hybridfree/eevblog-posts huggingface dataset:
Transformer Sourcing.  - Page 1
Forum section: electronics / repair

author: KG7AMV
author_rank: Frequent Contributor
timestamp: December 15, 2014, 05:20:08 pm
content: For a Neighbors Pellet Stove it let the smoke out!

author: SeanB
author_rank: Super Contributor
timestamp: December 15, 2014, 06:14:08 pm
content: Well, it is very likely a simple 120VAC to either 9 or 18VAC transformer, probably rated for around 200-400mA. Any small PCB mount transformer that fits the board ( or that can fit in the space there if you have to do some drilling of new pin holes and make some wire links) will probably work. 9VAC if the relay is a 12V unit, or 18VAC if it is a 24V one.

author: Seekonk
author_rank: Super Contributor
timestamp: December 17, 2014, 03:00:26 pm
content: Can't say the transformer actually looks smoked. Appears to be some flashover at the line voltage terminals and MOV. Have you figured out the root cause for the transformer failure or are you replacing just what looks bad?
SAMSUNG DSR9401 receiver, SMPS - Page 1
Forum section: electronics / repair

author: VanitarNordic
author_rank: Frequent Contributor
timestamp: December 12, 2014, 01:33:55 pm
content: Hi friends,I am repairing SAMSUNG DSR9401. the SMPS shows faulty with a bulged capacitor and two diodes which demonstrate fishy forward parameters at the diode test range, one shows 141 and another one shows 174. They are two diodes that I can not find in the local store unfortunately nor any datasheets. They are:DIODE-SCHOTTKY; SE55,45V, 5000MA, TO-220ADIODE-RECTIFIER; SHK55-65,60V, 3A, TO-220ACCould you help me to find any general replacement for these two parts?

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 13, 2014, 05:20:15 am
content: Schottky diodes are supposed to have low forward voltage drop.

author: VanitarNordic
author_rank: Frequent Contributor
timestamp: December 13, 2014, 10:20:57 am
content: Yes, you are right. specially for these two are quite low. The problem was a bulged cap and now the device is working.
HOWES CVF80 VFO HELP NEEDED PLEASE - Page 1
Forum section: electronics / repair

author: christopher iles
author_rank: Regular Contributor
timestamp: December 13, 2014, 10:16:41 am
content: Hello,I've just bought an old discontinued Howes CVF80 vfo kit but the coil is missing.Does anyone have the details of this coil so that I can make one myself please?Any help greatly appreciated.Thank you,Chris. G0VOE.

author: Riotpack
author_rank: Regular Contributor
timestamp: December 14, 2014, 11:04:03 am
content: Have you tried asking Tony herehttp://www.gqrp.com/howes.htm
Help identifying film caps - Page 1
Forum section: electronics / repair

author: cf_corp
author_rank: Newbie
timestamp: December 18, 2014, 04:10:10 am
content: Hi,Can anyone give me specific details on these caps?Ive got the datasheet but i cant exactly find the correct capacitance value.Ive got three types of epcos caps.type 1: b32923 x2 mkp/sh 40/105/56/b on the top its got the following info, b2-u22 k 305vtype 2: b32924 x2 mkp/sh 40/105/56/b b1-1u k 305vtype 3: b32922 x2 mkp/sh 40/105/56/b b2-u1 m 305vI can get an exact match or maybe im not reading the data sheet correctly lolAny help would be greatly appreciated, or if anyone can link me where to get these exact ones or other brand onesThanks guys

author: wraper
author_rank: Unknown
timestamp: December 18, 2014, 10:46:25 am
content: type 1: b32923 x2 mkp/sh 40/105/56/b on the top its got the following info, b2-u22 k 305v 0.22uftype 2: b32924 x2 mkp/sh 40/105/56/b b1-1u k 305v 1uFtype 3: b32922 x2 mkp/sh 40/105/56/b b2-u1 m 305v 0.1uFThey are X2 class safety capacitors

author: cf_corp
author_rank: Newbie
timestamp: December 18, 2014, 04:09:10 pm
content: hi wraper,thanks very much for that, the codes make more sense now that you gave the capacitance reading.very much appreciated

author: cf_corp
author_rank: Newbie
timestamp: December 18, 2014, 04:13:58 pm
content: Also with these film caps, is it ok to replace the uf value with a slightly higher value like you might do with regular cap's?for example replace a 1uF with a 1.5uF with all the other specs the same, although the width and height may be lager but the lead spacing remains the same.thanks guys

author: wraper
author_rank: Unknown
timestamp: December 18, 2014, 04:27:18 pm
content: Quote from: cf_corp on December 18, 2014, 04:13:58 pmThere is no objective reason to do that, so better do not. That won't increase reliability at all but might have some negative effect depending where they are used. As they are X2 capacitors, guess they are located in the mains filter or probably in some snubber circuit. In the mains filter higher capacitance will mean bigger spark when inserting the mains plug or tripping the switch. Capacitor discharge by bleeder resistor will take a longer time too. Why do you want to replace them, are they faulty? Generally they do not fail often unless of crap quality,very old (especially with paper dielectric) or heavily loaded.
Fluke 85 III - Page 1
Forum section: electronics / repair

author: Gangway
author_rank: Contributor
timestamp: December 03, 2014, 11:01:45 am
content: Have problem with microAmp range selected, display goes into test mode only.All other ranges operational & cal check on 9100 shows within spec.Have stripped down main switch wafers & tracks / contacts look ok.Switch test on all other ranges correct codes.Cannot find circuit for this rev (101) of main board.Any ideas?

author: retiredcaps
author_rank: Super Contributor
timestamp: December 03, 2014, 06:17:04 pm
content: Quote from: Gangway on December 03, 2014, 11:01:45 amHave you looked on both sides and cleaned out any debris? See modemhead's 83 III blog entry for ideashttp://mrmodemhead.com/blog/fluke-83-iii-rotary-switch/QuoteThe expected number for the microamp range is 192 for the switch test. What do you get?QuoteYou won't find any schematics for the Fluke 80 III or V series. Only the original series I schematic is available.

author: ModemHead
author_rank: Frequent Contributor
timestamp: December 03, 2014, 08:03:54 pm
content: Yes, pay particular attention to the switch on the back side. Those little fingers between each setting provide a reset while switching functions. Sounds like yours is being held in reset at the uA position.

author: Gangway
author_rank: Contributor
timestamp: December 04, 2014, 05:36:44 am
content: Thanks for replies, cannot see switch code for uAmp range as it gives two clicks & goes into display test mode ( All LCD figs & symbols). Have removed both wafers and re cleaned metal tracks and wipers.Continuity checks of switch & reset tracks look ok. Considering mA range works, i must have missed something in the uA range circuit. Will keep at it (when time permits))

author: retiredcaps
author_rank: Super Contributor
timestamp: December 06, 2014, 02:42:48 am
content: Quote from: Gangway on December 04, 2014, 05:36:44 amCan you post some pictures of the backside and frontside of your meter? Sometimes, Fluke has several different revisions of the pcb and we might be spot something if you post some clear focused pictures?

author: Gangway
author_rank: Contributor
timestamp: December 07, 2014, 12:13:42 am
content: Thanks again for replies. Did some checks with switch wafers, but need three pairs of hands as LCD plastic shroud has cracked two lock tabs, which requires one hand to hold lcd in place.Noted by bridging uA range select resistor (10k) to lower value 5k, moving selector from mA , reset, to uA , display shows uA as normal? Unable to confirm if range code correct or if uA reading correctly as i ran out of hands..Christmas commitments mean this project will have to go on hold for now.Seasons greetings to all.

author: Gangway
author_rank: Contributor
timestamp: December 07, 2014, 12:16:44 am
content: Second pic of main pcb
Dremel 3000 not working (switch) - Page 1
Forum section: electronics / repair

author: cHops
author_rank: Newbie
timestamp: December 11, 2014, 06:12:46 pm
content: Hello,I am having issues with my dremel. It is fairly new, however, the machine no longer turns on (at any variable speed level). I opened it up and i think I discovered the problem. I have done some research and have seen that this model dremel (the 3000) has issues with the switch. I am not an expert in electronics but I am pretty sure that what I found is not right. Check the picture that goes along with this post.I saw a post with a similar issue and the person replying suggested two parts, however i am not sure which one i need. The page that sells the parts is a bit ambiguous in the product description (there is none).Here are the links:http://www.ereplacementparts.com/search_result.php?ssq=1&categories_id=15440&products_class_id=85&dsk=1http://www.ereplacementparts.com/dremel-3000-rotary-tool-parts-c-15440_15456_205856.htmlAnyways, let me know what you guys think.Thanks,cHops

author: ivan747
author_rank: Super Contributor
timestamp: December 12, 2014, 01:32:54 am
content: Is it under warranty? That's a manufacturing defect in my books.

author: DmitryL
author_rank: Regular Contributor
timestamp: December 12, 2014, 11:22:21 am
content: Quote from: cHops on December 11, 2014, 06:12:46 pmLooks like burnt resistor. I think, that if the motor itself is OK, you can short the regulator and use external one, any triac-dimmer will do.

author: cHops
author_rank: Newbie
timestamp: December 12, 2014, 01:41:12 pm
content: Yes it is under warranty, but rather than spending the money and time on shipping it to them for them to tell me that they cant fix it, I would rather buy the part if it is a cheap fix.What about links to the replacement parts that i posted? Would any of those work for this?ThankscHops
Identifying a component to fix welder - Page 1
Forum section: electronics / repair

author: phillrulz
author_rank: Newbie
timestamp: December 03, 2014, 10:02:24 pm
content: Hi guys at work im gonna try fix a welder cant remember which type, the "high frequency box" had a nice short across it not sure of the voltage of the board, board was fried as it had charred down to the fibreglass ( it failed and conducted) from what i remember the char was from R1 to R10 so skipped out 176k of resistance obviously blowing the resistor ( cracked ) in the past this board has been fixed from memory a track between two resistors blew out so there is a small bond wire between two resistors acting as the track. this schematic is purely from memory and should be taken with a pinch of salt there is 4 components which i labeled as diodes im not sure what they are, they look like diodes as they are black axial through hole components maybe 15mm long where you would expect diode polarity line there is what i could describe as chevrons, see bottom right pcb picture, could anyone possibly help identify them, ive tried using a multimeter to check ( continuity across both ways diode check , resistance, capacitance ) problem is they are open circuit so i cant tell what they are... the welder is obsolete so im the only chance it has of surviving.

author: Rasz
author_rank: Super Contributor
timestamp: December 03, 2014, 10:46:25 pm
content: start with some pictures of damaged pcb

author: phillrulz
author_rank: Newbie
timestamp: December 03, 2014, 10:49:35 pm
content: Quote from: Rasz on December 03, 2014, 10:46:25 pmhave to wait till friday not in the workshop till then.
'just reflow it', or how not to do it - Page 1
Forum section: electronics / repair

author: Rasz
author_rank: Super Contributor
timestamp: November 26, 2014, 12:21:10 pm
content: I told someone to try and reflow bad solder joints, this is what happened. I call this reverse dunning kruger - I always assume people know basic stuff, turns out its only basic for a practitioner :/

author: Kjelt
author_rank: Super Contributor
timestamp: November 26, 2014, 12:55:06 pm
content: Well those are not easy chips to say "just reflow".Only thing that would have a chance is use flux and put it in a really good reflow oven.What did he do to tombstone it, put a heatgun on one side?

author: Monkeh
author_rank: Super Contributor
timestamp: November 26, 2014, 01:00:09 pm
content: I suspect that sticker 'helped'.

author: DmitryL
author_rank: Regular Contributor
timestamp: November 26, 2014, 01:40:03 pm
content: Quote from: Rasz on November 26, 2014, 12:21:10 pmThere is a proverb in Russian, saying something like "If a god would give a crystal penis to a fool, that fool will break it into pieces and cut his hands as well "

author: idpromnut
author_rank: Unknown
timestamp: November 26, 2014, 05:38:07 pm
content: Is it just me, or are all of those ICs also cracked in half through the middle?

author: senso
author_rank: Frequent Contributor
timestamp: November 26, 2014, 05:58:30 pm
content: Due to the support you used there is a thermal gradient across the board, and the sticker wrinkled and seem to have pulled the chips.

author: Rasz
author_rank: Super Contributor
timestamp: November 27, 2014, 03:01:12 pm
content: Quote from: senso on November 26, 2014, 05:58:30 pm1 wasnt me, just a dude on a computer forum I tried to help2 support looks as good as you gonna get, from the looks of it it is a cake oventhere are no cracks, this module has 8 chips (or maybe 16, no picture of the other side)It was totally my fault. I told the guy to support pcb on the corners so chips dont touch anything, I forgot/didnt occur to me some pc memory modules have those stupid stickers across multiple chips. This is one of those things you do automatically without thinking when reworking smd (glue, stickers, plastic, spacers).

author: wagon
author_rank: Frequent Contributor
timestamp: November 29, 2014, 04:48:21 am
content: I've reflowed stuff like that with just a bit of flux and a heatgun with a very small nozzle. I do one side, let it rest, do the other. Works well.
Resistors for 33120A - Page 1
Forum section: electronics / repair

author: Justincase1979
author_rank: Contributor
timestamp: November 18, 2014, 08:23:42 pm
content: Hello everyone, first post...I am trying to fix a burnt out output attenuator in an Agilent 33120A. The resistors I need to replace are 69 ohm, 0.1%, 1206's, and these seem almost impossible to get a hold of in small quantities. Anyone have any good ideas as to where I could get hold of just a couple of these??

author: KJDS
author_rank: Super Contributor
timestamp: November 18, 2014, 08:35:54 pm
content: Have you tried some calculations of the affect of using a readily available resistor?

author: Justincase1979
author_rank: Contributor
timestamp: November 18, 2014, 08:53:03 pm
content: As far as I understand it would directly affect the accuracy of the output amplitude from the function generator, 1Vpp on the display would no longer equal 1Vpp output. But I haven't done any calculations as to the degree of change with other values, just wanted to see if it is at all possible to get a hold of the correct values first...

author: tautech
author_rank: Super Contributor
timestamp: November 18, 2014, 09:09:20 pm
content: Why not stack 3 x 210 Ohm 1206 ?Get say 10 x and select for value to get a spot on combination.

author: brillopad
author_rank: Contributor
timestamp: November 18, 2014, 09:50:28 pm
content: These any good ?From Amazonhttp://www.amazon.co.uk/s/ref=sr_nr_seeall_2?rh=k%3A69+ohm+resistor%2Ci%3Aelectronics&keywords=69+ohm+resistor&ie=UTF8&qid=1416347282

author: lowimpedance
author_rank: Super Contributor
timestamp: November 18, 2014, 10:16:34 pm
content: Stacking is the best way to get what value you need, but be mindful of the temp co. as well.

author: Justincase1979
author_rank: Contributor
timestamp: November 19, 2014, 10:48:47 am
content: Ok, so I have decided to stack one 69.8 and one 6.04k, should give 69.003 total and both of these values are pretty easy to get hold of. My plan was getting .1%, 25ppm resistors, those specs should match the manufactureres parts acording to the manual.One thing, is thin film the best option since we are dealing with freq up to 15MHz??

author: Justincase1979
author_rank: Contributor
timestamp: November 28, 2014, 07:17:41 pm
content: OK, new resistor in place and it works great, didn't even have to recalibrate it.I also replaced the U205 SRAM to fix a 604 error, and that kind of worked. The 604 error disappeared, but now I get a 606 and 607 error. (They were probably there all along, just the self test that stopped at the 604 error.) Anyone have any idea where to start troubleshooting this??
Help with LG TV 32LC7D power supply repair - Page 1
Forum section: electronics / repair

author: wilfred
author_rank: Super Contributor
timestamp: November 28, 2014, 04:38:27 am
content: /.

author: retiredcaps
author_rank: Super Contributor
timestamp: November 28, 2014, 05:53:53 am
content: Some people say fuses die on their own due to age or fatigue. In my limited experience in troubleshooting, that has never been the case. If the main fuse popped, the usual suspects are shorted bridge rectifier, shorted power mosfet, etc.

author: tautech
author_rank: Super Contributor
timestamp: November 28, 2014, 05:57:14 am
content: Quote from: wilfred on November 28, 2014, 04:38:27 amUsually a blown/shorted Mosfet in the SMPS but asretiredcapssays you need to look further.Use a dim bulb tester to limit mains current on power up.

author: retiredcaps
author_rank: Super Contributor
timestamp: November 28, 2014, 06:13:32 am
content: Be careful when checking for shorts in the primary/hot side. A couple of consumer electronics items that I have worked on over the last 4 years had 170V+ DCV stored on the big filter capacitor despite being unplugged for weeks!!!Checking or discharging the big filter cap first is now my first step before doing any measurement.For countries with 220ACV or PFC in the circuitry, the DCV could be as high as 400VDC. A few weeks ago, I worked my first device with PFC and saw 335V DC.

author: Yago
author_rank: Frequent Contributor
timestamp: November 28, 2014, 07:33:23 am
content: Quote from: retiredcaps on November 28, 2014, 06:13:32 amShariar from SignalPathBlog covered this very subject in his last vid.

author: retiredcaps
author_rank: Super Contributor
timestamp: November 28, 2014, 07:53:16 am
content: Quote from: Yago on November 28, 2014, 07:33:23 amYes, I was going to include that in my reply, but then got distracted and forgot. Thanks for linking it.
Samsung Power Supply Board - Page 1
Forum section: electronics / repair

author: myeeth22
author_rank: Newbie
timestamp: November 27, 2014, 11:52:24 pm
content: Recently, I pulled a power supply board out of a smashed Samsung LCD tv. The rest of the TV's junk, but the power supply board is in good condition. No cracks, everything looks fine. I plug it in into the mains, (US) and measure the output on the pin headers, red probe on 24V, black probe on GND. Nothing. 0V. Multimeter's set on 200DC, should be fine. I check the 5V out put in the same way. Nothing. Ok, I check the fuse. Fuse's blown. Grab some new ones (250V, 5A), pop em in, and measure again. Still, nothing. Again, I check the fuse, it's blown. WTF? All the caps look good, no bulges, they're United Chemi-Con brand capacitors. The board in general looks good, no obvious faults. I'm at a loss here as to why the fuse keeps blowing.I'll post some hi-res pics once the camera's battery charges.EDIT:http://imgur.com/a/x6f4G

author: retiredcaps
author_rank: Super Contributor
timestamp: November 28, 2014, 05:56:10 am
content: As I just wrote in another posthttps://www.eevblog.com/forum/repair/help-with-lg-tv-32lc7d-power-supply-repair/Some people say fuses die on their own or due to age or fatigue. In my limited experience in troubleshooting, that has never been the case. If the main fuse popped, the usual suspects are shorted bridge rectifier, shorted power mosfet, etc.

author: myeeth22
author_rank: Newbie
timestamp: November 28, 2014, 07:11:12 am
content: This ishttps://www.shindengen.co.jp/product_e/semi/list_detail_NEW.php?category_id=01&sub_id=03&product_id=D10XB60bridge rectifier, and I see no physical shorts. I'll have to check the mosfets, but they have no physical shorts either. How would I test these?
Motech / Voltcraft FG 708S DDS function generator - Page 1
Forum section: electronics / repair

author: e61_phil
author_rank: Frequent Contributor
timestamp: November 27, 2014, 01:12:19 pm
content: Hello,I have an defect fg 708s function generator. The unit shows strange things on the display and doesn't react on any key at the frontpanel. Sometimes the display shows complet rubbish and sometimes one can read "FRQ:.000 Hz". Therefore, I think it is an problem at the digital side of the unit. I measured the voltages at the voltage regulators (DC an Scope) an they look fine.Has anyone experience with thsi function gen fault?Philipp
Fluke 79 Series III Meter - Page 1
Forum section: electronics / repair

author: simonsez84
author_rank: Newbie
timestamp: November 26, 2014, 01:46:53 am
content: Hi all,I have a Fluke 79 series III meter that was given to me a couple months ago by a friend who was returning to live in the UK. I live in Canada. The meter is fine except that the LCD screen on it is shot. It was left out in the cold overnight before it was given to me so the screen is largely black and is no longer legible at all. I have scoured the internet trying to find a replacement LCD screen as I would really like to get this meter working again. Unfortunately I have come up empty handed. All I seem to come across is Fluke 79 series II screens. Is it possible to put one of those in to the meter? If so, what would the difference(s) be? Any light into this matter would be greatly appreciated. Thank you in advance.Regards,Simon

author: lowimpedance
author_rank: Super Contributor
timestamp: November 26, 2014, 02:17:30 am
content: The series 2 and 3 are different so no.Fluke themselves cannot help? (and not too expensive hopefully). I would think that's going to be your best bet.Otherwise keep your eye out for a dead unit with a good LCD, but you may be waiting a 'loonnng' time!.

author: retiredcaps
author_rank: Super Contributor
timestamp: November 26, 2014, 06:03:11 am
content: I have never dealt with Fluke service, but it is my understanding, that you have to call Fluke with the correct part number before they give you a quote. Since I can't find a 79 III service manual (yet), calling Fluke probably won't get very far.The only ebay seller that might have it is USA based a-fluke and he doesn't ship Internationally.As I'm also in Canada, finding a dead Fluke 79 III to scrounge for a lcd is not zero %, but close to it. While ebay offers more stuff to Canadians via the global shipping program, the odds of finding a 79 III for parts at a reasonable price considering taxes, custom/duties, exchange rate, etc, is not zero, but again close to it.Fluke meters sold for parts can sometimes reach mind bending prices.The Fluke 79 II glass was sold off by a seller who had no clue to what they were worth. He sold batches of 50 (fifty) starting at 99 cents. I alerted someone here and he has a lifetime supply of lcds for 99 cents + $10 shipping.Pretty soon all the Fluke refurbishers/resellers caught on and bought them around $10 for 50 lcds and resold them for an outrageous $15 each or more. Sadly, many people bought them at $15 or more.

author: retiredcaps
author_rank: Super Contributor
timestamp: November 26, 2014, 08:30:31 am
content: No service manual, the the calibration manualhttp://media.fluke.com/documents/7926____cieng0200.pdfhas the Fluke LCD part number and instructions on how to replace it. With this information, a call to Fluke Canada might yield a replacement?
Genius speakers set for PC - SJ2025 audio amp - Page 1
Forum section: electronics / repair

author: atferrari
author_rank: Frequent Contributor
timestamp: November 25, 2014, 08:39:07 pm
content: Genius speakers set for PC. Model SP-E120Audio amp inside is SJ2025. I could find the datasheet in Chinese language only.After replacing the dual pot damaged when falling from a desk, I noticed that at low level (pot progressively CCW) the audio output is more and more blurred, the lower the noisiest. That is awful!With the pot fully CW, (maximum output), no matter what input, audio in the speakers is good.The IC is hot to touch but I see that in the bottom, 4 pins (2 on each side) are soldered to what I believe is a thermal pad, with a generous amount of solder.My daughter insists that in the past it worked OK at low levels.At least I would like to know what to look at before giving up here. Two pots already changed and the main filter cap as well. Caps look OK, no leaking nor bulging.Self esteem is at stake here.Gracias for any help.

author: LA7SJA
author_rank: Regular Contributor
timestamp: November 25, 2014, 11:47:55 pm
content: I think that the SJ2025 is a china version of TEA 2025, from the datasheet it looks like this circuit is some what unstable and need a lot of decoupling caps. You should check with a scope for high frequency oscillations in case some of the caps have been knocked loose or destroyed in the "accident". Is there two bridged amps or only one for left and right speaker? Have you checked the DC voltage on output 1 and 2. How hot is the amp (max power with no sound 0.5W and it should be less than 40C). Not much help, but not to much info fore me to work with.TEA2025 Datasheethttp://www.st.com/web/en/resource/technical/document/datasheet/CD00000172.pdf
Uni-t 61E - Page 1
Forum section: electronics / repair

author: Electric flower
author_rank: Regular Contributor
timestamp: November 23, 2014, 09:36:38 pm
content: My DMM suffered from a short transient spike which was in 230 rms voltage, after it, it is shows ohms when range switch is in V, mV, uA, mA positions.Is there any way to repair it?Inside everything looks clean, no burned components or carbonated traces, everything looks fine.It can't measure resistance when in volts, it just shows random numbers.I can post pics but there is not much to see.Sorry for English mistakes.

author: Lightages
author_rank: Unknown
timestamp: November 23, 2014, 11:47:03 pm
content: This indicates t me that the main chip damaged. I don't think you can repair it without a new chip. When I damaged mine while testing the imput protection of my meters, I took it to 2500V and my UT61E showed the same symptoms. Sorry, time to buy another meter and one with proper input protection.

author: retiredcaps
author_rank: Super Contributor
timestamp: November 24, 2014, 03:37:12 am
content: The ES51922 datasheet indicates that FC1 through FC5 are used for mode selection. You can check to see if FC1 through FC5 match the mode selection as per datasheet.Looking at the UT61E schematic, bear in mind I suck at reading them, it looks like D4 (near VB+ battery terminal) might have some influence on how the mode selection works?If yes, it could be shorted? It would be easy to test.

author: mzzj
author_rank: Super Contributor
timestamp: November 24, 2014, 07:37:59 pm
content: Same here exept my meter is trying to measure frequency. I also suspected blown chipset and didn't really look much further.
HP LP2465 constant screen flicker - Page 1
Forum section: electronics / repair

author: TheCaller
author_rank: Newbie
timestamp: November 23, 2014, 03:11:20 pm
content: Hi Folks.I am new to the forum so please excuse me for any mistakes or repetitive questions.After much thought i have decided to try and repair the screen flicker on my HP LP2465 monitor instead of sending it for probably a costly repair. The screen constantly flickers but i get intermittent flashes of a clear picture.I have managed to remove the back casing of the monitor revealing the boards. From what i have read, the symptom points to damaged capacitors? However, i am not able to see any damaged capacitors at all. None of the Capacitors are showing any signs of damage.The left board has 3 CapXon 220uF 35v Capacitors.The power board has 5 Elite 470uF 35v Capacitors, 1 black TB 1uF 100v Capacitor and 2 brown KY 47uF 50v Capacitors and 1 large brown Capacitor.The right board has 9 black TB 220uF 25v Capacitors, 10 TB 47uF 25v Capacitors, 4 TB 100uF 25v, 8 KY 22uF 50v Capacitors.I have taken a number of pictures which are attached.Does anyone have any ideas what the cause of the screen flicker may be or what remedial actions i can perform? Bear in my mind, my electronics knowledge is very limited.Any help would be greatly appreciated.Many thanks.

author: tautech
author_rank: Super Contributor
timestamp: November 23, 2014, 07:41:42 pm
content: Quote from: TheCaller on November 23, 2014, 03:11:20 pmWelcome to the Forum.Caps often show NO signs of degradation.The CapXon brand have a universal reputation of poor quality.Most often the smoothing caps of the SMPS output decrease in value to low uF values.They are subjected to substantial ripple levels and often fail.I have seen 1000 uF caps measure only 100 uF.This causes considerable ripple in the DC power rails and all manner of apparent circuit faults.If you have a Cap test mode on your DMM, it should show you this.Any E Cap that measures ~10% below its label value should be replaced.However for SMPS, the ESR value of a cap is important too.This can only be tested with a meter that shows the ESR value.Some people go for a overall replacement of the caps, I will measure a few outside the SMPS, but normally only replace SMPS caps with same value Low ESR types.

author: marshallh
author_rank: Unknown
timestamp: November 24, 2014, 12:43:02 am
content: Replace them all.Get on digikey and find replacements using parametric search within the Panasonic FC/FM series.You can test them individually, but if you have to desolder them anyhow, just put a new one in.

author: EMUD
author_rank: Regular Contributor
timestamp: November 24, 2014, 04:31:09 pm
content: Hi,often this is a problem with the xformers of the backlight cfl. I have seen a lot of them in your screen. You may check secondary and primary with a ohm meter and compare them, a difference more then 10% is bad. There is normally no need to desolder them check them.Good luck!EMUD
Grundig MO22 / Siemens D1011 service manual needed - Page 1
Forum section: electronics / repair

author: phil
author_rank: Regular Contributor
timestamp: November 21, 2014, 11:14:51 am
content: Hello,I recently got aGrundig MO22 20MHz scopeby luck - absolute beauty! However, it is way out of spec and needs some recalibration.The problem is: I could not find any service (or even user) manual for this scope. I know that it was sold under the name "Siemens Oszillarzet D1011", too.Does anyone here have a service manual or other documents for this scope?Thanks in advance,phil

author: phil
author_rank: Regular Contributor
timestamp: November 23, 2014, 02:42:12 am
content: Never mind.I took it apart to see whats inside - and was very suprised. It was my first time taking a Grundig apart, so I did not know what to expect. This scope is especially designed to be repairable. The front plate is split into modules that plug into a frame. That means that you can take out a board without having to unscrew any knobs. The corresponding front plate segment just comes off, too.Also, there is some excessive silk screening that is nearly as good as a service manual with explaining whats going on. All pots have a description printed besides them. Recalibrating the unit was easy with that.This is a late 80ies unit afaik. Even though it has only 20MHz BW they added a delayed time base and replaced the horizontal selector switch with a digital solution. And that solution comes with a horizontal auto set functionSuch a bummer that I cant find any documentation besides a schematic.
LCD Monitor Repair Suggestions, Symptom Washed Out Image - Page 1
Forum section: electronics / repair

author: dnyberg
author_rank: Contributor
timestamp: November 21, 2014, 03:16:14 pm
content: I was recently given a monitor with problems, and as I currently have more time than money, I'd like to try my hand at fixing it; no tragedy if it seems impractical. It was destined for the trash anyway.It's a Hyundai D90+, an older, modest quality 19".I'm familiar with the rule of thumb that "90% of LCD faults are bad caps in the power section", so if the symptom were consistent with that, we gamble a couple dollars worth of caps, swap em in, see if that worked. Dave did that in one of his episodes, in fact.The symptoms on this unit are that it works perfectly, except that the image is very bright and washed out. Owners called it "bad focus/fuzzy", but I'm not sure there's actually a resolution problem there. On screen brightness/contrast controls have a slight effect only.I'm wondering if this less common problem has a known likely cause? Any thoughts or suggestions?

author: ruffy91
author_rank: Regular Contributor
timestamp: November 21, 2014, 03:49:52 pm
content: IMHO it's the contrast voltage thats too low. Look on the power supply for a negative voltage (normally between -15 and -25V).

author: dnyberg
author_rank: Contributor
timestamp: November 21, 2014, 03:54:18 pm
content: Ah, interesting. So though the symptom is less commonly seen, you're thinking it might still be power supply related? That might be feasible to fix. Thanks!

author: Rasz
author_rank: Super Contributor
timestamp: November 22, 2014, 08:19:48 pm
content: look for AS19-HG on tcon board
philips TV main board: A nice challange .. - Page 1
Forum section: electronics / repair

author: saronno
author_rank: Regular Contributor
timestamp: November 19, 2014, 04:46:45 pm
content: I am trying to troubleshoot a philips lcd tv main board. This board is based on a mips32 processor PNX8543.There is no t-con board because it's all on the same board.The board is booting (I have access to the serv.u. port that is a serial port actually and I can see the log),audio is working, remote control too and the backlight is up and running.The problem is the lvds signal. At first I tought it was a cable problem ... no, no signal on the cable (of course I have a scope).Then I checked the output of the timing chip (lg8500f ... i can't find a datasheet ... anyway it take the lvds signal fromthe main processor, make something with it and send it to the panel) ... no signal.Actually this is what I expected, no surprise. Then I check the output from the main processor ... no lvds signal ... what?This is unexpected since it can't be faulty ... it's working.My guess is that it expects a feedback from the timing chip or the panel or something like that. Or maybe there is a softwareproblem or a corrupted chip containing the params he needs ...Any experience with this kind of problem?I have also the rest of the manual with the schematics B09A, B09B, B09C but it's a bit difficult to put it here at a good resolution.

author: saronno
author_rank: Regular Contributor
timestamp: November 22, 2014, 01:57:35 pm
content: This is the log from uart ...http://pastebin/WQ0Ag90n
Weller DEC 1001 station repair - Page 1
Forum section: electronics / repair

author: Leadfootin
author_rank: Contributor
timestamp: November 21, 2014, 03:46:56 pm
content: I have a Weller DEC 1001 dual temp controlled station. Both boards have failed, possibly from a power surge and I would like to repair or replace them. Alternately I could make new control boards.Anyone have a good circuit for a temp controlled iron? 24V ac in, 2 amp max to iron.
Leader 718-20D/GW GPR 1820-HD Info help needed - Page 1
Forum section: electronics / repair

author: Potential
author_rank: Newbie
timestamp: November 20, 2014, 04:07:06 pm
content: I have been unable to find any schematics on the net for either or both of the following supplies, (Both are basically the same supply (made by GW)):- Leader 718-20D- GW (Instek) GPR 1820-HDI'm in the process of repairing one. The only information that is available are the user manuals.They only show the adjustment pot outlines for calibrating the units. I've tried in the past inquiring from both GW Instek and Leader. The only thing they will give out is the user manual.Would like to find a real schematic.If no one has a schematic, but actuallyownsone of these, I need the actual part numbers of the each of the Op-Amps on the main control board. This would require someone to open theirs up and actually look. My main control board is labeled as GPR-797A-1.Thanks in advance for any help!
Dim oscilloscope screen - Page 1
Forum section: electronics / repair

author: yugu
author_rank: Contributor
timestamp: November 18, 2014, 09:44:33 pm
content: (I posted this post in the test gear forumhttps://www.eevblog.com/forum/testgear/dim-oscilloscope-screen/before I realize this may be a better place.)Hi guys. I bought a $50 analog oscilloscope from ebay (I'm a fan of Dave). It's Instek GOS-635G. It works fine except that the screen is quite dim. When I turn the intensity knob up from the min position, the screen doesn't show anything before 70% position. From 70% to 90% position, the brightness keeps going up. And then it starts to drop if I continue to turn it up. So the maximum brightness happens when the knob is at 90%. But it's still very dim. I can barely see the trace.Does anybody have any clue about what's wrong and how to fix it? I am wondering maybe there's something wrong with the potentiometer (it feels smooth though). But would like to hear what you guys have to say before I open it upThanks!

author: lowimpedance
author_rank: Super Contributor
timestamp: November 18, 2014, 10:21:57 pm
content: Follow the replies in the other thread, and as you suspect check the intensity pot. Perhaps post a photo of it so we could see if its a special or just a generic style pot. (ie sealed , open , high voltage rated etc)

author: oldway
author_rank: Super Contributor
timestamp: November 19, 2014, 11:54:13 am
content: Follow the replies in the other thread too, and it seems to be a faulty crt. (low cathode emission)If HV stabilisation is faulty, pattern expand with higher brightness ajust.Low cathode emission was a common fault in crt TV sets and HP digital scopes with crt, but I have never seen any analog scope with this fault.
Circuit or repair tips for Meggar MIT310 - Page 1
Forum section: electronics / repair

author: all_repair
author_rank: Frequent Contributor
timestamp: November 19, 2014, 02:40:14 am
content: Come across a few of these testers, Meggar MIT310, that are defective. Anyone come across a technical manual or has some experiences to share on repairing this meter.

author: tautech
author_rank: Super Contributor
timestamp: November 19, 2014, 05:56:23 am
content: Quote from: all_repair on November 19, 2014, 02:40:14 amDon't you mean Megger not Meggar?

author: retiredcaps
author_rank: Super Contributor
timestamp: November 19, 2014, 06:11:11 am
content: No experience myself, but if you post clear focused pictures of the inside and explain what is wrong, we can try to help?
Could it be these resistors, or should I suspect one of these tiny caps - Page 1
Forum section: electronics / repair

author: guitchess
author_rank: Regular Contributor
timestamp: November 18, 2014, 01:05:59 pm
content: I'm trying to fix this dumpster dive TV without guessing and replacing whole boards. Someone else has tried that because the box that the set was found in contained an extra power supply board.Prelim details.1. When power is applied, nothing. No flashing LEDs, sounds, smells, etc.2. When opened, there are no obvious signs of damage. In fact, the set looks brand new.When I test voltage, the P board is supplying 4.3 volts on the standby pin when everything is connected. According to the service manual, it should be around 5.8v. When I disconnect the A board(main board in Panasonic terms), the P board output jumps to 6.5v. Which led me to believe that something on the A board was drawing too much current.On the A board, voltage stays at the 4.3v all the way to IC5000, which leads to my main question(for now). The two resistors in the partial schematic are shown to be 1% tolerance, and in circuit neither tests within spec(they are both more that 10% out). First, do you think is this situation that it would be necessary to remove them from circuit for an accurate read? They are so tiny I doubt I will be able to reinsert them if they are not the issue, that is, if I don't loose track of them as soon as they're out of circuit. Second, do you think that these resistors being lower than spec would cause the voltage to be lower than spec thereby not letting the set power on?The service manual that I am referencing came from here.http://www.csweb.lar.panasonic.com/viewing/NA/TC-L32X5/SVC/MTV1202010CE_PRINTDB/NEW_TC-L32X5.pdf

author: guitchess
author_rank: Regular Contributor
timestamp: November 18, 2014, 01:14:00 pm
content: FYI, the 22k tests in circuit as 19.4k and the 56k tests at 39.3k.

author: wraper
author_rank: Unknown
timestamp: November 18, 2014, 02:38:27 pm
content: They are unlikely to be faulty but shunted by surrounding components which gives you lower reading.

author: EMUD
author_rank: Regular Contributor
timestamp: November 19, 2014, 04:34:18 am
content: Hi,resistors normally raise their value when they are gone.EMUD
SCR Thyristor Question? Replacement & Cross?  - Page 1
Forum section: electronics / repair

author: KG7AMV
author_rank: Frequent Contributor
timestamp: November 18, 2014, 01:31:20 am
content: I need to replace a couple Littlefuse S4010LS2 SCR's I do have a tube of MCR310-10 SCR's not sure if they would be an acceptable / comparable replacement? I know in the littlefuse cross chart the MCR310-6 crosses to S4010LS2 but dont list a cross for a -10. Would going from 400V to 800V on the Peak Repetitive Forward and Reverse Blocking Voltage be to big of an issue?Little Fuse Data Sheet,http://www.littelfuse.com/data/en/data_sheets/littelfuse_thyristor_sxx10xsx_sxx10x.pdfON Data Sheets,http://www.onsemi.com/pub_link/Collateral/MCR310-D.PDFLittle Fuse Cross Page 18http://www.littelfuse.com/~/media/electronics_technical/cross_references/littelfuse_thyristor_triacs_scrs_diacs_sidacs_rectifiers_cross_reference_guide.pdf

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 18, 2014, 10:26:21 am
content: The MCR310 does not specify t_q so I presume it's intended for line frequency switching only. If that's what the application is, it shouldn't be too bad. It also has a very sensitive gate, comparable with the -S2. dV/dt is also inferior, so if the application requires snubbing, it will likely require a more aggressive value.Tim

author: KG7AMV
author_rank: Frequent Contributor
timestamp: November 19, 2014, 02:21:38 am
content: T3sl4co1l, ThanksThis SCR keeps popping after some time it seems to be the weak link!. So I was thinking of bumping up either the voltage or the amps or both but even in the past never messed with Thyristors except for just some rework in the cable tv industry so learning about them!The MCR310-10 SCR's were a standard part that failed in Cable TV Head End Amps stuff I used to repair over a decade ago. They were such a common failure we installed 3 pin terminal strips plugged them in and screwed them down! But the engineers at scientific Atlanta just supplied the upgrade parts list when we had the amp open we did the work.
Sencore SC61 square wave causes DMM error - Page 1
Forum section: electronics / repair

author: Cyberdragon
author_rank: Super Contributor
timestamp: November 18, 2014, 07:40:45 pm
content: The internal DMM errors out with random numbers from 200 to 800 (depending on the actual frequency) if you feed in a square wave under 2KHZ and try to read frequency. I input 20HZ and it reads 200 to 400 jumping randomly. 200HZ reads 500 to 800 randomly. The wave is perfectly stable on the screen though. It does seem to read ok with a sine wave and above 2KHZ square wave.The scope was working before, it just recently started doing this. It was intermittent at first, but now it's permanent so something failed.I don't have the service manual, only the calibration manual. (I couldn't find any others) Any manuals or advice will be appreciated.
Old Melag autoclave with tecsis pressure sensor, where to get replacement part? - Page 1
Forum section: electronics / repair

author: tolland
author_rank: Newbie
timestamp: November 15, 2014, 05:24:44 am
content: Hi all,we have a fairly old (2001 model) Melag Autoclave, and today it caused the breaker to pop when it was powered up. I was actually in the process of investigating errors on its vacuum test when it completely malfunctioned. It was consistently tripping the breaker, or the RCD plug that I was using.I isolated each of the parts and identified that it was actually the pressure sensor that was causing a residual current between its 24 V DC line and ground and tripping out. However its a sealed unit, and it doesn't look like I can get inside it, other than for post mortem purposes.The pressure sensor appears to be a tecsis 3296.073.149 which uses a 24 VDC line as power, and providing a DC 0-10 V over 0..4 bar for its signal.http://www.yuden-tech.com.cn/catalog/tecsis/3296.pdfhttp://www.farnell.com/datasheets/320169.pdfUnfortunately I can't find anywhere that stocks that part. The nearest thing I can find is this;http://uk.rs-online.com/web/p/pressure-sensors/0178695/however that is quite pricey, and is going to be about 140 GBP including shipping. I was wondering if I have any other options... to get a 10 V DC signal for 0..4 barCheers,Tom

author: N2IXK
author_rank: Frequent Contributor
timestamp: November 17, 2014, 08:27:17 pm
content: 24VDC powered pressure transducers with a 0-10V output are pretty standard industrial fare. But industrial instrumentation doesn't come cheap, and safety critical parts on an autoclave are no place to pinch pennies.Omega Engineering in the US is a good source for this kind of stuff, but this isn't the kind of component you are going to get "cheap" outside of a lucky score from a surplus supplier or eBay.