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Old 19th Jul 2021, 7:18 pm   #1
IAmATeaf
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Default Grundig VS 680 VPT

Hi there, new member alert 😀

Iíve been given a pair of faulty Grundig VS 680 VCRs. Iíve replaced the paper X2 capacitors with modern equivalent capacitor and both VCRs now power up but they both show the dreaded AO status on the display. Iíve also replaced the dead battery in one of them but canít get past the AO status on the display.

Iíve read a thread here on a similar model and have tried entering 4934 and 8500 as codes but I donít have a remote so am not too sure if entering the unlock code from the front panel is even allowed, it doesnít seem to work anyway.

One VCR accepts the tape, goes through the motions of loading the tape then move back into its rest position after which the tape canít be ejected. The other refuses to accept the tape, nothing seems to draw the tape in but Iím still looking into this.

In the other thread it was mentioned that there are some points on a circuit board to temporarily reset the VCR but Iíve not been able to find any points like this so am wondering if anybody here knows which board and where the reset points actually are.

Would be a shame to bin them so any help would be greatly appreciated 👍
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Old 19th Jul 2021, 7:50 pm   #2
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Default Re: Grundig VS 680 VPT

I should also add that I’ve managed to get a copy of the service manual for it. I’ve also taken the tape decks out from both to check them over.

The manual states that the deck mechanism must be in the winding position which is the position the deck that accepts the tape ends up in but when I check the alignment nothing matches up to the alignment holes given in the guide. I’ve checked both decks and taken them through the loading and unloading cycles and they both match each other in terms of the position of the alignment marks.

So this has left me throughly confused as surely both decks can’t be out can they?

The desks when I manually cycle them through loading and unloading do so without any issues and nothing has to be forced.
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Old 19th Jul 2021, 10:22 pm   #3
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Default Re: Grundig VS 680 VPT

Hi

Every time that i have this error. I use the remote control and the reset procedure works.
You can use also the KONIG remote controls as replacement

Check the link for the procedure steps

https://masterelectronicsrepair.blog...lectronic.html
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Old 19th Jul 2021, 11:59 pm   #4
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Default Re: Grundig VS 680 VPT

Isn't A0 indicating it's on the audio input?

Grundig models from the late 1980's up to and including the first generation of Philips Grundig joint venture models from 1993/1994 do suffer from leaking electrolytics on the power supply, though. If the copper traces on the secundary side are discoloured or if there's a bunch of parallel 470u 25V electrolytics on most supply lines, those need to be replaced.
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Old 20th Jul 2021, 12:49 am   #5
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Default Re: Grundig VS 680 VPT

Quote:
Originally Posted by IAmATeaf View Post
One VCR accepts the tape, goes through the motions of loading the tape then move back into its rest position after which the tape canít be ejected.
I have some Grundig machines of this era which use the Panasonic G mech. If this is the case on yours, I have a very faint bell ringing in my grey matter that says something about is a resistor going high which is responsible. Will give it some more thought!
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Old 20th Jul 2021, 8:20 am   #6
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Default Re: Grundig VS 680 VPT

Thanks for the replies. Any suggestions on which remote I should be looking out for?

All the searches I’ve done for Grundig AO seems to suggest that it’s in parental lock mode and needs to be unlocked.

Powered the 2nd unit up last night after changing caps and this one definitely has been messed with. The deck mechanism had been prised open, presumably to get a stuck tape out and when switched on the head motor makes a pulsing sound, so it spins the head up to speed, then backs off and the back on again but looking at the head it doesn’t appear to slow down. With this deck the mechanism to draw the tape in also doesn’t work so will take a look to see if I can figure out what is going on.
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Old 20th Jul 2021, 5:51 pm   #7
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Default Re: Grundig VS 680 VPT

You can find the type of the remote control in the specifications label on the back side of the VCR. The remote control type start with letters "RP"

Have you recap all the secondary side ofthe PSU?
If you can exchange the PSUs between VCR and check if you have the same problem with the mechanism.
Be careful how do you connect the black cable assemblies with green line.
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Old 20th Jul 2021, 7:08 pm   #8
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Default Re: Grundig VS 680 VPT

I actually swapped the pulsing deck between the VCRs and it does the same when installed in either. I think I need to dismantle the loading mechanism and put it back together properly.

In another thread, not the exact same model somebody mentioned some reset points which temporarily overcomes the AO lock, does anybody have any ideas as to where these might be as at least it will allow me to test the rest of the functionality of the VCR that seems fine.

I also had another read of the service manual and the position for STOP and/or WINDING MODE mentioned means none of the deck mechanism alignments mentioned line up with the service guide which is really confusing me. But on the deck that appears to work it draws the tape in, fully loads it around the drum and then parks itself in the STOP mode.

I have had this deck actually play a tape at FF search speed where it then proceeded to load the tape around the drum and then play the tape at 2 or 3 times speed but again none of the buttons on the front would do anything so had to power off which put me back into STOP mode and AO. ��
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Old 20th Jul 2021, 8:10 pm   #9
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Default Re: Grundig VS 680 VPT

Quote:
In another thread, not the exact same model somebody mentioned some reset points which temporarily overcomes the AO lock, does anybody have any ideas as to where these might be as at least it will allow me to test the rest of the functionality of the VCR that seems fine.
They were on the front clock/timer keyboard panel on the VS500/540 series as two testpoints, they only need to be shorted together momentarily with the machine powered up to clear the lock, the back-up battery is probably flat, at least this was the case on the VS400/500 series, your model I am not a 100% sure
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Old 20th Jul 2021, 8:28 pm   #10
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Default Re: Grundig VS 680 VPT

I’ve replaced the battery on one of the decks, to confirm the battery as working I also left it unplugged for a few hours and it maintained the time on the clock when plugged back in.

I’ve been searching eBay for a suitable remote but haven’t seen one for this specific deck yet.
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Old 21st Jul 2021, 2:04 am   #11
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Default Re: Grundig VS 680 VPT

Euras says to check C437 470u 50V when AO is displayed, especially if the drum motor is also running.

I'm not convinced AO or A0 has anything to do with a child lock. Any child lock should be possible to clear with code 4934.
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Old 21st Jul 2021, 9:57 am   #12
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Default Re: Grundig VS 680 VPT

@Maarten thanks for that I’ll pull the capacitor and check and replace and will report back if the deck behaves any differently.

I’m wondering if I can program up a Logitech programmable remote maybe?
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Old 28th Jul 2021, 8:57 pm   #13
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Default Re: Grundig VS 680 VPT

Been busy so not had a chance to play around but I changed the capacitor as above and that made no difference to the non working deck.

So I swapped the decks between the player and the non working doesn’t work in the other player either. I had a look at the mode switch on the non working and noticed that it does look like the mode switch had been removed so I’m going to pull it out and check it to make sure the internals look OK.

In the meantime I’m still hunting for a suitable remote on eBay as I’ve not found a way to enter 4394 using just the front panel.
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Old 29th Jul 2021, 2:50 pm   #14
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Default Re: Grundig VS 680 VPT

If you can clean the mode selector switch and check also the alignment with pinch roller gear.
If you still have problems check the alignmemt of all gears of the mechanism.
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Old 31st Jul 2021, 11:45 am   #15
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Default Re: Grundig VS 680 VPT

Quote:
Originally Posted by vhs doctor View Post
If you can clean the mode selector switch and check also the alignment with pinch roller gear.
If you still have problems check the alignmemt of all gears of the mechanism.
That is what I have been checking but according to the service manual and putting the deck in the STOP/WINDING MODE means that nothing in both decks lines up but 1 deck will accept and load a tape, wind it onto the head drum and then put the deck into the STOP position, after which none of the front panels will do anything so I canít even eject the tape, have to them remove the deck and manually eject the tape.

Iíve still not been able to find a suitable remote which is what I think I need to get past AO on the front display.
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Old 31st Jul 2021, 12:28 pm   #16
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Default Re: Grundig VS 680 VPT

Check the voltages on the psu and on the front panel are they OK?

On the back of the VCR what model of remote control is suitable for your VCR? Start with letters RP
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