hybridfree/eevblog-posts huggingface dataset:
Sony DAT DTC-670, distorted or no playback - Page 1
Forum section: electronics / repair

author: davorin
author_rank: Unknown
timestamp: November 08, 2014, 03:47:23 pm
content: Good afternoon (o;I just acquired a Sony DTC-670 which I knew it was defect, but not the ral cause..Now when I put in a cassette it closes, pulls the tape in, starts rorating the head and soon after stops with a "CLOSE" blinking in the display...Closing the lid without a tape shows no errors...Some simple mechanical switch gone wrong?

author: radhaz
author_rank: Regular Contributor
timestamp: November 09, 2014, 11:07:24 pm
content: It sounds like a switch problem. Here is a service manual:http://www.hifiengine.com/manual_library/sony/dtc-670.shtml

author: davorin
author_rank: Unknown
timestamp: November 13, 2014, 05:10:44 pm
content: Well..the service manual I already have...and only some end consumer type fault messages are included....Got hold of a second one now...and swapped the drive...after few tries the tape starts playing now....also recordong...though strange with recordings that now and then some milli seconds are missing...just like a bad CD with lots of scratches...

author: davorin
author_rank: Unknown
timestamp: November 15, 2014, 10:47:59 am
content: This is really weired....got it now at that point that it records fine from SPDIF in with audio feed from a Wandboard Linux board...But when I power off the DAT device and switch it on next day to play back...there is no recording anymore..just the 48kHz is blinking...

author: davorin
author_rank: Unknown
timestamp: November 15, 2014, 04:09:25 pm
content: Hmm...happens even with frsh recordings....sound is fine for a few minutes, then distorted (not nice to hear through headphone ;o)...and then okay again...Now suddenly plays back the Pink Floyd Endless River recording from yesterday (o;Time to throw away the tapes? I already cleaned the drum head....Hmm..just discovered that the distortion is not as the same spot when I rewind and play it back again....

author: davorin
author_rank: Unknown
timestamp: November 15, 2014, 06:03:03 pm
content: Signal on the drum head seems fine during recording....

author: davorin
author_rank: Unknown
timestamp: November 16, 2014, 10:49:08 am
content: Swapped the RF preamp board from another 670 and now it palys back a recording...let's see for how long ;-))Though it doesn't write the Start ID automatically anymore...

author: davorin
author_rank: Unknown
timestamp: November 16, 2014, 06:37:06 pm
content: Hmm...no joy....no playback anymore.....Even replaced the capacitors on the RF amplifier board as suggested on a Youtube video....No wonder Ebay is full of Sony DAT recorders marked as broken/for repair....Just never bid for one...you will never get it fixed (o;

author: Cyberdragon
author_rank: Super Contributor
timestamp: November 17, 2014, 04:59:27 pm
content: Sounds like it could be a loose coil connection inside the read/write head itself causing intermittent failure. Try finding a replacement.
VEX Cortex Repair Help - Page 1
Forum section: electronics / repair

author: capatainespinoza
author_rank: Newbie
timestamp: November 15, 2014, 06:30:01 pm
content: Hello folks. I am a teenager in a worldwide robotics competition called VEX Robotics. We use micro controllers called VEX Cortex that are proprietary to the VEX company. A few days ago, we had a few motor and two batteries hooked up using a power expander(a normal load for this device), when we started smelling something. A search guided by smell eventually lead to the Cortex. I've linked images below showing the results. I'm not sure how to fix this, if it is even possible, and don't even know the cause of this issue. You'll find that the bottom of the PCB yielded what I think was the capacitor that was melting the plastic under it. I've used this controller in my robots for three years now, with no issues save this one. I come to your expertise for assistance. Many thanks for your responses.http://imgur.com/gallery/V4CO3/new

author: poot36
author_rank: Frequent Contributor
timestamp: November 17, 2014, 06:51:34 am
content: Could you please post or attach the picture to this forum so that is is easily viewed? I would use a multimeter on the ohms (?) setting to test if the capacitor is shorted. If it is then you will have to find a replacement one of the same or greater voltage rating as well as the µF rating.

author: miguelvp
author_rank: Super Contributor
timestamp: November 17, 2014, 07:08:33 am
content: The money shot image is all blurry but that IC has had it, it can be seen even with the blurry picture.

author: fictive
author_rank: Newbie
timestamp: November 17, 2014, 07:15:48 am
content: I did VEX last year when I was still a senior in high school. I believe that burnt IC is one of the H-bridge IC's for the integrated motor drivers on the Cortex.The two ports with integrated drivers would be ports 1 and 10 (2-wire motor ports).Check the motors in ports 1 and 10 to see if the wires have shorts. Normally the PTC in the motor would protect against things like this, but they don't protect against shorts outside the motor.You could try to get the Cortex replaced under warranty, or desolder and replace the H-bridge driver yourself. There are two drivers per 2-wire port, one on top of the board and one below. See for more info here:http://www.techspin.info/archives/856(3/4ths of the way down).The burnt part on the bottom of the PCB is this PMOS:https://www.fairchildsemi.com/datasheets/FD/FDS4935BZ.pdf
Dallas DS1287 Replacement - Page 1
Forum section: electronics / repair

author: Unknown
author_rank: Unknown
timestamp: November 15, 2014, 02:11:03 am
content: I'm in the process of fixing up an old IBM PS/2 Model 30 machine. It has one of those pesky Dallas RTC chips with the battery inside. I'm aware of the hack, that involves cutting into the casing but I'd rather do a 'proper' job of it and replace the chip altogether.Does anyone know of a substitute that would work in place of the DS1287 and where I might be able to get one from (Element14 ??) I believe it's socketed in these machines so it should be an easy job if I can find the right part.Update: Element14 have the DS12887+ which is marketed as a drop-in replacement and specific for IBM AT computers. Has anyone actually used one of these in place of the DS1287?

author: Paul Price
author_rank: Super Contributor
timestamp: November 15, 2014, 07:27:21 am
content: The spec sheet (alldatasheet.com) says:DESCRIPTIONThe DS1287 Real Time Clock is designed to be a directreplacement for the MC146818A. For a completedescription of operating conditions, electrical andmechanical characteristics, bus timing, and pin descriptionssee the DS12887 data sheet.----------------------------------------Looks like the same to me.

author: Kjelt
author_rank: Super Contributor
timestamp: November 15, 2014, 08:51:37 am
content: You can try this exercise:http://www.mcamafia.de/mcapage0/dsrework.htm

author: TheBay
author_rank: Unknown
timestamp: November 17, 2014, 12:07:44 pm
content: What about the RTC65271 also?
Kenwood KA-78 stereo amplifier repair - Page 1
Forum section: electronics / repair

author: CodyW
author_rank: Contributor
timestamp: November 13, 2014, 11:53:24 am
content: Hi everyone,Just recently, my Kenwood KA-78 stereo amplifer stopped working. The relay, K1 is making a clicking noise but nothing else is happening with the device. K1 is located on the high voltage board. I'm completely stuck. Would anyone have any idea? Any info would be greatly appreciated.Cody

author: mzacharias
author_rank: Frequent Contributor
timestamp: November 13, 2014, 08:18:06 pm
content: Hi. Need a much better problem description that this. Does it click once when you press the power button? Click repeatedly only when you press the button? Does the display (if it has one) light up? Have you made any measurements, voltage checks, etc?

author: Vito_R
author_rank: Regular Contributor
timestamp: November 13, 2014, 10:27:49 pm
content: Does it power up properly? Find a schematic for it and start by checking all your power supply voltages.
Multimeter lcd- FINEST 701/ uei dm391 - Page 1
Forum section: electronics / repair

author: Simon123
author_rank: Regular Contributor
timestamp: August 29, 2014, 01:00:40 pm
content: Hello!I broke my multimeters display.What should i be looking for?I checked aliexpress for fs9721, but i can only see chips, no lcds ...

author: Lightages
author_rank: Unknown
timestamp: August 29, 2014, 11:12:25 pm
content: Try emailing UEi and ask for the part:irmah@ueitest.com

author: Simon123
author_rank: Regular Contributor
timestamp: August 30, 2014, 07:40:31 pm
content: Thanks!Sent mail, hope i get response.

author: Simon123
author_rank: Regular Contributor
timestamp: September 23, 2014, 09:20:16 pm
content: Hello, again.I didnt get any response from uei, so i tried finest mail, but i got some strange reply, that mail couldnt be sent or something.

author: Simon123
author_rank: Regular Contributor
timestamp: November 13, 2014, 02:45:54 pm
content: I kinda didn't think about contacting place where i bought it.So i contacted em and they sold me a replacement for $10+shipping and tax.Now i'm happy camper again.
Tracing an active short - Page 1
Forum section: electronics / repair

author: Stonent
author_rank: Super Contributor
timestamp: November 16, 2014, 08:18:05 pm
content: No expensive FLIR to find your short? Here's an easy way from one of my favorite car repair channels using a circuit breaker, a test light and a auto-parts store analog ammeter. In this case, the fuse keeps blowing when you try to start the car. But where is the short? The fuse feeds a lot of circuits so you need to know where to look. This guy owns his own repair facility but he also teaches college classes on vehicle repair.

author: TheBay
author_rank: Unknown
timestamp: November 17, 2014, 12:22:37 pm
content: Interesting video, there are some better ways of doing this however but his method does work.Though on a modern vehicle I would not be using this method unless you want to replace expensive control modules. I also use a PowerProbe PP3, but you really have to know what you are doing especially keeping away from CAN/Data wires.
Fujitsu Simens V5355 motherboard unknown crystal - Page 1
Forum section: electronics / repair

author: hobo2566
author_rank: Contributor
timestamp: November 09, 2014, 09:04:15 pm
content: Hello,I have motherboard for this laptop, FS V5355, that needs small repair. Whole laptop went thru lot of damage, almoast like some 1 was jumping on it. By some miracle motherboard was posting and could enter bios, but there was some issues after saving bios(would not post after default+F10) and screen flickering.Opened it up and saw a broken crystal, X6, and some damage on mosfet(bent pins) near chipset.I managed to saw it was crystal but unable to determine value since it is completely broken off and could identify it via pictures on net. Also didn't manage to find schematic.Does any one know or by any chance can check the value of this crystal? I will attach picture of it and circle it red.Thank you.

author: poot36
author_rank: Frequent Contributor
timestamp: November 10, 2014, 07:23:57 am
content: I am going to guess that it could be in the 20 to 48Mhz range due to its proximity to the southbrige. Some laptop boards have the crystal frequencys silk screened on the board (some times hidden under a glued down piece of plastic) somewhere along with a component designator and number. Try removing the bad crystal and see if there is any markings under it. Did you check the clock battery?

author: rob77
author_rank: Super Contributor
timestamp: November 10, 2014, 08:08:20 am
content: isn't it 25000 ? the number is visible on the crystal in the red circle... and actually 25MHz is pretty common on MBs.

author: hobo2566
author_rank: Contributor
timestamp: November 11, 2014, 07:35:18 pm
content: Quote from: poot36 on November 10, 2014, 07:23:57 amI desoldered what was left from crystal but nothing underneath it or on board could tell what value it was. Checked battery, was bad also, replaced but problem still remained.Quote from: rob77 on November 10, 2014, 08:08:20 amQuite an eye you got thereIt wasent able to see anything at all... now when you said it i am pretty sure it is 25000especialy seeing this picture:http://www.notebook-service.biz/bilder/Notebookzubehoer/Boards/V5535.jpgBut to make it sure ill try to get answer from some one on ebay selling board for scrap. If not will go with 25k... also any one here confirming will do.

author: poot36
author_rank: Frequent Contributor
timestamp: November 11, 2014, 11:48:29 pm
content: Assuming that the chip that the crystal controls has a pll of sorts in it it will not mind a somewhat out of spec crystal. I have seen chips that let you choose from a decent range of crystal frequencys and work properly. The 25Mhz is just a recommended value.
HP 54601a failed checksum test - Page 1
Forum section: electronics / repair

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: November 10, 2014, 08:05:17 am
content: Hello everyone,I just got a HP54601a oscilloscope. I tested it for more than one day, and all the channels were working perfectly.I made all the internal tests of the machine with success.Then two days later, when powered on, it just could not start.It failed to boot with the messageillegal instruction : 0Hsetup memories failed checksum test - defaults loadedwith nothing more. Impossible to go beyond this first page.Any suggestion on what happened ?Jacques

author: rf-loop
author_rank: Super Contributor
timestamp: November 10, 2014, 02:11:39 pm
content: Of course in fail case nothing is absolutely sure until find what is exactly wrong.But, strong supect: NVRAM internal lithium battery is dead.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: November 10, 2014, 06:46:48 pm
content: Thanks a lot for the hint.I see that there is a DS1220AB SRAMDo you mean that I need to change it. Is there any HP software on it, or is it safe to simplychange the component, without having to worry about any firmware ?Thanks

author: rf-loop
author_rank: Super Contributor
timestamp: November 11, 2014, 08:07:08 am
content: If think this scope age and NVRAM specs it is like final of its life. If it have never changed.You can run full selfcal and watch if it keep cal and your personal settings and stored things after power off.But it is very typical NVRAM battery start fails at these years after manufacture.In 5450x models NVRAM do not keep any other data than cal data + what user have stored to NVRAM (example swaveforms, settings etc)I do not know exactly 100% sure how it is on 5460x models. I have quite strongbelievethere is nothing else. (because it is HP and related to knowledge about some other HP 80-90 years digi scopes).

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: November 11, 2014, 10:46:18 pm
content: Hello rf-loop,After your hint, I could search on the web about the problem of dead battery on a DS1220, and I decided to tryto fix the HP54601.The first thing was to desolder the DS1220 (which is not that easy) and to install in place a socket forfuture use.Then I order a new DS1220, but as was impatient to see if that was the right problem, I tried to change the batteryon the DS1220 following some indications which appear in several places on the web, ashttp://www.vk2hmc.net/blog/?p=245I use my proxxon drill to dig into the epoxy from the bottom, and manage to remove the battery.Then I soldered two wires on the ground and + former connections of the battery (see photo).I glued a CR2032 holder on the top of the DS1220, and putit back in the socket.Bingo, it works !Maybe the calibration is lost, and I will have to do it. This is a nice fix. I would not have known how to startwithout your very helpful comment, rf-loop. Thanks again.
Mystery Connector on HP 1652B - Page 1
Forum section: electronics / repair

author: Minifig666
author_rank: Contributor
timestamp: November 11, 2014, 07:59:37 am
content: Hi All,Back on the HP 1652B, I'm trying to locate a replacment mains power connector for the PSU.See the attached photo.It's 5mm pitch. There's an Amphenol logo lurking at the back of one of the barbs.I've had a dig round RS and Farnell but turned up nothing. I don't suppose anybody knows the type or where I can get a new one?Thanks,Mini

author: JSnyder
author_rank: Contributor
timestamp: November 11, 2014, 08:53:16 am
content: I think this connector is made by TE Connectivity, and is in their Metrimate, AMP series.http://www.digikey.com/product-detail/en/208117-1/A113035-ND/292432Check out the Datasheet/drawing, I think it's what you're looking for. If not, it gives you a place to start looking.Mating part as well:http://www.digikey.com/product-detail/en/208116-1/A115050-ND/292431

author: Minifig666
author_rank: Contributor
timestamp: November 11, 2014, 12:48:03 pm
content: Spot on, thank you very much!Shame there's no UK stock with any of my favorite distributors. Looks like a salvage job might be the best.
Motherboards - Page 1
Forum section: electronics / repair

author: DestinySpork
author_rank: Newbie
timestamp: November 09, 2014, 03:18:58 pm
content: I know this is not really the right thing for this forum, but I'm sure someone will know.I built my new computer recently, and had it working fine. However, when I upgraded my PSU to power the graphics card, my motherboard refuses to work, even on the old PSU. I have tried the reset and leaving the mobo without power for several days without power, and still nothing. Is it dead? Please let me know, and also any way I could fix it.

author: TheBay
author_rank: Unknown
timestamp: November 09, 2014, 03:26:43 pm
content: Have you got the 4 or 8 pin ATX additional power plugged in? And it's the right one, not the PCIe one!!

author: hobo2566
author_rank: Contributor
timestamp: November 09, 2014, 08:45:37 pm
content: When you power it up with new PSU does it give any signs of life(fan spinning, led lights, etc.)?Was your "new" PSU out of box, like brand new?Any info on psu, motherboard, gpu and other hardware info would be appreciated.

author: allikat
author_rank: Contributor
timestamp: November 11, 2014, 08:15:45 am
content: Things die in transit, it's known as DOA or Dead On Arrival.1: Check the PSU for the smells of departing magic smoke,2: Go round and double, then triple check all your connections. They are all keyed to fit only in the right places. Any plug that needs force is being plugged into the wrong place.3: and tell us that the user of an electronics forum didn't buy the cheapest one-hung-low brand PSU? Please?Things that bite people:There are 2 different 8 pin sockets, one on the board, one on graphics cards with very similar sockets. They are keyed differently and have different pinouts, but a strong person can force the wrong plug into the socket, leading to possible magic smoke loss as you connect high current +12v directly to ground.Low cost PSUs are junk. Clean power is important in your projects and it's important in your computer.
Is an 11V laptop battery compatibie with a 14.8V battery? - Page 1
Forum section: electronics / repair

author: ByteMe
author_rank: Contributor
timestamp: November 15, 2014, 04:09:15 pm
content: So I've got a bit of a weird question.My mother's laptop(dell 1545) has a dead battery, doesn't hold any charge whatsoever. I'm looking for a replacement and would like to upgrade the battery too. However, all 9 cell batteries are 11.1V and the original battery is a 14.8V 4-cell one. The tricky thing is: dell only sells the 9 cell for the 1545. Can I safely buy a 9cell(on aliexpress of course, it's like 5 times cheaper!)?

author: amyk
author_rank: Super Contributor
timestamp: November 15, 2014, 05:19:27 pm
content: 9 cell batteries are 3S3P - 3*3.7 = 11.1V4 cell batteries are likely 4S(1P) - 4*3.7 = 14.8VThere is also a 6 cell version which is 3S2P - also 11.1VA quick Google shows that this laptop can use either 11.1V or 14.8V batteries so you should be fine with it.
Logitech z-506 amp/speakers - Page 1
Forum section: electronics / repair

author: awyeh1234
author_rank: Contributor
timestamp: November 07, 2014, 08:48:21 pm
content: Hello i have this set of logitech speakers and one day out of the blue they just stopped working. the power light turns on but if you put a signal into it nothing happens. any suggestions?

author: poot36
author_rank: Frequent Contributor
timestamp: November 10, 2014, 07:29:28 am
content: Have you taken them apart and measured the voltages on the amp chips pins and compared them to the datasheets values?

author: Whales
author_rank: Super Contributor
timestamp: November 10, 2014, 08:25:21 am
content: Although the light is coming on, the power supply might be faulty (feeding out-of-spec power). If you have a power supply/plug pack rated to the same output voltage, try that on it.
MFAE A10 smd code - Page 1
Forum section: electronics / repair

author: stoica adrian
author_rank: Contributor
timestamp: November 06, 2014, 06:40:58 am
content: Hallo,I have a smd SO8, marked MFAE A10 . On the internet I can not find anything about him. I have it into i45V Switching Power Suplly. Does anyone have an idea what is this

author: niflheimer
author_rank: Contributor
timestamp: November 06, 2014, 12:31:07 pm
content: mfae alone might be a flash chip , i do remember seeing a few of them - and in sot 8 to boot. can't find anything about a10 though.edit ; might be an unobtainable from a FST Foster Group , Un-Hung-Lo chinese forge. No datasheet , no pinout nothing.
Thermistor 137103B Data or suitable substitute? - Page 1
Forum section: electronics / repair

author: navzptc
author_rank: Contributor
timestamp: November 06, 2014, 12:44:50 pm
content: I am trying to fix my daughters food mixer which has a faulty thermistor located by the fan. This causes the motor to pulse when warm to cool the motor down - unfortunately it is faulty and causing the motor to pulse all the time.The markings on the 3 legged ic are 137103B, but I have been unable to track down any information on this device in order to obtain a replacement/substitute.Any information gratefully received.Andy
Samsung plasma power supply repair - Page 1
Forum section: electronics / repair

author: dans2530
author_rank: Newbie
timestamp: November 05, 2014, 03:11:16 am
content: Hi everyone,This is my first post and topic!I have a very weird problem with a samsung power supply, bn44-00222a, it works fine until you turn up the plasma cell brightness then it shuts the tv down. The vs voltage sags lower until, I'm assuming, some protection circuit cuts the power to the board.I have measured across the main caps and they read about 350v, far too low. I did some additional tests and found that the power factor controller (L4981A) wasn't producing an output to drive the mosfets. I replaced the IC, same deal. It is getting power as this was the first thing I checked (15v).I took out the L4981A sub board and powered it up from a bench power supply, and it produces a 90% duty cycle from its output. So it seems to work.If anyone has a schematic for this power supply it would help me immensely, I can't seem to find one, or if anyone can offer their opinion on where I should look that would help too as I'm out of ideas.I have been reading this forum for a while, so I know there is a lot of sharp people on here that will have a good idea how to fix this.I will upload pics as soon as my phone is charged, they are all on there.Best regards to everyone,Dan.

author: nukie
author_rank: Frequent Contributor
timestamp: November 05, 2014, 12:21:13 pm
content: Check the blue monolith caps for short. I have seen it twice now on Samsung plasma. If you have a thermal cam you will see it glowing nicely. I swap it with ceramic on both clients screens still working after two years.
HP3325A Function Generator - Page 1
Forum section: electronics / repair

author: Malcolm Raven
author_rank: Newbie
timestamp: November 03, 2014, 10:12:11 am
content: I have a HP3325A Function Generator in which the HP-IB (IEEE 488-1975) has recently stopped working properly. It no longer recognizes data characters received and issues Error 8. The Basic GPIB card and programme used have been working satisfactorily for several years and work OK with other instruments. The HP3325A works normally except for the HP-IB. Any ideas most welcome.Malcolm

author: KJDS
author_rank: Super Contributor
timestamp: November 03, 2014, 11:06:27 am
content: I would start looking at the obvious, is the connector ok, any cracked solder joints. Is the 5V rail in the vicinity as it should be?

author: c4757p
author_rank: Super Contributor
timestamp: November 03, 2014, 11:14:14 am
content: When you debug it, don't miss the optocouplers! Mine failed and took out the GPIB - not usually something you might normally suspect.

author: Malcolm Raven
author_rank: Newbie
timestamp: November 03, 2014, 12:35:36 pm
content: Thanks very much for the quick replies. I will try these immediately.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: November 04, 2014, 07:49:19 pm
content: The one I'm working on had a -hitload of problems. This is a very early 85th unit production, so A, and Rev B boards. Someone else had been working on this. They replaced the big 8000uF cap on the PS board but did not take the board out. Bad solder intermittent connection. The Fractional N 28 pin IC was overheating!!! Bummer! Unobtainium!BUT!!! checking the +15 revealed weak 15V with 500mV of 60 Hz ripple on it, BUT !!! INTERMITTENT! So I ASSumed the IC was bad, because disconnecting the +15 line removed the ripple, and load. WRONG!!! Turned out to be an intermittent +15 regulator on the chassis heatsink. Replaced it, and BAM! no overheating, no ripple.Found broken transistor leads on two TO-92's MPSH10, and MPSH81 comp pairs on the output amp. Bam! got rid of the bootup A-CAL Failure. No keyboard keys seem to work. Noticed key strobe signals without pushing any keys. Stuck key failures! Removed three, and there is still one more to go. Did get it to boot, self test, works fine, and passes all tests. Whew!Just need some new key switches. was it worth it? Not sure. But I sure did learn alot! Quite entertaining.
looking for Schematic of REK RK8511 Electronic Load (Manyuo M9711, BK8511) - Page 1
Forum section: electronics / repair

author: Xoneoo
author_rank: Newbie
timestamp: November 04, 2014, 04:03:28 pm
content: HelloI search for a Schematic of the Electronic Load REK RK 8511 it's similar to Maynuo M9711 , or BK 8511.My Problem with this Unit is, the shown voltage on the Display and on the PC-Software too is ~2V below the real Voltage without any load.But when I use the Rear Terminal the Voltage is only ~1V below and when I connect the Frontpanel und Packpanel Ground ( and switch to backpanel) the Voltage is right!Perhaps anyone can help me.I have checked the PCB and the Relay but I cant find any issue, I think a Schematic can help me very much.Thank You!
looking for farnell AP30-80 power supply diagrams - Page 1
Forum section: electronics / repair

author: Simon
author_rank: Unknown
timestamp: November 02, 2014, 01:07:13 pm
content: I have acquired my works old AP30-80 bench power supply that one fine day while i was using it decided to use a resistor as a candle wick when current demand went over a about 20A.I have found a manual for it with basic explanation of how it works and diagrams. I'm not sure if I have all of the diagrams, and the main power section has two shematics, one seems to be "conceptual" (for example it shows 1 switch mosfet instead of all 3) while the other has all of the parts. Then there is a diagram for the "control board" which is quite large and so has no come out well in the scan. Does anyone have a good quality copy of this diagram ? I can read most ofg it but much is almost unreadable.

author: Andy Watson
author_rank: Super Contributor
timestamp: November 02, 2014, 03:32:10 pm
content: A.k.a. HiTekPower, but that probably doesn't help much.

author: Simon
author_rank: Unknown
timestamp: November 02, 2014, 03:36:35 pm
content: Well the manual was produced by Wayne Kerr with mentions of Farnell on the chematics so I guess it was designed for farnell by someone else.

author: miguelvp
author_rank: Super Contributor
timestamp: November 02, 2014, 04:41:41 pm
content: This threadhttp://www.vintage-radio.net/forum/showthread.php?t=59046has a pdf that poster number three thinks the Farnell MP3080 is a variant of the AP3080 1kW power supply, so he attached the AP3080 pdfEdit: tried to attach it but it's over 1000KB

author: Simon
author_rank: Unknown
timestamp: November 02, 2014, 05:24:06 pm
content: That is the one i found, and yes i tried to attach it too for reference but hit the 1M limit. It has AP3080 on the manual and seems to closely reflect the unit i have.I have seen adverts and datasheets for more modern looking versions of this unit which in some case are nearly identical but I don't know if they are made the same inside.

author: Towger
author_rank: Super Contributor
timestamp: November 02, 2014, 05:30:34 pm
content: Would Toploser be able to lay his hands on a copy?

author: miguelvp
author_rank: Super Contributor
timestamp: November 02, 2014, 05:33:29 pm
content: In the operating instructions, the front panel reflects the same configuration, and all the diagrams at the end are Farnell's.But yeah, the control board and front panel diagram are less than perfect as in scan quality.

author: miguelvp
author_rank: Super Contributor
timestamp: November 02, 2014, 05:43:50 pm
content: Maybe someone can clean the diagram up. It's almost readable but not quite everywhere.Caution: very large in resolution

author: m100
author_rank: Regular Contributor
timestamp: November 02, 2014, 05:53:32 pm
content: Quote from: Simon on November 02, 2014, 03:36:35 pmFarnell Instruments was iirc acquired by APS, they do a repair service for their PSU'shttp://www.advanceproductservices.co.uk/index.html
Tektronix 2246 time trigger error - Page 1
Forum section: electronics / repair

author: viperrepair
author_rank: Newbie
timestamp: November 02, 2014, 01:43:38 am
content: Hello everyone. First Id like to say how impressed I was when cs.dk posted for help with his scope: EEVblog Electronics Community Forum » Electronics » Test Equipment » Tektronix 2246 - No beam!I also received a 2246 with no beam and seemed like it would never get one till I found this thread and found that my diode was broken as well!! Big thumbs up to all the people who contributed to his (now our) success!Alas, although I now have a trace the machine fails the 5us time test and consequently the trigger wont trigger this is the only thing the scope would do when it had no beam. I thought the diode would repair everything but the problem still exists. Sooo I was hoping you guys and girls could put your big fat brains together and help me diagnose this problem. Any ideas??
Need a replacement for this "Inrush current limiter"  - Page 1
Forum section: electronics / repair

author: K3mHtH
author_rank: Regular Contributor
timestamp: October 30, 2014, 02:48:44 am
content: Hey everyone,I'm repairing an amplifier and one of the components looks shot (picture attached). In the schematics, it is referred to only as an "INRUSH CURRENT LIMITER" with a value of "CL30". Digikey has part KC003L-ND that is an inrush current limiter with a manufacturer part number of "CL30" - all that sounds very good, but I don't know if that's just a coincidence.The component in the amp itself has "025 081" on it as the only markings. It seems that there are many inrush current limiters with different specs.. help!

author: HalfSpace
author_rank: Regular Contributor
timestamp: October 31, 2014, 12:55:32 am
content: Hi K3mHtH,This component may have failed due to fatigue or there could be another fault in the amp which caused it to fail. Can you post up the schematic of the amp and what the fault is with it?HalfSpace

author: Seekonk
author_rank: Super Contributor
timestamp: November 01, 2014, 06:57:47 pm
content: Don't you have a junk box? These are very non critical items. Sometimes I just replace them with a couple ohm resistor. Only critical use for them is in old CRT TVs where they operate the degaussing coil.

author: Smokey
author_rank: Super Contributor
timestamp: November 01, 2014, 07:13:33 pm
content: That is most likely an NTC resistor.http://www.ametherm.com/http://en.wikipedia.org/wiki/Inrush_current_limiterThe way it works is that is starts out at a high resistance when cold and that limits the current that can inrush into the caps behind it. Then as the current starts to flow, it heats up and the resistance lowers to some nominal value. When it's hot, it's essentially a dead short (short term repair hint). Where they are really important is when you have a lot of equipment that would all turn on at the same time and combined might trip a breaker or something. Another thing to watch out for is that you need to give it enough time to cool off when the equipment is off to let it return to the high resistance state to be effective. Fast cycling makes these useless.They typically have 4 main parameters.1) Cold resistance - Must be high enough to limit the current to acceptable levels.2) Hot resistance - Must be low enough to not get in the way of the circuit or overheat.3) Max Current4) Max voltageMatch those up as best you can with how you think the circuit is working and you should be good.

author: rob77
author_rank: Super Contributor
timestamp: November 01, 2014, 07:21:08 pm
content: yes it's just a NTC - take one from anything elseall SMPS have those at input (PC power-supplies...etc).

author: Smokey
author_rank: Super Contributor
timestamp: November 01, 2014, 08:10:51 pm
content: Quote from: rob77 on November 01, 2014, 07:21:08 pmJust make sure you don't take one from something lower current or lower voltage...The KC003L-ND noted was 8A continuous...
HDMI cable - are shield wires exchangable ? - Page 1
Forum section: electronics / repair

author: boo9
author_rank: Contributor
timestamp: October 31, 2014, 03:23:12 pm
content: A connector for HDMI cable broke (the cable comming out of a wall , no way to replace whole cable)I am going to cut off at broken connector and solder new cable with good connector.I rung up group of 3 wires in a common foil shield and the pins arewire1 - pin1 - TDMS Data2 +wire2 pin3 - TDMS Data2 -wire3 pin5 - TMDS Data1 Shield/Ground)according tohttp://en.wikipedia.org/wiki/HDMIand other sources, the wire3 in data2 group should be leading to pin2 "DMTS Data2 Shield/Ground", but it does lead to data1 shield/ground.Is this OK ?Are the shield/ground wires from each group (3 wire groups, there are 5 such groups, each shielded with separte foil shield) brought to same point at the device ?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 01, 2014, 02:48:52 pm
content: Quote from: boo9 on October 31, 2014, 03:23:12 pmCan you use the existing cable as a "fish" to pull in a new one?

author: boo9
author_rank: Contributor
timestamp: November 01, 2014, 05:18:46 pm
content: > Can you use the existing cable as a "fish" to pull in a new one?No, the cable is walled w/o any encasing pipe.

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 01, 2014, 05:22:30 pm
content: For practical purposes, it probably won't make any difference. All the grounds are likely joined together at the connector or very near the connector any way. It indicates rather sloppy manufacturing (where they don't distinguish between the several ground conductors). But, assuming it was working before, it should work again.

author: boo9
author_rank: Contributor
timestamp: November 01, 2014, 05:41:56 pm
content: I just rung up a new (different) cable (which is to replace the broken one) and I see same ping group scheme (1,3,5), (2,4,6) (7,9,11)Hmm....could HDMI WIKI be wrong ?

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 01, 2014, 06:50:30 pm
content: All of the HDMI pinout references I looked at (only the top half-dozen) agree with the info on Wikipedia.Perhaps you have discovered that it doesn't make much difference which ground is which.
Leroy scope - Page 1
Forum section: electronics / repair

author: kjn4685
author_rank: Regular Contributor
timestamp: November 03, 2014, 05:19:29 am
content: Dave I was watching our episode #401 Could it be you have a bridge a cross one of the pins

author: marshallh
author_rank: Unknown
timestamp: November 03, 2014, 04:35:11 pm
content: I think he's long since tossed that one.
MKS 919 Hot Cathode Ionization High Vacuum Sensor System   - Page 1
Forum section: electronics / repair

author: MFC
author_rank: Newbie
timestamp: October 27, 2014, 05:52:33 pm
content: I have a MKS 919 Hot Cathode Ionization High Vacuum Sensor System that needs to be calibrated, but I cannot find any Service Manual or a Calibration Procedure online.someone has the service manual or knows where to find it?Thanks for any help.

author: Cyberdragon
author_rank: Super Contributor
timestamp: October 29, 2014, 03:05:05 pm
content: http://www.mksinst.com/Docs/R/919man.pdf

author: MFC
author_rank: Newbie
timestamp: October 30, 2014, 08:19:21 am
content: Dear Cyberdragon,Quote from: Cyberdragon on October 29, 2014, 03:05:05 pmthanks for the reply, but this is the operation manual, not the Service manual which I need...
Tektronix 2445B No Readout Display - Page 1
Forum section: electronics / repair

author: tec5c
author_rank: Frequent Contributor
timestamp: October 25, 2014, 02:35:28 pm
content: Hi all,I recently got given a Tek 2445B with the fault description "No display" I ran it thinking that it meant no display at all and it was displaying the traces fine. I then tried to turn on the readouts and haven't been able to get them up.Is there anyone here with knowledge of this bit of gear that has seen this fault before or would know of some places to check? I'm hoping it's not a discontinued IC at fault here...Thanks in advance.

author: HalfSpace
author_rank: Regular Contributor
timestamp: October 31, 2014, 01:25:52 am
content: Hi tec5c,Do you have a manual for the 2445? If not here is a link to download one.http://bama.edebris.com/manuals/tek/2445/Does it have the readout PCB still in it? The readout PCB diagram is on page 238/239 of the manual.HalfSpace
UT136 multimeter - Page 1
Forum section: electronics / repair

author: guruji
author_rank: Newbie
timestamp: October 27, 2014, 08:21:46 pm
content: Hi Guys I have a UT136 multimeter and when I tried it's frequency option showed no readings.Is there a way to fix this? Can I hook up this frequency meter to the 240v ac mains to check frequency and check if this meter works?Thanks

author: Shock
author_rank: Super Contributor
timestamp: October 28, 2014, 06:22:30 am
content: If you don't have a signal generator, you can generate a 1KHz tone on a PC (google it) and measure it at the back of a speaker. The signal needs to be greater than 600mV rms and lower than 10V rms.Make sure you have leads in the correct hole and are on the correct setting.

author: retiredcaps
author_rank: Super Contributor
timestamp: October 28, 2014, 06:32:34 am
content: Quote from: guruji on October 27, 2014, 08:21:46 pmUT136 manual saysNever input higher than 10V rms for test frequency and duty cycle.

author: guruji
author_rank: Newbie
timestamp: October 28, 2014, 06:44:53 pm
content: Hi guys thanks for response. Today I downloaded a freq generator on my android but still nothing on my meter.I think it has a fault. Is there a technician here? maybe I try to fix the circuit boardThanks

author: Shock
author_rank: Super Contributor
timestamp: October 29, 2014, 03:12:56 am
content: Did you measure the signal voltage on the AC setting?

author: guruji
author_rank: Newbie
timestamp: October 29, 2014, 09:02:35 pm
content: Hi Shock yes the signal on AC setting is working ok.
Tyco QS862A Rectifier - Page 1
Forum section: electronics / repair

author: dogcatdog
author_rank: Newbie
timestamp: October 29, 2014, 05:19:04 pm
content: anyone have a service manual for the Tyco QS862A rectifier made for the telcom industries or familiar with trouble shooting it? It's suppose to be a 48V 30A DC rectifier. I got it cheap off ebay trying to convert it to be a power supply, when I plug it in the alarm light continuously flashes. ...... The AC to DC supply part produces 6 leads of 160V each, the two 12V cooling fan runs when unit is plug in, the big capacitors at the PFC and converter units have 400V DC?? But stops at a transformer.
Just fixed backlight problem on MacBooc 5.2, documented. - Page 1
Forum section: electronics / repair

author: Teljemo
author_rank: Contributor
timestamp: October 23, 2014, 06:45:57 pm
content: Hi people =)I just need to share this in here.If someone else got this problem with there old mac.I talked about it a little in another post.https://www.eevblog.com/forum/chat/new-to-macbook-help-me/15/But here it is in total.Would love some feedback on how you understand that this clip is just a part of the guide on the site and not the guide itself.. cause that would be a very bad guide.. its more of the diagnostics of the puter.. but people need to click links in the descriptions to go to the site.. and I hope that is made clear from the clip where I added som text to tell them that..And here is the complete guide:http://www.workshopprojects.net/macbook-5-2-backlight-fix/First time i opened a mac.. first mac i own.. so I had to open it right..Don't turn it on.. Take it apart

author: wraper
author_rank: Unknown
timestamp: October 23, 2014, 07:56:45 pm
content: That CG robotic arm just drive me nuts. Too much of it for so short video.

author: Teljemo
author_rank: Contributor
timestamp: October 24, 2014, 07:52:15 am
content: I'm working on new graphics..Some friends told me that too.. the in between clip was just to short too..So your comment made the difference!!.. the robot is gone by the next clip!!!Thx for the feedback.. im all new to the video editing world so I really appreciate all feedback I can get!
Displays for Agilent ESGs ??? - Page 1
Forum section: electronics / repair

author: Co6aka
author_rank: Unknown
timestamp: October 21, 2014, 11:25:31 pm
content: Anyone know of a decent replacement for the display in the Agilent ESG signal generators; E44xx-series?

author: Mr. OBrien
author_rank: Contributor
timestamp: October 24, 2014, 05:47:45 am
content: You may have already found this but here.eBay auction: #280732547492

author: picburner
author_rank: Frequent Contributor
timestamp: October 24, 2014, 06:52:17 am
content: This one costs half and it is new:http://www.ebay.com/itm/DMF-51043NFU-FW-1-CBL51043-LCD-PANEL-/170640244444
Tuning a PS23023 power supply - Page 1
Forum section: electronics / repair

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: October 15, 2014, 09:08:50 am
content: Dear All,On my power supply PS23023, the tracking is slightly off, as well as the max valuesfor the two channels. It seems to need a little bit of tuning.On the boards (master and slave), there are three pots described also on the schematics :https://www.velleman.eu/downloads/2/ps23023gbnlfresd.pdfRP1 : 4.7 kohmsRP2 : 220 ohmsRP9 : 10 kohmsCan anyone tell mewhat are the functions of these 3 pots. Which one will tune the max V, min V, and tracking balance ?ThanksJacques

author: Kevin.D
author_rank: Frequent Contributor
timestamp: October 15, 2014, 02:26:03 pm
content: Hi .Rp2 will adjust your max Voltage range .RP1 will adjust your max Current range .Rp9 adjust's your input offset Voltage of the CurrentError amplifier . (so you'd use it to allow current set to 0) .None of these will make any difference to your tracking balancein series mode (which doesn't really have to be ultra precise ) .The precision of this is set by R100,R101 (fixed 47k voltge divider).The centre of these two should be exactly (chan A+B)/2 when both channels are in series.(these two simply divide the voltage of the combined channels in seriesand feed it to 2N1 opamp via your two mode switches) .If it has slight offset one resistor could have drifted out of spec.If these are ok then your probably got a bad connection through one of the2 mode switches contacts (check to see if voltage drop between R100/R200 junction and OP 2n1 inv input .(note :- I think this should actually go to the non inv input and there is a mistake on this schematic you linked , it show's the slave channel opamp inputs reversed but they should be as in the master channel I would think) .

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: October 15, 2014, 03:15:53 pm
content: Hi Kevin,Your answer is really great ! Thanks a lot.I have searched extensively on the net and was not able to find any information on this.(note :- I think this should actually go to the non inv input and there is a mistake on this schematic you linked , it show's the slave channel opamp inputs reversed but they should be as in the master channel I would think) .You are most probably right here. I had the same thought, and actually checked the connections on the two boards. They are exactly the same. So the slave board opamp have the same connections as the master, and the schematic is wrong.I have not the power supply on hand here, but will test what you suggest in two weeks when I will go back to the house where is my electronics workshop.Thanks again,Jacques

author: pegase1985
author_rank: Newbie
timestamp: October 22, 2014, 04:37:41 pm
content: hi,I got the same dual power supply and one of these relays is whisling (K2) on the left electronic card when i'm increasing the voltage (between ~ 12.2V and 15.8v ....)do you have any ideas ?i'm a newbie in electronicsMany thanks
Nanking MF47 - Cannot adjust needle to zero (Solved) - Page 1
Forum section: electronics / repair

author: neutrino
author_rank: Newbie
timestamp: October 16, 2014, 12:06:23 pm
content: This is a old analog meter with no pcb, it belonged to my grandpa. The components are wired and mounted on a transparent orange plastic kinda board.I noticed that the readings aren't accurate and that I cannot adjust needle to zero by turning the panel center pin screw, doesn't reach zero mark. Disassembling the panel shows the end of the center pin screw is a little scratched from wear.How can I solve the adjustment problem ? Can I adjust manually, without the center pin?What about increasing the thickness of the pin ?

author: PA0PBZ
author_rank: Super Contributor
timestamp: October 16, 2014, 12:23:43 pm
content: As far as I remember you set the needle position rotating the U shaped piece of metal below the center. The other side of the spring that is connected to the needle is connected to this. However, yours might be different of course.

author: G7PSK
author_rank: Super Contributor
timestamp: October 16, 2014, 05:46:54 pm
content: Check the adjuster forks are astride the hair spring still, I have seen many cases where the meter has been knocked or dropped and this caused the hair spring to come out of the fork.

author: neutrino
author_rank: Newbie
timestamp: October 17, 2014, 09:34:43 am
content: Solved by rotating the U shaped piece of metal to the left.Putting back the panel together was hard, the center adjustment screw pin barely fit inside the U.