorted. I have removed all the transistors from this channel, power up and still have same issue.I decided to swap some cards with the other amp to eliminate them from the circuit. When placed the video PC board onto the amp without the protection fault with in 3 min of power up this amp went into protection. Now I am thinking this board may be causing the protection fault. I can see this has a power supply and feed the poff & poff2 plus other supplies to the main processor. Has anyone had this problem and is there something on this board that is worth me checking out first. I am thinking a capacitor problem or transistor on the power circuit causing this.
Replacement IC - Page 1
Forum section: electronics / repair

author: Tony.T
author_rank: Regular Contributor
timestamp: September 30, 2017, 08:45:20 am
content: I have a broken USB charger for car.The IC chip does not give out 5V ..just 0.5VThe IC is HC1005 (HW) EF6V4R 12V to 5V step converter.I tried to find it on ebay but no successhttp://img.hqew.com/File/Images/230000-239999/239027/Electronic/2017614104616590641.pnghttp://product.hqew.com/26437088.htmlI do not understand Chinese :-).Is there anybodu out there that can point out a replacement IC with same pinout as this one?Thanks a lot in advance...

author: Armadillo
author_rank: Super Contributor
timestamp: September 30, 2017, 09:44:42 am
content: Try AD84064Q.or 34063AEdit : or AD85063

author: chhrisedwards
author_rank: Contributor
timestamp: November 27, 2017, 01:31:43 pm
content: You can try this MAX756. It accepts a positive input voltage down to 0.7V and converts it to a higher pin selectable output voltage of 5V (or 3.3V).

author: james_s
author_rank: Super Contributor
timestamp: December 02, 2017, 12:17:05 am
content: I'm all for repairing things, but is there something special about this USB charger that makes it worth buying replacement parts when you can buy a whole unit for a few dollars?
Tektronix 2445a - Page 1
Forum section: electronics / repair

author: kaborex
author_rank: Newbie
timestamp: December 01, 2017, 01:29:05 pm
content: Hi all,I am new here. interested in buying a scope to fix. I have seen one with the following issues, any ideas where to start troubleshooting or what could be causing this?The unit comes on initially and works fine approx. 5 minutes, after which time the x scan collapses.regardsKaborex

author: tggzzz
author_rank: Super Contributor
timestamp: December 01, 2017, 04:34:38 pm
content: Presumably you are too late; thishttps://www.ebay.co.uk/itm/Tektronix-oscilloscope-model-2445A/152800788852has already been sold.Apart from that, there are many sources of information on this forum and at the Yahoo! Tekscopes group.

author: David Hess
author_rank: Super Contributor
timestamp: December 01, 2017, 10:24:59 pm
content: Quote from: kaborex on December 01, 2017, 01:29:05 pmI recommend avoiding that one. While this is a known problem with the 24xx series analog oscilloscopes, repair requires a replacement hybrid from a parts mule.If you are looking for an oscilloscope to repair, then I recommend something older which will be easier to diagnose and maintain.
Tektronix RSA 6114A Default XP Password - Page 1
Forum section: electronics / repair

author: Johnny10
author_rank: Frequent Contributor
timestamp: December 01, 2017, 04:05:06 pm
content: I have been looking at a Tek RSA6114A but need password for Win XP.I do have a chance to examine before buying.Is there a default password ?Can't seem to find it in manual.

author: SaabFAN
author_rank: Frequent Contributor
timestamp: December 01, 2017, 08:08:49 pm
content: For Windows XP, there are quite a few tools out there to crack the password, I believe.Even Windows 7 isn't secure. It starts to get harder with Windows 8.

author: Johnny10
author_rank: Frequent Contributor
timestamp: December 01, 2017, 09:44:55 pm
content: Yes I have software to find the password but thought there might be a default to try first.
Alpine 3566 - Page 1
Forum section: electronics / repair

author: Devcam
author_rank: Newbie
timestamp: December 01, 2017, 05:31:03 pm
content: Hello my amp seems to power cycle off an on for a while before it finally settles when powered on in the mornings.I have changed all caps in power supply any suggestions .once on it works fine.Sent from my SM-J320F using Tapatalk
Repairing a ubiquiti edgeswitch, need help - Page 1
Forum section: electronics / repair

author: asgard20032
author_rank: Regular Contributor
timestamp: November 27, 2017, 10:45:39 pm
content: Symptom : not working, led not light up, but fan spinning...First, I confirmed that the power supply is working. After, from the label on the pcb, i was able to identify some critical voltage : 3.3, 5, 1, 1.5... and confirmed they where all working. One voltage did not match the label : 12V (there was 6v there). I tried to find which chip would regulate that voltage. Unfortunately, by probing the chip, my multimeter probe did a bridge between 2 pin the the chip, and i heard a spark, then no voltage is right anymore.Can someone help me find the datasheet?It is the chip labelled VR1. I am pretty sure it is a voltage regulator with a name like that. There is a 24V comming inside (from the powersupply unit.)

author: Monkeh
author_rank: Super Contributor
timestamp: November 27, 2017, 11:18:24 pm
content: AOZ1212.

author: asgard20032
author_rank: Regular Contributor
timestamp: November 28, 2017, 05:10:00 am
content: Fortunately, i shorted the pin 7 and 8, so it must be repairable... only that chip should be damage, since it mean i shorted the Vin (24 volt) with the vbias pin (this pin is only connected with a cap to ground). Thus, i just fried that chip... at least, thats my guess, until i see other thing not working.

author: Old Don
author_rank: Regular Contributor
timestamp: November 29, 2017, 12:58:02 pm
content: If it was reading 6volts prior to your probe damage then something was drawing too much power pulling down the output. So I'd supply 12V from a current limited power supply and see what gets hot before repairing the regulator chip.

author: asgard20032
author_rank: Regular Contributor
timestamp: December 01, 2017, 01:45:10 pm
content: Define low current... this regulator is suppose to power up the whole thing, including a broadcom IC and a custom IC that does all the processing. Since I don't know the spec of that ASIC, I cannot just guess them and say that it should not draw more than 200 mA for example... this ASIC has an internal CPU for sure, running a linux (edgeOS, a derivate of VayOS or something like that, that is a linux), and a whole hardware accelerator for swtich, vlan and other thing).
Oscilloscope focus - Page 1
Forum section: electronics / repair

author: Cortical
author_rank: Newbie
timestamp: November 30, 2017, 07:28:24 pm
content: I have recently acquired a very old oscilloscope, and had just figured it all out when it went out of focus. Adjusting the focus dial works to some extent, however when turned all of the way it brings the line into much better focus (2cm wide rather than 6) however this is still so much that it is not easy to work with. Is there a simple fix, or is this a very complicated issue?(I would love to give a model number, however I do not know my self, all I know is that it it is very simple and basic)Thanks

author: tautech
author_rank: Super Contributor
timestamp: November 30, 2017, 07:40:13 pm
content: Welcome to the forum.Post some pics please as there'll be someone here that can identify it.Then maybe we can find a link to a service manual so it can be fixed.Unless you have some experience with CRO's will be bumbling in the dark so let's start like this.PSU values need be checked before you do anything, value and ripple specs for the rails must be right before you touch anything else.When that's all OK there's often a bias trimmer for focus and that allows you to set the focus control midway for most usage. But you need have all above correct before you touch anything.Use the Attachments below the post window to add a pic file. Max= 1 Mb but 100-200 Kb gives plenty of detail. Resize/compress as necessary.

author: Cortical
author_rank: Newbie
timestamp: November 30, 2017, 08:03:21 pm
content: Looking at it I see that it says OS250 on the front, and looks a lot like the OS250B image on this website:https://www.radiomuseum.org/r/gould_adv_oscilloscope_os_250b.htmlI will also attach an image.

author: Specmaster
author_rank: Super Contributor
timestamp: November 30, 2017, 08:14:46 pm
content: Quote from: Cortical on November 30, 2017, 08:03:21 pmThe owners manual which also incorporates the service manual for this can be downloaded from this sitehttps://elektrotanya.com/advance_os-250_oscilloscope_10mhz.pdf/download.html.
Fluke 87 series one repair brief - Page 1
Forum section: electronics / repair

author: mzacharias
author_rank: Frequent Contributor
timestamp: November 30, 2017, 04:08:42 pm
content: OK, so I bought a broken Fluke 87 off eBay. I could see in the pictures the low-battery symbol was on, so I took a chance that it only needed a battery. It did, but it had other problems as well, mainly pertaining to the milli-volt, ohms and diode test functions.On inspection, I could see it had been worked on before - the LCD bracket was missing one edge holder and another was wobbly, so obviously the digits weren't there unless pressure was applied. OK, I can fix that later.With no battery, the input resistance at the volt/ohms jacks was only about 400K on milli-volts, and 3K or so in Ohms mode. With no leads inserted, about 140 mV showed on the display, and in Ohms mode, about 138 ohms, IIRC. The unit could not supply the standard 1mA current output in Ohms mode. The circuit board appeared uncontaminated but I had not ruled out a problem hereThe service manual, as good as it is, lacks certain things, like voltages at the pins of U4, a clear explanation of reference grounds for testing and repair (that I found anyway) so I spent time here and there over several days becoming more conversant with what the schematics were telling me, and testing various internal protection components. The MOV's, diodes, transistors etc were all ok. I was on the verge of condemning U4, but I really wanted to prove it was bad before doing that.Additional poking around, opening the circuit by lifting the 1.5K RT1 thermistor, suggested to me the problem involved the switch itself.Long story short the switch had been re-assembled at some point in the past - with the small black plastic shaft and it's associated black plastic switch / feeler assembly on the rear side of the board, precisely 180 degrees out of phase, such that the deposited carbon tracks were the source of my leakage. Positioned the black plastic shaft in the opposite orientation, snapped the rear switch back in place, all functions now work as intended.A good learning experience and I got a "fair-to-good" condition Fluke 87 for 75.00 freight included.Aside from me getting to brag a little bit, I hope this information may be helpful to someone. There was really no indication the switch was wrong or that anyone had messed with it.

author: purpose
author_rank: Frequent Contributor
timestamp: November 30, 2017, 05:25:09 pm
content: Result.
FLUKE 741B - Page 1
Forum section: electronics / repair

author: lionelkjh
author_rank: Frequent Contributor
timestamp: October 31, 2017, 01:18:47 pm
content: Hello everyone! I recovered a FLUKE 741B calibrator in very good condition, but failed. Opening it, I realized that it was missing the flash memory removed by the former owner, who was probably defecteueuse. Could someone tell me what was his name? And, most importantly: how to do the calibrator data ?? (unless someone has the file, by chance!) .. Thank you to all who can help me in this troubleshooting

author: Tony_G
author_rank: Super Contributor
timestamp: October 31, 2017, 04:04:59 pm
content: I don't know if there is a service manual available but here are theUserandCalibrationmanuals for it. Unfortunately I've never used one so I don't have anything more than this (and I suspect you already have these).TonyG

author: lionelkjh
author_rank: Frequent Contributor
timestamp: October 31, 2017, 05:48:13 pm
content: Good evening; I have already looked in the service manual before posting on this forum, there is no schema or nomenclature on integrated circuits. Cdt

author: footware
author_rank: Newbie
timestamp: November 30, 2017, 07:22:39 am
content: I can open a Fluke 743B (which seems the same calibrator) for look inside. Can you communicate the identifier of the missing component?
Component identification - BMW 525d - Page 1
Forum section: electronics / repair

author: BBenj
author_rank: Newbie
timestamp: November 29, 2017, 04:35:25 pm
content: Hello,New here but long viewer of EEVI'm looking for help to identify a component (see pic), I can't find anything.Ref:NEC JAPAN12233766A1001E300BMaybe someone knows that ref?It's some sort of decoder. An encoded signal from a car remote gets feed in (from the bottom, the resistor array), and some signal should come out (two red dots on top) to unlock the doors. Something is broken on that board, and I'm trying to find what! That component is the last thing between the output and the remote.If you have any idea...Thanks!Best regards,Benjamin

author: mc172
author_rank: Frequent Contributor
timestamp: November 29, 2017, 04:48:11 pm
content: Just searching "12233766a" and "nec" returns this:https://www.elektroda.pl/rtvforum/topic3070614.htmlWhich suggests it's this:https://4donline.ihs.com/images/VipMasterIC/IC/NECC/NECCS04000/NECCS04000-1.pdf?hkey=EF798316E3902B6ED9A73243A3159BB0

author: BBenj
author_rank: Newbie
timestamp: November 29, 2017, 05:42:40 pm
content: Indeed, that's it! Thank you!I don't how I missed that, I'm pretty sure I searched with these terms tooAnyway, it's a micro controller, so nothing to repair here unfortunately, not worth the time. Too bad!Thanks again,Benjamin

author: mc172
author_rank: Frequent Contributor
timestamp: November 29, 2017, 07:35:10 pm
content: It was the first result in Google Images for me.

author: james_s
author_rank: Super Contributor
timestamp: November 30, 2017, 12:12:31 am
content: I wouldn't be too quick to condemn the microcontroller though. At least check the voltages first, and make sure the clock signal is present, unless it's using an internal clock.
Samsung un55ks8000f vertical stripes - Page 1
Forum section: electronics / repair

author: PINKBOY1006
author_rank: Newbie
timestamp: November 28, 2017, 03:40:11 am
content: So pretty much got this tv for free and the TV has vertical lines when it powers up. We have already replaced the main board (There's only 2 boards in the tv!) and practically no change. The power supply voltages (to my knowledge) are fine, 12.8 volts for all main power rails. And I have pressed on the top connecting flex, re-seated all of the connectors and I'm just at a loss. Here is a picture of the problem

author: Samogon
author_rank: Frequent Contributor
timestamp: November 28, 2017, 04:17:34 am
content: Most likely problem in the flex cable where it is soldered/glued to the panel. Usually it is beverage damage.So basically you have got main board and psu for almost free.

author: Armadillo
author_rank: Super Contributor
timestamp: November 28, 2017, 10:35:29 am
content: I think there is a T-con board hidden behind the black heat shield/covering in the Top middle section.Could be T-con lvds or rvds problems though likely are the flexs, TCP problems.its a reasonably good large TV, I would try to the very end.So if it is convenient, swop a T-con.I would probe the T-con, but it is too difficult and lengthy to explain here.the simplest is to swop T-con board, press in all connection etc...

author: Armadillo
author_rank: Super Contributor
timestamp: November 28, 2017, 08:22:30 pm
content: Only single color vertical stripes, maybe still a ray of hope there.Can beverage damage be whole TV length long? ehm... maybe?See the joy of someone's repair;
Portable air conditioner. - Page 1
Forum section: electronics / repair

author: paulca
author_rank: Super Contributor
timestamp: November 28, 2017, 01:53:48 pm
content: I have an old portable airconditioner unit. About a year ago it failed. I have already bought a new one, but I've been considering fixing the old one, it can't be that hard.Symptoms are:When the unit is powered the lights come on, the temp display reads normally, the fan runs, everything looks okay. However when I switch the active cooling mode on, no matter what the temperature is set to, the actual compressor does not start. There is no relay click, nothing, it just sits dumbly doing nothing.These units get pretty hot inside when running, I'm wondering it this is a classic case of electrolytic capacitor failing or maybe just a failed/stuck relay for the compressor.I suppose a first test would be to open it and connect the mains directly to the compressor (or just bypass the relay) and see if it runs. if it does it comfirms it's a control failure and diagnose from there. If it doesn't run then the compressor is toast.Any experience with these units on here?

author: Armadillo
author_rank: Super Contributor
timestamp: November 28, 2017, 07:55:13 pm
content: You should visual if the condenser fan is running.If its running, the relay to the comp is energized.if so, those are capacitors start motors. Easy cake to check those ac cap. Otherwise the motor or comp is fried [double confirm ac voltage at terminal]If relay not energized, then is either protection [freeze switch, short cycle timer switch, high pressure switch], you can check if these devices are close circuit [with power off].if the high pressure switch is open, then safest and cheapest to bin it, otherwise you need a AC mechanics.
Capacitor replacement on a VP22 Mainboard (16902a Logic Analyzer) - Short HowTo - Page 1
Forum section: electronics / repair

author: DocBen
author_rank: Regular Contributor
timestamp: November 28, 2017, 05:41:56 pm
content: You will need:- the service guide for the 16902a (if thats where your vp22 lives) to get a lay of the land- capacitors:6x 1500uF 6.3V 105°C caps (while your at it might as well be Low ESR) - for example Panasonic FR series or Yageo SC series depending on your budget2x 1000uF 16V 105°C1x 680uF 6.3V 105°Cpolymer capacitor6SEPC680M (dont be fooled: these things have about ten times the ripple current of low esr electrolytic caps -> much smoother output current)all 5mm lead spacing, any diameter <= 10mm should be fine- some kind of soldering tweezers because the caps are soldered to power planes without thermals.- a desoldering pump is quite handy- scalpel with a sturdy handle to cut the elastic between the capacitors and under them where it touches the board, otherwise it is very difficult to remove the capacitors, this stuff really doesnt want to let go.disassembly is hindered in a few places:both the motherboard and the pci/backplane connector card are held in place by a metal stub. I needed to compress it slightly to get them free (and remove the screws of course)all the standoffs of the mainboard i/o connectors are screwed through the rear panel, so you have to remove those too before you can remove the boardthe rest is easy: remove old caps, solder in new caps, reverse dismanteling, power on and pray nothing explodes. done.
Sharp R-430CD Microwave Repair (Completed) - Page 1
Forum section: electronics / repair

author: MWisBest
author_rank: Contributor
timestamp: November 27, 2017, 06:20:21 pm
content: My dad was going to fix this microwave years ago but never got around to it before his unexpected death this summer, so I decided to give it a shot myself for sentimental reasons. Itisstill a pretty nice microwave by today's standards though. 1100W, sensor cooking, etc.Initially I thought it was just going to be the blown thermal fuse. The inside of the chassis was completely clogged up with dust and debris, so wasn't exactly surprising that it got too hot inside. But then I discovered this:Yeeeeahhhh. That transistor appears to be kinda cooked. It is part of the regulator circuit for all the microelectronic stuff on the control panel.Unfortunately this is a proprietary transistor and package by Rohm (2SB1238) that is no longer made. It's designed to have more thermal dissipation than a standard TO-92. I did not have a TO-220 on hand that would work, so I came up with this:That is a TO-92MPSA56with a wire crimp connector wrapped around it as a heatsink (plus some thermal grease in there). With the pins bent around because the pin-out was different. But other than that it was fairly close specification-wise to the 2SB1238, and more importantly I had it on hand in the salvage bin.Here it is on the board:I soldered the emitter to the extra unpopulated-but-connected hole there in order to increase the structural stability a bit, and give me more room for the swapped collector and base leads.Just for good measure I replaced the electrolytic capacitors on the board as well, and created some solder bridges around that transistor to add some extra thermal mass:Final result, works just dandy! It appears I may have broken a connection to the LCD, as one of the vertial lines is out, but it's still legible and more importantly the microwave works now. I'll take it.

author: Armadillo
author_rank: Super Contributor
timestamp: November 27, 2017, 06:28:47 pm
content: Well Done !
The Infamouse leaky capacitors of Keithley: A list of replacements? - Page 1
Forum section: electronics / repair

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: November 27, 2017, 04:38:52 pm
content: Hi guys,I have a Keithley 2000 on the way. I would like to replace all the electrolytic capacitors as soon as I get it, I don't want to run any risks. Does anyone have a list of replacement capacitor parts, or perhaps the sizes and ratings etc? This way I can order replacements already and don't need to wait untill the unit is there to figure out what I need. I figure it might also be usefull to just list them here, so others can find them in the future.
HP E3631A voltage and current measurements problem solved - Page 1
Forum section: electronics / repair

author: wictor
author_rank: Regular Contributor
timestamp: November 27, 2017, 05:01:47 pm
content: Hi,Here comes yet another repair story...I had following problem with my power supply: All the outputs were working and voltage and current could be set in limit mode. But voltage and current measurements were not working. Display was showing usually over limit values and sometimes when it was not on the limit, all values were fluctuating a lot.By reading the forum I quickly realized that measuring the ADC part can be tough, since it's based on current and it is multiplexing couple of channels. I measured that muxes were ok. I measured all the resistors and input voltages, ADC references and those were ok. For opams I decided to build test bench for measuring their performance and see if any of those is faulty. I knew that it would be easier to just change all opams, but I didn't have those and I would need to order them and wait some time to get them. And problem could still be somewhere else. So I built voltage follower circuit to breadboard and tested OPA27(U6) and it was behaving ok.AD711(U8) was not behaving so nicely. I had following setup for opamp: +10V positive supply, 0 negative supply and test signal to non inverting input was square wave 6V p2p with 5V offset. Following is picture with 10kHz input:Channel 1 is input(pin3) and channel 2 is output and inverting input.And with 100kHz:I managed to find TL071 for testing and after replacing AD711 with TL071, power supply display is working normally again. Now I just need to order new AD711 to fix it properly.
Identifying a Capacitor - Page 1
Forum section: electronics / repair

author: megaman
author_rank: Newbie
timestamp: November 21, 2017, 11:44:03 pm
content: Hi, I have a Dell U2312HM Monitor with a faulty PSU. It looks like one of the SMD ceramic caps has gone pop as you can see in the photo. The issue I am having is I am not sure what value I need to replace the component with as I cannot find a service manual. The cap is 5mm long and 3mm wide, the mosfet you can see above the cap has a part number of PB210BD (http://products.niko-sem.com/images/product/128927539636.pdf) if it helps. Any help would be great,Cheers,

author: ataradov
author_rank: Super Contributor
timestamp: November 21, 2017, 11:59:45 pm
content: There is no way to tell for sure, but you can make an educated guess. To figure out the rated voltage - look at the voltage rating of the electrolytic cap next to it (C122).The exact capacitance probably does not matter all that much. Put something like like 10 uF and see what happens.

author: megaman
author_rank: Newbie
timestamp: November 26, 2017, 12:21:11 pm
content: Just posting an update, I checked C122 and it was rated for 100V, taking this in to account the highest value cap I was able to find that was in stock was 3.3uF. I have installed the cap and so far we have picture and no smoke so it looks good to me! Thank you for the helpThe manufacturers part no: C1812C335K1RACAUTO in case anyone stumbles across this in the future.
Can anyone identify a "AN3102" sop/soic-8 chip? - Page 1
Forum section: electronics / repair

author: NeedsMoreFlux
author_rank: Newbie
timestamp: November 26, 2017, 02:41:19 am
content: I am trying to repair a piece of Chinese electronics for my brother and there is a burned 8 legged SMD chip.I can read "AN3102" on the top half of the chip. If there is anything else written on it; it is either burned off Or I'm not seeing it.I assume "AN" refers to the manufacturer, though I haven't been able to find a manufacturer with those initials.Nor have I been able to find a chip with that "3102" number even looks similar.If anyone has any idea I would really appreciate you filling in this mystery for me. I'm pretty stressed out about this one, because it only burned up after I changed a toasted diode on it.Thanks again.

author: amyk
author_rank: Super Contributor
timestamp: November 26, 2017, 03:26:29 am
content: Pictures please.Most certainly does not help that "ANxxxx" is how other companies usually number their application notes...

author: NeedsMoreFlux
author_rank: Newbie
timestamp: November 26, 2017, 04:41:19 am
content: can you see them?

author: NeedsMoreFlux
author_rank: Newbie
timestamp: November 26, 2017, 04:46:50 am
content: lol.

author: NeedsMoreFlux
author_rank: Newbie
timestamp: November 26, 2017, 04:49:08 am
content: lol2

author: Armadillo
author_rank: Super Contributor
timestamp: November 26, 2017, 04:53:56 am
content: I think is a custom part number.Zoom out so that at least neighboring components can be seen.What device are we looking at?
DE5000 cant mesure anything - Page 1
Forum section: electronics / repair

author: YU2
author_rank: Regular Contributor
timestamp: November 25, 2017, 03:12:32 pm
content: After probing one cap that should be empty, but supposedly had some charge, my DE5000 showed ERROR on the display and then shut itself off. After turning it on it cant measure nothing any more. Display just jumps from CP/CS, RP/ESR and shows no results. Cant also calibrate, when probes are short it shows FAILED. My oscilloscope shows it outputs decent sine way on all 5 frequencies.Cant see nothing is fried on PCB. Any suggestion is welcome.

author: YU2
author_rank: Regular Contributor
timestamp: November 25, 2017, 05:49:55 pm
content: Repaired it.tiny R33, 100 ohms marked as 01A was measuring 300k + ohms.Capacitor that caused the defect was 10uf, 250V. At the time of measurent must to had about 100V.
Weller WHA700 - Page 1
Forum section: electronics / repair

author: Charlie86
author_rank: Regular Contributor
timestamp: November 24, 2017, 09:12:21 pm
content: Hi,I have Weller WHA700 hot air station. Can I attach Weller HAP 200 hot air pencil on it? From factory HAP 3 was attached but I do not have it. Can I use HAP 200 as alternative?Thx