hybridfree/eevblog-posts huggingface dataset:
55w UV Lamp Ballast - Page 1
Forum section: electronics / repair

author: rodrigopires
author_rank: Regular Contributor
timestamp: April 26, 2019, 04:02:29 pm
content: Hello fellow enthusiasts, i'm looking for a UV light filter for my pond and came across a great deal on a 55w Aqua Medic UV Filter but it has a failed ballast (external) i been looking online for 55w ballast to replace but didnt find any good fit only 58w... My question is: what chould i do in this situation? What can i use to substitute the ballast?Some data:Power: 55wVoltage Input: 220-240VAC 50/60HzSound Rating: AClass: PHigh power factor: (Lambda)max=0.99Thanks in advance for the help!

author: kosomsk
author_rank: Regular Contributor
timestamp: April 27, 2019, 04:51:10 pm
content: Hi! Ballast power = lamp power, isrecommended. 58 will work, but the life of the lamp may decrease slightly.

author: Kjelt
author_rank: Super Contributor
timestamp: April 27, 2019, 05:15:08 pm
content: Can you show the lamp, is it plasma like tl ?Do you know the lampvoltage?

author: james_s
author_rank: Super Contributor
timestamp: April 27, 2019, 05:39:42 pm
content: We need to know more about the lamp in order to suggest a suitable ballast. The wattage only tells you part of the story, the lamp current, voltage and ignition method are more important. Is it a compact fluorescent style germicidal lamp?

author: rodrigopires
author_rank: Regular Contributor
timestamp: April 27, 2019, 07:49:53 pm
content: That is the problem i want to save the lamp and give it the right amount of power... the lamps is a generic uv lamp like the jebo filters don't know any characteristics tho... this is the original lamp:

author: james_s
author_rank: Super Contributor
timestamp: April 27, 2019, 09:30:03 pm
content: That picture is a 11W PL lamp, I'm guessing that your lamp is a Biax 55W 4 pin PL, so a generic ballast for one of those should work fine. Something like thishttps://ballastshop.com/tss-uv55pbxm-55w-ac-electronic-t5-and-pl-l-electronic-ballast/

author: rodrigopires
author_rank: Regular Contributor
timestamp: April 28, 2019, 11:51:24 am
content: That is the original lamp only the 11w but i think the 55w is the same. I can only find 58w electronic ballast for o reasonable price, could i use that with a series resistor or a PTC on the output?

author: Kjelt
author_rank: Super Contributor
timestamp: April 28, 2019, 01:14:18 pm
content: I have a Philips HF performer.You can have this one for free if you pay for the shipping.It is suited for a PL-L 55W so first ckeck that the lamp has four connections and is PL-L 55W compliant.If that is the case and you want it contact me via PB.

author: Zero999
author_rank: Super Contributor
timestamp: May 01, 2019, 12:17:14 pm
content: Quote from: rodrigopires on April 28, 2019, 11:51:24 amNo, it's imperative to use the correct ballast for the tube, otherwise it will shorten its life and could pose a fire hazard.

author: rodrigopires
author_rank: Regular Contributor
timestamp: May 02, 2019, 01:32:23 pm
content: The problem was solved! A big thanks to everyone!
60v Battery charged but not enabled? - Page 1
Forum section: electronics / repair

author: marce002
author_rank: Regular Contributor
timestamp: March 07, 2024, 09:33:30 pm
content: HelloI have charged cell by cell this 16s10p 18650 doohan etanl battery because was not charging with its charger.. cells were 0.4 vol aprox... cells are now 3.9v stable so they are alñ 160 cells in good shape but bms does not allow to charge or discharge... what can be done in the board maybe or any trick fuse to reenable it? thks in advance

author: Gyro
author_rank: Super Contributor
timestamp: March 07, 2024, 09:59:35 pm
content: It probably has a microcontroller that has logged (and latched) the out-of-range cell voltages to prevent the fire risk.

author: p.larner
author_rank: Frequent Contributor
timestamp: March 09, 2024, 04:26:49 am
content: I think your best bet would be to replace the cells that were low+also the bms,if the cells were that low even if you charged them the capacity will be well low+a fire risk!!.

author: Greybeard
author_rank: Frequent Contributor
timestamp: March 11, 2024, 12:24:55 pm
content: There are BMS that blow internal non-resettable fuse in the failure case.

author: marce002
author_rank: Regular Contributor
timestamp: May 08, 2024, 02:35:28 pm
content: worked after reseting the bms thks
Optical Encoder Replacement - Page 1
Forum section: electronics / repair

author: 2X
author_rank: Frequent Contributor
timestamp: May 31, 2024, 09:04:58 pm
content: Hi to everyone,I want to replace the Optical Encoder "Part Number: 62P22-H4", but I can't find it anywhere. Do you know if can I install another with different part number and what characteristics have to be the same?https://gr.mouser.com/datasheet/2/626/Opt_Encoder_62P-334478.pdf

author: m k
author_rank: Super Contributor
timestamp: June 05, 2024, 04:03:14 pm
content: You can use all encoders that support waveform and truth table stuff from page 2.
65inch lcd tv. Can it be fixed? Panel issue? - Page 1
Forum section: electronics / repair

author: jastreb
author_rank: Contributor
timestamp: November 07, 2020, 04:39:19 am
content: I seen bright spots where led diffuser falls off. Ut these are almost like burn spots. What you think?

author: TheMG
author_rank: Frequent Contributor
timestamp: November 07, 2020, 06:49:55 pm
content: Is this a full-array LED backlit panel?Almost looks like some LEDs have failed and overheated causing the diffuser to discolor.Can it be fixed? Maybe. If it's just the diffuser that's discolored and you can find replacement diffuser sheets. Obviously the backlight may need fixing too. Only one way to tell... Take it apart.

author: jastreb
author_rank: Contributor
timestamp: November 07, 2020, 08:25:14 pm
content: Thank you TheMG. Yes I am pretty sure its led backlit full array display.I will definitely take it apart when I pick it up. Someone sent me the photo and I was trying to figure out if its a panel issue or as you say like burn mark on diffusers. I just noticed though, uf you look at picture along bottom row where it shows the active icon, there is a "^" right in the middle of a dark spot but it seem brightly lit up. I would have expected it to be blemished by the burn mark underneath but looks normal. Hmmm thanks again for your input.
65uf6800 LG TV - Page 1
Forum section: electronics / repair

author: JP Pritchard
author_rank: Newbie
timestamp: April 09, 2022, 02:36:15 am
content: Any recommendations on where one might obtain a schematic or service manual for the LG TV (65uf6800)? And on a related matter, anyone looking for a good set of boards for one of these? Friend cracked a 65 inch screen and I've pulled all the boards out of the thing, but haven't started playing with/stripping them yet and would like to have a set of schematics to see what I'm working with here, but if someone needs the boards, I expect we can work something out... JP12jp23@gmail.com

author: fzabkar
author_rank: Super Contributor
timestamp: April 09, 2022, 04:35:30 am
content: https://elektrotanya.com/lg_65uf6800-sx_chassis_lj5um_sm.pdf/download.html
68020 uP at slower speed than rated - Page 1
Forum section: electronics / repair

author: wn1fju
author_rank: Frequent Contributor
timestamp: October 10, 2019, 09:42:46 pm
content: I think the Motorola MC68020RP16E microprocessor in my Tek TDS520 scope is hosed. This is a 16 MHz part. Can I use a MC68020RP20E part thatis rated for 20 MHz without any problems?

author: Fraser
author_rank: Super Contributor
timestamp: October 10, 2019, 09:54:34 pm
content: Yes.Microprocessors of this era and architecture were identical dies and were speed selected at time of manufacture. Even the 16MHz unit’s might run at 20MHz but were not guaranteed to do so reliably. A 20MHz MC68K series processor is just one that has passed the higher speed tests and is theoretically a better ‘quality’ than the 16MHz version. In this case, a faster rated microprocessor may be run at a lower clock frequency without issue. Do not be tempted to change the microprocessor clock to 20 MHz though, that can cause complications in the rest of the system.Fraser

author: wn1fju
author_rank: Frequent Contributor
timestamp: October 10, 2019, 11:17:49 pm
content: Thanks for the info.
6825A amplifier fully repaired! end saga, hats off to HP for building it tough - Page 1
Forum section: electronics / repair

author: coppercone2
author_rank: Super Contributor
timestamp: October 02, 2022, 09:21:59 pm
content: Ok, I got the ammeter working. I deleted a bunch of crap because it was a wild goose chase based on a bad solder joint on a capacitor and some loose crap(I almost wrote bad transformer socket! for some reason, wow I am agitated, this does not have a transformer socket on it, I just started imagining words ).I don't know the exact problem but I think I basically swapped a transistor on one of the PCB now when I measured them all, so the A2 board has all of the power resistors go on fire, but I got it working by overrating the fuse by 300%. At least the transformer voltages are normal, the rectified voltages are normal, hopefully at this point I just need to swap some transistors and maybe it will work. Have not ran it for more then 3 seconds like that.yep, swapped a transistor. works fine, bit a buzz at full power unfortunately even with all the work, but at least the ammeter works. Problem was mostly a capacitor that via got dissolved making the -45V rail go screwy (everything from oscillation in certain output voltages to the ammeter causing the rails to change. problem was that I replaced a 5 lead cap with a 2 lead cap and one of the vias cracked, at least I think there was a via there, because the screw terminal capacitor has one.Maybe it will stop rattling when i replace a few screws but god damn that is a load off my chest, hoorah. buncha crap is still loose. (only at max power).what a fucking beast though, survived swapped cards in wrong polarity, swapped transistors, a missing power rail and only some resistors got hot when I upped the fuse by 300% to run it on overload for trouble shooting purposes. if it passes after the damagesincurred by the insane repair man, its a fine instrument. I wanna see this thing go up against starfish prime lol

author: coppercone2
author_rank: Super Contributor
timestamp: October 02, 2022, 09:24:14 pm
content: this is the abstraction
7 Segment LCD display - Page 1
Forum section: electronics / repair

author: hpmaxim
author_rank: Regular Contributor
timestamp: November 13, 2021, 10:21:56 pm
content: I have a radio transceiver with an LCD which is having faded and missing segments. The interesting thing is, the segments are not behaving consistently -- that is the behavior of a segment can depend on the other segments. Unfortunately, I know I was the cause of this. The LCD is mounted on a board with an encoder, a microcontroller, and a few other things. The board is then glued into an aluminum housing, and the house housing is screwed into the radio chassis. I removed the housing, and then sprayed Deoxit D5S-6 through a hole onto the front side of the board with the encoder (and the LCD) on it. Unfortunately, that hole (a few mm in diameter) is really my only access unless I remove the silicone glue and hope that's all that's holding it in.I'm sure the LCD is something custom. I suspect the radio itself is a circa 2000ish design, and this particular unit was probably manufactured in the mid to late 2000s. The display is backlit with the format:xxxx.x 1XX.XX--- ---- ----Where the "----" is a solid line and "x" is a 7-segment, that's smaller than "X". Soooo, total of 69 addressable segments?Since I haven't been able to remove the board it's hard for me to find markings on the display or even how it's mounted (soldered versus zebra foam). The only thing I tried (in case not all the fluid had evaporated) was to stick it in a plastic bag, and then bury it in a sandbox, and then stick the sandbox in my oven at 75C for 12 hours. I figured this would gently raise the temperature up enough to dry accelerate evaporation without being hot enough to risk damaging anything. It might have improved things, but I can't really tell... The display goes through a self-check on power up and indicates on all segments, and they all work when in this mode.

author: hpmaxim
author_rank: Regular Contributor
timestamp: November 15, 2021, 02:21:43 am
content: It looks like the Deoxit deformed the zebra foam a bit and it hung out the end of the bezel that was pressing it in place. When it did that, it bent away from the LCD a bit. If anyone knows where to get the display, I'd be very curious.
700mv+ ripple on Akai sampler linear PSU. Please help me troubleshoot - Page 1
Forum section: electronics / repair

author: sumilumi
author_rank: Newbie
timestamp: January 02, 2022, 05:14:48 pm
content: Hi fellow troubleshooters. This is my first post on EEVblog. I’ve recently setup an electronics workbench. i’m also building a music studio with old equipment bought faulty at low cost.I’ve been into electronics since the mid 80’s and particularly in the last few years though only getting hands on with repairs now. My knowledge gaps are significant so I’ll be posting here to seek guidance advice and general practical applied learning.On my bench today is an old ca. 1993-95 Akai hardware sampler. This runs on both a linear and Smps supply. Both are getting on in age and ripple seems fairly high. My guess is simply tired caps but I'd like to post here so someone experienced can help me troubleshoot in order to isolate the problem and of course learn.I havent looked at the the smps that drives the digital side of the sampler. This gives me some 150mv ripple on average which I guess is high but rather alarmingly the linear AC to DC supply that feeds the samplers sensitive DAC output stage carries 22odd volts under load complete with a nice juicy 700+mv ripple. This dirty power goes to two LDO + - -15v regs that run the analogue output stage and in turn feed the dac (an old PCM63p) through a couple of 78/7905sBy this point ripple is down to 34mv but that's probably still high for a DAC opamp I/V stage so I'd like to minimise what the main supply feeds this circuit and get on top of this rather loud ripple.The sampler isn’t playing well either. I see ringing peaks on square and saw wave edges so there are other issues but i figure start with the supply.I’ve attached a shot of the psu board. this is fed by a separate smps which appears ok given its age. These were expensive devices back in the day and Akai specd them quite well.I’ve done a quick in circuit cap esr test with a ‘peak’ meter and most including the main filter caps look good. The only suspect is the small .47 next to the rectifier which I’ll desolder for test later today.I’ll also measure all voltages under load and update the image with these printed in case that helps the process.So I’d be most grateful for suggestions on what could be amiss here. Is 700mv ripple normal ?Thanks in advance
70's Grundig Radio - Volume Issue Repair Help - Page 1
Forum section: electronics / repair

author: thomieboy
author_rank: Contributor
timestamp: May 15, 2021, 06:18:32 pm
content: Hi everyone, I am currently trying to repair a Grundig radio from the 70's. I found a schematic for this radio here:https://www.radiomuseum.org/r/grundig_rtv_500.htmlISSUES:- It still seems to work, but the volume slider is extremely sensitive. Putting it at 10% of the sliding range is already too loud.- I also notice that only the left speaker seems to work, but pressing the 'mono' button makes it play through both, so I won't put too much time in this issue. (But would be nice if this is fixed as well)INFOAttached you can find the volume control & balance part.- Top is left channel, bottom is right channel- R44 & R47 is the balance sliding potentiometer (orange)- R55 & R56 is the volume sliding potentiometer (green)OBSERVATIONS/QUESTIONSIt seems that the volume potentiometer has 5 connections for each channel. I do not understand how these are connected inside, I would think that any potentiometer has only three connections (left, right, wiper). Anyone knows where the other connections are for?When I measure resistance between ground and wiper output of the volume potentiometer (blue arrow), I notice that it rather quickly jumps from 0 to 68K in the first 10% and stays there for other 90% of the sliding range. Does anyone know what could be causing this? I would expect a nice linear increase over the whole range. I do not see any obvious sign of broken caps or resistors.Let me know if there are things that I should measure etc. I very much appreciate any help!

author: mikerj
author_rank: Super Contributor
timestamp: May 15, 2021, 06:58:18 pm
content: The extra two taps on the potentiometer are to add a form of tone control, usually providing bass boost at low frequencies (e.g. "loudness").Sudden jumps on volume are most often due to wear on the carbon tracks, and this will usually be at the low volume end of the slider. With most of these older potentiometers it's not hard to disassemble them for cleaning and inspection. If you find a badly worn track one trick I've done a few times in the past is to bend the wipers to use a fresh part of the carbon track. Injecting some potentiometer cleaner (e.g. Deoxit) and working the pot up and down would probably be a good start, the wiper contacts can get oxidised over time and make poor contact with the track.Have you measured end to end on the potentiometer, and if so do you get something close to the 500k it's specified at?
7633/7ct1n - Page 1
Forum section: electronics / repair

author: particleman
author_rank: Regular Contributor
timestamp: July 21, 2025, 02:03:27 pm
content: Been awhile and long story short we moved and it took me some time (4years) to start setting my "lab" back up. I fired up the 7633 and no trace, Replaced the HV board and all seemed fine. went to use my 7ct1n curve tracer and these are the symptoms I'm seeing.Put 7ct1n into the vertical slot. Turn up collector drain and there is no X axis deflection just intensity of the dot get brighter. BUT hooking another scope to the collector and you can see X deflection. And when turning up the step amplitude there is the normal Y deflection.Put the 7ct1n into the horizontal slot. Turn up collector drain and X axis deflection works normally BUT turning up the step amplitude there is no Y deflection it just causes the X axis to pulse.I have confirmed that XY on the scope is working. I guess what I am wondering, does this sound like an issue with the curve tracer or something I could have mis-wired when replacing the HV board?

author: particleman
author_rank: Regular Contributor
timestamp: July 21, 2025, 03:27:14 pm
content: call off the dogs. Shes been solved, bad cable.
7L12 tektronix spectrum analyzer - Page 1
Forum section: electronics / repair

author: evripides
author_rank: Newbie
timestamp: March 24, 2019, 10:20:18 pm
content: Hello dear sir(s)I own a 7L12 spectrum analyzer and now is nearly dead I can see no trace on screen exept the readout characters as you can see to attach pic. Can anyone has a repair advice?regardsEvripides

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: March 24, 2019, 10:40:32 pm
content: evripides,welcome to the forum!!Can you post another couple of pictures?It would be good to see the complete front of the 7L12 and the settings of the mainframe.Regards,Jay_Diddy_B

author: evripides
author_rank: Newbie
timestamp: March 25, 2019, 12:13:47 am
content: main frame is ok i use other plugins 7b53,7a18,7a26 and works great .

author: evripides
author_rank: Newbie
timestamp: March 25, 2019, 12:14:31 am
content: see here

author: evripides
author_rank: Newbie
timestamp: March 25, 2019, 12:16:08 am
content: and here

author: texaspyro
author_rank: Super Contributor
timestamp: March 25, 2019, 02:23:44 am
content: Check ALL tantalum caps. Also the YIG is known to be a problem in these units.

author: Kartika
author_rank: Regular Contributor
timestamp: April 01, 2022, 10:37:01 pm
content: Do you fix ?

author: evripides
author_rank: Newbie
timestamp: April 01, 2022, 11:12:28 pm
content: not yet not have time for this
8 button IC replacement of Pasapair desiccator - Page 1
Forum section: electronics / repair

author: Tarien
author_rank: Contributor
timestamp: February 14, 2025, 12:36:42 pm
content: Having trouble while repairing a Pasapair OL20 BD030BM desiccator. The issue is clearly a lack of response from the capacitive touch buttons. After powering on, the device boots up normally and waits for the power button to be pressed, but there is no response.I took a closer look, and I found that the Chinese no-info IC QTC5168F is responsible for this (only one picture is available online). I verified the power and all surrounding components, and they are good, so the IC itself seems to be the main issue.The problem is that this IC isn't available anywhere, so I tried to improvise by replacing it with my own driver. Only one output with a pull-up resistor is connected to the microcontroller (picture included)(SDA only, its possible that is some kind of weird i2c?).I attempted some brute-force testing:❌ 1-Wire – No response after the reset signal.❌ PWM – No response.❌ Analog signal with random values – No response.❌ Currently testing UART with different baud rates – No response at 9600 baud so far.I wonder if anyone with experience can help me figure out which protocol I'm actually dealing with?

author: benj38
author_rank: Frequent Contributor
timestamp: February 14, 2025, 02:37:55 pm
content: Here is the datasheethttp://icdemi.cn/viewManual.aspx?p=QTC5168F.pdfThey are using a very simple, yet proprietary, serial encoding.

author: Tarien
author_rank: Contributor
timestamp: February 14, 2025, 07:19:18 pm
content: Thank you! Just make thru arduino simulation but still no answer i wonder is uC is faulty

author: benj38
author_rank: Frequent Contributor
timestamp: February 14, 2025, 07:46:27 pm
content: Shouldn't your second channel (which I assume is your simulated AF line) be low?Also, it looks like you should repeat this with 8ms intervals.

author: Tarien
author_rank: Contributor
timestamp: February 15, 2025, 03:15:06 pm
content: AF pin is not connected anywhere. Im trying to simulate k8 button wich is power. K8 Low 1500us than d8 500us low as mentioned in documentation, ODC 500us. Also i make 8ms interval between the packets in photo is lower just to catch it more easly in logic soft.

author: Tarien
author_rank: Contributor
timestamp: February 15, 2025, 03:41:16 pm
content: I translate datasheet and im not sure if i correctly understand the D8-D1 function, as inverted i understand inverted time 500/1500us. For k8 detected 1500us and inverted time for d8 500us. Its that correct or im making some mistake?

author: benj38
author_rank: Frequent Contributor
timestamp: February 17, 2025, 09:09:32 pm
content: Quote from: Tarien on February 15, 2025, 03:41:16 pmThat was also my understanding as well. In other words, it looks like you are not doing anything wrong. It may be indeed that the MCU input connected to this is damaged
8020A LCD replacement w/Varitronix VI-302-DP-RC-S - Page 1
Forum section: electronics / repair

author: Madmanguruman
author_rank: Contributor
timestamp: February 16, 2022, 09:43:52 pm
content: Hi folks,Just sharing what is probably obvious to most of you. I recently completed an LCD swap on my old Fluke 8020A using this handy guide:http://mrmodemhead.com/blog/fluke-8020a-lcd-replacement/The referenced Lumix LCD-S3X1C50TR/B wasn't easily available so I found on Mouser the Varitronix VI-302-DP-RC-S. This LCD has different pin names but is 100% pin-compatible with the previously posted instructions.The results are attached. It floors me that this meter is getting close to 50 years old and the ohms offset with shorted leads is 0.00 - amazing. You can see off to the right side the condition of the stock LCD screen - badly leaked.
80E02 80E03 Tektronix Sampling Module Repair - Page 1
Forum section: electronics / repair

author: richardb
author_rank: Newbie
timestamp: February 22, 2020, 03:45:45 am
content: Hi. Has anyone had any success repairing these modules? I could find little to no information regarding the servicing of them.Richard

author: nonconvex
author_rank: Newbie
timestamp: December 28, 2020, 06:46:34 pm
content: HI Richard, I used to repair it. The older series suffered from sample&hold chip overheating, so it either should be replaced, if you are lucky to find a good working one, or reworked with a daughter board.-Andrei
8562A Display Glitching - Page 1
Forum section: electronics / repair

author: rogersstuart
author_rank: Contributor
timestamp: December 17, 2021, 11:11:02 pm
content: I have an HP 8562A that I don't use very often. I turned it on the other day and I guess it didn't appreciate my long absence because it decided to break. The CRT was pretty sharp and didn't have any burn-in. I assume this is the result of dried capacitors? It seems to work fine over GPIB, so other than the display problem and needing to be calibrated it's fully functional. The fault is intermittent right now so I think that I should do something about it before it gets worse. Does anyone have experience with this? Is there a pot that needs to be tweaked or a specific cap that always goes bad?

author: rogersstuart
author_rank: Contributor
timestamp: December 22, 2021, 10:53:42 pm
content: I decided to open the unit and have a poke around. My analyzer seems to be one of the original 1987 6 ROM models and reports that it has close to 10k hours on it. There was a tamper sticker which indicated some maintenance or a calibration occurred during 2019 but I can't be sure of what occurred or why this unit was defected and sold to me for such a low price. The only problem when I received it was a dead fan which was causing overheating after 30 minutes.I looked though the service manual. Based on what I read I decided to probe the A2 board near the line generators. The fault is intermittent which is a bit of a hassle since I can't reliably trigger it. There's definitely something wrong. The waveforms don't exactly match what is shown in the manual when the unit is displaying the CRT test image. The LCHAR signal stood out. There is no change when I look at it with the test screen displayed (there should be) but it looks fine during normal operation.I didn't see any power rail test points on the A2 board explicitly called out in the manual. I probed around until I saw a few stable voltages and then checked them in AC mode on the scope. None seemed to indicate that an LDO is oscillating from a dried cap. Even when the display was messing up. I tried tapping all the line generator components with a plastic tool. None of them seem responsive. Spraying them with freeze spray did get a response but I was unable to localize it. I can only say that spraying that region of the board with freeze spray seems to correct the severe glitching and has a stabilizing effect until the unit is power cycled. Last night I was able to stabilize it for hours. Today I found it bouncing between working and not working after being left alone for some time.What could it be? A cracked component would have responded to the plastic tool right? As would a broken trace? Could it be a semiconductor or even a bond wire? I don't have much experience with this so I may have to live with it.
8562EC Power Supply Repair - Page 1
Forum section: electronics / repair

author: CrazyTiger
author_rank: Regular Contributor
timestamp: August 22, 2022, 05:53:45 am
content: Hi,I am trying to repair a 8562EC Spectrum which is not turning on. The power supply is doing a on and off cycle. I have looked into all most of the major startup area and secondary area, so far I am yet to find anything shorted or open.To be sure I have also removed and checked all the FET out of circuit, capacitors tested and mosfet driver IC's been replaced as well. Everything looks good so far, except few capacitors which I have replaced.Looking at the small board, I have my doubt on a component marked LT2105, I am able to find this being sold in aliexpress, but I am not able to find a datasheet for this chip. I can find a LT210 but not 2105 Any idea what this chip could be?

author: eblc1388
author_rank: Frequent Contributor
timestamp: August 22, 2022, 07:15:03 am
content: It is a 5V ultra low drift 5ppm/oc voltage reference LT1021.https://www.analog.com/media/en/technical-documentation/data-sheets/1021fc.pdfAlso, have you downloaded the maintenance manual for 8562EC at the following site, which has a very detailed troubleshooting procedures regarding the 1.5 second "on/off kicking" startup of the power supply on Page 624?https://www.testunlimited.com/pdf/an/08562-90219.pdf
8562EC power supply - Page 1
Forum section: electronics / repair

author: hp197
author_rank: Newbie
timestamp: May 21, 2023, 12:30:21 pm
content: Hi,I've blown the power supply of my 8562EC. Don't know how, but the mains switch on the back of the unit was on 110v while I live in the EU and have 230v(ish).I clearly heard a *poof* when powered on and expected magic smoke, but none.Line fuse was blown and once replaced the machine tries to start but shuts itself down again (the power on, pop, down sequence indicating a fault in the power supply).So I dissembled the unit, got the power supply board out, fetch the service manual and watched TSP #116 on YT.Following the service manual, chapter "Supply Restarting Every 1.5 Seconds". I attached a probe on TP208 and TP206.Since TP208 goes high before TP206 is going low, I should suspect a short in the secondary (output rectifier, voltage regulators, or another assembly) albeit the manual.So next chapter I started working on is the "Dead Power Supply". There I come to bullet 14: "Connect the positive output of a current-limited dc power supply to the cathode of A6CR201 (TP206) and the ground to A6TP201."I think I searched the whole board, top and bottom, but for my life I cant find TP201, also I find it a little intimidating to piggy back a voltage feed the circuit.Also point 18: "C207 nearest C209" is impossible to find (I cant find a cap with one of the 2 markings on the silkscreen).Are there people here with experience repairing the 8562EC power supply (note that the EC's have a updated power supply board, without the high voltage part, the screen is a crt)?and/or are there people who had this before (selected wrong line voltage), what did they do to repair it?

author: m k
author_rank: Super Contributor
timestamp: May 23, 2023, 08:05:00 am
content: Seems that TP 206 and 208 are pretty shorted.Over voltage can be a bad rap but constant restarting means that something is at least sort of sane.With some luck it's just a little bit off balance but that pop is not promising.Do you have a proper manual?That missing TP is connected to somewhere, try to find those components.Is there a room for an add-on PSU?
Agilent 8563E ERR 456 AMPL - Page 1
Forum section: electronics / repair

author: syau
author_rank: Frequent Contributor
timestamp: January 11, 2022, 12:17:24 pm
content: My Agilent 8563E developed “ERR 456 AMPL” after I dig out from storage today. Reading through the Service Guide yield no hints. All the yellow LED in A2 light up correctly which I presume all power ok.Believe this error is related to A5 IF board but don’t know how to start the troubleshooting.

author: syau
author_rank: Frequent Contributor
timestamp: January 12, 2022, 01:24:47 am
content: After reseating the ribbon cable on A5, those error gone and I now have error 201 580 596 567The service guide neither help on those errors

author: syau
author_rank: Frequent Contributor
timestamp: January 13, 2022, 03:41:59 pm
content: Looks like my unit is thermal related as those ERR gone away after turn on for a while. I have it turned on for few hours now and feeding it an FM modulated FM signal and everything sport on compare to another SA.
8563EC spectrum analyzer amplitude problems, no codes, odd cal - Page 1
Forum section: electronics / repair

author: NickyDoes
author_rank: Contributor
timestamp: January 27, 2022, 08:59:09 pm
content: Hello,I came upon an Agilent 8563EC 26.5 GHz spectrum analyzer. I'm getting into RF, but am not experienced at this point - and don't have much in the way of cables, adapters, let alone synthesizers. I do have an older HP 1.8 GHz analyzer that works great, so I can check some things. I checked the attenuator, for example. The attenuator appears to work well.This SA is failing in ways unknown to me. I've read through the service manual, and could do quite a few of the checks - but would appreciate a bit of guidance in the rationale of what to check and what just doesn't make sense to try.I attached photos rather than describe all the situations. I get normal looking spectra with excessive amplitude when measuring the Cal output with a span under 1.8 MHz. At and above 1.8 MHz, the measured amplitude moves to saturation. I realize there's a mode switch at 1.8 MHz, but I'm not yet grasping the fundamentals of what is going on.
85645A Range 3 not showing up on the Spectrum Analyzer - Page 1
Forum section: electronics / repair

author: tchiwam
author_rank: Regular Contributor
timestamp: April 29, 2021, 11:38:45 pm
content: Anyone her ever played with the 85645A ?FYI:Band 1 Up to 6.46GHzBand 2 5.7 to 13GHzBand 3 12.36 to 19.7GHzband 4 19.031 to 26.5GHzIn CW it is able to make a nice spike between 12.36 and 19.7GHz (band 3)But when I use tracking (offset or not) it is not working.I did the service procedure a couple of times and Band 1 2 and 4 are getting flatter every time I do the procedure again.I did adjust the frequency and I am getting something within a few Hz in band 1 2 and 4 in tracking modeI guess the module A6 SYTM (Multiplier by 1 2 3 4) is working and I guess the filter is following too as they work in CW.Anyone having the diagram of the A3 board ? I want to know the difference between the CW and tracking.If I use 0 span and a frequency in that range I have a spike really far off wide band thing ....Lucky enough I have 2 Spectrum analyzer to play with today... Even if one is a little hurt.

author: tchiwam
author_rank: Regular Contributor
timestamp: April 29, 2021, 11:41:40 pm
content: Some pictures

author: tchiwam
author_rank: Regular Contributor
timestamp: April 29, 2021, 11:48:05 pm
content: The 85645A itself...
8568A No display, Both INSTR CHECK LED off - Page 1
Forum section: electronics / repair

author: Thirtykay
author_rank: Contributor
timestamp: October 20, 2023, 07:59:25 pm
content: Hello everyone,I have recently acquired an HP 8568A and his 85662 IF/Display. As usual with AS-IS item/Found in a trash item, they are not working.I have no CRT activity and both INSTR CHECK LED off, keyboard inoperative after start up, so not an easy failure.What i did so far:Checked both RF/IF Section supplies - OKChecked 50-wire interconnect cable - OKChecked keyboard while startup - OKRan HP-IB Test - OKRan LONG-POP Test - OKRan Digital storage Test - NOK, No test pattern but INSTR CHECK LED left on, as expected.Hooked an external XY monitor - OK but it seems to lack some dataChecked CRT Filament resistance - 19 Ohms, OKChecked CRT Voltage on A1A3TP1AB - 0V , NOKChecked +18V on A1A6TP100-5 - +18.12V, OKChecked DRIVE on A1A6TP100-4 - No oscillation, NOKChecked CRT DSBL at 0V on A1A6 - 4.5V, CRT is disabled, NOKVisual check of A4A9 Board and U6 in charge of CRT DSBL signal - OKNow i can say my HV Power supply and my CRT are good, they are just disabled by the RF Section but why ?Like i said display is working on an external XY display, but it lacks quite a lot of data, see attachments.Have anyone encountered this problem before ?In the waiting for your kind answers, i'm going back to the service manual !Best regards,May the force be with you.

author: Thirtykay
author_rank: Contributor
timestamp: October 23, 2023, 09:03:54 pm
content: Having real trouble to narrow down the failure, here's what i found recently:By shunting CRT Disable line, the CRT indeed start, so definitely no power supply issues.I did a display test pattern, it's ok so far.I also did a reseat of all the A3 Board. Gave me nothing.And still the keyboard is inactive after selftest.Now i dont where to go next, if someone can give me an advice i would thank him a lot.

author: m k
author_rank: Super Contributor
timestamp: November 03, 2023, 06:59:38 am
content: My guess is some sort of a memory problem.It's like an occasional dot has an incorrect address.Not very typical that a dot has an address, but that's how it looks to be.The dead center of wrong crossing may be just a bad coincidence.
858 analog hot air rev eng schematic and mod suggestion - Page 1
Forum section: electronics / repair

author: doktor pyta
author_rank: Frequent Contributor
timestamp: June 13, 2020, 12:16:36 pm
content: After long operation (~1h) my hot air refused to heat. I've checked heater- OK (cold resistance approx. 70 ohm).I decided to draw schematic from the PCB to understand what is going on.The failure was open R4 instead of 100R. It dissipates about160mW300mW.This resistor biases 7V5 Zener which is the only regulated voltage in this device (!).My suggestion is to increase the resistance to 220R but this change may affect temperature calibration.So after this mod I used thermocouple thermometer to calibrate the device using front panel accessible 'CAL' potentiometer.

author: aqibi2000
author_rank: Regular Contributor
timestamp: June 14, 2020, 09:15:04 am
content: Good going!!

author: fzabkar
author_rank: Super Contributor
timestamp: June 15, 2020, 07:55:18 pm
content: AISI, the voltage across R4 is 5.5V (= 13V - 7.5V), so the power dissipation is about 300mW.If you increase the resistance, then the Zener may not regulate properly at higher load currents.

author: doktor pyta
author_rank: Frequent Contributor
timestamp: June 15, 2020, 10:09:16 pm
content: Fzabkar, thanks for pointing out bad value typed.Voltage of +13V rail drops to 12V when heater is at maximum power.I still claim that it is a bad idea to pass 45mA through 7V5 Zener (340mW into 400mW rated diode) and dissipate 200mW in 250mW rated resistor.Whole PCB has no ventilation and is further heated by linear fan controller circuit.If You carefully analyze the schematic You will see that there is no significant loading on +7V5 rail.

author: fzabkar
author_rank: Super Contributor
timestamp: June 16, 2020, 12:27:32 am
content: Yes, I agree that your mod is OK. Sorry, I should have looked closer at your diagram. I'm surprised that the resistor failed before the Zener. Usually it's the other way round.

author: aqibi2000
author_rank: Regular Contributor
timestamp: June 16, 2020, 10:13:44 pm
content: Chibesium resistor, doesn’t meet the power dissipation specified. I don’t find this surprising
861DW burnt out transformer part - Page 1
Forum section: electronics / repair

author: iQuick
author_rank: Newbie
timestamp: November 03, 2020, 07:47:05 pm
content: Hello,This is my first post. I mistakenly plugged my 861DW rework station into a 220v/240v wall socket today instead in though my 110v step down transformer.It appears the only part damaged was the internal "Transformer 861DS" "In:110v" "Out 23v" "Out 10v" (see images attached)Where can I order a replacement transformer and even better can I change this unit to a 220v/240v capable rework station?Thank you,Michael

author: bob91343
author_rank: Super Contributor
timestamp: November 03, 2020, 08:03:42 pm
content: Who is the manufacturer? I would correspond with them to discover if they will sell a replacement part with 240V rating.

author: notsob
author_rank: Frequent Contributor
timestamp: November 03, 2020, 09:02:51 pm
content: looking at spare heating element for 861DW on union repair there are 2 different varieties 110V and 220V - so just swapping the Transformer is probably not going to work. You could try contacting them to see if they will help- shipping to SA could be another problem

author: ambrosia heart
author_rank: Regular Contributor
timestamp: November 03, 2020, 11:59:20 pm
content: No need to think of. Taobao helps you.You can have a tailor-made one.https://m.intl.taobao.com/detail/detail.html?id=16122812448
862D+ Soldering Iron Station - Page 1
Forum section: electronics / repair

author: sedmes
author_rank: Newbie
timestamp: August 03, 2018, 11:59:41 am
content: Hello I have one 862D+ Soldering Iron Station that is not working, I need a circuit diagram or data sheet for the condenser valuesPlease help

author: mertzkeaton
author_rank: Newbie
timestamp: May 10, 2019, 11:32:19 pm
content: Hello, I know this is an old post, but I would be happy to provide you with part numbers/values if you tell me which components you're looking for. I am looking for the values of R2,R3 and the part number of U1.Thanks,Keaton
[SOLVED] 8753ES firmware upgrade issue - Page 1
Forum section: electronics / repair

author: syau
author_rank: Frequent Contributor
timestamp: June 07, 2021, 06:11:19 am
content: Got a 8753ES with firmware 07.70, everything works fine until I upgrade it to 07.74 today. Self test passed after firmware upgrade but the VNA is not responsive to any key except the "Preset". First boot up after firmware update with a red "CAUTION: INSTRUMENT STATE MEMORY CLEARED" but subsequence boot without this caution.Anybody has idea how to fix ? Or, have I missed anything during the upgrade ?The VNA come with option 002 006 010

author: syau
author_rank: Frequent Contributor
timestamp: June 07, 2021, 07:14:23 am
content: Quote from: syau on June 07, 2021, 06:11:19 amFound I used 8753EE firmware instead of 8753ES which ended up to incorrect keyboard mapping
8904 HP Multifunction Synth Floating impedance disparity - Page 1
Forum section: electronics / repair

author: coppercone2
author_rank: Super Contributor
timestamp: June 24, 2021, 05:24:06 pm
content: https://www.artisantg.com/info/HP_8904A_Service_Manual.pdfPage 135 has the circuitI have two of these units, when floated one unit measures some megaohm to ground, the other unit measures 1.000 K to ground. It looks like its measuring the R423 resistor behind the CM choke, while the other one is not, at least thats my hunch. Both boards look the same on thermal and it looks like the correct relays are getting warm on float switching.I am probobly missing something simple, but why is there such a big difference in input impedance? Both units have 2 output cards, so 3/4 cards measure 1 megaohm, while 1/4 cards measure 1k.If I set it on a 5Vpp output and measure sine wave while its floating, 3/4 channels measure 1 megaohm and the other channel reads 300 ohms to earthground (dancing around), but the output voltage is correctwhere should I look?so in short1) channel 2 on unit #2 has a 100x lower isolation impedance when measured with DC ohmmeter2) isolation impedance on channel 2 unit #2 has a isolation voltage that seems dependent on output voltage setting of output amplifier

author: coppercone2
author_rank: Super Contributor
timestamp: June 24, 2021, 07:08:01 pm
content: or a real test on float impedance would be nicei thought to measure voltage drop on a ground ref resistor?

author: coppercone2
author_rank: Super Contributor
timestamp: June 24, 2021, 07:25:51 pm
content: when I put a 10 ohm resistor across the output the float button does the same thing and same attenuation ratio to both channels. I am guessing there is something fundamentally wrong with using a DC DMM to measure resistance on the output stage for some reason even if the result seems convincing, because I tried it at DC and 50Khz sine wave and the isolation seems very similar (impressively so).Don't know why 1 instrument does this, maybe something with the filter or attenuation, they have a slightly different PCBs where the 2nd output PCB has a jumper on it but the other one does not for some reason.. the jumper is involved with the isolation when measuring itI was not expecting 'good' results from a DMM but I thought exactly 1Kohm vs 1.1Megohm was a little suspicious.. maybe its soft overloading some stage that lets it measure true DC impedance on one channel because of happenstance of component values and setpoints? whereas on the other channels its somehow fighting the amplifiers.Any ideas on if there is a better test the voltage drop on output resistor to verify the float?
8920B display inop after shipping - Page 1
Forum section: electronics / repair

author: Dmoff
author_rank: Newbie
timestamp: January 28, 2022, 01:47:11 pm
content: I've got a 8920B rf comm test set that we received for cal with a inop display. replaced Crt drive board and display worked. finished cal sent back to customer. unit shows back up a week later with same problem, resat all boards and was working again. a few days go by and its back with the same problem. narrowed it down to reseating the processor board being the problem, but after looking all over the connectors and everything theres nothing that stands out. Any ideas as to what could be causing it? I dont think its coming undone as it requires quite a bit of force to get it out and we've tried to replicate shipping and unit worked just fine after. Any help is appreciated, Thank you.

author: bob91343
author_rank: Super Contributor
timestamp: January 28, 2022, 06:18:35 pm
content: Check solder joints and board cracks. You need to get out the scope and DVM and make some measurements while it's not working.

author: MouldyOldGit
author_rank: Newbie
timestamp: January 29, 2022, 09:02:52 am
content: Possibly you have an intermittent inter-electrode short in the CRT.
90° 3006 trimmer  adapter / direction changer - Page 1
Forum section: electronics / repair

author: gmac34
author_rank: Regular Contributor
timestamp: June 04, 2024, 10:17:38 pm
content: Hi, I have been working on an old lab scale form Sartorius, 1979 vintage. inside I have found some odd (to me) plastic contraptions that are used to make a couple of trimmer adjustable from the top.They snap on regular 3006 trimmers and allow them to be adjusted when the scale is assembled.Being old brittle plastic they didn't take to well being adjusted and are broken.are this thing still made anywhere? I cannot even find the right therm to search them.