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 Post subject: PVM-1953ST troubleshooting
PostPosted: Mon Jan 27, 2020 12:19 am 



Joined: 01 Jun 2019
Posts: 14
Hi all, I recently picked up a broken Sony PVM-1953ST. I'm trying to figure out if I can get it working, but no luck so far. Here's what's happening and what I've tried.

The PVM turns on and the green power light near the button comes on, but that's about all that happens. The larger rectangle green light at the top of the front bezel also lights up. No other lights on the front panel light up, like the input selection, menu, etc. Nothing appears on the screen at all. No lines, light, no menu, etc. I tried to plug an SNES into the composite inputs but didn't get anything; no picture or sound.

Here's a video of me turning it on.

I noticed a capacitor (C621) on the (G) power board had a slight bulge on the top, so I ordered all of the caps on the G board and replaced all 11. Weirdly, the G board I have only had 11 caps on it, but there are 2 more empty spots on the board for capacitors. I know this can be normal for boards that are used in different sets, but the service manual even has the parts for them listed like they should be there. Anyway, I replaced all 11 that I started with and that didn't change anything.

Picture of G board with missing parts circled.

Next I started to check the voltage coming off the output lines on the G board.
The 15 V pin was at 14.15 V DC
The 115 V pin was at 120.9 V DC
The 5 V(A) pin was at 4.9 V DC
The 5 V(B) pin was at 4.93 V DC

The 15V (Spec: 16V +- 1V) and 115V (Spec: 115V +- 0.1V) seem to be out of spec according to the service manual, but I'm a bit past my ability to troubleshoot at this point.

I checked the 180 V spot on the (C) neck board and that was only reading at 120.4 V DC.

So, this is where I'm at. It seems like this thing isn't getting power correctly, but I could also be way off. There is a wire connector that runs from the G board to the back A/V input panel board that is supposed to have -15V and 7V on it, but it's reading zero. If I follow the traces on the board where these pins run they run into the missing jump lines (not sure if that's what they are called) and capacitors, etc. that I mentioned earlier. That's weird right?

I took a look at the main board and this thing has had some work done before. Lots of caps have been replaced, but they all look normal. Several screws from the back A/V input plastic frame are missing, as well as the screws for the power supply board frame, and the heat shield itself that covers the power supply board.

There is a weird blob of something that looks like gum on the main board.

Blob picture 1.
Blob picture 2.

Also, this PVM is a 1953ST, but I'm reading a 1953MD service manual. From what I can find online these are the same, or close enough that basically no other manuals can be found for an "ST" model. Both seem to be designed for medical use.

Anyone have pictures of a PVM-1953 G Board that I can compare with? Or have any ideas of what I can try next?

Thanks!
Mike


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Sun Mar 08, 2020 5:07 pm 



Joined: 01 Jun 2019
Posts: 14
Still working on this PVM. A fellow enthusiast who had a spare working power board sent it to me to see if that fixed anything, but it did not. :( At least that's narrowed things down some. It seems there was at least 2 revisions of the G board for this model, and the missing caps and other components is normal.

When I power on the PVM I get two different behaviors. The first time I power on, I get a solid green tally light with no picture or other input lights as described in the first post. If I push the power button off and then back on again right away I'll get a second behavior where the green tally light is repeatedly ticking on/off. Video of tally light ticking.

I replaced the horizontal output transistor (Q501) on the main board, but that didn't change anything. I've been checking diodes and inductors on the main board, but haven't found anything that's shorted. I'm reading 120V on the main board and on the neck board where it should be reading 180V. I've disconnected the neck board, and get the same voltage reading on the main. Not getting any voltage between H1 and H2.


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Sun Mar 08, 2020 6:55 pm 



Joined: 02 Feb 2005
Posts: 322
The 180V is 180V only when the flyback is working. It's 120V i.e. same as B+ because it's coupled to the primary side of the flyback. The horizontal drive pulse which would make the flyback work is not present. It's generated by IC507 and from pin 10 is sent to the other end of the primary side of the flyback. The x-ray protection in IC507 prevents the oscillator (in the IC itself) from outputting the horizontal drive. The protection uses a voltage of about 110V from the flyback (pin 7) to IC500 (pin 11) and IC500 outputs a voltage from pin 8 to pin 6 of IC507. If this voltage is too high IC507 stops working and there's no HDrive. Too high is above 0.1V according to IC507 datasheet (PVM schematics says 0.2V). A voltmeter should be connected to IC507 pin 6 (or R560 if it's more handy) before powering the monitor and when you give power you should watch the meter for a voltage higher than 0.1/0.2V. This would only last 1-2 seconds before IC507 is shut down. This method is safer than opening the path of the protection voltage (e.g. by removing R537 or D5339) and see if the flyback turns on. When done this way the monitor must be turned off as soon as high voltage is heard or a picture shows up. When you prove that this is what happens you should find what's causing the anode voltage to go too high. This is generally due to a B+ too high (120V instead of 115V?) or some vital parts for horizontal drive coupled to the collector of the horizontal output transistor Q501, in particular the capacitors C525, C514 and a few others.
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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Mon Mar 09, 2020 10:07 pm 



Joined: 01 Jun 2019
Posts: 14
Thanks!
I'm reading .4 V on pin 6 of IC507. It stays at that voltage until I turn the PVM off.

Here's a video of my multimeter while I'm turning it on.
  • 15 seconds in is where I turn on the PVM for the first time.
  • After that I turn it off and on a few more times.
  • 43 seconds in is where I turn it on quick enough again to get the ticking on/off behavior. Voltage goes up and down here.


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Tue Mar 10, 2020 7:08 am 



Joined: 02 Feb 2005
Posts: 322
Now do the same with the cathode of D533. Voltage here is expected to be higher than 120VDC. But before doing that check the voltage on pin 11 of IC507 (you can use the leg of R556 common with pin 11). It must be 13V.
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Im running games with a vga to tv converter on my Shangai Novel, with composite and it looks amazing, Im not interested in RGB or Scart.

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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Wed Mar 11, 2020 2:40 am 



Joined: 01 Jun 2019
Posts: 14
IC507 Pin 11: reading 7.2 V
IC507 Pin 21: reading 1.9 V

D533 Diode - Am I doing this right? black lead on ground, red lead on the cathode side of the diode? I'm reading zero, not getting anything.


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Wed Mar 11, 2020 8:42 am 



Joined: 02 Feb 2005
Posts: 322
This tells that the flyback is not working at all and the horizontal drive is missing because IC507 is not supplied (7.2V is not enough, it cannot be lower than 12V) and not because of x-ray protection.

IC507 pin 11 is the 13V supply voltage for the horizontal section of the IC (much more important than the vertical one). The source is the B+ voltage (115V) from the power supply so it's independent of the flyback. On one side of R556 you must have 115 and on the other 13V. It's not the resistor that lowers the voltage but a zener diode inside IC507 (cathode = pin 11, anode = ground). It could be the diode itself (which can be fixed only by replacing the IC) or some other parts connected to pin 11, in particular R556 and C552.
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Im running games with a vga to tv converter on my Shangai Novel, with composite and it looks amazing, Im not interested in RGB or Scart.

- Anonymous on Facebook


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Wed Mar 11, 2020 4:03 pm 



Joined: 01 Jun 2019
Posts: 14
Thanks MKL! I'll check these out.

I put my meter on R556 while it's still in the board and it's reading all over the place. I'll take it out and see what it looks like that way. I can test the cap but I may just replace C552 anyway.


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Fri Mar 13, 2020 4:11 pm 



Joined: 01 Jun 2019
Posts: 14
I haven't done anything with this part of the board myself yet and I'm wondering what is up with all the pins from IC507 that have some solder running to a nearby component. Check out Pins 4, 8, 10, 19, and 20. Shouldn't the traces in the PCB itself be doing this?

IC507 close up picture.

My plan is the replace the IC with a socket and a new IC. Do I need to bridge these pins in the same way when I do that?


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Fri Mar 13, 2020 6:18 pm 



Joined: 02 Feb 2005
Posts: 322
The traces may have exposed parts where the mask is not present (see also R534, R554, D517 etc.) and when the IC was resoldered (apparently it has already been replaced) some excess solder went on them. Not a problem (but some soldering farther away from the IC is so-so). Too bad they didn't fit a socket though.
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Im running games with a vga to tv converter on my Shangai Novel, with composite and it looks amazing, Im not interested in RGB or Scart.

- Anonymous on Facebook


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Sun Mar 22, 2020 4:07 pm 



Joined: 01 Jun 2019
Posts: 14
I replaced IC507, R556, and C552, but still getting the same behavior. Same voltage readings everywhere as well. The resistor and cap tested normal when I had them out of the board.

When I replaced IC507 I cut the legs off the old IC since I didn't need to save it. When I was pulling the legs out I held them with pliers from the top side and applied heat to the bottom side. A few legs in I noticed that some of them were coming out with a collar or some other part of the board with them. I switched to putting heat on the leg from the top of the board and pulling out from the same side, that seems to have worked better. In the end I think the socket and the IC are fine. I tested the continuity from the socket legs to the next component on the path in the board and everything checks out.

Some pictures here:
New IC in socket.
Socket installed.
IC removed. Pings 4,5,6,7 were the ones I think had the collar that came out.
IC leg aftermath. The ones on the bottom have the extra collar.


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Mon Mar 23, 2020 10:14 am 



Joined: 02 Feb 2005
Posts: 322
Check the connection (continuity) between pin 11 and R556.

I wish the closeups weren't so narrow.
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Im running games with a vga to tv converter on my Shangai Novel, with composite and it looks amazing, Im not interested in RGB or Scart.

- Anonymous on Facebook


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Tue Mar 24, 2020 5:52 pm 



Joined: 01 Jun 2019
Posts: 14
Continuity between pin 11 and R556 checks out. I get a beep on the right leg (right side from the pictures) of the resistor.

Here are some more pictures of the full board.

Larger A board view
Alt view

Another thing I tried was to pull some of the connectors off the power board and see if anything different happened when I turned it on. Even with the cables removed that run to the main board, I can still get the power board to do this click-click-click noise. It's a slightly different noise this way. Maybe it's coming through the speaker or something when the cables are hooked up. Is this click-click happening because I'm turning off and then on again quickly? Or is this an indication something is wrong? Like I said before, I have two power boards and they both do this. One of them was known to be good.

Picture of connectors removed from the power board.
You can see (kinda) the 3 connectors on the top that run to the main board and the back panel are disconnected. The 3 connectors on the bottom of the G board are still connected.

Video of power on behavior with these connectors removed.
Turn up the volume to hear the click-click-click. First noise is pushing the power button in. After that I push again to turn off and then in again quickly to go back on.


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Wed Mar 25, 2020 9:26 am 



Joined: 02 Feb 2005
Posts: 322
The power supply has a voltage regulator that provides exactly 115V but you measured 120V so you should disconnect the power supply from the rest of the chassis (leaving only power input and switch) and test it with a dummy load (a 40-60W light bulb is typically used for this) connected like this:

https://i.imgur.com/T4bxc1r.jpg

Insulated alligator clips are recommended. Here's an example of the same test on a different power supply:

https://i.imgur.com/SJguLzg.jpg

If you're unsure, before giving power post a pic.
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Im running games with a vga to tv converter on my Shangai Novel, with composite and it looks amazing, Im not interested in RGB or Scart.

- Anonymous on Facebook


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Thu Mar 26, 2020 3:29 pm 



Joined: 01 Jun 2019
Posts: 14
I tested both power boards that I have, and both measured 120 V DC with a 60 Watt bulb connected. The board that was given to me and known to be working measured 120.6, and the board I got with the PVM measured 120.9. The main A board was not attached. There are 3 connectors plugged in the to G board. One is AC in, one is the PVM power switch, and I'm not sure what the 3rd one is. It's right next to the switch, and the black/white wires are coming from the same place as the switch.

I had to turn on the PVM first, and then turn the lamp switch on to get the bulb to light. If I had the lamp switch on and then turned on the PVM I got the click-click-click behavior - on both boards.

Here's a video of me turning the switch on the lamp a few times while the PVM power has power running to it.
https://drive.google.com/file/d/1S8eY3ARGzY4Y_EXOx6TwrDXCu7CgmidC/view?usp=sharing

The video starts with the lamp on and then I turn it off right away using the lamp switch. Then back on, and off...


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Fri Mar 27, 2020 11:42 am 



Joined: 02 Feb 2005
Posts: 322
Weird. Is the regulator an STR-S3115? Maybe your multimeter is a little off? (but 5v is not so little).

Anyway, the real problem is the lack of 12V at pin 11 of IC507. You could try this (it's a little tricky but better than desoldering SMD resistors):

Insert IC507 in the socket leaving out pin 11. Lift the legs of R556 and C552 shown in the pic. Connect together (the tricky part...) the lifted legs to pin 11 (the actual pin hanging loose, not the socket pin). Check voltage at the pin (12-13V expected).

https://i.imgur.com/2sjJy0W.jpg
_________________
Im running games with a vga to tv converter on my Shangai Novel, with composite and it looks amazing, Im not interested in RGB or Scart.

- Anonymous on Facebook


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Fri Mar 27, 2020 7:26 pm 



Joined: 02 Mar 2017
Posts: 1082
I apologize, I'm at work and can't read this entire topic, just wanted to add this (which I'm hoping will fix my FOUR 20 and 14" PVM's from this same line-up with the undocumented tally light error) if it hasn't already been talked about:

https://archive.org/details/pvmrepairgu ... t/mode/2up


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Sat Mar 28, 2020 5:49 pm 



Joined: 01 Jun 2019
Posts: 14
Thanks for the link. I've got 4.9 and 5.0 volts on the 5V (A) and 5V (B) pins respectively. I think those are OK.

Dochartaigh wrote:
I apologize, I'm at work and can't read this entire topic, just wanted to add this (which I'm hoping will fix my FOUR 20 and 14" PVM's from this same line-up with the undocumented tally light error) if it hasn't already been talked about:

https://archive.org/details/pvmrepairgu ... t/mode/2up


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Sat Mar 28, 2020 5:54 pm 



Joined: 01 Jun 2019
Posts: 14
MKL wrote:
Weird. Is the regulator an STR-S3115? Maybe your multimeter is a little off? (but 5v is not so little).


Yes, STR-S3115. On both G boards. Checked with a different multimeter as well.


MKL wrote:
Anyway, the real problem is the lack of 12V at pin 11 of IC507. You could try this (it's a little tricky but better than desoldering SMD resistors):

Insert IC507 in the socket leaving out pin 11. Lift the legs of R556 and C552 shown in the pic. Connect together (the tricky part...) the lifted legs to pin 11 (the actual pin hanging loose, not the socket pin). Check voltage at the pin (12-13V expected).

https://i.imgur.com/2sjJy0W.jpg


So doing this will remove a bunch of surface mount resistors from the path that normally starts with R556 and runs through C552 into the IC? I'll try this next. Lucky I ordered extra parts last time. :)


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Sat Mar 28, 2020 7:54 pm 



Joined: 02 Feb 2005
Posts: 322
The circuit that supplies voltage to IC507 is very simple. It's called zener diode voltage regulator (or shunt voltage regulator):

Image

The unregulated input voltage is the 115V B+ voltage, the current limiting resistor is R556 and the zener diode is built in the IC. The output voltage is given by the breakdown voltage of the diode. In this case it will be in the 12-13V range. The decoupling capacitor C552 is there to smooth out the voltage. Once the other parts connected to the output are bypassed you should get 12-13V at pin 11. At that point it's a matter of finding what parts hold the voltage down.
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Im running games with a vga to tv converter on my Shangai Novel, with composite and it looks amazing, Im not interested in RGB or Scart.

- Anonymous on Facebook


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Sun Mar 29, 2020 4:29 pm 



Joined: 01 Jun 2019
Posts: 14
Ok., just want to take a sanity check here before I turn anything on. Does this look right? It's not pretty.

R556 leg -(wire)-> C552 leg -(wire)-> Pin 11

https://drive.google.com/file/d/1vm0dooD3DPuRX1-abpIdHc7PqjhHTNmV/view?usp=sharing


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Sun Mar 29, 2020 4:52 pm 



Joined: 02 Feb 2005
Posts: 322
Yes. The IC goes in the socket of course (except for pin 11).
_________________
Im running games with a vga to tv converter on my Shangai Novel, with composite and it looks amazing, Im not interested in RGB or Scart.

- Anonymous on Facebook


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Sun Mar 29, 2020 8:30 pm 



Joined: 01 Jun 2019
Posts: 14
Ok, I tried it out. Now reading 9.4V from Pin 11. Pin 6 is reading .2V. Still same behavior (green tally light, no other lights, etc.).


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Mon Mar 30, 2020 7:35 am 



Joined: 02 Feb 2005
Posts: 322
Try with pins 6, 7, 8 out of the socket. If you hear high voltage from flyback/tube turn power off quickly.
_________________
Im running games with a vga to tv converter on my Shangai Novel, with composite and it looks amazing, Im not interested in RGB or Scart.

- Anonymous on Facebook


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Mon Mar 30, 2020 6:28 pm 



Joined: 01 Jun 2019
Posts: 14
MKL wrote:
Try with pins 6, 7, 8 out of the socket. If you hear high voltage from flyback/tube turn power off quickly.


No change. Had my meter in the 180V pin that goes to the neck board when I turned it on and still only saw 120V.

Correction - I'm getting 5.6V on Pin 11 this way. .1V on Pin 6 (now out of the socket).


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 Post subject: Re: PVM-1953ST troubleshooting
PostPosted: Tue Mar 31, 2020 11:42 am 



Joined: 02 Feb 2005
Posts: 322
Not sure what is still holding down the voltage and until you don't have 13V on pin 11 it will never work.
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Im running games with a vga to tv converter on my Shangai Novel, with composite and it looks amazing, Im not interested in RGB or Scart.

- Anonymous on Facebook


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