Trasistor Cruve tracer + Hameg 1004-3 XY weirdness  - Page 1
Forum section: electronics / projects

author: AngraMelo
author_rank: Regular Contributor
timestamp: October 13, 2019, 11:51:42 pm
content: Hello everyone,I have a Hameg HM1004-3 and just bought and soldered this transistor curve tracer kit:https://www.ebay.com/itm/Transistor-Curve-Tracer-adapter-Oscilloscopes-Plus-Power-supply-UnAssembled-Kit/291531434190?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649On the Hameg manual, it says that Channel 2 is the X and Channel 1 is Y. When i connected the curve tracer that way all I get is a fuzzy picture (like there is no ground connection or something). If I connect it the other way around, making the necessary adjustments of the Volts/Division and triggering I get a clear picture of the curves but the curves are now going vertically.The thing is, the scope seems to be triggering fine on both channels. Trying both channels out with signal sources produced the same image.Ive read the manual over and over and I cant understand what is going on.Any tips?During the 2+ hours I spent trying to figure out what was going on, there was a moment (around 2 seconds) where it briefly worked, the curves where horizontal and I could see them clearly, but then it changed back to the fuzzy mess.Pictures for reference

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 14, 2019, 09:50:19 am
content: Over in this thread we talk about the fuzzy issue.https://www.eevblog.com/forum/testgear/transistor-curve-tracer-kit-on-ebay/Basically, don't try using shielded test cables, keep them as short as possible and apart from each other, and put a ferrite bead on all the wires.

author: AngraMelo
author_rank: Regular Contributor
timestamp: October 14, 2019, 06:42:25 pm
content: Quote from: TERRA Operative on October 14, 2019, 09:50:19 amThank you so much!!

author: AngraMelo
author_rank: Regular Contributor
timestamp: October 14, 2019, 10:11:52 pm
content: Quote from: TERRA Operative on October 14, 2019, 09:50:19 amIve tried using EMI beeds, changing the cables to bnc/banana then a alligator clip to the board, but nothing seems to be even a tiny bit better. The crazy thing is, inverting the channels works just fine, but the lines are vertical. So how on earth can I complete distort the signal just by swapping the leads??

author: AngraMelo
author_rank: Regular Contributor
timestamp: October 14, 2019, 11:44:44 pm
content: This situation is truly ridiculous. Here is another picture of the scope measuring channels 1&2 and then "2&1". They look exactly the same, but when you plot the XY one gets distorted the other doesnt.

author: w2aew
author_rank: Super Contributor
timestamp: October 14, 2019, 11:50:31 pm
content: Can't see all of your scope settings, but...- make sure both channels are DC coupled (looks like one of them is AC coupled)- triggering shouldn't matter in XY mode on an analog scope

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 14, 2019, 11:55:51 pm
content: Yeah, I was just going to suggest checking the coupling settings..

author: AngraMelo
author_rank: Regular Contributor
timestamp: October 15, 2019, 12:10:48 am
content: Quote from: w2aew on October 14, 2019, 11:50:31 pmI tried both AC and DC coupling. It doesnt matter how I adjust it, I can only see the curves when XY are inverted. If I switch the curve tracer to "power transistor" mode, I can see them on the screen on both ways, vertically and horizontally. It seems that if I use the correct inputs for the XY, somehow the scope is more susceptible to noise/interference.Tried moving the cables, things around the scope... all to no avail. I even have crazy amounts of EMI chokes everywhere.What is weird to me is why would I be able to see them on YX and not on XY? It would make sense if one of the channels was showing some malfunction but the pictures of my last post show that both channels are working apparently fine.

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 15, 2019, 04:13:12 pm
content: All I can think of is a somehow faulty or otherwise quirky scope, or the volts/div settings aren't correctly set on the scope?

author: AngraMelo
author_rank: Regular Contributor
timestamp: October 15, 2019, 05:35:56 pm
content: Quote from: TERRA Operative on October 15, 2019, 04:13:12 pmIt is very weird. If I change the Curve tracer to power transistor mode, I can see the curves, otherwise its just a blur in the shape of what the curves would be.I changed the Volts per division multiple times. It has to be on the scope but I have no idea what to look for for a "malfunction" such as that.

author: duak
author_rank: Super Contributor
timestamp: October 15, 2019, 07:15:41 pm
content: I would check the following:One of the solder joints of the output connector may be bad.Does the oscilloscope have a bandwidth limit control that reduces the bandwidth of the input channels? I couldn't see one on the sales sheet from Hameg. If there is one, does it make a difference when activated?The current sense signal (CH2) will be of small amplitude. I suggest getting a proper shielded cable with the correct connectors. A 10:1 probe will definitely add noise.There are some design features in the schematic from the other link that I don't understand. However, I don't want to comment until the above things have been tried.

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 15, 2019, 10:38:35 pm
content: Quote from: duak on October 15, 2019, 07:15:41 pmThis could be a thing.For my unit, I have shielded cables from the X and Y outputs on the PCB to the front panel BNC jacks, then standard BNC cables directly to the scope inputs, so it's shielded and 1:1 all the way on both channels.

author: AngraMelo
author_rank: Regular Contributor
timestamp: October 16, 2019, 02:25:07 am
content: Quote from: duak on October 15, 2019, 07:15:41 pmUntil now, all my tests were done either with a BNC>banana cable or the scope probes that are all 10:1. Im just finishing the enclosure (actually it is finished, it's the transformer that is taking some time to arrive) and during the assembly process I made sure to use coax from the board to the bnc connectors and Im making provisions to make a very small BNC>BNC cable.The Hameg has no bandwidth limit but that is an interesting thought. Maybe the 2 Channels dont have the same bandwidth? so when I invert inputs (YX instead of XY) I get a clear picture? Or somehow the XY mode limits the bandwidth of one channel but not the other?What do you guys suggest about the transistor connections? Should I run a small wire with a croc tip to hook the transistors up? would that be horrible?Also, just ordered some more beads for the cables, Im going to load those suckers up with ferrite.

author: AngraMelo
author_rank: Regular Contributor
timestamp: October 16, 2019, 02:26:31 am
content: Quote from: TERRA Operative on October 15, 2019, 10:38:35 pmMy order will probably be here the beginning of next week. I order some BNC connectors to make a very small cable. Also ordered some more ferrite beads for the cables.

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 16, 2019, 02:37:01 am
content: I have 10cm leads from the PCB to binding posts on the front panel, then I use 10cm banana to test hook leads to attach the transistor etc.As long as I keep the test leads spaced apart, I get no issues at all.

author: Gertjan
author_rank: Frequent Contributor
timestamp: October 16, 2019, 05:49:44 am
content: Hi AngraMelo,Try switching the on-screen readout of the HM1004 off. (Long push on the button under the Intensity knob)In my experience the readout sometimes interferes with the traces. (the readout text is written with the same cathode ray beam as the traces, switching to and fro. At some frequencies there is interference....)Regards, Gertjan.

author: AngraMelo
author_rank: Regular Contributor
timestamp: October 16, 2019, 01:13:55 pm
content: Quote from: Gertjan on October 16, 2019, 05:49:44 amHello Gertjan,Unfortunately it didnt get any better, do you know if there is a way to limit the bandwidth?

author: AngraMelo
author_rank: Regular Contributor
timestamp: October 16, 2019, 01:14:43 pm
content: Quote from: TERRA Operative on October 16, 2019, 02:37:01 amThat is interesting, so the distance between the leads are more important than their length?

author: Gertjan
author_rank: Frequent Contributor
timestamp: October 16, 2019, 02:43:46 pm
content: Hi AngraMelo,Sorry to hear that switching off the on-screen readout was not the solution for your problem.The Hameg HM1004 doe not have a bandwidth limit function. It is not very necessary, as the specced bandwidth is only 100MHz.(Although I measured mine to have 150MHz (-3dB) bandwidth. CRT and Y amplifiers are identical to the HM1507. It is really a very nice scope!)Regards, Gertjan

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 18, 2019, 01:30:14 pm
content: Hmm, do you have access to another scope so we can narrow it down to either a curve tracer problem or maybe a faulty or weird scope?

author: AngraMelo
author_rank: Regular Contributor
timestamp: October 18, 2019, 01:49:03 pm
content: Quote from: TERRA Operative on October 18, 2019, 01:30:14 pmHey buddy,I only have another digital one and the sample rate and resolution goes to sh%$ on XY mode. It is kinda hard to compare them. I need to leave the "persist" on to be able to see some of the lines.

author: Ovi4
author_rank: Contributor
timestamp: June 07, 2020, 01:31:43 pm
content: Hi there, I just flicked thru a ton of posts on various websites in the hope I can get my scope fixed an HM1004-3. My problem is that I do not have the right kind of schematics manual. However, I found an online 1 schematic pdf file that says it is for HM1004-3 but my scope is different. in the schematic, the design revisions are from 1996 with all boards revision 1 or thereabout but my scope is 2002 edition and has a lot of boards that are totally different than what I see in the manual even ribbon cables are different. for instance, my PSU is revision 2A (a vastly different PCB design. I wrote to R&S several times with no response. I've searched the net and E-Bay high and low and just could not find the right schematics anywhere.So I wonder if you, somehow have the right schematics for me and are willing to share them, please? Any help is much appreciated Thank You.

author: Ovi4
author_rank: Contributor
timestamp: June 07, 2020, 01:35:29 pm
content: @ AngraMelo, is there any chance you could share your HM1004-3 schematic diagrams manual with me, please? I have a problem with my scope too and could not find any schematics but only the service manual for it. Thank you