Hello everyone I'm the deaf Pom first names Scott hopefully Dave chooses this video for his guest spots while says around holiday and I thought just a bit that me and my channel and what I do this unit here is one of things I'm working on currently I'll do a lot of repair videos mostly on test equipment I things do some review reviews as well on nuclear I've done some reviews of Siglent in the past. you may have seen those also anything that's sent to me as well I think mailbag videos, things I've purchased and and so on. I also do CP repair work and I've done videos on that. but most of you must do what I do these days is test equipment repairs.

So if you interested in you know seeing the fixed link test equipment stuff then carry on watching and check out my channel. So this is one a piece of gear I'm working on right now and I read it in my position for quite some time now for a few months and it's been a bit of a pain. I think every single bore them, it has a fault, every bolt is faulty I think as a parts unit which has been used for good parts for other ones, this is a fluke five two, zero zero a AC voltage calibrator and I'm working through it appears on this and I'm going to go through and show you a bit on troubleshooting at moment and just don't and diagnostic work so that's going to be a little bit technical but not overly so. I'm not a hugely technical person I very much you know out there and hung playing videos on to sit here and just speak and go through it.

I don't have a script during like that so hopefully you don't mind me putting words a little bit things on it. So it's all makai and I've been working through the cards. I've already got two cards repaired but I'm still doing some more diagnostic work. Nobody, power supply will be paid all that and Dance of Substitutions and so on.

so that's going to show you bits if you want to see more about this particularly repair. I've got a series on my channel of appear get so far up-to-date and there will be more as well as I progressed through it and but hopefully this is a little sample of you know what you might get to see if you come to my channel and have a look and hope you subscribe and so on. So hopefully Dave chooses me otherwise I've never seen a lot of date. Okay so start off with I should explain what's going on here Now this sport here is the oscillator and it isn't oscillating all right.

So what's supposed to happen as opposed to have a phase change as you go through each amplifier stage on this board. suppose you go three hundred eighty degrees in the first stage, 90 degrees and on two degrees again to get 360 degrees or there abouts which is in controlled electronically by the control board. Also that control card which then fine Tunes that frequency allows for any changes on the phone panel controls and so on. That's the theory, but the oscillator doesn't work.

So what I'm actually doing is injecting my own oscillator signal into the unit at the input which is in passing through the stages and then I can actually test each stage that way with an artificial injection of a signal which at least proves that each stage is working. I've done this previously in another part of video. another section are done which showed the gang of each sample file which is about 40 times gain so those are actually working. you know at least I know as far as implication goes but not as far as space and that's where I'm thinking the issue is now why it's not oscillating.

Of course if the phase is wrong then you won't oscillate because it's out of phase with itself and so it doesn't generate the consolation. But it's quite a complicated little setup. The guy going on here. it goes across two different cards which is influenced by a third card which is fed by a fourth card.

It's a case of eliminating which part is causing the problems and trying to prove which bits work which bits don't So it's It's a pain and it's been a long process, so hopefully this videos a little bit interesting for you. I'd down then actually achieve anything in this video. I'm gay I'm gonna fix anything today because it's a lot to go through and but hopefully you find interesting all right. So I got my test set up here now I'm using the new STS 1104 XC scope which I've been reviewing recently and I was playing around there still because it's four channels in, it's convenient and I've got this hooked up on to the oscillator controllable what also bots are and what I'm trying to measure here is the phase in between each oscillator stage.

It's supposed to change phases. it goes through all right. She haven't be a trouble measuring the first stage between the input and the output of the first stage, so I'm like to put it. come back to that bit for now.

I can move on this, test the upper stages and see if they look right? Okay, so let's move the camera down. I'll show you what I found so far. Okay, so I've teed off on the inputs and stuff on this card now so I'll catch you measure the phases on each stage. This is the input form isolator.

This is the output the first stage output the second stage at the third stage right. So you should be our set of phasing from each one. Now if I zoom in slightly should be I'll see a little bit better seeing see phase one to two is almost 90 degrees. depends with a frequency as well.

So if I actually adjust the frequency on the fluke, these phases will change slightly now. so say 89 degrees. Phase between 2 & 3 should is actually minus 87. so it's actually 200 degrees.

It's almost in phase of the first one. 3 to 4 I saw 2, 2, 3, 2, 2, 3. it's those two. So phase 3 is actually interface with the first one pretty much and phase 4 is over 90 degrees.

All right. so faithfully 207 degrees. Now it says - Rd-64 Sosa's thinks it's going out, but the issue here is that this first difference here between the input and the output the first stage is supposed to be a 180 degree phase difference, not 90 degrees according to the manual. so that's probably why it doesn't work properly.

All right. So I tested Each stage in each stage is amplifying and doing things are supposed to do, but this one's They come and check the phases because if this isn't right, then it froze the whole thing out. So say this first stage here is supposed to be 180 degrees, especially invert the input. it's not doing that.

So I find that quite interesting and these other two stages supposed to be 90 degrees out from each other? Well well here is 90 degrees, 270 degrees and just like too suddenly again effectively birds, it's not doing what you think it should do. So yes, we have a pain I need to investigate this first, but he because it's supposed to be inverting input. That's what's supposed to happen. Okay so this is the circuit diagram for the oscillator board.

Now these phases I'm looking at on the scope Now this is the input here. Tp2i measuring at EP 3 for channel 2 and C p5 for channel 3 and T p7 for Channel 4. So this first stage here is supposed to be 180-degree inversion. Then this stage here supposed to be a 90 degree inversion.

This is supposed to be 90 degree inversion. So your face face change and that's not what's happening. This phase here with a stage here is not doing 180 degrees is 1890. Now this has some other aspects along with it.

There's a summing amplifier out here which is in parallel with the device. summing amplifier ensample out. They go to the oscillator control board and it gets a bit more complicated certainly, but they actually have a capacitor across it which is used to tune this response. This also looks like a zero here.

I've tried just in that and is insane to change anything but so just look at the summing amplifier out and some point in let's see what those do. those are on the control PCB which is here Now they are here. some fighting over here and some fight out so those pass through. Knossos Go through this network here which goes back into here and into here this but this box.

Alright, so let's go back down to the next page and this is that box. So amplify in is here and summing amplifier out is where there's also labeled as H So how I look for that so shouldn't I H There we go there. all right. So oscillator control in is a liberal control.

Alright, so I did find some faults I think I'm replacing capacitors somewhere in this part of the circuit. Where was that over here? I think we replace these caps here I think it was so there was an issue with this particular baldness. I'm suspicious of this circuit here I think something in here isn't right. So this is supposed to come out of this device here.

Go to the amplifier fiiiai before I come back and go across this stuff here. so it's all amplifying DC Amps and stuff here as well. so it's supposed to be providing some amplification and it's probably affecting your slider. You know there's other stuff here.

Ding sitter too Now we got his various capacitors which are being switched in as well. Bodies Relays these are part the quadrature and before and Yossarian before those seen you work in ok days look about right? So I'm pretty confident these capacitors here were working okay and the always realized here okay as well. I've done individual testings but everything and I've actually eliminated a phase locked circuit by not having it turned on that disables that part of the circuitry. So just trying to figure out exactly which part is causing problems now which I believe is in this aperture control circuit here because it doesn't seem to be doing the right thing.

It's a bit of a tricky process because it's sort of one big loop and it's it's over pain now. Is that GAE bitten in the Diagnostics Here somewhere some find it. Theory of Operation Functional block diagram. Is it here? Somewhere we go? This is it.

All right? So what is that you hoping to try today was to try and do a shortcut here. Now you also like assembly I Know does oscillate now? sis see it shows us phase shifts. Hundred eighty degrees, 90 degrees, 90 degrees. Okay, so there isn't phase shifting like it should be, but that is controlled by just something.

Empathize In all right, it's from the oscillator control assembly, so this may or may not be working correctly. but is that because there's no amplifier control from here now? I've actually measured this test point here at connection 51 pin 51 on the card and now it's reading zero volts. So and it's supposed to be between minus 15 volts and 0 volts. So zero volts to me says it's fully out of one range.

So and that's without the amplifier installed because that's blind, all right. So everything's blowing. Reference assembly is fixed. They've all repaired this and I'm 99% sure this card is as good now, but well did.

Why she want to originally inject my own voltage here in pin 51 but had some other complications going on with the way it ties the reference voltages together because you use the reference power supply which is linked to AC to DC converter through this cable here which has a negative reference which then and gives the correct power supply outputs when the main power supply because it checks the reference voltage first and it's all tied together that way so it's a bit complicated and involved. I may still go that route yet though. So I actually want to inject a negative voltage here and see if it corrects the frequency here? It probably won't. It's supposed to be pampered you control, but if this is completely skewed off, it may be trying to do something else.

So the Facebook circuit when it's turned off, it disables all this isn't you. so that's not used. and this is news that doesn't matter. No I all this stuff doesn't matter.

So to say it eliminates a whole bunch of circuitry. So all its really doing here is looking at this roll-off here and this is tuning here. Alright, so 360 degree tuning that capacitor there could be at C-56 for example. The range selections work.

So yeah this, this units been a bit of a pain so it's been a long journey. Alright so let's talk about a bit of success for this: I'll just try changing some adjustments on the oscillator control board. enough chance that they're just completely out of whack because I wasn't playing with them and I turn them a little bit and is the oscillation got really unstable with my my own supplied oscillator signal it was jumping all over the place. And what's interesting though is conflicts between oscillations.

So I removed my on my injected signal and I now have an oscillation going on here and that is from the oscillator board Said your slave board is now oscillating and if I change ranges and it does all this grain changes just fine. Okay let's bring this up a bit. so have you got Spahn megahertz give or take a little bit. All right and so yeah, that's doing everything supposed to do now.

Awesome! I Got channel one connected right now so that's on one point one put down to 100 roughly won't hurt to start your frequency but I have to figure out how I tune the frequency itself but it's working now. The oscillator board is actually oscillating so it looks like is due to incorrect adjustments on the Oslo control board. So I don't you know as justments do I'm gone through the CG of Auslan of Calabrian appalled yet? But where does adjustments all right now? It makes this board oscillate. so at least now I know this ball can oscillate.

Yeah fun fun fun. So I'm gonna leave here that for now and I think that's probably good enough example for us. All things: I Do Don't forget his old sort of phony Kevin Live rush because I've only got like a day to get this video into Dave So yeah, I've been on holiday and stuff like that. So yeah.

so now I can be sure that that ball is actually capable of doing. what's supposed to do is oscillating it roughly to our frequencies. So I'm confident that that can do it. It's probably an issue on the control board itself, so we'll have to work through that one in the different video, but hopefully getting idea of what I do and to appear and playing around.

SOTA Scope Here's one a loaner from Siglent 4 I've done a review on this on a scope with usage review and I'm just play around it for this. You know, because it's convenient to set up right here. My own scopes are the back there. but alright.

so I forget to pop by my channel if you get a chance and have a look. and if you're interested in following the repair process on this and what I actually did have, finally calibrate this properly because it's got some adjustments on here that I'm I do you? I've got to go through all that, but I've got a full manual. Honest, need to go through the process now. Fernan The ball can actually oscillate by itself.

That's the biggest step because I've been trying to get this to work to some degree for a couple of weeks now. off and on, you know, just trying bits and pieces, but I'm pretty confident now. Look, that board is okay now. so one more down.

Thanks Dave for the opportunity.