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  #1  
06-24-2017, 01:02 AM
Bullabill Bullabill is offline
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I'm still hoping for help with my Panasonic NV-HS100 / AG4700 problem. When I apply power the video head drum spins up to a high speed and can only be stopped by pulling the plug. I checked the voltages on the power supply output pins: 1 had 3.5v, 2 had 5v, 2 had 6v, 2 had 12v, 3 had 15v, 1 had 10v, 3 had zero, and one had 43.2v.

To me that 43v seems wrong and could be the cause of my problem; the question is ' if it is incorrect, what could be the cause'?
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  #2  
07-03-2017, 10:08 AM
Quasipal Quasipal is offline
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Quote:
Originally Posted by Bullabill View Post
I'm still hoping for help with my Panasonic NV-HS100 / AG4700 problem. When I apply power the video head drum spins up to a high speed and can only be stopped by pulling the plug. I checked the voltages on the power supply output pins: 1 had 3.5v, 2 had 5v, 2 had 6v, 2 had 12v, 3 had 15v, 1 had 10v, 3 had zero, and one had 43.2v.

To me that 43v seems wrong and could be the cause of my problem; the question is ' if it is incorrect, what could be the cause'?
That will be the FLD display drive voltage. What else does the machine do? Does it have display or show an error code? Does load a tape?
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  #3  
07-04-2017, 01:16 AM
Bullabill Bullabill is offline
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Thanks, Quasipal,
I haven't used this machine for a few years and, when I tried it, it seemed to be reluctant to fully load tapes, -particularly when using the S-VHS compact cassette adaptor. If I gave the mechanism a little help they seemed to load OK so I cleaned the old grease from the mechanism and that seemed to improve things. Everything seemed to work OK, panel indications, tape transport modes etc., but at that point the video output wasn't connected. I moved the machine to where I could connect it to a screen and when I plugged in the power the head drum spun up to a very high speed and could only be stopped by pulling the plug. Whether there was any panel indication at that point I don't know but the front panel power switch had no effect.
I removed all the electros from the power supply and changed only two due to slightly high ESR. I removed a 20v zener MA4200H and replaced it with a 1N4747 - there was no change to the output volts so I changed it back.
There's two 'voltage dropper' IC's - SI3120C and SI 3050C which I thought I would change but it seems that they're discontinued.
Your info. re. the FLD display voltage says to me that the power supply might be OK and that the fault might be elsewhere.
I found a thread on this fault (I can't find out how to link it here) it was posted by jawasmell on 02.20.2016. He fixed the problem but doesn't know how, I might have to remove and clean all the ribbon cables as he did.
I appreciate your help.
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07-06-2017, 11:44 PM
Bullabill Bullabill is offline
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I removed and cleaned all the ribbon cables, - no luck!, the drum still spins at high speed. There is no display and no tape loading, the only indications on the front panel are On, s-vhs, and AI lights illuminated.

I'm beginning to think that this is a lost cause and that I'll have to throw an expensive machine into the bin, is there no one prepared to have an educated guess at the fix?
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07-07-2017, 04:36 AM
Quasipal Quasipal is offline
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Have you changed the drive coupler under the loading mech? I put a video here http://www.digitalfaq.com/forum/vcr-...e-loading.html about how to do it. If the coupler is split, then the machine will struggle to get to rest position and one of the symptoms of that is a spinning drum.

Don't scrap it - it shares many parts with all the K mech VCR's such as HS900, HS950 and the like which you may well come across needing a new head, clutch etc.
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  #6  
07-07-2017, 08:43 AM
juhok juhok is offline
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Upper drum cylinder is very easy to salvage from HS1000. Only 1 screw and it's off!

According to my HS1000 notes there are 2 different drums used:

Quote:
Variants: Blaupunkt RTV-965, Loewe OC-3800
VIDEO HEAD VXP1747 (NVHS900/NVHS950/NVHS1000)
VIDEO HEAD VXP1561 (doesn't fit HS-9xx)

Last edited by juhok; 07-07-2017 at 08:43 AM. Reason: grammar
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  #7  
07-07-2017, 08:05 PM
bever bever is offline
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This is a little bit redundant re the power supply but maybe some idea for you.

looking at the power schematic diagram for the for an NV-HS1000, connector P1102 shows PIN1 ground, 2 -8v, 3 unreg 45v (could be the 43.2 volts you see) 4 and 5 ground, 6 non sw 12v (which may mean even when power swith is off) 7 and 8 unreg 14v, 9 and 10 reg 12.3V, 13 and 14 reg 5.3v, 15 is called power off.

If you look at the power going in to cylinder drive IC 2901 it uses 5 volts regulated. This 5 volts reg does not show up in the power supply likely generated somewhere between the power supply and the cylinder drive cba. You can go directly to cba vex0235 and start checking some voltages at connector 2302. Pin 1 should have exactly 5 volts DC.

in the service manual, charts list the various ICs and the voltages to expect on each pin depending on mode you are in. Of course focus on the SYS control and drum drive ICs.

Quasipal made a good call about the loading being out of wack. You can use the timing chart for ic6001 fed by the mode switch to see what feedback it is giving the syscontrol.

Its kind of wierd that you have no display if you can figure that out then maybe avail yourself of the service information display and see what it tells you.


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07-07-2017, 09:52 PM
bever bever is offline
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timing chart

timing800.jpg


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  #9  
07-07-2017, 10:43 PM
Bullabill Bullabill is offline
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Thanks, folks.
I'm encouraged by all that info. It will take me some time to absorb it all but I'll work through it slowly.
I might be wrong here, but I think that when the VCR is plugged in normally the drum gives a slight 'kick' (a few revolutions) and stops. If that's right then what I'm seeing is normal up to the point of starting to spin, then something goes awry.
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07-10-2017, 06:46 AM
Quasipal Quasipal is offline
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I have only had one VCR do this - a Panasonic D80 (1987). As I started replacing failed capacitors it suddenly cleared up and never returned. I get the feeling that the spinning drum is a symptom of another issue unrelated with the drum - and that if it were the drum circuitry that was faulty you would get no spinning or uncontrolled driving - yet when the drum does this it spins at the 'correct' revs, showing that the drum is being turned on ready to take a tape.

Sorry not to be of more assistance.
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  #11  
07-10-2017, 08:32 AM
Bullabill Bullabill is offline
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Thanks,Q,
My problem is slightly different in that the drum spins at high speed, much higher than normal. I am following up some suggestions but because I am remote from any component suppliers it takes a while. If I make any advancement I will let you know.
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  #12  
07-10-2017, 12:28 PM
bever bever is offline
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Quote:
Originally Posted by Quasipal View Post
Have you changed the drive coupler under the loading mech? I put a video here http://www.digitalfaq.com/forum/vcr-...e-loading.html about how to do it. If the coupler is split, then the machine will struggle to get to rest position and one of the symptoms of that is a spinning drum.
I watched this video a few times already it is appreciated and it a great help. I ordered a 25 ml bottle of De-Oxit from Amazon which is made by Caig labs. This may be the same stuff I used in the 80's and was called c "Cramolin Red" at that time.
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07-10-2017, 01:01 PM
bever bever is offline
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Quote:
Originally Posted by Bullabill View Post
Thanks, folks.
I'm encouraged by all that info. It will take me some time to absorb it all but I'll work through it slowly.
I might be wrong here, but I think that when the VCR is plugged in normally the drum gives a slight 'kick' (a few revolutions) and stops. If that's right then what I'm seeing is normal up to the point of starting to spin, then something goes awry.
You are probably right about the slight kick my AG-1980 with a K-mechanism does the same thing a few seconds after being plugged in.

Bullabill, the following may not pertain to your machine but if you do get the display working again it may be useful info.

I just drug an AG-1980 up on the bench for evaluation and I saved/videotaped some data towards making a self help type tape similar but maybe a little more basic to the one produces by Quasipal. Unfortunately I screwed up the audio etc and it will take severe editing and to make it useful. I will work on it however.

This vcr with a K-mechanism had the symptom of loading a tape, no supply or take up reel action then spitting the tape right back out.

I wanted to determine if the cause was from system control signals to the various motors or the mechanical portions and switches in the mechanism. I had an extra K- mechanism from a bad cap vcr which was not being used at the time. I planned to switch the mechanism.

Before I took very much apart I put the VCR in service mode #2 and watched/recorded the service data number sequence. It was 0 (static) then 7 1 7 one second pause then 1 7 0 (static).

I swapped out the K-mechanism loaded a tape and watched/recorded the number sequence it is
0 (static) 7 1 7 pause 3 7 2 7 4 (static) at this time the tape is in play mode.

When I push eject it is 4 (static) then 7 2 7 3 7 pause 1 7 0 (static)


My machine works with a different K-mechanism.Before swapping the K-mechanism my machine was only showing eject and cassette down mode I don't know what what sequence 7 means. The timing chart for the 1980 is very similar to the HS-1000.

Last edited by bever; 07-10-2017 at 01:35 PM. Reason: to clarify last sentence
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  #14  
07-11-2017, 06:21 AM
Bullabill Bullabill is offline
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I checked the power supply output voltages against the schematic and found all OK bar two pins.

Pin 2 should be -8v was 0v
Pin 6 should be (non-switched) 12v - was 14.7v

Pin 2 derives its -8v via diode MA185. I removed it (it is open circuit) and fitted a small signal diode voltage now -9.8v. I can get an equivalent replacement for the MA185 which might get the voltage back to -8v.

Pin 6 is fed from pin 7 (14.7v) via diode SVO3YS which is described as a Stabistor diode. Its job is to reduce the 14.7 to 12v. (Data sheet range 2 - 2.5 volts approx.)
I can't find a replacement for it (it's discontinued), and have seen suggestions that it could be replaced with four small 1N xxx diodes in series giving a drop of 2.4v.

Thoughts, please??
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07-12-2017, 04:04 AM
bever bever is offline
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Quote:
Originally Posted by bever View Post

looking at the power schematic diagram for the for an NV-HS1000, connector P1102 shows PIN1 ground, 2 -8v, 3 unreg 45v (could be the 43.2 volts you see) 4 and 5 ground, 6 non sw 12v (which may mean even when power swith is off) 7 and 8 unreg 14v, 9 and 10 reg 12.3V, 13 and 14 reg 5.3v, 15 is called power off.

If you look at the power going in to cylinder drive IC 2901 it uses 5 volts regulated. This 5 volts reg does not show up in the power supply likely generated somewhere between the power supply and the cylinder drive cba.
Just to clarify, I missed pins 11 and 12 where 5 volts reg is located in the power supply.
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07-12-2017, 04:25 AM
bever bever is offline
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Quote:
Originally Posted by Bullabill View Post

Pin 2 should be -8v was 0v
This seems significant
Did this change the symptoms of no display or runaway drum revolutions?

I did follow the path of the -8v line and found it to meander through the luminescence and audio boards showing up at the HI Fi audio pack schematic diagram.

Quote:
Originally Posted by Bullabill View Post

Pin 6 should be (non-switched) 12v - was 14.7v
12 volts derrived through a Stabistor diode (wikipedea says similar to a zener) from unregulated 14.7 so it cant be expected to be too precision. It would be nice to see 12 volts here but what the load is on this circuit at the time of test could be a factor also.


Something to consider is troubleshooting the symptom of no display in hopes it will lead you to the cause of runaway drum. It might not hurt to unplug the drum if it seems to be self destructing do to running at full rpm.
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07-12-2017, 04:52 AM
Bullabill Bullabill is offline
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[QUOTE=bever;50149]
This seems significant
Did this change the symptoms of no display or runaway drum revolutions?
I did follow the path of the -8v line and found it to meander through the luminescence and audio boards showing up at the HI Fi audio pack schematic diagram.


Sadly, it made no change at all to the symptoms, but that might change when I get and fit the equivalent diode. Although the tiny diode I fitted gives somewhere near the correct voltage it might not be able to supply enough current to meander all the way to the Hi Fi audio pack (and elsewhere).
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07-22-2017, 07:52 AM
Bullabill Bullabill is offline
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I fitted the replacement diode but no joy, - symptoms unchanged. I then found an open circuit resistor (2.2k 3 watt) at one output on the diode bridge. I changed that resistor and it changed the symptoms. Instead of the drum head spinning at high speed when I plug the power in it now just twitches continually at a rate of about 750 milliseconds - the 'On', 'SVHS' and 'AI' lights all flash in concert with no other indication, - no display and no control by the On-Off power switch. I unplugged the drum power but that just stopped the drum twitch, the lights flashed as before.
There remains just one electrolytic cap to change, a 47u 400v across the diode bridge ( I have one on mail order and still waiting). Tester shows capacitance and ESR OK but who knows? The schematic I am working with shows that cap. to be 120u 400v, but the parts list calls for 47u and that's what's in the unit. I can't see that it would make much difference.
I still have two voltages incorrect - pin 2 should be unreg -8v it is -9.8 and pin3 should be unreg 45v it is 43.2v. Both pins are 1.8v low and both are supplied by the same tap of the transformer. I've changed the two electros and the diode on the -8v leg and the two electros on the 45v leg with no change to the voltages.
I don't know what part the IC1 - STRM6547LF plays in this, can anyone advise whether it could be culpable?
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  #19  
07-22-2017, 03:03 PM
bever bever is offline
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Quote:
Originally Posted by Bullabill View Post
but that might change when I get and fit the equivalent diode. Although the tiny diode I fitted gives somewhere near the correct voltage it might not be able to supply enough current to meander all the way to the Hi Fi audio pack (and elsewhere).
I didnt think this would make any difference as not sourcing enought current would already have shown up as a low voltage under load, Nothing wrong with using the correct part though.


Quote:
Originally Posted by Bullabill View Post
I then found an open circuit resistor (2.2k 3 watt) at one output on the diode bridge. I changed that resistor and it changed the symptoms. Instead of the drum head spinning at high speed when I plug the power in it now just twitches continually at a rate of about 750 milliseconds - the 'On', 'SVHS' and 'AI' lights all flash in concert with no other indication, - no display and no control by the On-Off power switch. I unplugged the drum power but that just stopped the drum twitch, the lights flashed as before.

I presume you mean the resistor at the low side of the full wave bridge. I cant make out the number on my schematic, however on a similar schematic (see attached) I found it is R1102. If so it may mean there was too much current draw and replacing it is part of the solution.



Quote:
Originally Posted by Bullabill View Post
I don't know what part the IC1 - plays in this, can anyone advise whether it could be culpable?


Notice that transformer T1101 takes the rectified voltage and uses the healthy amount of ripple intentionally left on it to drive diodes on the output side.
IC1101, (a type of oscillator power supply regulator) is fed the ground side of the bridge diode output input at pin 3. It is not immediatley clear to me how the IC works though pretty sure it handles the low side of your bridge. The low side of the bridge rectifier needs to be referenced to ground

Culpable possibly but check the voltage outputs of the power supply and voltage on the ic pins(with an oscope if possible) to rule it out.

The initial power supply output voltages seem to have been pretty close to spec for having found an open diode and resistor. Is it possible that you missed some poorly filtered dc voltages when you first analyzed the output of the power supply? Also these are fairly complex power supplies and really need a picture (oscilliscope) Also do suspect caps as may people report bad caps in this vintage of electronics.


Attached Files
File Type: pdf STRM6547LF.pdf (186.3 KB, 19 downloads)
File Type: pdf STRM6547LF page 2.pdf (170.7 KB, 17 downloads)
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  #20  
07-23-2017, 11:05 AM
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Originally Posted by bever View Post






Notice that transformer T1101 takes the rectified voltage and uses the healthy amount of ripple intentionally left on it to drive diodes on the output side.
IC1101, (a type of oscillator power supply regulator) is fed the ground side of the bridge diode output input at pin 3. It is not immediatley clear to me how the IC works though pretty sure it handles the low side of your bridge. The low side of the bridge rectifier needs to be referenced to ground

I found what I think is good info on these switching power supplies. take a look here https://www.repairfaq.org/sam/smpsfaq.htm#smpspre
The author even has some Panasonic specific information on the repair of these power supplies.

use control F and search through the page for panasonic
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