hybridfree/eevblog-posts huggingface dataset:
What is this capacitor? - Page 1
Forum section: electronics / repair

author: ezalys
author_rank: Frequent Contributor
timestamp: April 27, 2018, 08:31:30 pm
content: I’m looking here at a capacitor from an older HealthKit oscilloscope. Would someone be able to explain what these markings are, and what the terminals correspond to? There seem to be multiple terminals on the bottom, not connected to the chassis of the cap, which are identified with different symbols. What’s going on here?Sent from my iPhone using Tapatalk

author: mbless
author_rank: Regular Contributor
timestamp: April 27, 2018, 08:45:54 pm
content: Looks like an electrolytic capacitor with multiple capacitors inside the can. I just happened to watchMr Carlson's Labthat used one. Watch the link for an explanation.

author: tautech
author_rank: Super Contributor
timestamp: April 28, 2018, 12:47:09 am
content: Yep just as mbless says.The symbols shown alongside the marked values indicate the pins to which those values apply and are stamped on the pins underneath.They're polarized and share a common negative.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 28, 2018, 01:47:50 pm
content: Also, you may wish to consult the schematic -- should be easy to find, Heathkit stuff is well documented -- which will show what that capacitor is and how it's connected.Tim
Agilent DSO1012a not turning on [Solved] - Page 1
Forum section: electronics / repair

author: OmegaHyperion
author_rank: Contributor
timestamp: April 26, 2018, 10:51:43 pm
content: Hello,So i got a Agilent DSO1012a in non working condition (it dose not turn on), i don't know why exactly, or how it ended up in this state. Before i take it to bit and start the troubleshooting, i decided to ask, has anyone encountered this on this or a similar agilent scope before, if so, how was it fixed?Some help would be appreciated!(the service manual would go a long way as well, if anyone happens to have a copy)

author: nfmax
author_rank: Super Contributor
timestamp: April 27, 2018, 04:10:31 pm
content: I had a similar issue with my DSO1014AThis may help:https://www.eevblog.com/forum/repair/only-just-out-of-warranty-agilent-dso1014a/msg793986/#msg793986Max

author: OmegaHyperion
author_rank: Contributor
timestamp: April 27, 2018, 07:57:27 pm
content: Good news, it works now. Not quite the same problem as in the linked forum topic. After checking every component of the power supply, i found it was working properly now (it didn't when i started) i could not find any faulty components in the power supply board.What i also did was the clean the membrane button board surfaces (a residue had built up there), after a quick fright that i may have busted the screen flat flex connector, i put it back together, and it started working all of a sudden.Its odd what a little bit of an unknown substance (i lack the means to analyze it at this time), can do to a scope like this.Now lets hope it keep working for the forseeable future.

author: Peabody
author_rank: Super Contributor
timestamp: April 27, 2018, 08:14:49 pm
content: Glad you got it working. Can we have a review?

author: nfmax
author_rank: Super Contributor
timestamp: April 27, 2018, 08:15:00 pm
content: I'm glad you got it working! They aren't bad little scopes, though rather dated now.
Tektronix TDS694C triggering chips mystery solved?  - Page 1
Forum section: electronics / repair

author: flyte
author_rank: Regular Contributor
timestamp: April 27, 2018, 07:21:19 pm
content: Hi all,I'm currently working on a TDS694C repair.It is a well known fact this scope has its trigger chips burnt out, sooner or later. Now, about everywhere you read that you can swap two of the ACQ board's chips by the defective ones, and it indeed works again. Supposedly Tektronix included "free spare chips" on the board.Because of the repair job, I've been analyzing the triggering circuits and my prediction would be that is a false statement.The trigger input signals are being fed into the 44-pin PLCC ASICs. There are two of them and each one has two direct connections from the input ASICs. So one chip is CH1/CH2, the other one is CH3/CH4. The PLCC ASICs are the level comparators in my understanding.Both PLCC ASICs have two outputs. Next, the 4 signals, in differential setup so 2 lines per signal, are fed into GaAs SPDT switches made by M/A COM. Then they pass through the infamous "burner" chips, and then again through a series of SPDT switches. This stage seems to be some kind of signal conditioning/amplifying part. So the "burner" chips must be some kind of (controllable?) amplifiers. This corresponds to the setup and the pads layout, clearly with lots of power connections.After the last stage you get 4 differential signals which are fed into the main logic ASIC (big one in the front).In the usual trigger mode, each of the PLCC ASICs switches between either CH1/CH2 or CH3/CH4, depending on what you select, and then obviously always feeds the selected channel into the same amplifier stage lines. Otherwise it could never work with only two of those "burner" chips.Great if you only use that. But one of the triggering modes in the TDS694C is called logic triggering combining logic state of up tofour channels.And here my hypothesis comes: a logic trigger based on four channels will no longer work as expected on units which had the two "spares" removed.Now, as I'm not really willing to remove these chips just for testing my hypothesis, it would be great if someone with such a unit could test this. Then we all know it works but there may be a trade-off, and Tektronix didn't include free spare chips.Greetz to all,flyte
Late 70s / early 80s Philips Test Gear Bezel / Cover Replacement - Page 1
Forum section: electronics / repair

author: ch_scr
author_rank: Frequent Contributor
timestamp: April 27, 2018, 06:35:17 pm
content: The late 70s / early 80s Philips Benchtop Test Gear like PE1539 Series, PM6620 Series, PM2527, PM6670 Series etc. all share similar construction, I like to think of as "soft shell, hard core". Soft aluminium top and bottom cover, metalized plastic front and back bezel. The rest is pretty sturdy. I ended up with two Units with missing bezel / cover, that obviously had a harsh life. Have seen more on Ebay with busted Bezel. I would like to publish my 3d design files, so you can give your Units a second life. Maybe you have similar stuff to post below? I had both bezel sizes printed for my units, they look and fit great, see below.
need help identifying SMT Resistor - Page 1
Forum section: electronics / repair

author: Tony_G
author_rank: Super Contributor
timestamp: April 27, 2018, 05:07:17 pm
content: Hey All,I'm trying to find this resistor (the 20 ohm one towards the right end of the connector):The pad seems to be an 1812 imperial 4532 metric and the resistor measures roughly 2.5 x 3.3 x 2.5mm and needs to dissipate as close to 2W as I can get.I can't seem to find something that either fits the size or the power.Any suggestions? I know I can double up 2 x 40 ohm 1W ones but I was hoping to get the same component.Thanks,TonyG

author: Tony_G
author_rank: Super Contributor
timestamp: April 27, 2018, 05:09:59 pm
content: BTW They don't show up in the parametric search at DigiKey or Mouser so I suspect that I have somethign wrong (ie size code, wattage etc).Again any tips appreciated.TonyG

author: eb4fbz
author_rank: Regular Contributor
timestamp: April 28, 2018, 11:20:11 am
content: That could be a ferrite bead.

author: wraper
author_rank: Unknown
timestamp: April 28, 2018, 01:39:41 pm
content: I doubt it has 20 Ohm resistance and doubt it's a resistor. Why do you want to replace it? Does it measure open/short? BTW there is corrosion in between of connector pins.

author: DaJMasta
author_rank: Super Contributor
timestamp: April 28, 2018, 06:38:14 pm
content: Quote from: eb4fbz on April 28, 2018, 11:20:11 amOr even a 20uH inductor, both with the same intent of filtering the input. That said, 20uH in that package size probably has a bit of DCR... so I wouldn't really expect that value on a high current rail.

author: Tony_G
author_rank: Super Contributor
timestamp: April 28, 2018, 11:40:54 pm
content: Damn - Didn't even think that it would be an inductor but the cap next to it does call out that it is an LC Filter (the cap is connected to Gnd and the inductor to +12V). 1A rating on the input so I can find 20nH inductors on DigiKey rated 2.2A with a DCR of less than 50 mOhm.These are CCFL inverters where it seems that those inductors went open circuit.Thanks for the help.TonyG
Need help finding a buck converter - Page 1
Forum section: electronics / repair

author: german77
author_rank: Regular Contributor
timestamp: April 26, 2018, 03:45:17 pm
content: I have a lot a devices that fail with voltage spikes. Each time the same component burns and I would like to fix them. The real problem is finding the name of the component, as I only know that the package is probably a sot457 , has written the numbers 209 and it's in a buck converter configuration.The voltage input it's rated at 9v, 0.6A. The output voltage could be 5v or 3.3v. I tried finding the component in digikey and Mouser but had no luck finding the same pin out.If anyone know a better way to find smd components or know a buck converter with the same pin out even if the package it's a little bit bigger or smaller I would be very happy.

author: madires
author_rank: Super Contributor
timestamp: April 26, 2018, 04:08:00 pm
content: I'd guess it's a TPS562209.

author: german77
author_rank: Regular Contributor
timestamp: April 26, 2018, 04:45:04 pm
content: Wow I'm impressed. Just by curiosity how did you find this component so fast? It's so sad that they are out stock, I guess my search continues, thanks any way now that I have a reference it will be much easier.

author: madires
author_rank: Super Contributor
timestamp: April 26, 2018, 05:21:18 pm
content: Basic google-fu.I searched for "smd code 209 buck converter".

author: SaabFAN
author_rank: Frequent Contributor
timestamp: April 27, 2018, 12:14:09 am
content: Check the portfolio of Linear Technology (now Analog Devices) for Chips with the same pinout.You should also get a outlet-strip with spike-protection to prevent that kind of damage in the future (if the spikes come from the mains)

author: german77
author_rank: Regular Contributor
timestamp: April 27, 2018, 12:30:46 am
content: Quote from: madires on April 26, 2018, 05:21:18 pmHahaha. That was my first try, but I din't put "code" the results are totally different .Quote from: SaabFAN on April 27, 2018, 12:14:09 amThanks I will take a look on it. These devices are for customers, who were told to put spike-protection but they din't, like always.
AIM-TTi EX354t (Rev 1?) pictures? - Page 1
Forum section: electronics / repair

author: staze
author_rank: Frequent Contributor
timestamp: April 26, 2018, 01:35:58 am
content: Hi All,I've got a busted EX354t that's not working, but the schematics and board layout provided by TTi seem to be wrong. Most obvious issue being the board layout shows two bulk caps, where the board only has one (the schematic only seems to show one as well).Anyone have one of these units and care to post a picture of the board? The main board for mine shows board model 1460, but the service manual seems to indicate it should be 1540.One of my main concerns at this point is the power switch wire connection order. When I got it, it seemed to be wrong. I think I've fixed that, but I'm not entirely sure.Also suspicious is the main SMPS section that drives the rest. It seems to be largely based on a 7555, and then a the regulated power supply derived from some zeners and an LM393. But the location of these zeners on the board does not match the layout, and I am not sure I can trust the schematic. =/The unit does not power up. The LM393 gets ~12V, but the 7555 is getting less than a volt. I assume this is a failure in the VREG section, but it's super hard to troubleshoot when TTi placed the component markings UNDER the components (so the resister/diode covers it's designator).So, pictures would be a great start. Attached are the schematic and the incorrect layout. =/ I'm suspecting either the 79C36 or 79C18 is bad... but I'm not super positive.Thanks!
HP 6115A going CC over 72V - Page 1
Forum section: electronics / repair

author: LazyJack
author_rank: Frequent Contributor
timestamp: April 24, 2018, 06:56:18 am
content: Hi,I just got a very nice HP6115A power supply for cheap, as it was blowing fuses. That was quickly traced back to a shorted rectifier and sorted out.However, an other problem persists, the supply works nice up to 72V, over that it goes to CC mode, independent of the setting of the current limit.I'm sure it's going to be possible to fix it, once I dig deeper into the unit (which is a paint to remove the main board), but maybe someone has already experienced similar problems and could give some pointers.Thanks.

author: BravoV
author_rank: Super Contributor
timestamp: April 24, 2018, 07:40:56 am
content: Just fyi, I made a "stiched & colored"schematic in single page for this PS, you can get it from ->HERE, beware, its huge image.Hope this helps in troubleshooting.

author: LazyJack
author_rank: Frequent Contributor
timestamp: April 24, 2018, 07:47:11 am
content: Wow, thanks! This helps a lot. This is a great piece of work.

author: alm
author_rank: Super Contributor
timestamp: April 24, 2018, 08:44:24 pm
content: First place I'd suspect would be the overvoltage crowbar circuit. Either it is adjusted to 72V, or due to a defect it does not go beyond 72V.

author: LazyJack
author_rank: Frequent Contributor
timestamp: April 25, 2018, 03:46:26 pm
content: That is unlikely, the crowbar once triggered stays on until power is removed and the output is clamped to 0. Here, the output stays at 72V, but changes to CC mode. Once the voltage is lowered, normal operation is restored.I'll dig into deeper today.

author: LazyJack
author_rank: Frequent Contributor
timestamp: April 25, 2018, 09:51:38 pm
content: All right. So fixed it.I did have a suspicion that the gross current limit circuit may be faulty, which later turned out to be true.However, i first went ahead to localize what is going on, why why it goes into CC mode. Turned out that it was not the constant current circuit, but the voltage regulator, that went out of regulation, which also results in lighting the CC LED.The reason it went out of regulation, because its input voltage wouldn't go above 70 something volts. The way this power supply works is it has 2 sets of winding, rectifier and capacitor, both giving around 75 volts. They are in series, but if the load is high, the gross current circuit disconnects one, throttling back the voltage and the dissipation.Now, this always happened, only one was used, therefore the regulator never had input over 75 volts. This was not immediately evident, as simply measuring the voltage at the filter capacitors showed the correct value.Once I found this, it was easy to locate the problem, a shorted VR2, a6.24.2V Zener. Replaced and it works very well, voltages are spot on. Not bad, that I only paid 30 bucks for the "for parts" unit.
DSO150 Rotary Encoder. - Page 1
Forum section: electronics / repair

author: SirAlucard
author_rank: Regular Contributor
timestamp: April 22, 2018, 05:11:19 pm
content: Hey all, does anyone happen to know the identity of the Rotary Encoder used for the DSO150 Shell? I've been searching around and even on the JYE Tech Website but can't seem to find the actual part number for it. Other than buying a new encoder and mount from them, I'm trying to find a decent quality one and can't seem to find a proper replacement.

author: Peabody
author_rank: Super Contributor
timestamp: April 22, 2018, 06:55:32 pm
content: I believe it's similar to the Alps EC11 and the Bourns PEC11L series, both I believe available from Mouser. It's 15 pulses per revolution, and 30 detents per revolution. But I never found one that didn't have a shaft that was way too long. I'm sure the JYE encoder is a no-name item. There isn't a mark on it.But before you spend money on a replacement, you may want to try taking yours apart and cleaning it. That's what I did, and it works fine now. No guarantees of course, but you can bend up the four little tabs holding the metal plate to the green plastic, and it comes apart. In addition to cleaning it, I bent the contact arms up just a little so they would press against the disk a bit more forcefully.Mine behaved very erratically, but now works fine. I never did see what was causing the problem, but the process worked. You have little to lose trying this. You can always order a new one from JYE, or order the PEC11L from Mouser and cut off the shaft. But I suspect you can make the existing one work fine. The hardest part is desoldering it from the Shell, but you'll have to do that at some point anyway.

author: Peabody
author_rank: Super Contributor
timestamp: April 22, 2018, 09:59:44 pm
content: However, this one looks like a match:https://www.ebay.com/itm/401475259389But I don't see a US source for it.

author: SirAlucard
author_rank: Regular Contributor
timestamp: April 22, 2018, 10:01:50 pm
content: I did take mine apart, and one of the pins are misaligned. I was able to get it from just not working, to only slightly working. I really don't have enough knowledge on it to be able to realign it properly. It ended up melting out of place when I went to desolder it out and swap it around for a battery mod.

author: SirAlucard
author_rank: Regular Contributor
timestamp: April 22, 2018, 10:08:46 pm
content: Quote from: Peabody on April 22, 2018, 09:59:44 pmFor $5.60 it'd be cheaper just getting a replacement board and encoder.

author: SirAlucard
author_rank: Regular Contributor
timestamp: May 03, 2018, 06:24:50 pm
content: So I ended up contacting JYETech and wow for such a cheap device they have amazing customer service. The person that I was in contact with was quick in helping me and he'll be sending me a new one free of charge. I wish some companies gave this kind of support.
Tektronix T922 calibration - Page 1
Forum section: electronics / repair

author: Zeyneb
author_rank: Regular Contributor
timestamp: April 25, 2018, 03:52:51 pm
content: Dear people,I'm having a Tektronix T922 scope and the trace rotation potentiometer was falling apart so I was able to replace that one. It's nice to solder on such an older (through hole) technology board. Actually I took the Y-axis potentiometer off, also 2K, and soldered that into the trace rotation position. For the Y-axis function I installed a new multi-turn potentiometer because these pins where 0.1" pitch in a single line.I successfully managed to put the crt & vertical amplifier board back together. And applied mains power to the scope. Now the trace rotation can be set properly but the problem I'm facing is to understand the terminology in the service manual regarding the Y-axis alignment calibration.Here is the link for that service manual:www.logwell.com/tech/oscilloscopes/t921_922_sm.pdfNow I'm on page 52 of that with the paragraph title "4. Y-Axis Alignment"For now I just have a basic function generator set to some 5 kHz square wave. I also need to install some 50 ohm terminator resistor to do this properly.If I turn on the Y-axis potentiometer I see a feature similar to the vertical position knob on the front panel. Is that what it is supposed to do?From the instructions in the manual I don't understand the terms baseline and marker.In particular the steps e and f are problematic to me:"e. ADJUST-Y-Axis, R474, (see Fig. 4-3) to align center marker with center vertical graticule line.f. INTERACTION-Position display baseline to center horizontal graticule line and check that baseline aligns with horizontal graticule line. If not, re-adjust trace rotation. Then re-check Y-axis alignment."I understand center vertical/horizontal graticule line. But what is "center marker" exactly?As I do not have a time-mark generator should I set the function generator to swing to a negative voltage during the low period of the square wave or should that be 0V?Thank you very much for your attention and time!Best regards,Zeyneb
Voltcraft DSO-1062 NAND K9F1G08U0D-SCB0 is malfunction - Page 1
Forum section: electronics / repair

author: kwalter
author_rank: Newbie
timestamp: April 24, 2018, 04:52:48 pm
content: Hello,on myVoltcraft DSO-1062D, theNAND K9F1G08U0D-SCB0is malfunction.Have him exchanged for a new K9F1G08U0D-SCB0.Now I need a manual like the firmware in the new Nand with OpenOCDcan flashing and of course the firmware file.Can someone help me there?Sorry for my bad English!Kind regardskwalter
Can anyone identify these connectors? - Page 1
Forum section: electronics / repair

author: urbis
author_rank: Unknown
timestamp: April 23, 2018, 09:30:31 pm
content: I've just bought a folding camper with a Sargent PSU2005 distribution board.The wiring is already there, but there's a couple of 12v fuses that aren't used and I'd like to wire them up.This is the "connector kit" which I already have, but I need to populate some other terminals on the 12 way connector.https://sargentltd.co.uk/shop/product/psu_2005_connecting_kit/178By the looks of things, it's the female pins that go into there (male on the PSU side).For reference, if it matters, the pin outs are below:http://www.swift-owners-club.com/support/oem-handbooks/sargent/PSU-2005-User-Instructions.pdfThanks!

author: coromonadalix
author_rank: Super Contributor
timestamp: April 23, 2018, 09:51:39 pm
content: it says on the web page JST - L series of connector you can easily find some reference

author: urbis
author_rank: Unknown
timestamp: April 24, 2018, 12:04:11 pm
content: I saw that, but struggling to find that exact one

author: drussell
author_rank: Super Contributor
timestamp: April 24, 2018, 12:39:09 pm
content: What physical size are they? You should be able to tell what series they are by carefully measuring the pin pitch, etc.Are they the same size as a PC ATX style power supply? I would think they would be much larger since that style is only good for about 5A per contact. I am assuming your application would need 15 or 20A capability on each contact of the connector.Perhaps they are something like the VL series, which are 6.2mm pitch and rated for 20A per contact?http://www.jst-mfg.com/product/pdf/eng/eVL1.pdf
Samsung 2433bw - Page 1
Forum section: electronics / repair

author: Charlie86
author_rank: Regular Contributor
timestamp: April 21, 2018, 01:37:03 pm
content: Hi,I am trying to repair LCD monitor Samsung 2433BW,Monitor works fine for lets say 1h then backlight goes of, usually if I turn it off and on again it works again. Sometimes it just flick backlight for second or two and then works well again.I was assuming bad caps so I replace all except big one 120microFarad 450V, but this one is for power not for backlight,.. Board is also a bit black because of overheating. Pics are in att. I am now assuming bad transformer inverter or transistor. Can some one please give me advice how to test for bad components. I have oscilloscope and multimeter bad not enough knowledge to test them.Thank you and have a nice day.

author: oldway
author_rank: Super Contributor
timestamp: April 21, 2018, 01:52:02 pm
content: QuoteReflow this region adding flux and new solder.

author: LateLesley
author_rank: Frequent Contributor
timestamp: April 21, 2018, 07:22:55 pm
content: could we get a picture of the underside of the board? I'm betting there's some circuitry underneath (probably a backlight controller and a couple of SMD FETs, along with a load of passives), which could be overheating. It might need a couple of new fets, i've had them burn up in monitors before. I usually replace them, and add some thermal pad to heatsink them to the chassis, to save them from dying again.

author: wraper
author_rank: Unknown
timestamp: April 21, 2018, 07:31:08 pm
content: Most likely not cause of the current issue but you used unsuitable capacitors. Samwha RD are general purpose series and will fail maximum in a few months of use. Check both secondary windings of CCLF transformer, they should measure around 1k and match closely. Also check blue capacitors connected to secondary windings of CCFL transformer. CCLF lamp may be going bad as well. Not that bad that it does not completely work but bad enough to cause protection eventually kicking in.

author: wraper
author_rank: Unknown
timestamp: April 21, 2018, 07:36:07 pm
content: QuoteJust don't connect them to secondary windings of CCFL transformar while monitor is switched on. High probability to destroy them due to 600V+ voltage. Also don't touch primary side of PSU with oscilloscope. Many people unaware that oscilloscope probe is grounded got expensive lesson.

author: wraper
author_rank: Unknown
timestamp: April 21, 2018, 07:42:08 pm
content: Quote from: oldway on April 21, 2018, 01:52:02 pmDangerous suggestion, especially for people who have hot air, as phenolic PCB will most likely popcorn if heated with hot air. One might look for cracked solder joints of through hole components and resolder anything suspicions. But suggestion of reflowing everything is not very wise.

author: Charlie86
author_rank: Regular Contributor
timestamp: April 22, 2018, 07:26:31 am
content: Hi,I currently do not have pic of other side of PCB because, I resolder cold joins of transformer and assembly it back in housing of monitor. For now monitor is working. I think "oldway" have a point hereThank you!
HP E3615A power supply OVP light wont go away - Page 1
Forum section: electronics / repair

author: CaTx
author_rank: Newbie
timestamp: April 19, 2018, 07:30:09 pm
content: Hi,My HP E3615A power supply has an OVP light that wont go away. Does anyone know what went wrong and how to fix it? Thanks.

author: MadTux
author_rank: Frequent Contributor
timestamp: April 19, 2018, 10:06:41 pm
content: Does clockwise turning the the OVP pot in the middle of the front panel solve the problem?

author: PedroDaGr8
author_rank: Super Contributor
timestamp: April 19, 2018, 10:17:39 pm
content: It might not just be the OVP light, if it is triggering the instant that the device powers on, then you need to look at the turn-on overshoot voltage control circuit as well. The service manual has a lot of good data and schematics, plus test points to observe and diagnose. Including a table of tests to perform and diagnosis to make from said test. Way better and easier than me going through it here.

author: CaTx
author_rank: Newbie
timestamp: April 19, 2018, 11:02:03 pm
content: Nope, turning the OVP Adjust wont help. I am new, so can someone give me pointer. Following the service manual now, but it seems like a maze.

author: CaTx
author_rank: Newbie
timestamp: April 19, 2018, 11:13:26 pm
content: R102 = 146.8 Ohms, in specsR103 = 1.4xx KOhms, and drifting even when powered downAm I close to catching the culprit? What is happening with R103?

author: CaTx
author_rank: Newbie
timestamp: April 19, 2018, 11:43:27 pm
content: Alright, following Table A-7.Short U19 pin 4 to TP6 --> OVP indicator OFF --> U20 defective or C57 shorted

author: PedroDaGr8
author_rank: Super Contributor
timestamp: April 20, 2018, 04:47:39 pm
content: Quote from: CaTx on April 19, 2018, 11:43:27 pmIf the indicator went off, that is good news. U20 is an LM393 comparator and C57 is a 50V 47uF electrolytic capacitor. BOTH of those are super cheap to the point that shipping will be WAY more expensive than the part.
ERSA Wave Solder 330-F Spray Fluxer issues - Page 1
Forum section: electronics / repair

author: CoreTechnology
author_rank: Newbie
timestamp: April 20, 2018, 02:33:37 pm
content: We purchased a ERSA Wave Solder 330-F machine recently "As Is", with NO warranty.Trying to get the machine started, we've ran into trouble with the Spray Fluxer ESF module. During the initial verification run, the spray fluxer would move 4 times to the center of tank, and then fault out. This also prevented us from moving past this error and test all other components of the machine.Initially we thought the problem could be the Light Barrier, as it counts the 32 notches on the track to determine position and speed. But after testing showed even without the barrier attached, the machine moved 4 times to center, and faulted the "Moving Error" during verification run. After checking all air lines, pressures, sensors, and everything in between I finally thought it had something to do with the programming.I then reset the control module inside the Fluxer to factory defaults, thus allowing the Wave Machine to then be started in Manual mode and all other functions tested. The machine works great other than the Fluxer.Question is: The ERSA ESF is now asking for configuration. These are exact messages:...Hello PLC...Waiting for Config.OPUS-12-S V4.07*Data Compare Err*01 02 06 15 FFFFI can't seem to figure out how to load any program or configuration file into the system. With the ERSA PC software or by keyboard on machine, you can set the Fluxer controls but it doesn't seem to bind with the Fluxer config.Again, we have no technical support or warranty for this machine. ANY help would be greatly appreciated... Even if it's just how to get a config loaded, and I can then program myself.ThanksShawnCore Technology, INC
Diodes on Yamaha Music keyboard query. - Page 1
Forum section: electronics / repair

author: geobee
author_rank: Contributor
timestamp: April 20, 2018, 09:00:11 am
content: Hi all, just wondering if anyone would know the purpose of the string of diodes, think they would be the old 1N914, on the key circuit strip. The diodes are off the carbon track switching pads. Any ideas would be great.

author: Moshly
author_rank: Regular Contributor
timestamp: April 20, 2018, 09:06:48 am
content: Look up N-Key rollover

author: capt bullshot
author_rank: Super Contributor
timestamp: April 20, 2018, 09:08:52 am
content: My guess:The diodes are used to decouple the key switches for a multiplexed scanner. If they weren't there, pressing multiple keys at the same time would short out some of the scanning lines and the keyboard scanner wouldn't work. Using the diodes enables the scanner to detect any number of simultanously pressed keys.

author: LateLesley
author_rank: Frequent Contributor
timestamp: April 20, 2018, 09:16:24 am
content: It'll be part of the keyboard matrix.There's an example halfway down this page -http://musicfromouterspace.com/analogsynth_new/OLDIESBUTGOODIES/CONTROLLERS/scanningmatrixkeyboard2.html

author: geobee
author_rank: Contributor
timestamp: April 20, 2018, 09:23:16 am
content: Many thanks to all, well explained. Looks like they are just performing a ''one way street'' from the keys.
Leslie 910 Solid State PS - Switching PNP? - Page 1
Forum section: electronics / repair

author: jdak907
author_rank: Contributor
timestamp: March 16, 2018, 06:47:55 am
content: Hello all,I need some help. I am working on a Leslie 910 rotating speaker cabinet which has a 70's era solid state amplifier in it.Q33 - a TZ-525 PNP transistor had the leads twisted off some how and I need to find a replacement. I've tried googling it many different ways and can't seem to find any reference to an equal.I am not sure but I believe this is used in a switching application. Can anyone help? See attached, sorry no schematic just a board layout available.Thanks,Jeff

author: coromonadalix
author_rank: Super Contributor
timestamp: March 17, 2018, 04:12:58 am
content: similar modelhttp://www.organplus.com/technique/leslie/lesli%20925sm.pdfI would try any pnp transistor at 100v 1 amp currentlike : 2N2904 2N2904A 2N2905 2N2905A in to39 casing with an small heatsink toobut yours is an to92 casing with an small heatsink on itlike an 2n3906 or bc557 at 200ma but it maybe not enough in currentan 2N2907 would be more powerful at 600ma ...

author: Rog520
author_rank: Regular Contributor
timestamp: March 17, 2018, 04:50:44 am
content: Check this place out. They have a PNP transistor with a part # 033571 listed:http://www.organservicecompany.com/parts.html

author: coromonadalix
author_rank: Super Contributor
timestamp: March 17, 2018, 04:54:10 am
content: hum not sure about this one, but it cost 5 box to try it

author: floobydust
author_rank: Super Contributor
timestamp: March 17, 2018, 04:55:46 am
content: I have that style of transistor, it's TO-92HS or a TO-92 with a flag heatsink good for 1W.I would put in a TO-220 part, it's closest.Q32 NPN 2N4425 40V 0.5A 0.9W hFE 180-540Q33 PNP Sprague TZ525It's a two-transistor limiter circuit, controlled from the console Rev/Aux switch P1-4 and Q33/Q32 turn on the LDR light bulb M1 to limit volume.I would use:TIP41C, TIP42C100V 6A 2W hFE=100. hFE is lower but the circuit has feedback to accommodate.TO-126 parts are OK too likeBD140/BD139I could not find specs on the driven light bulb, it seems to get up to 15V off the 33V rail, and is mated with assembly LDR 030379 on the crossover board.

author: jdak907
author_rank: Contributor
timestamp: April 16, 2018, 09:29:32 pm
content: Quote from: floobydust on March 17, 2018, 04:55:46 amHey thanks a bunch! I used the TIP42C and it seems to be working. I do have some crackling at higher volumes but still need to clean pots and verify passive component health.Jeff

author: floobydust
author_rank: Super Contributor
timestamp: April 19, 2018, 10:27:08 pm
content: That board looks very goodI repaired two Leslies, buzzing speaker- was dead bugs (moth) fell in the horn, landing on the driver diaphragm and the second had metal shavings in the driver magnet-gap.Pulled the voice coil out and used masking tape to clean up the metal chips, they stick to the tape. Have to use plastic sticks.
Keithley 2001 - Floating DC - Page 1
Forum section: electronics / repair

author: dhillman
author_rank: Contributor
timestamp: April 19, 2018, 09:23:33 pm
content: I recently acquired an older 2001 and have noticed something odd with DC Volts with no connection. The displayed voltage will float up to roughly +/-2 Volts. When connected to a source or shorted, the meter reads correctly. Is this an oddity of these?Background- all electrolytics have been replaced, and the board cleaned around them. There was no sign of prior leakage thankfully.Diagnostic tests pass repeatably.Possibly related, or due to old calibration is that the AC self calibrated will fail with +415 error. I do not know why this is not caught in the diagnostic test.

author: David Hess
author_rank: Super Contributor
timestamp: April 19, 2018, 10:08:57 pm
content: On the low DC voltage ranges (200mV, 2V, and 20V), no high input impedance divider is used and there is no 10 megohm input shunt so the input leakage current charges whatever input capacitance is available until the leakage cancels out. This occurs with any DC voltmeter when a high, >10 gigaohms in this case, input resistance is used and it is completely normal.On some meters but apparently not the 2001, the input resistance on the low input voltage ranges can be selected between 10 megohms and "infinite". This can be important for measurement consistency or if you are using an external divider which is expecting a 10 megohm input resistance.
Agilent 8560E Repair - Page 1
Forum section: electronics / repair

author: NHnewbie
author_rank: Contributor
timestamp: May 02, 2018, 07:24:47 pm
content: I recently acquired a used Agilent 8560E in very good condition. It works as described in the initial checkout section of the user manual. I do see one possible issue, however. The alphanumeric characters on the screen vary in brightness, to the extent that some lines in a single character are brighter than others. Perfectly readable, but probably not supposed to look like this. Because this occurs at many positions on the screen, it doesnt seem to be a CRT issue, but maybe something in the character generator. Any suggestions as to where to begin looking?

author: SaabFAN
author_rank: Frequent Contributor
timestamp: May 02, 2018, 08:48:53 pm
content: Without looking at the service manual, I'd say there's a problem with the Video-RAM. It's losing the "bright/dark"-information.Probably an SRAM-Chip that's gone bad.Is the problem constant with temperature? Are the bright areas moving when the picture changes?Another source of the problem could be one of the ROMs. If the device was build in the early 90s, they have reached their specified data-retention time. If they are socketed and you can find a firmware (preferably a newer one), rewrite the ROMs and see if the problem goes away.If that doesn't help, the video subsystem is your next area to check.Edit: It also could be something as simple as a cracked solder-joint on one of the SRAM-Pins that just barely transmits AC. Apply slight pressure to the processor-board or the RAM to see if the problem changes/goes away - That should be the first try.

author: NHnewbie
author_rank: Contributor
timestamp: May 02, 2018, 10:16:48 pm
content: Thanks, SaabFan,Will check all these possibilities out. No observed temp correlation.
Where to start with an HP 1720A oscope? - Page 1
Forum section: electronics / repair

author: orngnr
author_rank: Newbie
timestamp: April 18, 2018, 11:17:43 pm
content: I have an old HP 1720A oscilloscope. I'm not sure if my mind is going empty, but I can't get even a DC signal to show up on either channel. All I've got is a horizontal line that I can't get to move up or down, or change no matter what my inputs are. I don't think the unit is broken just yet, more likely I'm missing something simple about these older scopes. Any ideas?

author: edavid
author_rank: Super Contributor
timestamp: April 18, 2018, 11:26:15 pm
content: 1. Read the Tektronix tutorial "XYZs of Oscilloscopes":http://ecelabs.njit.edu/student_resources/XYZ-Scope.pdf2. If you still can't get it to display anything, post a clear picture of the front panel so we can see how all the controls are set.

author: orngnr
author_rank: Newbie
timestamp: April 19, 2018, 01:03:21 am
content: Thanks for the tutorial, helped me brush up on some topics I'd forgotten about. I'm able to get a signal displayed now, which is great.Now, it's sweeping really slowly. I think this is a characteristic of an analog scope I'm not used to. Do you know how I can speed up the sweep so that it can show the 10 Hz square wave reliably?Here's a video of what it's doing now.https://youtu.be/0xijk8Gf32A

author: edavid
author_rank: Super Contributor
timestamp: April 19, 2018, 01:21:42 am
content: 1. That is too low resolution to see how the controls are set2. You need to adjust the time/div knob3. It's going to be hard to view a 10Hz square wave on an analog scope... try 1kHz

author: vk6zgo
author_rank: Super Contributor
timestamp: April 19, 2018, 07:24:28 am
content: (1)It isn't triggered.(2)"Focus" is not set correctly.A reasonable analog Oscilloscope should be able to display 10Hz, but it would be easier to trigger at 1kHz.
Therm-App USB port & pad repair - Page 1
Forum section: electronics / repair

author: mwesleyroper
author_rank: Contributor
timestamp: April 18, 2018, 03:10:04 pm
content: The phone fell from its place in a VR box too many times resulting in the camera's USB port & pads detaching. The connection got progressively worse until it stopped functioning. I've contacted a few businesses which were ready to perform the repair up until they learned the port is for a thermal camera. I'm hoping someone here can take the job or point me in the right direction.Thanks,Mike
marking smd  - Page 1
Forum section: electronics / repair

author: lionelkjh
author_rank: Frequent Contributor
timestamp: April 18, 2018, 06:38:39 am
content: Hello everyone! I'm looking to identify this smd component, I think it's a diode. Its case is either SOD123 or SOD523. Marking: F25 (see attached photo). Can someone help me? Thank you very much!

author: Chriss
author_rank: Frequent Contributor
timestamp: April 18, 2018, 08:43:16 am
content: Hi!Yes it's a diode.Maybe an ultra fast recovery diode.Can you show the part of the circuit where this diode is?Sent from my GT-I8260 using Tapatalk

author: lionelkjh
author_rank: Frequent Contributor
timestamp: April 18, 2018, 10:53:21 am
content: Hello; the component is next to the varistors in blue. It is a FLUKE 83V.

author: Samogon
author_rank: Frequent Contributor
timestamp: April 18, 2018, 02:04:47 pm
content: Depends on package, check size25 EDZ12B Z-diode 11.74..12.24V, Izt=5.0mA, Zzt=30?, 150mWSOD-5236d 1a Rhm25 HMSZ5225B Z-diode 3V±5%, Izt=20mA, Zzt=29?, 225mWSOD-3235d 1d Hsn
Tek 2232 Should Signal Invert In Store Mode? - Page 1
Forum section: electronics / repair

author: Hornethandler
author_rank: Contributor
timestamp: April 05, 2018, 12:50:46 pm
content: I have a Tek 2232 that seems to be working fine; however, the signal inverts 180 degrees when switching from Non-Store to Store... is that normal?I didn’t see anything in the Adjustment Procedure or Performance Check Procedures that indicates the signal inverts when switching from Non-Store to Store.Thanks,

author: Testtech
author_rank: Regular Contributor
timestamp: April 05, 2018, 02:20:42 pm
content: One channel, or both? I think that the inverted channel has had the ribbon cable connection from the main board to the storage board reversed.It is also possible that the wrong A/D hybrid (the large plugin modules on the storage board) has been installed. There are two versions, that look identical, but are not, as the input polarity is swapped.

author: Hornethandler
author_rank: Contributor
timestamp: April 17, 2018, 04:24:43 pm
content: Thanks for your help.I believe I found the problem; it was finger trouble.While calibrating the scope I discovered a trigger position setting in the Acquisition Menu. While In Store Mode you can set (and save) the trigger position anywhere on the signal via the Acquisition Menu. It had been set to trigger on the negative going signal. I repositioned it to trigger at the beginning of the first positive going pulse and now the signal doesn't invert when switching to Store Mode.
repairs of HP 8594A spectrum analyser   - Page 1
Forum section: electronics / repair

author: kenramesh
author_rank: Contributor
timestamp: April 17, 2018, 09:13:49 am
content: hello all ,I have been facing problem with HP 8594A spectrum analyser.1.As the instrument is switched on , FREQ UNCAL is displayed which is a permanent fixture.2.When i try to calibrate using CAL OUT the result is SIGNAL NOT FOUND & SRQ110.3. The trace line is slow in movement , data entry response also appears to be slow.I couldn,t find service manual for 8594 series , but tried using 8590 series one.As per that manual either A7 analog pcb, A16 processor , counter lock , or YTO may be faulty but not able to zero-on by using this manual.I observed the following:1.on A7 analog interface board Q1 is getting warmbut if cable running to YTO removed from the PCB, heat is normal.2. FREQ UNCAL disappears & trace line moves fast when Counterlock board flat cable is removedwaiting for ur help Pls suggest how do proceed.Thanx in advanceLocked due to duplicate thread:https://www.eevblog.com/forum/repair/help-needed-to-repair-hp-spectrum-analyser/msg1494742/#msg1494742
Tektronix TLA704 1-Non-System disk or disk error 2-Operating System not found - Page 1
Forum section: electronics / repair

author: denimdragon
author_rank: Regular Contributor
timestamp: April 17, 2018, 03:05:29 am
content: I have a couple of Tek TLA704s that are showing these errors. I'm wondering if the one just needs the OS reinstalled and the other is a possibly a bad hard drive. I wanted to ask here first to see if anyone else has had these issues before I crack the cases open blindly.Also both displays are acting quirky. They have been sitting in a storage and I'm sure for how long. Maybe lose connections? Pics below.Thanks as always for the info

author: Samogon
author_rank: Frequent Contributor
timestamp: April 17, 2018, 03:22:07 am
content: First picture looks to me that it set to boot form floppy drive. Set it in BIOS to boot from drive 0. And definitely bios battery have to be replaced.Other pics just insult to post

author: denimdragon
author_rank: Regular Contributor
timestamp: April 17, 2018, 03:25:05 am
content: Quote from: Samogon on April 17, 2018, 03:22:07 amGood catch! Thanks for that."Other pics just insult to post", can you clarify please. I appreciate it.

author: Samogon
author_rank: Frequent Contributor
timestamp: April 17, 2018, 03:32:10 am
content: Hehe no offense,But they are not readable. Is it bad display?I could guess that second has bad drive doe to different post message.But third, who knows what there is written.

author: denimdragon
author_rank: Regular Contributor
timestamp: April 17, 2018, 04:19:39 am
content: Quote from: Samogon on April 17, 2018, 03:32:10 amAh... Yes the displays are bad as well. I'm seeing if I can use the VGA out to connect to an external monitor. I can't even read the BIOS very well right now. Also no offense taken
Copper Mesh Tube fell out of Digital Tek Scope - Page 1
Forum section: electronics / repair

author: dzarren
author_rank: Contributor
timestamp: April 16, 2018, 05:28:51 am
content: I had this TDS 210 Tek scope, and it had a wonky display, it would show static-y horizontal lines. I thought maybe the LCD display might just have been poorly connected so i went in with the plan of opening up the scope and wiggling that. It was much harder to get in than i thought, but this was just because I didn't know how to get it apart. I ended up snapping a couple retention clips, but it's okay.It turned out i couldnt actually get to the screen connector, it was hidden away quite deep into the scope, I could only access the power section. I removed the connections i could get to and sprayed some contact cleaner, and reseated the connections.At some point this copper mesh tube fell out of the scope and I cant figure out where it goes. But i forgot about it as i was assembling back the scope, and it scope turned on and appears to be working fine, it seems fixed.Where does this tube go? does it even belong? should I worry since it works now? Perhaps it never belonged and it was actually shorting something inside maybe causing the issue to start with? thanks!

author: tautech
author_rank: Super Contributor
timestamp: April 16, 2018, 05:55:24 am
content: You can see where the braid fits here:https://youtu.be/PHB2XC_l7Eg?t=151

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 16, 2018, 09:34:29 am
content: Short-circuit havoc waiting to happen!
Spectracom SecureSync OCXO Morion MV197 - Page 1
Forum section: electronics / repair

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: April 16, 2018, 04:07:54 am
content: The standard OCXO option in the SecureSync units is a Morion MV197. I have had 2 of these die on me.It appears the heater circuit fails inside. They start getting cold and go way off frequency. I also noticed this was exacerbated by the fan cooling the unit, but making the heater in the OCXO work harder to keep it warm. The first one I actually had Spectracom replace the OCXO at great cost. It's a big risky job pulling the OCXO off the mainboard. The part is through hole mounted but the vias/holes are tiny and fragile, and the pins are tight fitting. I decided to swap it with a Morion MV89A, which will not mount to the board, or fit under the top lid of the 1RU rack enclosure. It works far better than the MV197 did. Have a request for a sample (MV197) in at Morion USA, in San Jose, CA not sure yet the cost. Funny these guys have an address that's a very big Post Office. It used to be San Jose's Main Office. My guess is they just have a PO Box there. I assume they are still operating in this country, even though our dealings with Russia are a bit tense at the moment.So I may go with a separate enclosure outside the main chassis for the MV89A depending on the quote I receive (if any).