Quantcast AG4700 restoration project, lot of issues? - digitalFAQ Forum
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  #1  
02-16-2019, 10:31 PM
ofesad ofesad is online now
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Hi people!

Finally I got two Panasonic AG4700 (PAL) for proper capture.
The seller said they were used and have been stored for several years.
They used'em for showing students how to edit some videos, however students started using PC's so the equipments were stored.
Based on that info I assumed that the VCR's would be used but in fairly good condition...

How wrong I was.

For better undestanding let's call each VCR1 and VCR2 (VCR2 will become a donor for VCR1).

As just got'em, I plugged VCR1, put a VHS in... it ejects it right back. Try'd a few more times, then it took it in. Starts to play... no image. Plays stops. Self ejects.

My firtst tought was: of course, dirty head drum. I clean it with Isoprophyl 99%. Still the same
Checked the Mode Switch, and in my inocent yet futile attemp: I took it off and forgot to mark it's position.
Still, later I downloaded the K mechanism manual and I follow'd the steps and checked that every gear is set up correctly. This is what I did:

1) took the carriage off.
2) took the motor off.
3) moved the wheel gear until main cam gear sets to cassete down position (a circle appears on the front of the main wheel).
4) checked all alignments. Everything was perfect.
6) took the mode sw off and aligned it properly (arrow->notch), then put it back to where it was.
5) moved the wheel gear until main gear shows to eject position (triangle slightly off centerd).
6) put motor back
7) put carriage back (not in load position).

Sadly it didn't work either. (see Video Part 2)

In fact, VCR1 mechanism seems to be a little stiff for some reason. Eject and cassete down does ok, but then when it has to go into play or FF, it really makes my fingers hurt to move the wheel.

On the other hand, VCR2 system has issues too. The head drum seems to have a vertical scratch and I broke the retention post of the pinch roller (a brief moment of brute force).
How ever the mechanism seems to work ok-ish. I did disassemble it and relubricate almost every moving part and it doesn't take as much force like the one of VCR1. (see video PART 3)


Here I been uploading some videos of mi (lack of) progress:

Part 1
Part 2
Part 3

So I come to you, my dear Digital Faquers. Ok, that doesn't sound right.

If any had some experience with the calibration of this models or just wanna seeme fail over and over is welcome to comment. Also some advices will be welcome.



Please feel free to comment and any help is welcome.

Let's hope I can can get to these to work, at least one of them.


Ofesad.
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  #2  
02-18-2019, 05:04 AM
vgf1962 vgf1962 is offline
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Did you check if the motor coupling is broken?

You could also check the loading motor powering it with 4,5V and see if the mechanism works well or not (4-14 of the service manual)

For the cassete holder, follow the steps from 4-15 and double check that the marks are aligned properly (Fig. K17).

Btw, A3 code just means INSERT.


Attached Images
File Type: jpg tabella2.jpg (336.5 KB, 3 downloads)
Attached Files
File Type: pdf Service Manual Mechanical Chassis K (OCR).pdf (2.90 MB, 0 downloads)
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  #3  
02-18-2019, 08:21 AM
ofesad ofesad is online now
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Some mayor update: I got a working system: it loads, plays, rewinds, ff etc.
But still has a issue:
I press stop and press Rewind. When is getting to the end (the beginning of the tape) and slows down, it turns itself off. After that I turn it on again and it eats the tape (not much). And wont eject no matter what. In fact, I can hear the motor spinning internally but afther further inspection, it doesn't move or spin the worm gear.

Check Part 4
video

Quote:
Originally Posted by vgf1962 View Post
Did you check if the motor coupling is broken?
Yes. At first sight is has a vertical line that makes me think it's not in the best shape. But I cleaned everything and it seems to work. Also fits nicely in the motor shaft and when moved it doesnt have any play or false movement.

Quote:
Originally Posted by vgf1962 View Post
You could also check the loading motor powering it with 4,5V and see if the mechanism works well or not (4-14 of the service manual)
I haven't but I will!

Quote:
Originally Posted by vgf1962 View Post
For the cassete holder, follow the steps from 4-15 and double check that the marks are aligned properly (Fig. K17).

Btw, A3 code just means INSERT.
Thank you! All alignments are correct now. The main issue was the encoder switch (mod switch). I replaced it from the donor system (previously it took a bath in contact cleaner).

Sadly these mod switchs doesn't seem to be possible to open'em to do a proper cleaning.
(You can see pictures of it google by the part number: VSS0365)


Now I only have the issue I show'd in the Part 4 video: when rewinding and gets to the tape beginning it stops and turns off. When turned on again it eats tape and won't move (motor spins but doesn't move).
I had to take the motor off and turn the wheel by hand. It was pretty hard and that step. However when starts moving it gets easy'er and softer.

Probably needs more greasing in some part?
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  #4  
02-18-2019, 10:06 AM
hodgey hodgey is online now
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I can't say much about fixing the mechanism on this, thankfully our NV-HS1000 (consumer version of this) doesn't have any mechanical issues other than rewinding being a bit noisy.

Though I wanted to mention, another user - bogelein - posted this handy cross-reference which tells what other decks use the same mechanism (and drum) which could be helpful to scavenge spares from much cheaper decks.


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File Type: pdf Audio Video Ersatzteile.pdf (26.98 MB, 6 downloads)
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  #5  
02-18-2019, 10:07 AM
vgf1962 vgf1962 is offline
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Quote:
Originally Posted by ofesad View Post
Yes. At first sight is has a vertical line that makes me think it's not in the best shape. But I cleaned everything and it seems to work. Also fits nicely in the motor shaft and when moved it doesnt have any play or false movement.
That's the common issue about this little piece of plastic: that vertical line means it's broken.
Look at 3:17 of this video: https://www.youtube.com/watch?v=3SoFaaks-SE
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  #6  
02-18-2019, 09:01 PM
ofesad ofesad is online now
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Quote:
Originally Posted by hodgey View Post
I can't say much about fixing the mechanism on this, thankfully our NV-HS1000 (consumer version of this) doesn't have any mechanical issues other than rewinding being a bit noisy.

Though I wanted to mention, another user - bogelein - posted this handy cross-reference which tells what other decks use the same mechanism (and drum) which could be helpful to scavenge spares from much cheaper decks.
That's very usefull! Thank you a lot!!

I was considering buying two AG4700 more that are for sale quite cheap (10usd each). Of course they don't seem to work properly.

Also I was checking some online sites that can ship internationally some spare parts. Seems like for under 40usd (shipping included) I could get the pieces I need and some spares!.

Quote:
Originally Posted by vgf1962
That's the common issue about this little piece of plastic: that vertical line means it's broken.
Look at 3:17 of this video: https://www.youtube.com/watch?v=3SoFaaks-SE
Yeah! I saw a video of Quasipal (user of this forum) that said the same. I wasn't quite sure about that line and the motor seems to rotate properly (sometimes). But when it set to certain modes it struggles to operate/spin. I trye'd lubricating the mechanism a little more but no success.

Also, thanks to your video, I decided to open one of the Mode Switchs (the one that was noisy). Seems that the mode disc brokes off from the wheel, but still fits and it could be superglued.
Actually the tracks looked fine. No dirt or black junk. I cleaned with isopropanol and contact cleaner to be sure... but sadly the noise came from the legs of the mod switch. One was bended backwards and when I tryed carefully to put it back in position it felt off.

So I will be needing some Mode Switches for sure.


[PS]
I didn't realize until now, but one of the VCR's has 2 buttons more than the other (remember, both are AG4700) one has AVLINK and PAL/MESECAM, the other don't.


Ofesad
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  #7  
02-19-2019, 08:53 AM
vgf1962 vgf1962 is offline
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Quote:
Originally Posted by ofesad View Post
I was considering buying two AG4700 more that are for sale quite cheap (10usd each). Of course they don't seem to work properly.

So I will be needing some Mode Switches for sure.
Ofesad
I'd buy those two AG4700 at 10 usd, that's a steal!

As far as I know the VSSO365 mode switches are no more available as spare part.
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  #8  
02-20-2019, 09:15 AM
ofesad ofesad is online now
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Quote:
Originally Posted by vgf1962 View Post
I'd buy those two AG4700 at 10 usd, that's a steal!

As far as I know the VSSO365 mode switches are no more available as spare part.

I Just hang Up talking to the owner.

He is the original owner, he bought it around year 2006 for editing his tesis for the Cinema Career at the local unversity.
After that he did some tape digitalization but not much.
He says that the VCR works perfectly.
And he has the manuals and remote.

Asking price: 15usd.
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  #9  
02-23-2019, 10:18 PM
ofesad ofesad is online now
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I just got ANOTHER AG4600!

This one worked perfectly when tested it!
I just ended up cleaning it and putting new grease.
THE MOTOR COUPLER IS IN PERFECT CONDITION!

For the sake of understanding this will be called VCR3.

The head seemed pretty clean and it was used very little compared to the VCR1 and VCR2.
Sadly seems to have some issues with the picture...

It has some white horizontal lines from time to time and kindda noisy.
Thing that doesn't happen on VCR1 and VCR2.

I will do a more intense cleaning of the VCR3 head and test again.

Also will try to capture the white lines for showing here and ask recommendations.

Thank you all for your help!

Ofesad.
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  #10  
03-14-2019, 06:33 AM
ofesad ofesad is online now
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Time has passed now I have a working AG4700. Took a looong time to properly set it.

However today I found it another issue. This time regarding the built-in TBC.


For better understanding:

VCR1 (main unit), working deck (with some spares of the others).
VCR2 awaiting replacements. It's a AG4700 but it has differences in buttons.
VCR3 awaiting replacements it's the same as VCR1 but newer.


The issue:
I have been doing some captures and noticed some sound issues, mainly getting sound out of sync or speeding the sound up. Not a lot, but it was noticible and for me that's a no-no.

I decided to swap the working deck from VCR1 to VCR3. Colors were AWFULL! (see pic)
So I took the TBC module from VCR1 and put it in VCR3. Colors were back to normal again.
Then I decided to took the TBC from VCR2 and put it in VCR3. Made a capture with almost no issues!. There are minor drops but the sound is WAY more stable.

So, in short:
TBC1 = from VCR1, has some minor sound sync issue.
TBC2 = from VCR2, so far seems to work ok
TBC3 = from VCR3, colors look way off.

Then I decided to inspect these TBC's modules. (see pic)

The TBC module (VEP03A53), has 8 variable resistors: DIG. C LEVEL, W.B1, W.B2, R-Y LEVEL, 1HDL GAIN, TBC SYNC LEVEL, TBC OUT LEVEL, NOISE GATE.


Question time:

a) Could the TBC3 be fixed by tweakin some of the variable resistors? I personally don't think so. Most sure it has some bad caps.

b) Could the TBC1 be fixed by tweaking some of the variable resistors? Probably TBC SYNC LEVEL?

c) Any guide on how to tweak or tune TBC's?

Later I would do some measurements in TBC2 to check at what values (impedance) are the variable resistors set and apply the same to TBC3 and TBC1.

Any help on this matter is very welcome!


Attached Images
File Type: jpg PRESENTACION LIBRO RAW PANASONIC SVIDEO TBC 3.avi_snapshot_00.02.190.jpg (113.9 KB, 3 downloads)
File Type: jpg IMG_20190314_0815128.jpg (101.2 KB, 3 downloads)
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  #11  
03-16-2019, 07:26 PM
ofesad ofesad is online now
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After further testing: wasn't the TBC (altought TBC3 had some variable resistors with low values compared to TBC1 and TBC2).

What seems to be the problem?: the Y/C card of the VCR3.

So took the deck back to VCR1. Now it work and plays smoothly.

Also dissasembled all the PCB from VCR3 for checking caps. Will update on this later.
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ag4700, alignment, mechanism, panasonic

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