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Philips N1700 ...getting there...but still have issues

 
Vipersan
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So ..I now own 3 of these beauties..

One has been designated 'spares bin'..mainly on account it was fitted with 1500 Audio control heads....thus not a viable restoration project.

All 3 had working video heads..though these varied quite a bit performance wise.

I decided to concentate my efforts on the machine with the figure 8 mains lead..as this was likely the most recent...the other 2 had captured mains leads.

Belts were replaced on the 2 complete almost working machines...and the best parts were canibalised from all 3 17Ks to make up the later 17k to a higher standard...hereafter fered to as 17K A

The 17k which would also be viable but house the poorer parts designated as 17K B

..and parts bin was christened 17K C

I located an old copy of Television magazine with an article on s

'speed modding' a 17K for extended play and emplyed this mod on 17K A ...

Now pushing channel selector 8 switches 17K A to extended play mode in both record and playback.

I then went through all the UXXX modules from all 3 units to establish workers and faulty units..

I found 2 faulty units amongst them ..and these have since been repaired.

Time to concentrate on 17K A ..

Thorough cleaning followed..and this unit plays back old tapes with content fairly well...but has fast forward and rewind issues...which I can only assume is related to tape speed..as a capacitor which chrges has to be constantly discharged to maintain tape movement ..or it goes into 'protect' mode and shuts down automatically.

This is exactly what is happening here..

As one spool or the other gets heavy with tape during 'spooling' the tape speed slows down and the reset ocurrs.

I put this down to the friction of tape through guides and around the heads...but cleaning these didn't help..

OK I thought ..maybe it is just internal friction between spools as the tapes are old ?

So ..I purchased a new old stock tape still shrink wrapped to try..

It helped..but still doesn't comple the rewind cycle without shutting down.

There has to be more to this problem I'm just not seeing.

The other reason to buy a 'new' tape is that I want to create a testcard tape..

which is going well -ish.

using a BBC2 testcard F image with music from a DVD played on my old KISS dvd player which has AV out ...and using a Sony betmax recorder as a passthrough moulator ..producing UHF output to feed the 17K A tuner.

It works....

but there are errors creeping in due to the condition and age of the pinch roller..(remember 17K A has the best pinch roller fitted and video heads)...so I have contacted Terry Witt in the USA who refurbishes old pinch rollers with new rubber.

It wont be cheap 35$ per roller and another 35$ to ship it back to me.

So ..I will be sending him 2 rollers to re-furb.

In the meantime I want to fix the FF/REW issues..so any help here would be greatly appreciated

All 3 of these 17Ks have been fitted with AV out pcbs which is great for signal out ..but signal in for recording is still using UHF through the tuner.

any help and encouragement is greatly apppreciated...as this 'lockdown' 17K marathon continues.

Oh ...and I have a second VR2020 coming on monday/tuesday next week..so more fun to be had.

rgds

VS

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Topic starter Posted : 06/02/2021 8:49 pm
Katie Bush
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I may be wrong here, but I think you'll find that the "figure 8" power lead model is the early one, mine was a November 1978 model, and the hard wired versions came later, mine were all dated 1979.

Rewind issues plagued my recorders for years, and I sort of got used to the issue, but, and it's a big but, the issue as I recall is in part at least down to the rubber tyre in the FF/RW intermediate wheel, and the spool hubs themselves. It can be mitigated in part by cleaning the rubber tyres and friction surfaces of the hubs with methylated spirit, or IPA etc. As long as whatever cleaning fluid you use leaves no residue, you should be fine. The tyre becomes glazed over time, and may respond to cleaning with a fine emery paper.

Also, the tapes can be part of the issue if they've been stored in less than ideal conditions. Even the slightest dampness will make them 'drag' to such an extent that the VCR's drive train can't deliver the power to the hubs - The tyres will start to squeal. Keeping the tapes in a seriously dry location, and warm too, will help enormously. Baking the tapes before using them might help too, but keeping them warm and dry is the key, or at least as I found, about 40 years ago in my cold and (relatively) damp bedroom in my parents house.

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Posted : 06/02/2021 9:22 pm
Vipersan
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@katie-bush..

Thanks for the advice Kate..

I have actually tried rubber renue on the idler type but it didn't have any great effect..

I'm currently contemplating taking apart the dual spool drive 'cone' to clean and lubricate the spindle and drive surfaces.

Hopefully tomorrow...I'll have some news on that.

I do love these old machines...complete with major design flaws..

8 track style tape cassette being a major flaw imo.

Thank higgs...the future was linear 2 spool side by side action instead of stacked.

rgds

VS

interesting the figure 8 lead is earlier..

which to me seems to me a step backwards to use captive leads.

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Topic starter Posted : 06/02/2021 9:30 pm
Vipersan
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Ok ..so taking apart the supply/take up spool turntable assembly cleaning and lubricating everything..plus rubber renue on the idler rubber didn't help much at all.

What did appear to make a difference was adjusting R75 preset on the tracking slider pcb..a few degrees aticlockwise.

This pot directly affects the friction motor I believe...

It may well be that I might swap out the friction motor and try another belt here.

I have yet to try making another testcard recording since adjusting R75...and am still getting periodicic brief slowdowns to tape speed during playback of the recording I've already made...

approx every 30 seconds but this is not predictable to high accuracy.

So this could just be friction drag on the tape...or indeed ..the pinch roller which hopefully I may one day eliminate completely if I get those refurbs done in the USA.

I also get field jitter or bouncing on a recording of a testcard image..

At some point I'll try and grab a short video and upload it in my dropbox ...adding a download link here..

I'd say ...overall ...getting there.

but we shall see

rgds

VS

btw Chris does your scan of the 1700 service manual include diagnosis flow charts..

Sadly my mauritron scanned paper copy of the service manual doesn't include such detail..

I suspect it is incomplete.

rgds

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Topic starter Posted : 07/02/2021 3:49 pm
Vipersan
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So grabbed a couble of video captures with audio of the testcard recordings at full/normal speed and at half speed.

In half speed mode it is possible to record 4 hours of video on a 2 hour tape so to speak..

Both clips show the frame bounce/jitter..but ironically the audio is more stable in half speed mode.

normal speed

https://www.dropbox.com/s/p32yfbvycqdvebv/testcard%20at%20normal%20speed.AVI?dl=0

half speed..

https://www.dropbox.com/s/m5yz9ioh4s4lumq/testcard%20at%20half%20speed.AVI?dl=0

just in case anyone is interested.

sorry for my shaky captures.

hand held camera ..held by an old guy with MS

lol

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Topic starter Posted : 07/02/2021 5:52 pm
Vipersan
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Another video treat for you..

a short clip as proof of concept..

I will be creating something more practical in the future..

What is it you my well ask ?

A method of re-spooling tape.

Tansfering VHS tape from its case to VCR spools so as to replace crappy old tapes which have suffered years of use..age..and sticky shed syndrome.

Granted the VHS tape isn't exactly recent....but came directly from a sealed new/old stock tape.

It _has_ to be better than what _was_ in the 17K case.

The only problem is that a full spool of VHS tape (180 min) only half fils the 17K spool...

I wasn't sure just how muchit would fill of the spool ..but I expected it to be considerably less tape.

https://www.dropbox.com/s/dytv8mdibh81xxp/P1000537.MOV?dl=0

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Topic starter Posted : 07/02/2021 9:47 pm
jcdaze
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@vipersan I've got the diagnosis flow chart section in the service 1700 service manual and will try to scan and upload them later on today.

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Posted : 08/02/2021 2:03 pm
Vipersan
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@jcdaze Very much appreciated buddy..

That's what I love about this community..

Very very helpful.

rgds

VS

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Topic starter Posted : 08/02/2021 2:34 pm
jcdaze
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@vipersan I've uploaded that fault section of the 1700 manual and Chris has put it in the Philips video section of the data library.

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Posted : 08/02/2021 10:23 pm
Vipersan liked
Vipersan
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@jcdaze Thanks buddy..

A little light reading for later

😊 🙂

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Topic starter Posted : 08/02/2021 10:42 pm
Vipersan
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So ..what am I not understanding here...??

In order to record AV modulated signal to my 17Ks through the UHF socket ..I have been using an old sanyo beta VCR ..as a loop through

Audio and video inputs to the mono audio socket and bnc on the beta ..and switched to external source.

The output from the sanyo to the 17K via coax.

This works just fine but is big ..bulky and wastes power ..so I treated myself to a maplin model RF-0811N..which I assumed would be a better option.

I have tried it with the default settings B/G ...and what I assume is PAL I

I6.

And although I can modulate a very acceptable picture to the 17K via the UHF aerial socket...I cant get audio at all ?

I assumed that because the audio input to this modulator is only 2 phono.

Audio and video ..it would handle the job nicely.

but I can only get picture without sound.

I guess this modulator isn't really suitable..or I have it set up wrong..

Can anyone suggest a cure for my stupidity ?

rgds

VS

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Topic starter Posted : 10/02/2021 2:39 am
Vipersan
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So ...todays project is to find an alternative to using a vcr as loop-through for UHF .

To that end I'm going digging in my loft to hopefully find an old VIC20 RF modulator ..

Maybe you remember these metar boxes that plugged into the back of a VIC20 computer to provide an RF signal ..thus allowing you to use a TV as a monitor ?

No Idea if I still have one..nor if it will do the job...but I gotta try.

rgds

VS

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Topic starter Posted : 10/02/2021 1:16 pm
Vipersan
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Not tried this as yet ...hopefully it will work.

Having found an old VIC20 modulator..

The photo socket RF/out was replaced with a 75 ohm coax socket..

2 x phonos were side mounted for A/V in..

..and the supply which I think is 12v ..though I need to research this...brought out on 2 wires red/black.

we shall see.

rgds

VS

modulator external
modulator internals

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Topic starter Posted : 10/02/2021 4:34 pm
Vipersan
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The good news is that this bodged modulator works..

It runs at 5 volts not 12v.

But because it is basic and crude..not very stable and prone to drift.

I'll be opening the maplin unit to see if I can spot anything obvious..

rgds

VS

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Topic starter Posted : 10/02/2021 8:33 pm
Vipersan
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Chose my 2 worst Pinch Rollers and sent them off to the USA yesterday..$107 with return tracked postage.

No idea what to expect but I'm hoping to receive 2 practically new pinch rollers eventually.

It aint a cheap hobby this one...but I'm hoping to soon be the proud owner of 2 x re rubbered rollers for my 2 working  N1700 machines.

😎

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Topic starter Posted : 11/02/2021 10:56 pm