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Hello Fellow retro tech enthusiasts;N1700 Fault Assistance

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crustytv
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Posted by: @vipersan

Are 1500 audio heads interchangeable with 1700 heads.

Looking up the parts numbers in the respective manuals show they have different idents. Is that due to them being characteristically different electrically or just how they mechanically mount? Your guess at that is as good as mine.

N1500 K3/K4 Audio/Sync Head Part No. 4822 249 10071
N1700 K3/K4 Audio/Sync Head Part No. 4822 249 10093
N1700 K3/K4 Audio/Sync Head Part No. 4822 249 10098 (until WD02)

I dug out a couple of old pictures of two players, they show the Audio/Sync head as used in the 15K and 17K. They do look very similar. Unless someone knows of a way of telling or testing, you're going to have to fathom this out for yourself. I'll try and remove the heads from their respective chassis' and take photo's for a better, clearer comparison later.

15K
17K

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Posted : 01/12/2020 4:26 pm
Katie Bush
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From Chris' photos, above, and optical illusions aside, it looks like the N1700 has wider tracks for the sync and audio.

First though, can I check with you exactly which VCR made the recording on the tape you're using?   I always understood that the N1500 could not be converted to the quasi-N1700 format, and that only the N1502 could be, but it's 40 plus years and a lot of different coloured waters have passed under the bridge.

One reason I seem to recall being cited for the N1500's non-compliance was that the audio and sync tracks were transposed (t'other way round, in other words), but I can't even be 100% on that, and that the N1502 and N1700 shared the same track layout. - Could be worth checking that out, if not for any other reason than to eliminate any potential confusion there?

Electrically, N1502 was far closer to N1700 than it ever was to N1500.

 
Posted : 01/12/2020 7:03 pm
crustytv
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Maybe this will help show the two distinct heads, the difference can be clearly seen now. Hopefully from my examples you should now be able to determine which is fitted to yours.

achead1
achead2
achead3

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Posted : 01/12/2020 7:57 pm
Katie Bush
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Well, there's no disputing the difference there, and it also looks to me like the tracks are spaced differently from one head type to the other. If the machine that recorded the tape was an actual N1500, as opposed to an N1502, then I'd say it's hardly surprising that this machine can read one track, or the other, but not both at the same time.

What's needed now is a recording from an actual N1700 machine.

 
Posted : 01/12/2020 9:39 pm
Vipersan
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The original 1700 I had which I have never managed to get working 100%. The problem appeared to be a tracking issue. No amount of tweaking of the audio control heads would make both audio and servo lock. It is either solid lock with no audio or perfect audio and no tracking, never both together.

It was as though the heads couldn't be positioned to get both tracks at the same time. This had me extremely perplexed as you can imagine. So, I finally plucked up the courage to remove the control head assembly and the one from my second fully working 1700 to compare them. The head on the unlockable machine was measured particularly the distance between the heads and the second (good) heads. They are different !!

It looks to me at least that somewhere in its past the audio control head had been replaced but with a 1500 head or more likely a 1502. Which has a gap between the audio and control heads of 11 mm + - and the 1700 has a gap of 12.5 mm + -

This explains what I have long suspected, someone fitted the wrong heads, so basically I'm stuffed with this one. I guess it will never be more than a kit of spares. Unless of course someone has a set of audio control heads in whatever condition for the 1700 I can clean up and fit. I'm gutted as you can imagine. Apart from this major problem the n1700 is working fine in all other respects.

 
Posted : 20/12/2020 7:46 pm
Vipersan
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Looking again at the photos Chris posted the heads I need are like the one labelled N1700 in that photo.

Can anyone help me ?

rgds

VS

 
Posted : 20/12/2020 8:39 pm
Vipersan
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@katie-bush

Indeed I do have a recording made on a working 1700 Kate, sadly it will only play on the working 1700. Once I have re-fitted the A/C Head of course, not looking forward to that part but at least I have now confirmed my suspicions.

 
Posted : 20/12/2020 9:01 pm
Vipersan
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Hi Chris, is the 17K A/C head assembly in your photo from a working machine or scrapper? If from a scrapper would you be interested in selling it? The whole assembly that is so as not to have alignment problems.

rgds

VS

 
Posted : 21/12/2020 3:21 pm
crustytv
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Hi Viper, I'm afraid not otherwise I would have already offered.

I have limited spares to maintain my N1700 machines. If I have more than one of something then I'm always happy to offer up the additional spares to fellow members, as I did with the N17K pinch roller but in this case these are my only stock of AC heads one for a N15 & one for an N17.

Getting spares is not as difficult as you may think, you'll just have buy a full machine from e-bay and use it as a cadaver, that's what I did to maintain my 15K & 17K machines. N1700's turn up all the time and for not a lot of money. 👍 

The only dilemma you face is once you get a machine for spares, you have to be strict with yourself and not try to repair it. Otherwise you end up back at square one but with another machine needing spares and none for the original requirement. 😲 

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Posted : 21/12/2020 4:11 pm
Vipersan
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Totally understandable Chris, it is just a pity that this machine is now fully working but for the A/C head issue. I'd be happy to buy a non worker say with damaged video heads. That certainly would discourage me from attempting a repair.

Hopefully I'll spot one eventually, such is life.

I am my own worst enemy as I admit I try and repair just about anything.

doh!

 
Posted : 21/12/2020 4:19 pm
1100man
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Posted by: @vipersan

 It looks to me at least that somewhere in its past the audio control head had been replaced but with a 1500 head or more likely a 1502. Which has a gap between the audio and control heads of 11 mm + - and the 1700 has a gap of 12.5 mm + -

 

Well that is just weird! Although where Philips are concerned, weird is par for the course! The pictures of the heads that Chris posted are interesting, The 1500 one looks to have one head narrower than the other whereas the 1700 one looks much more 'normal' with both heads the same width. As it's the normal looking one you need, I would have thought a VHS head would possibly have the correct spacing?

Might be worth comparing the measurements between the 1700 one and a VHS one. I'm sure it would work electrically with some jiggery pokery to actually mount it. It would be interesting to see a drawing of the track layout of the 1500 & 1700 machines to see exactly what the differences are.

Obviously it would be better to try and get the correct head, but it would be interesting to see if a VHS one could be made to work.

Cheers

Nick 

 
Posted : 21/12/2020 10:07 pm
Vipersan
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@1100man I had already considered this Nick and yes the spacing of the heads is similar but mounting it could be very awkward indeed since the Philips heads are physically taller. The pinch roller in the Philips could theoretically drive the tape to hang over the head surface above and below causing tape damage in the process.

Also mounting it far enough forward might be an issue since VHS heads tend to be much thinner and often have a 'guide' at the top to stop 'wandering'. Do-able? Probably yes, do I want to try it ...errrr no, I'd be risking my old tapes.

rgds

VS

 
Posted : 22/12/2020 1:16 am
Vipersan
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Curiously ..thinking about it.

Whoever owned this 1700 with the 1500 A/C head would not have been any the wiser unless he/she had tapes made on a 1700 as the recordings made on it although incompatible with other N1700 machines would probably have played back perfectly well.

Another custom format like the hybrid 1700/1500 modded LP machine if you will.

c'est la vie

 
Posted : 22/12/2020 1:57 am
crustytv
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Jim @jcdaze sent me these extracts on the tape specifications for the N1500/N1502/N1700, he thought they might be of use/interest with regards to the issues raised in this thread.

N1500

1500 Tape layout

N1502

1502 Tape Layout

N1700

1700 Tape Layout

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Posted : 22/12/2020 12:47 pm
Vipersan
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Thanks for the pix Jim/Chris, I guess that confirms my suspicions, a definite change of format on the tape.

 
Posted : 22/12/2020 1:54 pm
Katie Bush
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Posted by: @crustytv

Jim @jcdaze sent me these extracts on the tape specifications for the N1500/N1502/N1700, he thought they might be of use/interest with regards to the issues raised in this thread.

And now, that all makes sense of the symptoms exhibited by this machine.

 
Posted : 26/12/2020 5:01 pm
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