CPD1604S Vertical Collapse

[Alex KL-1]

So the multiscan not operates correctly? We presume then the wrong auto setted voltages as a result.
What is the scan rate detector, a µcontroller or a bunch of logic IC's?

[vol.2]

Originally Posted by Alex KL-1

So the multiscan not operates correctly? We presume then the wrong auto setted voltages as a result.
What is the scan rate detector, a µcontroller or a bunch of logic IC's?

A bunch of logic ICs and discrete components.

The Horizontal and Vertical Sync signals come in directly from the VGA cable to the Multisync PCB, while the color information is sent directly to the Neck PCB.


EDIT:

Ok, I managed to get the raster back to what I had last week where I can see the image, but I do not have (much) Vertical Position control. I have Vertical Size, Horizontal Size, and Horizontal Position, but Vertical Position is just a tiny little bit, and it's always basically too low down on the raster. I have no Pincushion controls (even less than when I first started).

I removed IC604, IC250 and IC302 and replaced them with new parts and just kind of did my best to reflow anything I had reworked and that made the raster come back.


I still have the problem with Zero Volts in the area beyond Pin 5 of IC604.

I switched the resolution to 1024x768 to see how that would change things, and I am seeing 18V on the base of Q317, which I don't think should be there. This connects to a Relay on the D PCB, so I thought maybe it's a problem on the D board, but I measured the Pin on the connector that goes out to the RELAY and it's around 4.3V while the Base of Q317 is 20V. It interacts with Q616, so I measured the Base of that and it's at it's correct 5.5V, so I don't think this is a problem over there.

I guess it must be all coming from the other side of the circuit?

[vol.2]

Okay, I maybe tracked down a possible cause, but I'm not sure exactly what might be wrong.

I followed bad voltages around on the board, and I found one that I can trace back to the D PCB through the Vertical Position Signal (which seems to be what's FUBAR).

The Base of Q255 connects to D257 and to the D PCB through Pin 19 of P302. This should be at 8.3V but it's 1.3V. This has got to be wrong I'm thinking.

This 8.3V is supposed to be driven by Q202 and Q203. I actually did think that this might have been contributing sometime a couple weeks ago, so I pulled these two transistors and they tested okay with a simple diode test out of circuit.

I measured the voltages on Q202, and the other two voltages are pretty close to correct, so something here is amiss.

Again, I still don't really understand this stuff totally, so for all I know, the 1.2V is being pulled down from the other side where D257 and Q255 live.

This is what the area looks like:

[Alex KL-1]

With 0V on pin 11 of these IC, indeed we can have low voltage in the V_POSI.
So the command for this IC can be wrong (like wrong scan detect or some fault, or false protection detection maybe). If the IC is good.
But then, Q203 must follow it and then this emmiter voltage needs to be low, or it is inoperative.

[vol.2]

Originally Posted by Alex KL-1

With 0V on pin 11 of these IC, indeed we can have low voltage in the V_POSI.
So the command for this IC can be wrong (like wrong scan detect or some fault, or false protection detection maybe). If the IC is good.
But then, Q203 must follow it and then this emmiter voltage needs to be low, or it is inoperative.

Thanks Alex

I measured Q202,203 and I found that the Base-Emitter was very higher, like 1.5V which is way to high, so I assume it's toasted and that would explain the lack of 8.3V.

I am wondering if this situation can be responsible for the lack of 6.5V on Pin 1 of IC604?

There's supposed to be 25V on Pin 11 of IC250. This is missing because the 8.3V is missing on the Base of Q255 and the Anode of D257.

Maybe the 25V on Pin 11 of IC250 closes the transistor input at Pin 6 (of IC250) and bring it to zero. That closes anodes of D255 and then zero volts appears at Collector of Q612. This causes 6.5V to flow through Base of Q612 and to the collector of Q613 and Pin 1 of IC604. Possibly make sense?

In this explanation I am suggesting that the input of IC250 (Pin 6) is being pulled high because of the lack of voltage on its output (Pin 11)

I traced out the voltage path to look at how it's flowing and maybe how it should flow:

[Alex KL-1]

The pins 2 and 3 of IC604 are with proper correct levels? I presume these being from the scan rate detector section.

[vol.2]

Originally Posted by Alex KL-1

The pins 2 and 3 of IC604 are with proper correct levels? I presume these being from the scan rate detector section.

Yes they are correct. Pin 2 is at 5.2V (supposed to be 5.5, but seems close enough), and Pin 3 is at 0 volts. All Pins on IC604 are correct except Pin 1 and Pin 5.

I spoke a little with someone who has suggested to me that the 2.7V on the Base of Q613 is probably correct, and it's because the Service Manual must use the "Manual" setting on the Auto/Manual control which grounds out the D609/D608 OR Gate switch.

I had been assuming that the switch was supposed to be set to "Auto" for schematic voltages because Service Manual mentions to use "Auto" setting for setting up voltages and frequency potentiometers on the board in the setup instructions, but it doesn't actually ever say what setting that switch should be at for the schematic voltages.

So doing the math, this person was able to figure out that 2.7V is the correct voltage for that spot when the Cathode of D609 is biased towards the Base of Q613.

So that 2.7V is a red-herring and the whole Auto/Manual switch area is fine. The problem is all on the Collector side of Q613.

I think pretty certainly that Q203 is the cause of the missing 6.5V on Pin 1 of IC604.

This is still not clear if it will fix the problems with the Pincushion circuit that I started with though. I am hoping that it will because I can see that the missing 25V on Pin 11 of IC250 is both the cause of the missing 6.5V, and it also connects to Q255, which is connected directly to Pin 2 of the Pincushion IC303. Pin 1 and 2 of IC303 are responsible for creating the parabola which effects Pincushion control, so if a bad voltage on Collector of Q255 effects the current present on its Base, then it could be the whole source of the problem.

I think the determination will be if Q203 is newly broken, or if it was already starting to fail before I got to the monitor. I think there is a case to be made that the 24V line might have damaged Q203 because it's connected to that supply. There was some failure on the 24V line before I started working on it which I fixed by replacing the fusible resistor. Probably caused by all the bad capacitors inside.

I ordered a couple replacement transistors which seems to be close enough to the ones that came out, but I won't get them until probably Monday.

[vol.2]

I got my replacement transistors and installed them. I now have all the correct voltages on those places I was concerned about.

I also now have my parabola on Pin 7 of IC303, but it's not right. The voltage is something like 2X what the SM calls out, and it looks all messed up, especially if I try to tweak any of the Pincushion controls.

Not sure what would be specifically responsible for the parabola being too big; the voltage at this point is basically correct, so it's more like something in the current generation I guess. I think the issue must be in the controls for the Side Pin or near it. Nothing I can find from Service Manual voltages.

[Alex KL-1]

Yes, this is current-driven and/or generated.
this TEA IC are "class D" output (chopped), so a interference here is nrmal. But, if parabola is larger and image is ok, is nothing to worry (for example). Assuming image are distorted, something in the current path are wrong (good to re-check the TEA datasheet). For trying to reduce the parabola amplitude or gain.

[vol.2]

Originally Posted by Alex KL-1

Yes, this is current-driven and/or generated.
this TEA IC are "class D" output (chopped), so a interference here is nrmal. But, if parabola is larger and image is ok, is nothing to worry (for example). Assuming image are distorted, something in the current path are wrong (good to re-check the TEA datasheet). For trying to reduce the parabola amplitude or gain.

So I found that IC304, which generates the Horizontal Width Voltage, was regulating 22.5V and it wasn't changing with the potentiometer RV314. I swapped it for a new one and now I have most of my Pincushion controls back. It's definitely still a little hampered, but all the controls are now clearly doing something. There's still some kind of issue with the Side Pin controls as they jump around too much and too quickly. It's like when you have a bad potentiometer and you skip across dirty, broken carbon traces.

Except I know the pots are all fine because I removed all of them from circuit and tested them carefully for smooth continuity to the wipers from both sides.

I don't know what is possibly left to swap out. I have a new IC301, but the signals coming out of that IC seem fine. I also have new logic ICs for the switching stuff but, again, the switching seems fine.

I suppose that maybe it's just something sinking a little current and pulling down on the parabola a bit, so the ICs wouldn't have to be totally bad to cause an issue?

The main remaining issues is the Side Pin controls really. They don't quite work completely as expected.

The area I fixed:

[vol.2]

I removed IC301 and IC303, put in sockets and put in NOS ICs. That made the Pincushion controls just better enough that I can almost dial it in.

I found that the yoke is misaligned. It was twisted a little bit, so I went in and twisted it only to find that it's now slightly pointing up, so I'll have to go in and fix that.

This Monitor has a replacement tube in it that was put in sometime later in its life, which is good, but it seems the Sony Service place didn't take too much care when they oriented the tube. It's clear that they tilted it somewhat and then performed static convergence with it tilted in place.

[Alex KL-1]

So a multitude of issues... too bad, s&¨%¨$ can happen in the life of equipment...

[vol.2]

Originally Posted by Alex KL-1

So a multitude of issues... too bad, s&¨%¨$ can happen in the life of equipment...

Hahahaha. Yep, it's a bit of a endless pit. Honestly though, it's fine.

All of the remaining problems seem to be of the setup and calibration nature, which are all doable with the correct procedure. I'm happy to spend the time dialing everything in now that I know the electronics are functioning.

I was much more frustrated about it when I wasn't sure if it would ever work correctly and it was taking up space on my bench.

I've got other projects to work on!

[vol.2]

Well I went in and pulled all the yoke wedges and set it up the best I could. There's still a tiny bit of weirdness in the upper corners, but not sure what I can do about it. I think it looks pretty good in usage, and it tracks color very well.

[Alex KL-1]

Fantastic!
Seems great, even with these small distortion I bet it can pass easy with normal usage (will not much noticed)...