CURVE TRACER REPAIR - ASA HW-210K - Page 1
Forum section: electronics / repair

author: BTO
author_rank: Frequent Contributor
timestamp: March 15, 2025, 02:18:54 pm
content: HI GUYS....BACKGROUND INFORMATION :I've been looking into curve tracers for the last half a year or so , I came across this Ebay Jobbie, Model Number : ASA HW-210K.I Ordered 4 , 2 for me , 2 for a mate.off the 4 only 2 worked, Actually 3 worked originally but then due to over current (I assume) one of them (Included in this post) Burned out and WE GOT MAGIC SMOKE LOLThe idea of this post is to get assistance in repairing these. I imagine if we pull this off it will help many others.Obviously the parts that are burned out need to be replaced,Now we have 2 situations hereSituation 1 - 1 of the units was delivered inoperable , it won't switch, it won't produce a waveform when in Y-T Mode on the scopeSituation 2 - The other unit is completely friedI want to perhaps reverse engineer this unit or identify the compoents so we can replace them and get this working againTHE PROBLEM :The Bastards have scratched the markings offMY THEORY :This basically is an Octopus circuit, right ?I'm guessing it shouldn't be too hard to reverse engineer or figure out the components that should be on it.I'm hoping i can get some help from the forum from those who are more familiar with this circuit and in turn hopefully figure outwhat components can be used to replaced the burned out ones and in the case of the unit that powers on but doesn't produce a waveform and doesn't switch between frequencies,i'd like to troubleshoot this unit.I have 32 Detailed Photo's that no doubt i will have to attach in Multiple posts.so here we goPhoto 1 - The Faulty Unit (Front Face) as i received itNow let me explain the connectors and buttons before we go aheadThe Top left input jack is Power, Centre Positive, it requires 24V DC on the output and up to 1500mANext to that is the BNC For Channel 1Next to that is the BNC for Channel 2Right at the bottom we haveRED BLACK BLUE input jacksThe unit is capable of taking measurements between Red and Black (Mode A) and Blue and Black (Mode B)Above that you'll see an A/B Button. when this button is pressed it switches (as you may have guessed) between the 2 modes.it literally alternates automatically between the 2Now the 2 lights to the left of that signify which Mode you're inTo the far left there is a POT, this pot Adjusts the Frequency of the switchingAbove that we have 4 Blue buttons labelledLOW MED 1 MED 2 HIGHAbove that there are 4 Led's respectively to indicate which mode is onNow.. these meters are not really clear on what they do and the manual is useless.so i figured it outThe buttons use alternate frequencies to conduct Tests.since i have 4 of them i was able to compare them.they are similar in frequency, but not identicalLOW = 20 HzMED 1 = 225 HzMED 2 = 2 kHzHIGH = 15 kHzPhoto 2 - I've attached labels to make things clearerI'll now start a new post for the teardowns

author: BTO
author_rank: Frequent Contributor
timestamp: March 15, 2025, 02:40:47 pm
content: OK so nowPhoto 3 - Side by Side comparison of both Non functional meters.You'll notice the unit on the left (Even though identical Model Number) Has 2 Capacitors but no Bridge Rectifiersand the unit on the right no caps but 4 bridge rectifiersso the unit on the left is the one that Powers on (Power Light comes on) while it has the correct voltage 24 Volt 1500mA DC Power supply, but no switching occurs and no waveform is present on the scope.I have taken the liberty of desoldering the jacks on this so i can see all the componentsThe unit on the right is the burned out unit, which occurred because i initially did not have a 24V 1500mA Supply, but instead i had a 24V 4A , Now it shouldn't have drawn more current than it needsso i figured it'd be fine.. but.. it wasn'tPhoto 4 - Close up of the RIGHT unitPhoto 5 - Close up of the LEFT unitPhoto 6 - Close up, RIGHT (Burnt Unit) - Top Right cornerPhoto 7 - Close up, RIGHT (Burnt Unit) - Top Left cornerPhoto 8 - Close up, RIGHT (Burnt Unit) - Bottom Left cornerPhoto 9 - Close up, RIGHT (Burnt Unit) - Bottom Right cornerill now start a new comment

author: BTO
author_rank: Frequent Contributor
timestamp: March 15, 2025, 02:50:14 pm
content: Photo 10 - Close up, LEFT Unit - Top Right cornerPhoto 11 - Close up, LEFT Unit - Top Left cornerPhoto 12 - Close up, LEFT Unit - Bottom Right cornerPhoto 13 - Close up, LEFT Unit - Bottom Left corner

author: BTO
author_rank: Frequent Contributor
timestamp: March 15, 2025, 03:01:40 pm
content: Ok now the (i think) this 5 legged do whacky is not a MOSFET but instead some sort of power regulator. Markings are scratched offPhoto 14 - Power RegulatorPhoto 15 - Electrolytic Capacitors 25V, 470uFPhoto 16 - IC's on the LEFT Unit , all the main IC's seem to have scratched off Markings, it would be cool to know what these areI haven't tested any of them yet but i plan to. any advice would be appreciated(Note this is the faulty unit that doesn't produce a signal)Photo 17 - close up of one of the IC'sPhoto 18 - close up of one of the IC'sPhoto 19 - close up of the 2 IC's

author: BTO
author_rank: Frequent Contributor
timestamp: March 15, 2025, 03:08:47 pm
content: Photo 20 - The bottom side of that potentiometer that controls the switching frequency to the A/B channelPhoto 21- Bottom view of the board out of the coverPhoto 22 - Close up of the boardPhoto 23 - What i thought ws 4 Bridge rectifiersbut now turns out they are COTO Reed RelaysDatasheet :https://www.digikey.com.au/en/products/detail/coto-technology/9007-12-00/301698?srsltid=AfmBOoq3JxWSAIvXCPGKQDU45kr1TCgVPWfBiTUhN_GP6ikLhrgKDn9yPhoto 24 - Primary RelayPhoto 25 - Primary Relay Close up

author: BTO
author_rank: Frequent Contributor
timestamp: March 15, 2025, 03:15:59 pm
content: Photo 26 - Close up of Trim Pot 5k OhmDatasheet :https://au.mouser.com/ProductDetail/Bourns/3006P-1-502?qs=%2FCfpRHMDaeiBZLVxtBFJxw%3D%3D&srsltid=AfmBOood_z37YfJN3lUvYH4tBlcncy7xtcWYxUlL2nj9Z8gnliPiEPXOPhoto 27 - 100k Trim Potentiometerhttps://leobot.net/viewproduct.aspx?id=17&srsltid=AfmBOoptnP-sQJ4Nenndeoz0z6EcAzF4vhpjz_ZHif9ac_sywjB6aI4UPhoto 28 - 10k Ohm (103) Adjustable Trim PotPhoto 29 - Burnt out BoardPhoto 30 - Another close upPhoto 31 - Close up of RelayPhoto 32 - Relay again

author: BTO
author_rank: Frequent Contributor
timestamp: March 15, 2025, 03:18:07 pm
content: OK, so what do we reckon guys.GOALS :1 - Attempt to , By any means necessary identify the components so that we can purchase replacement components and make the faulty units working again2 - Possibly reverse engineer the entire board, i'm happy to give that a crack , i feel i have enough experience to do that , Perhaps with a little assistance, i think it'll be fun.SO WHAT ARE YOUR THOUGHTS ?You can reckon we can bring these units back to life ?EDIT : Ohh i forgot.I reckon these curve tracers are worth fixing because the 1 that i have that does work, Works beautifully.I've tried others. and ... Without having to fork out $3k to $4k for a curve tracer, i think these are brilliant, Especially since they have adjustable frequencies.so yeah, i would love to get these working again, if possibleEDIT again :This youtube video has proven to be useful

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: March 15, 2025, 08:27:40 pm
content: Hello BTO,Starting drawing the schematic would certainly help to identify the unknown parts.Then you'll need to poke inside the circuit to identify voltages and waveforms. Of course this is only really possible with a working unit.These testers have often multiple grounds, so consider using an isolated oscilloscope to avoid destruction of a working unit.I also noticed that there are different versions of the motherboard, which of course makes the reverse engineering more difficult.Failure seems to occur at different locations which denotes a not state of the art design. To gain some reliability, the exisiting schematic will probably need some improvement.I would suggest to start at picture #6 : the TO220-5 part + 4.7µH inductor might be aDC-DC switcher.

author: BTO
author_rank: Frequent Contributor
timestamp: March 16, 2025, 10:58:32 am
content: Quote from: timeandfrequency on March 15, 2025, 08:27:40 pmQuoteI Agree and i've already started reverse engineering it slowlyQuoteExactly.. Also what i was thinking and i've already started to do that as wellQuoteNo need to worry here i think.The Power supply is a 2 Pin (Active and Neutral) (Australian Residential) so.. 240V AC @ 50Hz, There is no Earth pin on the supply.The supply itself is isolated as a result of the Primary Transformer to the DC Side of the power supply.The only thing i migh poke a stick at is... The Outer shield of the BNC Connecters, As they would be connected to the Scopes Ground.Although, i wouldn't be too worried here and this is easy to check anyway.QuoteIndeed...Let's call it BOARD 1 (The Burnt out Board) - Has the Unique Number of 1086496A_Y35_240920and.......... BOARD 2 (The one that was delivered faulty ) has Unique Number of 1423452A_Y25_241221Make what you will of this, i would interpret it as FIRST PART(Serial Number)_YXX(Version Number)_(Revision Number)but then.. that's a wild guess as wellFrom what i can see so far- 1086496A_Y35_240920 (The Burnt out Board Has these 4 thingy's that Look like Bridge Rectifiers), They are actually Relays, Also Denoted by "K1" on the PCBFor anyone out there who is new to the conventionL = InductorC = CapacitorR = ResistorT OR T2AL = FuseBR = Bridge RectifierXTAL = Xtal OscillatorD = DiodeandK = Relayso they are 4 Relays. and they are connected to that I.C. that is Below the Y Input (BNC), The 14 Pin D.I.P. (For the newbies, DIP = Dual In Line Package) which is a through hole component.For the newbies (for More information on Chip Package Types)https://en.wikipedia.org/wiki/List_of_electronic_component_packaging_typesNow when i look at the 1423452A_Y25_241221 Board (Faulty on Arrival, Let's call it), in the place where the 4 relays should be there are 2 SMD I.C.'s(For the newbies.. SMD = Surface Mount Device).Now each I.C. is an SMD 14 Pin S.O.I.C. . My logical initial conclusion would be that these are 2 Dual Relay Packages.if each relay is using 7 Pins and 2 have to be for VCC and GND, we are left with 5. that sounds about right...2 for the coil and 3 for the other side to form 2 circuitsNow when i examine the Datasheet for the relays (COTO) (Post#4) also attached here,and i examine the pinout and contact diagram THIS RELAY ONLY USES 4 4Contactsso perhaps that last pin is either a GND or N/C (For the Newbies... N.C. = NO CONNECTION)so i reckon those 2 I.C.'S Are the 4 Relays in a dual Relay package. Given that i have the datasheet for the other relays i don't think it's gonna be hardEstablishing which chips to buy for this purpose. I don't know yet. But i reckon that's probably those 2 out of the way. (Almost)QuoteNOT GONNA LIE....... YOU'RE GETTING ME EXCITED NOW...Can we really ? can we huhBut yeah.. it did notice that, I did find it strange that it blew at the bottom of the board where the probe contacts were as well as the top where the Power supply input was.I also had an idea to integrate a Diode at the input on the Positive rail (So at the least) You can't reverse polarize itAlso.. I'm happy to reverse engineer this board and make changes to it and make it better and then manufacture it through a fab house and get the schematics and Gerbers ready.No problem... it'll be funUltimately, i think it's a simple circuit, it looks simple, it's a Dual Layer board and doesn't seem to have many traces and the traces seem rather thin (in my opinion) althoughi'm not an Electronics Design Engineer.The entire board seems to have 78 Components on 1 side and 12 Components on the other side, of that, i would say around 80% of the board is SMD's that have easily obtainable valuesOther ideas that i'd like to vocalizeLet's discuss the differences in the boards for a secondPhoto 3 - The burnt out Board on the right has 10k Ohm Pots at the top where as the board on the left does not.in the youtube video that i attached, the Author of the video said that these pots were there to adjusting the clipping of the signal.Given that 1 pot is next to the X BNC and the other next to the Y BNC that might make sense.Now Looking at those 2 Caps on the right board they are 470uF , 25V each.and looking at the left board there are 2 Caps as well , they are the same values but not in the same position.On board 1 there are 2 Caps up the top near the Power Input JackOn Board 2 there is what seems to be a power regulator in that position , But after the power reg we have those Capsboth boards have a power reg (seems to be the same component)Board 1 also has a Pot before the Power Reg and an Inductor (SMD) After the Power RegBoard 2 doesn't appear to have any Pots whatsoever, I would say Board 2 1423452A_Y25_241221 is the one where they cheaped out on the B.O.M.for the Newbies.. B.O.M. = Bill of Materials / aka List of parts on the board)So overallBottom to topThe Red, Blue, Black Jacks seem identicalThe big Blue relay is the sameThe pot on the right side is the same on both boardsall other components on the LOWER part of the board are identicalEXCEPT FOR 1 , Part R20 A Resistor with a value of "0" so.. A Dead shortso the lower part of the board seems mostly identicalthe input power part of it seems the same exceptBoard 1 has adjustment pots (which may be useful but perhaps not necessary)on the UPPER side of the board all the SMD's appear the same Except for the followingThe left board... The resistors to the left of the IC under the X Terminal has R45 and R46 (2 extra SMD resistors) it's 2 203 (20k Ohm) resistorsthen the right board has 3 SMD Capacitors at the power Jack and the left board only has 2The left board has 4 SMD Resistors after the Voltage Regulator the other board has nonenow for the middle of the boards, there are many differencesThe right board has those 3 large black reed relays as well as Q1 , Q2 Q3 and Q4 I imagine these are TransistorsThe left board doesn't have transistors it has 2 IC's surrounded by SMD Capacitors and resistorsand on surface value, those are the differences between the boardsSO FAR IT SEEMS LIKE IT WOULD BE PRETTY EASY TO REVERSE ENGINEEROh and as for the bottom of the board.... PFFT, Nothingthere's a few micro switches.. no biggie4 SMD LED's, No biggie here eitherThere's a PotNothing really to worry about on this side of the boardso that's where i'm up to

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: March 16, 2025, 12:52:15 pm
content: Quote from: BTO on March 16, 2025, 10:58:32 amMaybe you can check if the negative power rail at the 24VDC barrel jack is connected to the BNC grounds.In the negative, you already have 2 GND's on the board and the TO220-5 is probably not a DC-DC switcher as stated earlier, but a power OPAMP that splits the 24 VDC into ±12 VDC, hence the two identical electrolytic caps.If something goes wrong with that bipolar power supply, the SOT223 part at the bottom (LDO regulator ?) fries, and the S014 part at the top (quad opamp LM324 ?) too.Check with the reference of the reed relays if those are 5V, 12V or 24V coils.Other links to curve tracers :https://www.ebay.fr/itm/384724097923: this one has the series resistors that can be selected manuallyhttps://www.eevblog.com/forum/metrology/v-i-curve-tracer-component-tester/image 'IMG_1263' : again the same TO220-5 part but there's a transformer upstream.

author: BTO
author_rank: Frequent Contributor
timestamp: March 16, 2025, 01:34:16 pm
content: Quote from: timeandfrequency on March 16, 2025, 12:52:15 pmQuoteAbsolutely...I can CONFIRM it is NOTQuoteActually..... YOU'RE RIGHT, I forgot about , it needs a Negative and Positive because when working it's in X-Y Mode.somehow that skipped my mind. Yeah that sounds correctQuoteYES, that appears to be exactly what has happenedand i checked the datasheet for the LM324, Pin 4 and Pin 11 Are VCC and GND, directly opposite each other, Directly IN THE MIDDLE OF THE I.C. and that is exactly where that very clearly burn linehas occured. So i'm guessing we also had a Short circuit, otherwise, How else would VCC and GND Blow ?OK, so i can compare the Datasheet of the LM324 and confirm if the pins on the mystery IC Match up........ CoolI can do the same for the SOT223Quotesure.... the exact markings on them are9007 - 12 - 00COTO - 0418 - MNDigikey says 12Vhttps://www.digikey.com.au/en/products/detail/coto-technology/9007-12-00/301698?srsltid=AfmBOorRS6Q0T_NziVM9dyW1aLYbq9QvWQjFXIRWvdkttonYM93BECSuDatasheet says the naming convention is...9007 - XX - X XModel Number - Coil Voltage - Magnetic Shield Option General OptionssoModel 9007Coil Voltage 12 V (which makes sense why i have a 24V DC Supply)No shieldNo DiodeI'm working on the schematic and Reverse EngineeringI'm working on the B.O.M.I think so far we are probably on the right track.Thanks for your help so far, i knew it was a good idea to get another opinion before i started this

author: BTO
author_rank: Frequent Contributor
timestamp: March 16, 2025, 02:02:19 pm
content: Quote from: timeandfrequency on March 16, 2025, 12:52:15 pmRe the Link to the other curve tracer on ebay.From the French link you supplied it didn't ship to Australia (Sydney) so i went herehttps://www.ebay.com.au/itm/385405633702The price wasn't bad, all things considered, so i bought 2 of them .1. it's from the same company but seems to be a different model2. Yeah all the components seems to be the same don't they .3. I thought it'd be cool to compare those components with the one's in my unit at the moment4. Also i wanted to compare the frequencies used in this new purchase compared to the one's that i havethanks for the link

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: March 16, 2025, 02:22:49 pm
content: Great, that's already a good start.For your BOM, check out the TO220-5 layout against the TDA2030 datasheet. It's an audio power amp. Known to have a tendency to oscillate. So not sure if it's the right part. But it has the same pins than a vanilla opamp so it is a good candidate to devise a virtual ground.About the video I provided above : the youtuber suggested the DIL14 part could be a NE556 (= dual NE555).The A/B channel auto toggle signal (probably variable between 2 and 10 Hz) must exist somewhere and using that vanilla timer chip is plausible.It could be the blue relay that swiches between channel A and B.UPDATE:It's coil is 28V and the 24V power supply is sufficient to energize it. So one pin of the blue relay coil must be connected to the +12V rail and the emitter of it's driver transistor (let's assume it's an NPN) must be connected to the -12V rail (which should also be the GND at the barrel jack).

author: BTO
author_rank: Frequent Contributor
timestamp: March 16, 2025, 02:30:04 pm
content: Quote from: timeandfrequency on March 16, 2025, 02:22:49 pmQuoteQuoteAgreed, and worst case scenario i can test it on the blown unit. The worst that can happen is.... it blows again LOL....... No problem.QuoteYes, i heard that. Although i don't know how much weight i would put on it.After all he did also say that people that have more experience can probably confirm that. In any case, i have a 555 Test Circuit that i can pop it into if need be.if it is a 555 LMFAO.. that'd be both funny and cool at the same time.QuoteYeah.. Fair enough. I do know that that part of it oscillates, i do know that the pot Controls the frequency of switching between A and B.I haven't actually taken the time to clock it and see what the Max and Min is. I can probably get around to it

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: March 16, 2025, 02:47:22 pm
content: NE555 and NE556 in astable mode are easy to recognize because the exponential waveform is between 1/3 and 2/3 of Vdd.It is quite sure that the poton the front panelchanges the frequency of the A/B channel toggling.But such a low frequency oscillator can also be generated by a small microcontroller : the pot value is red by an ADC whose converted value presets a digital timer (internal peripheral).Some enlights about the LDO regulatorI selected at Mouser3.3 V and 5 V fixed voltage, 3 terminals positive LDOs in SOT-89 /SOT-223 packages.Unfortunately, among manufacturers, agreeing on a single pinout was not the goal they were pursuing, so all available combinations existTLV1117LV33DCYR GOIAP7365-33EG-13 OGITPS7B6933QDCYRQ1 IGOXC6203E332FR-G GIONCV33375ST3.3T3G ISO; 4 pins connected ; tab is GND; S = shutdownG= GND I= Input O= OutputD5 as clue ?On the fried board, I notice that the free wheeling diode D5 close to the blue relay is in bad shape.Did this allow a voltage spike generated by the coil to race through the supply rails, killing several parts ? Those then shorted to create even more havoc ?

author: BTO
author_rank: Frequent Contributor
timestamp: March 17, 2025, 12:26:02 pm
content: Quote from: timeandfrequency on March 16, 2025, 02:47:22 pmQuotei can CONFIRM that it does. I've tested it.QuoteThanks for the leg work, i appreciate it.QuoteThat HAS NOT gone unnoticed. I have noticed that that Diode is off it's pad on one sideand when i take a reading from Diodes of similar size on the board i get Vf = 0.40 V . But when i take a reading of the D5 Diode or the D1 for that matter, on the board that arrived faulty and doesn't switch..I get a Vf = 0.03 V (Basically a S/C)and that's interesting, i think as a first step i will transplant a Diode .. Say D4 from the board that arrived faulty and sub it out for D5 on the same board, But before doing so.i would test the value of D4 to ensure that it is Vf=0.4VAfter that i'll apply 12V 1A supply to it and if that passes, I'll apply the standard 24V 1500mA supply.Fingers crossed that that fixes it all

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: March 17, 2025, 01:51:28 pm
content: Hello BTO,For D5, that acts as asfreewheeling diode, any vanilla SMD or even THT silicium or shottky dode with at least 30V breakdown voltage will do it : M1 M4 M7 S1M S2M S3M SS14 SS16 SS24 SS26 SS34 SS36 RS1M US1M LL4148 1N4001 1N4004 1N4148 1N5819Cathode has to be connected to thepositive rail.THT = Through Hole Technology (parts with legs/wires)About the black relaysQuote from: BTO on March 16, 2025, 01:34:16 pmAs you have 24 VDC but also 2 x 12 VDC power rails, the latters suit well for the 9007 relays.They can be energied between -12 VDC and VGND or VGND and +12VDC. It depends on how the designer devised his circuit.VGND =Virtual groundgenerated by the TO220-5 part.

author: BTO
author_rank: Frequent Contributor
timestamp: March 17, 2025, 03:19:58 pm
content: NEW FINDINGS... Regarding the conversation we had on"WHAT IS THE SWITCHING FREQUENCY OF THE A/B BUTTON"In short...The slowest Switching Frequency when A/B is pressed is 625 mHzThe Fastest Switching Frequency when A/B is pressed is 5 HzIn more practical terms, Let's define SWITCHING as (From A and then to B) to be 1 Complete Switch.to make this practical we need to standardize both readings over 5 seconds and not 1 second as the slower switch frequency is below 1Hz.By this defintionIn 5 Seconds The Fastest realized number of switches is 15 Switchesin 5 Seconds the Slowest realized number of switches is 2 SwitchesHere are some photosPhoto 35 - Shows the Fastest setting to have an ON time of 200ms, Hence 5 HzPhoto 36 - Shows the Fastest setting and the number of switches over a period of 1 sec.Consider the reading was taken from 1 leg of the Blue Relay only so you can count the ON as A Mode and the OFF as B Mode.Here we can see 3 ON Periods per secondPhoto 37 - Shows the Slowest setting to have an ON time of 1.6 Sec, Hence 625 mHzPhoto 38 - It was not possible to get multiple switches into 1 sec so this photo shows at least 2 switches, 2 Switches occur in 5 seconds or lessPhoto 39 - This photo shows the PERIOD (so 1 complete slowest switch) to be 3.18ms which concurs with Photo 37 . 1.6 x 2 = 3.2 ms ... Close enough (Allow for human cursor placement correction)Photo 41 - Considering this unit is faulty I have tested the legs of this component while the unit was ON, and found the followingFrom Left to Right to pins are6V 6V 0V/GND 6V 12Vthe 6V readings are all Positive DCI also tested the Caps that come after this component and they both had 6V DCTHE ABOVE TESTS WERE CONDUCTED FROM A BENCH POWER SUPPLY WITH 12V DCNOW... SOMETHING INTERESTING HAPPENED- While on 12V DC supply , i switched on the A/B Switch and it worked, Although .. All 4 Blue lights for the 4 Frequency buttons come on (Where only 1 should come on to indicate the frequency in use)- Also, there is no waveform to speak off either- But the switching works- I then, While the switching was clicking away... Turned up the voltage to 24 V DC.The result was not good, I got sparks on the input jack pads- And the switching stopped- I then SLOWLY starting from 12V DC Again, while having the A/B Switching turned on, I slowly turned up the power supply- The Switching seems to stop at 17.3V DCI found this interesting

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: March 17, 2025, 04:40:17 pm
content: Great, now we know that there's a virtual ground.The voltage values you measured is compatible with the TDA2030 and the schematic is probably close tothatChecking out the layout will confirm the exact schematic.As the switching stops above 17 VDC cound mean that a part in the circuit starts to draw too much current. Kind of high voltage breakdown.Just before it stops toggling, what are the voltage at the both electrolytic caps ? Exactely half of the extenal power supply, that is 8.5 VDC ? Or does it become dissymetrical ?And above 17.3 VDC input, which rail breaks down ? The +12V or the -12V ? (reference voltage is VGND).Interesting to see that the switching waveform isOKratherreally noisy but frequency span is within the expected range.Could you track the switching signal ? Where does it come from ? From the DIL14 or the intact SO8 or SO16 parts ?The fact that all of the LEDs are ON simultaneously means that the part that drives those is not healthy.Are the leds connected to the intact SO16 part ?The latter might be a microcontroller, and in that case, replacement is not really doable without an extensive retro-engineeering of the board and write the dedicated source code.I would say that the next step is to draw the full schematic of the board, which is a significant amount of work.UPDATEOn the board that has no black relays, those are probably replaced by a bunch of analog switches.CD4016or CD4066 (in SO-14 packages on the board) are good candiates for that purpose.Check out the surrounding layout against the pinout in the datasheet.

author: BTO
author_rank: Frequent Contributor
timestamp: March 19, 2025, 02:04:09 pm
content: Sorry for the delay and i appreciate your assistance, Give me like 48 hours to get some work stuff out of the way.

author: BTO
author_rank: Frequent Contributor
timestamp: March 26, 2025, 03:45:21 pm
content: I'm back, Appreciate your patienceNow before i get cracking where we left off.UPDATE : that other Curve Tracer arrived.I ordered 2, 1 of them didn't work.What that means is ...- The Model Number is NI-210YJ V6.0 (it actually looks and feels pretty cool)- it has 4 differencing Frequency buttons, LOW , MED 1, MED 2, HIGHThe MED 1 button physically doesn't work and feels different to the others when pressed down- The unit does power on and the power light comes on- However the 4 L.E.D.'s for the Frequency buttons do not turn on- The waveform looks like crap- and Basically the entire rest of the board doesn't respondHERE IS A LINK TO THE VIDEO I SENT TO THE SENDER OF THE PARCELI thought it might be interesting in the interemhttps://mega.nz/folder/Fg9RGAwI#NgXHLG_Ip56H0PTesgDZaw

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: March 27, 2025, 09:34:55 pm
content: Hello BTO,Had a look to your video : at 345 kHz, the master oscillator runs much too fast and the device actually detects its own parasitic capacitance.The issue might come from an unsoldered or wrong value capacitor.Good that you asked the seller for a replacement.Seems that there's not QT on these devices before shipping : if you need one in good health, order at least three

author: BTO
author_rank: Frequent Contributor
timestamp: March 28, 2025, 02:45:39 am
content: Quote from: timeandfrequency on March 27, 2025, 09:34:55 pmThat's exactly why i posted the link to the video, i thought you guys might find this interesting.I mean , First batch i ordered 4 , 2 were faultyNext batch i ordered 2, 1 was faultyso can we assume 50% success rate LOLso yeah, if you need 1 order 3 or 4 to be safe.I imagine the people selling this do not have THE SLIGHTEST CLUE as to what a curve tracer is or how to test it.Anyway, Gotta rush out, I'll be home soonwe'll get stuck back into this shortly

author: sae
author_rank: Newbie
timestamp: March 28, 2025, 09:16:38 am
content: Smells like a Polar T1500 facsimile....https://www.polarinstruments.com/man/service/T1500%20Service%20manual.pdf

author: BTO
author_rank: Frequent Contributor
timestamp: March 28, 2025, 09:51:52 am
content: Quote from: sae on March 28, 2025, 09:16:38 amHi mate. Another Aussie huh .I'm from Sydney, Where you from ?Regarding this Polar T1500, i don't think these ASA Curve Tracer have the same adjustments inside.they actually come in 2 Models 1 has Ajdustment pots and the other doesn'tin any case, i'll check it out, Thanks mate, appreciate it

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: March 29, 2025, 06:18:42 am
content: Quote from: sae on March 28, 2025, 09:16:38 amHello sae,These small curve tracers are just really bad and weak functional copies of valuable and reliable TE from renowed manufacturers like Tektronix, Polar Instruments (as you mentioned), Huntron and Hameg.Execution is rather crappy, electronic design is close to bullshit, QC and service documentation is nonexistant.BTO’s counts show 50% of units defective at delivery.Curve tracers are TE intended to ease electronic repair of various equipement and appliance. But what I mostly see on this forum aredefective tracers that actually need repairChicken and egg problem.I have to admit that they are pretty cheap, but due to their flaws,none of them is a bargain.In an electronic lab, the most important features of TE are trust and reliability.No one can explain this better than Dave (also from Sydney) :

author: BTO
author_rank: Frequent Contributor
timestamp: March 29, 2025, 11:41:01 am
content: Quote from: timeandfrequency on March 29, 2025, 06:18:42 amQuoteyeah, but there's not much to service either.Even with this current model that i'm troubleshooting ON THE SAME MODEL NUMBER... i type has pots for Adjustment and another type does not.there really isn't much to serviceQuoteYeah and i dare say if i ordered 50 or 100 Units i would see a higher failure rate. i would say it would be closer to 60% or 70% the way it's going.Quoteand that's exactly why i started this thread..... So we can fix this stuff ourselves and not have to worry about sending it back.QuoteI would agree. but the way i'm approaching this is... before i go drop $4,000 on a quality Curve Tracer i want to see what the cheaper one's are like.i want to learn more about them , Sometimes the cheaper ones are pretty good and i didn't want to dismiss thatQuoteAbsolutely !!!it's also a question of HOW ACCURATE do you need to be on a certain test, Not everything requires 15 Digit Resolutionand my understanding with a curve tracer....... and .. correct me if i'm wrong ... and.. after i finish this thread and we work out all the kinks.i plan on starting another thread where we use the curve tracer in detail to test components to the level of ....Lets measure the resistance value of a resistor based only on the characteristic curveLet's measure a capacitor and it's valueLet's measure an inductor and it's value (i saw an interesting thing yesterday between 2 tested inductors) 1 had a curve like a parallelagram and anotherhad a curve like a leaf and one of them the higher you went up in frequency, Developed a kink in the middle of the curve. it turns out this kinkwas a ringing of the inductor. (Anyway, that's a story for another time)but i agree reliability is important and i want to see if these things are reliable. or .. if we can improve them to be reliableBasically, i just want to tear this thing apart and reverse engineer it and learn more about it.but ultimately... if it's utter garbage, i'm gonna bin it and possibly keep the parts as (like you) i don't have a place in my lab for unreliable equipmentand untrustworthy equipment.

author: BTO
author_rank: Frequent Contributor
timestamp: March 29, 2025, 05:27:58 pm
content: OK i'm back into it again.So i've started Reverse Engineering, I haven't got it onto Schematic yet, it's 4am and i need some rest.but see the Attached Photo's for the basics of the Power Input Side of things.For now i've just done this on Word and taken a screenshot of the previous component Obviously from this point it goes to the capactiors.but at this stage, i would just like to Identify that Component , which i think we already have . Then i'd like to buy the assumed part and sub it inand see if it works or something blows up.

author: BTO
author_rank: Frequent Contributor
timestamp: March 29, 2025, 06:10:16 pm
content: HOW INTERESTING IS THIS......Just as a sort of aside from the main project here but slightly relatedBrief Explanation :I was testing a Zener Diode on the curve tracer .I was using the ASA HW-210Kbut since my NI-210YJ_V6.0 Came in (which i suspect is also from ASA)i thought i'd test it as wellI GOT DIFFERENT RESULTS ON THE SAME ZENER DIODESETUP :So to be clear , i have two C.R.O.'s a Tek 2235 100MHz and a Kikusui COS 5041 40MHz (Both Have X-Y Mode) that goes without sayingNowSince i was getting different results ON THE SAME ZENER, i wanted to find out- Did my C.R.O.'s Accidentally fall out of Cal and i moved the Cal knobs- Was it the probes or the cables or...- Was it the Curve Tracers themselves- Were they not adjusted correctlyso.... to be clear and accurate- From my Rigol MSO5000 i generated a Sine Wave , 2V , 1kHz- As reference so the Rigol Sig Gen was not out, i connected The same Coaxial Cable with BNC's that i will later use. this was connected to my Rigol DS2000A on Channel 1Everything lined up perfectly with the cursors and frequency counter.. 2V, 1kHz on the nose- Then i disconnected that Coaxial from Ch 1 of my DS2000A and put it in Channel 1 of my Tektronix 2235 (Obviously in Y-T Mode). Everything was bang on, i didn't need to change a thing. CAL WAS GOOD- I then moved that Coaxial to Ch 2 of the same scope and again everything was bang on and CAL WAS GOOD- I then returned my Tek 2235 to X-Y Mode and disconnected the Coaxial from Ch 2 of the Tek to Channel 1 of the Kikusui and put the Kikusui in Y-T Mode. Everything was bang on, CAL WAS GOOD- I then repeated the same for Channel 2 of the Kikusui and everything was bang on, CAL WAS GOODSo.. Sig Gen is Goodboth CRO's are goodOhh, they are all on the same Time Base and Amplitude BaseNow..Photo 43 - Shows the D.U.T. is NI-210YJ V 6.0 , Power is On, Med 1 is selectedPhoto 45 - Shows the characteristic Curve of the Zener on the Tek 2235Photo 47 - Shows the same settings for both channelsPhoto 49 - Shows a Close up of the curvePhoto 51 - Shows the ASA HW-210K Under Test and also on the same MED 1 Setting (Granted the Frequency on MED 1 on this unit is 225 Hz and on the other it's 368.7 Hz)Photo 53 - Shows the characteristic curve of the Zener UNDER THE SAME CONDITIONS, on the same scope just different deviceNote : I repeated this test on both CRO's and got identical resultsPhoto 54 - Shows a side by sideBIG DIFFERENCE !!!Now this goes back to what i was saying before.The ASA HW 210K Comes in 2 versions that we can't really control which we get . this one here that i used to test DOES NOT HAVE ADJUSTABLE POTS.i do have another that does have it, but that unit has Blown upthe NI-210YJ V 6.0 does have adjustable PotsAnd i have adjusted this unit so that in Y-T Mode it's Channel 1 Sine wave is at 2.0V Amplitude Pk-PkSo as per the previous comment..... These things don't really come with Manuals or adjustment instructions (This one doesn't have the ability to be adjusted)the only way to get the 2 curves the same would be to Adjust the knobs on the Scope. but should i really have to do that ? NO ! they should both be the same.anyway.. i found this interestingOff to bed now.More Reverse Engineering tomorrow

author: BTO
author_rank: Frequent Contributor
timestamp: March 29, 2025, 06:26:19 pm
content: Quote from: timeandfrequency on March 27, 2025, 09:34:55 pmThe Seller has agreed to replace it, I've asked him straight up, How he wants to handle the return, he hasn't mentioned a word.Perhaps if it's not worth him paying for postage again. he may agree that i just keep it , in which case we can troubleshoot itit doesn't change the high failure rate on delivery, but hey we'll see if i get to play with it

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: March 29, 2025, 07:19:04 pm
content: Hello BTO,Quote from: BTO on March 29, 2025, 06:10:16 pmDUT seems to be a bidirectionnal TVSYour both CRO are calibrated and X and Y gains are identical.It is not really surprising that you do not see the same trace.If you want to see exactly the same trace (for the same DUT, of course) when using different curve tracers you need to have for each of these TE :- same AC voltage output towards the DUT- same AC source series resistor (can probably be adjusted by the 'RES' pot on one of your unit)- same AC output frequency (important when DUT is a capacitor or inductor)- same voltage conversion factor e.g 1V at output towards DUT = 1 V at the BNC output that has to be connected to the X channel of the CRO.- same current conversion factor e.g 1 mA measured through the DUT = 1 V at the BNC output that has to be connected to the Y channel of the CRO.If the voltage and/or current conversion factor is different between two curve tracers, of course you can cheat by changing the X and Y gains on the CRO.On basic TE, the series resistor is sometimes directly used as the current to voltage conversion device (for the Y channel).Don't forget that a curve tracer has often 3 or 4 modes (LO, MED, HIGH) and those change many of the above parameters.This can be seenhere. You will notice that a well desigend TE like the T1500 keeps the X trace width constant (in this case it is exactly 5 div) even when the DRIVE voltage is different (due to mode change).Same behaviour applys for the current conversion, and the trace height is always 4 div.Actually when selecting the different modes, the trace must keep the same X (check on open) and Y (check on short) size. Check it out on your different TE.This means that you should never have to fiddle the CRO controls when changing the mode on the curve tracer.

author: BTO
author_rank: Frequent Contributor
timestamp: March 29, 2025, 07:52:18 pm
content: Quote from: timeandfrequency on March 29, 2025, 07:19:04 pmQuotethat's basically what i concluded.... IF it was the model that had the adjustable pots i could get them the same.and if i adjusted the other i could get it the samethe issue being the ajustable one is adjusted how i like it, so there's no point adjusting that to suit the non adjustable one.Perhaps i can solder in Varistors or what notQuoteYou're correct, i generally don't need to fiddle with itand changing the Test Frequency doesn't really alter that much

author: BTO
author_rank: Frequent Contributor
timestamp: March 30, 2025, 08:27:30 pm
content: OK. i started Reverse Engineering the board (WITHOUT THE POTS)It would appear that the first component that we are trying to find outmay very likely be a TDA 2030(Give me your thoughts).(Datasheet Attached)Pinout also AttachedKiCad Png Schematic (Attached)I suppose for now, i want to order a TDA2030 and desolder the original part and drop in the TDA2030 and see if it works in a functional unit.If so.. Component 1 will be deemed "Identified".. ThoughtsEDIT : The SMD Caps "C 3" and "C 19", I Have not been able to identify their values as yet, Not even sure how i would go about identifying it (There are no Markings).- Of course i can desolder them and check the Capacitance.- As for the voltage, i suppose it's a guess, but it has to be above 24V, no doubt , as that's the input Voltagage. so perhaps a 30V might be appropriate ??

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: March 30, 2025, 09:00:24 pm
content: Hello BTO,Quote from: BTO on March 30, 2025, 08:27:30 pmMy thoughts have not changed since Reply #12: the TDA2030 is the part to try on a breadboar or as drop-in replacement.For 'C3' & 'C19', 30V should do it. 35 V and 50 V parts are standard.

author: BTO
author_rank: Frequent Contributor
timestamp: March 30, 2025, 09:13:56 pm
content: Quote from: timeandfrequency on March 30, 2025, 09:00:24 pmQuoteI Agree, and given that i might be repairing a few of these i'll probably order a fewQuoteI Agree, i'll probably go with 35V , i think 50V might be a bit of overkill.OK, i'll get those parts ordered inand i'll keep Reverse Engineering the boad with the KiCAD Schematic .I've looked forward a little, it doesn't seem to be too bad.i'll take a bit of a break for now, Get some rest then jump back into it