What's wrong with my Philips N1700 Longplay

Hi Harald, Welcome to the forum. ? 

Before trying to delve into the fault and what might be the cause, can we ask a few preliminary questions,

• What level of experience do you have with vintage electronics and in particular video recorder servicing?
• Do you have access to and know how to use a multi-meter and oscilloscope?
• Do you have service data for the video recorder? Not a problem if you don't as we can post in the thread, relevant snippets as and when required.
• What have you done by way of servicing to this VCR or have you just plugged it in?
• Have you checked the belts? If so were they OK or stretched?
• Did you replace them? If so, did you source the correct ones or fit ones you felt might be near?
• Have you cleaned the heads? I noted cotton buds in the youtube video, I hope they were not used on the heads.
• Have you cleaned the tape transport path?
• Have you cleaned the audio head?

All this and more, needs answering to enable the Vrat community to offer you advice and pitch it at the right level.

Without knowing answers to all the above, watching the youtube video leaves me with the first impression the transport or head drum is not running at the correct speed. This is sort of backed up by the video sync issue on screen and the accompanying sound track obviously running too slow. There are a whole raft of things that could be the potential cause of this, here's a couple of thoughts.

First it could be belts, hence the query about them.

Second, it could be a problem on the servo board, (panel 21) tape servo & tape sync modules and/or their associated components. Could be trouble around the head motor or tape transport motor, maybe voltages there, all this needs to be checked.

• Are the main supply rails operating at expected levels? First rule of servicing, check all supply rails, if they are out, fix them otherwise you're chasing phantom faults. Hence the other query about your experience and equipment to investigate.

All guess work at this stage without further input from yourself.

If you've limited or no experience with electronics in general, then you've taken on a real challenge. Its not impossible to remotely assist but it will test the limits of your learning, endurance and frustration. Also, there is only so much we can do remotely when relying on you interpreting what you are being presented with and relaying that to us.

If you have experience with electronics then most of the above will be teaching you to suck eggs. In which case apologies and can you supply us with the answers to the questions posed.

This may help, to find your way around and what is what on an N1700 

Well, from my experience, the take-up reel looks to be turning at a speed that I'd consider to be commensurate with an N1700's normal operation, so my surmise would be that, either the tape was recorded on an N1500 (which runs its tape at about  double the ips of a 1700) or it was recorded on a faulty N1700 (different machine).

Can you get an RF signal into the VCR? If so, try making a fresh recording on this machine. I'm guessing that you won't have a "Known To Be Good" recording?

As Chris pointed out, never use cotton buds to clean the video heads. They're okay for other parts, but never use them on the video heads/rotating drum.

It sounded to me as though there is some 'wowing' of the audio, which suggests that there could be a capstan servo problem, or the capstan belt may be slipping, but I'd bet on the servo being the problem. From observing how the machine was able to rewind the tape, I'd say the belt has good traction, but I'd still check it, and if needs be, clean it.

Of course, this is just the beginning, and there may be more problems ahead. Remember that this machine is around 40 years old and parts aren't made anymore, so handle with great care.

I would say that without knowing what machine that tape was recorded on then it makes diagnosing the fault(s) a bit difficult. It may have been recorded on a 1700 with the unofficial half tape speed modification applied. I did play the above clip on double speed but it still plays slow but kind of constant, (got me trying to guess what song it is now) Do you know that the tape does play correctly in another machine?

Posted by: @crustytv

What level of experience do you have with vintage electronics and in particular video recorder servicing?

I know what to touch and what not to touch. I clean the clay heads with isopropanol and lubricate gears and worm gears. So, this is my first video recorder service project.
I bought the VCR because I still found a lot of old tapes that were probably recorded with an earlier recorder.

Posted by: @crustytv

Do you have access to and know how to use a multi-meter and oscilloscope?

I own a voltmeter and am trying to build a Telecine Super 8 machine with Raspi and or Arduino. So, I have no idea about electronics.

Posted by: @crustytv

Do you have service data for the video recorder? Not a problem if you don't as we can post in the thread, relevant snippets as and when required.

I have no data on the N1700, just a Dutch service manual, which I cannot read.

Posted by: @crustytv

What have you done by way of servicing to this VCR or have you just plugged it in?

I cleaned some solder contacts with isoprophanol, the capstan roughened a little, everything that you can see on youtube videos.

Posted by: @crustytv

Have you checked the belts? If so were they OK or stretched?

The straps were crumbled or torn. They were sticky like licorice. The two small ones at the top of the counter are ok, I renewed one and left the other off the counter.

Posted by: @crustytv

Did you replace them? If so, did you source the correct ones or fit ones you felt might be near?

Yes I bought a new set, but I'm not so happy. The drive is only 0.6cm thick, the original was 1cm for me.

Posted by: @crustytv

Have you cleaned the heads? I noted cotton buds in the youtube video, I hope they were not used on the heads.

Yes, I also cleaned the head with isopropanol. What should be different on the cotton swabs than on these cleaning sticks.

Posted by: @crustytv

Have you cleaned the tape transport path?

Do you mean below the drum or head?

Posted by: @crustytv

Have you cleaned the audio head?

yes

Posted by: @vcrkowski

Yes, I also cleaned the head with isopropanol. What should be different on the cotton swabs than on these cleaning sticks.

I take it that's a yes, that you used Isoprop soaked cotton buds to clean the heads, lets hope you have not caused additional problems. With regards to cleaning video heads, hopefully you will find this article of use

Indeed as other members have pointed out, without knowing the source of your VCR recordings (N1500, N1700, N1702) it makes life difficult. Have you tried other tapes, do you know for sure which format they were recorded in. I still have my suspicions though with regards to the servo, this is a common fault on these players. Still, all speculation until you have a known good tape. As Marion indicated in this position you're best option is to get it hooked up to an RF source and make your own recording. In theory that should show if the VCR is OK making its own recordings or confirming my suspicion of servo trouble.

I had a similar problem when I first got my N1500 and N1700 machines, I only had a couple of tapes of unknown origin. I had been chancing my arm with tapes on e-bay of unknown quality and origin most of which were utter rubbish.

I ended up spending a small fortune (£300) on 40, known good tapes (10, N1500 and 30 N1700) from a respected Chap in the media industry. Also, a couple of brand new sealed blanks. 

I try to copy a film from a VHS source. Once with output program (RF signal?). Where is the recording head located and why is no audio signal recorded?

.

And here is a little video of my new belts.
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@vcrkowski  Did you actually tune the 1700 into the rf output of the vhs or is that picture in first part of the video just looping through the 1700? Also not sure what heads don't know the location of. 

Posted by: @vcrkowski

Where is the recording head located

Posted by: @jcdaze

Also not sure what heads don't know the location of. 

find your way around and what is what on an N1700 

@jcdaze VHS goes into Antenna VCR (RF in) and VCR (RF out) goes into TV.

@vcrkowski Yes but did you tune one of the 8 tuner locations on the 1700 into that rf out signal from the vhs because if you didn't you may well see the picture on the tv but you won't be recording what you see as that could be just looping through the rf in and out of the 1700. You still need a known good recording for sure and you should concentrate on getting playback working before trying the record side of the machine I'd say.

@jcdaze Good to know, unfortunately I have no background knowledge and I do not have a user manual.

N1700 is now running!
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What was the problem then ?

@red_to_black Look post from @jcdaze 

This is only a guess but i can see that it's channel 8 that is selected and maybe the half speed mod has been done on that machine and it wasn't on the right channel earlier and therefore capstan was running at wrong speed. Only a guess though. 

@jcdaze

There was a half speed mod that could be carried out on the N1502. It gave the '1502 a quasi compatibility with N1700. It involved reducing the capstan speed by 50% (required the capstan motor's drive pulley to be machined to half diameter). Also, required an extra capstan servo trigger magnet to be added to the capstan flywheel, 180 degrees away from the extant magnet, and it also required the machine to be equipped with an N1700 video head drum. Even then, the resultant recordings weren't really playable on a true N1700, but did at least give the 1502 a long play capability (theoretically, doubled the record/play time).

I'm not aware of any mods to the 1700, other than the development of the N1702 which squeezed about ten more minutes out of a two hour tape. If there is a mod for the N1700, I'd be interested to see it.

Posted by: @katie-bush

I'm not aware of any mods to the 1700, other than the development of the N1702 which squeezed about ten more minutes out of a two hour tape. If there is a mod for the N1700, I'd be interested to see it.

The N1700 speed conversion was described by Mike Phelen in the April 1983 Television magazine, page 296. Its in the library.