Philips N4506 - UK Vintage Radio Repair and Restoration Discussion Forum

Chindit · 16th May 2016, 8:28 am

Good morning,
I normally lurk on the domestic radio side of things but just this year I've rekindled a long-dormant interest in Philips HiFi separates. I've have a pair of working MFBs, AH762 tuner/pre-amp and a N2520 cassette deck.
I also own a pair of N4506 reel to reel machines, one imported from Italy and one from the Netherlands - these are the current focus of my activities. Both machines have had new belts fitted at some point, so no issues there.
At the weekend, I did a clean up and gentle lubrication of the NL machine and it now runs very smoothly and the auto-stop has even started working again!
However, despite the heads looking to be in good condition, I notice the pins on the tape tension arms appear to be out of round and have lost their shiny chrome finish due to wear. Also, the tape lifter pins have a definite 1/4" groove worn in them - the r/h one is worse; there is quite a rough step up at the lower end of the pin. I was wondering if this is any cause for concern - I don't want to risk damaging the edges of my handful of pre-recorded tapes. http://vintage-radio.net/images/smilies/huh.gif Has anyone dealt with this issue before and is it possible to grind/polish the step so that the sudden step is smoothed out or removed please? Many thanks, Colin.

SteveCG · 16th May 2016, 12:41 pm

Hmm, you raise quite a question.

If you leave it alone then indeed slightly wider tapes might get a crinkled edge - not much fun for recordings made on a 1/4 track machine. However if you try adjusting it only a little and alter the wear pattern position (ie the groove) in relation to the tape path then you may crinkle all your tapes.

Ideally you should either replace the worn parts with new so there is no groove - or if it is possible turn the pins around, again to give a new smooth surface.

I came across this issue with the guide pins of Ferrograph Series 7 tape recorders.

Chindit · 16th May 2016, 8:38 pm

Hello Steve CG and thanks for the reply.
Just to re-emphasise, it is only the lifters that are showing the stepped wear, so providing I don't wind forwards or backwards then no problem! Of course this isn't ideal and I'd like everything to be spot-on if possible. To my mind, it is strange to find so much wear here - perhaps the metal is softer than the other rubbing components? I'll have another look at it, but I recall the two lifter pins are mounted in a sort of plastic wishbone and the exploded diagram shows this as being a single assembly. If they will move, I could try turning them round but then the top portion, which is cranked over at an angle, will be facing in the opposite direction.
Perhaps I could try to find some similar pins made of stainless steel, or hardened steel, bend them to shape and fit them instead. It looks like I'll have to do some dismantling to get a proper look. Thanks for the ideas, Colin.

SteveCG · 17th May 2016, 1:37 pm

Fine Colin.

May I suggest that steel pins, whilst hard enough for the job, may get magnetized. So if you go that route then periodically demagnetize them using one of the tape head demagnetizing tools still to be seen on action sites. Indeed you should demagnetize the heads and the tape path anyway !

Chindit · 18th May 2016, 8:25 am

Hello,
I had another look and a bit of a play with it last night - the pins are definitely worn. They can be turned through 180 degrees with the aid of a pair of pliers but then the backward facing cranked top section faces outwards rather than inwards which makes threading the tape very difficult. So I guess the next step will be to remove the assembly and look at drifting the pins out from the underside. I can then hopefully source some hard steel rod of the same diameter. Are they made of a special non-magnetic material?
The inner section of the assembly is formed of a threaded rod that attaches to the solenoid - this end will just unhook from the yoke. However, the other (pivot) end has a tiny circlip that is very hard to dislodge - I think I may need a special tool for this. Once this is free, it looks like the whole assembly (including pinch roller arm and felt pad arm) should just lift out.
The machine operates well on playback with a pre-recorded tape, but when I tried recording last night, I got absolutely no movement on the meters. When I ran the tape afterwards, there was just the faintest impression of a recording. So it looks like I'll have to go through the recording circuit as well! I've got a demagnetizer and I'm prepared to use it! I'll keep you posted. Best wishes, Colin.

toshiba tony · 18th May 2016, 10:12 am

J have 2 4506 machines, do you mean the rollers on the tension arms. on mine the tape tends to run tight. i cleaned mine with duraglit and it improved things, faster wind speed. but for really quick winding i pull the tape off the arms. the tape winds neatly on the spools even though back tension is disabled during winding

Chindit · 18th May 2016, 11:58 am

Hello Tony,
Do your tension arms have rollers? Mine just appear to be smooth metal bollards on which the tape rubs. They might well be worth a polish if that improves the transport of the tape - good tip regarding running directly from reel to reel when winding/ rewinding - thanks!
The bits with the most wear that I am seeking to possibly replace are actually the thin metal lifter pins that move the tape clear of the heads when winding/ rewinding they are attached to the pinch roller operating linkage.
Best wishes, Colin.

toshiba tony · 18th May 2016, 7:04 pm

thats an odd question, i always thought that a roller rotated. when you remove the small end pieces by unscrewing them the so called rollers come off but they have a flat on the inside, so you cant rotate them to use a fresh area of the "roller". i dont know why philips made them like that. as the tape goes past i would have thought it kinder to the tape to make the rollers able to rotate on their shaft. but thats philips for you. oddities! they once made a transformerless audio output stage , again odd. one day ill machine my own bits that enable the rollers to rotate on the shafts. surely it would cut tape friction, good luck with yours, ill watch this post, cheers

toshiba tony · 18th May 2016, 7:07 pm

as an addition, where on earth did you get your mfb speakers, DO NOT POST YOUR ADDRESS ON HERE, you might get a visitor when you go out, jesting!!!!!!

Chindit · 19th May 2016, 8:02 am

Well, yes a roller should do just that - roll! Do other manufacturers' machines do this? I can foresee the problem that would result if they did! Being such a small diameter, there would never be enough friction between the tape and the roller to ensure the roller kept up with the tape. So I guess Philips for one, just decided to have them as fixed, smooth polished bollards over which the tape slides.
I've seen a few pairs of MFBs on Ebay over the past months although naturally, most of them seem to be in Holland. Mine came from a chap in Clitheroe, not a million miles from you and even closer to where I was brought up (Wilpshire). They stank to high heaven of smoke - I had to keep them in plastic bags until I could get around to dismantling them and cleaning up all the parts one by one. Everything inside was filthy brown. I recapped them using the kits supplied by Thomas at mfb freaks - expensive I know, but it was a convenient way to start for someone who has only ever previously messed with valve stuff. I never knew there were so many electrolytics in solid state electronics! Still, it was an easy and pleasant job as all the Philips stuff is beautifully laid out and easy to work on. They are the common 22RH541 speakers - I'd LOVE a pair of 545s though!
I'll post more as I get round to looking in greater depth - as mentioned, I have a recording fault to find now, so its back to printing out circuit diagrams and pasting them together so that I can colour them in! Best wishes, Colin.

ricard · 19th May 2016, 8:43 am

The tension arms on the Tandberg 9100X are not rollers but simply machined pieces, just to mention another machine that doesn't have rollers. The old Beocords do have rollers though.

toshiba tony · 19th May 2016, 11:16 am

Thanks for not assuming my last post regarding a nocturnal visit was serious. Being from Yorkshire originally can get me into bother, (warped sense of humour) I still think you were fortunate getting them though. From my days at tech. college I remember the speakers, and wanted a pair then. I know there are very clever souls on here conversant with reel to reel, but both of mine have been stripped down and rebuilt, and apart from the plasticy feel about them I like the way they play, hope you are as pleased with yours as I am, LOCK YOUR DOORS! What is your recording issue Colin.

Chindit · 19th May 2016, 2:18 pm

Hello Tony,
I've spent long enough around Yorks and Lancs folk to know their sense of humour so don't worry on that score! The recording issue was alluded to in an earlier post on this thread - basically, almost zero impression is made on the tape when recording. You can just hear the faintest sound on playback. I know there are no issues with the Tuner/pre-amp which was used as the source, because a Philips N2511 cassette deck records and plays back perfectly when substitued for the N4506. Anyway, I've printed off the schematic and stuck the pages together so I guess I have a bit of signal tracing to do when I get chance.
Colin.

Chindit · 19th May 2016, 2:22 pm

Hello ricard, I guess the Tandberg is unusual in having actual moving rollers on the end of the tension arms? Colin.

toshiba tony · 19th May 2016, 3:47 pm

Thanks Colin, I assume the needles are moving OK whilst recording, I got caught out by not selecting the appropriate input whilst recording. A silly mistake as I have been in the trade 45 years.

Chindit · 20th May 2016, 8:34 am

Hello Tony,

Well, come to think of it, they WEREN'T! Perhaps I need to look at the inputs again although I did try moving all the various input switches up and down.
I may have done something stupid along these lines as its strange that the problem affects both channels.
Colin.

ricard · 20th May 2016, 8:59 am

Quote:

Originally Posted by Chindit

Hello ricard, I guess the Tandberg is unusual in having actual moving rollers on the end of the tension arms? Colin.

No, the Tandberg I mentioned (9100X) does not have rollers. I just mentioned it as an example of another machine that doesn't.

There are probably various disadvantages and advantages to both rollers and static parts, and my guess is that's not a clear cut answer which is better in the end, all things considered.

toshiba tony · 20th May 2016, 9:03 am

Hello Colin,
Well I have been in the trade 45 years, had 4 strokes and was recently taken into hospital with a brain issue, and before you say "impossible, he's from Yorkshire" it's true. But I was caught out with this, and I'm still working, with LG and they class me among the brighter people!!!!
I will have a pint on you if I'm right, sounds favourite to me, can you believe I work on the newest tv's by LG and things are not what they used to be, don't forget, A PINT!!!!!!!!!!
Tony

Chindit · 22nd May 2016, 7:43 pm

Oh dear! How STUPID am I (Don't answer that question!)...it is even worse than you surmised - I HADN'T set the recording level - it was on ZERO!!!
Looks like you can have that pint on me as you suggested. Still, it does us all good to hold up our hands now and again and say 'I'm an ass!'
The recorder now appears to work very well on both record and playback; all I need to do is sort out the worn lifters - might swap them with the ones on my other N4506 (the Italian one) which currently doesn't run.
You mentioned that you completely stripped yours; what did you do, change the electrolytics?
Best wishes, Colin.

16th May 2016, 8:28 am	#1
Chindit Tetrode Join Date: Feb 2011 Location: Bishop Auckland, County Durham, UK. Posts: 97	Philips N4506 Good morning, I normally lurk on the domestic radio side of things but just this year I've rekindled a long-dormant interest in Philips HiFi separates. I've have a pair of working MFBs, AH762 tuner/pre-amp and a N2520 cassette deck. I also own a pair of N4506 reel to reel machines, one imported from Italy and one from the Netherlands - these are the current focus of my activities. Both machines have had new belts fitted at some point, so no issues there. At the weekend, I did a clean up and gentle lubrication of the NL machine and it now runs very smoothly and the auto-stop has even started working again! However, despite the heads looking to be in good condition, I notice the pins on the tape tension arms appear to be out of round and have lost their shiny chrome finish due to wear. Also, the tape lifter pins have a definite 1/4" groove worn in them - the r/h one is worse; there is quite a rough step up at the lower end of the pin. I was wondering if this is any cause for concern - I don't want to risk damaging the edges of my handful of pre-recorded tapes. http://vintage-radio.net/images/smilies/huh.gif Has anyone dealt with this issue before and is it possible to grind/polish the step so that the sudden step is smoothed out or removed please? Many thanks, Colin.

16th May 2016, 12:41 pm	#2
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Re: Philips N4506 Hmm, you raise quite a question. If you leave it alone then indeed slightly wider tapes might get a crinkled edge - not much fun for recordings made on a 1/4 track machine. However if you try adjusting it only a little and alter the wear pattern position (ie the groove) in relation to the tape path then you may crinkle all your tapes. Ideally you should either replace the worn parts with new so there is no groove - or if it is possible turn the pins around, again to give a new smooth surface. I came across this issue with the guide pins of Ferrograph Series 7 tape recorders.

16th May 2016, 8:38 pm	#3
Chindit Tetrode Join Date: Feb 2011 Location: Bishop Auckland, County Durham, UK. Posts: 97	Re: Philips N4506 Hello Steve CG and thanks for the reply. Just to re-emphasise, it is only the lifters that are showing the stepped wear, so providing I don't wind forwards or backwards then no problem! Of course this isn't ideal and I'd like everything to be spot-on if possible. To my mind, it is strange to find so much wear here - perhaps the metal is softer than the other rubbing components? I'll have another look at it, but I recall the two lifter pins are mounted in a sort of plastic wishbone and the exploded diagram shows this as being a single assembly. If they will move, I could try turning them round but then the top portion, which is cranked over at an angle, will be facing in the opposite direction. Perhaps I could try to find some similar pins made of stainless steel, or hardened steel, bend them to shape and fit them instead. It looks like I'll have to do some dismantling to get a proper look. Thanks for the ideas, Colin.

17th May 2016, 1:37 pm	#4
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Re: Philips N4506 Fine Colin. May I suggest that steel pins, whilst hard enough for the job, may get magnetized. So if you go that route then periodically demagnetize them using one of the tape head demagnetizing tools still to be seen on action sites. Indeed you should demagnetize the heads and the tape path anyway ! Last edited by SteveCG; 17th May 2016 at 1:38 pm. Reason: spelling

18th May 2016, 8:25 am	#5
Chindit Tetrode Join Date: Feb 2011 Location: Bishop Auckland, County Durham, UK. Posts: 97	Re: Philips N4506 Hello, I had another look and a bit of a play with it last night - the pins are definitely worn. They can be turned through 180 degrees with the aid of a pair of pliers but then the backward facing cranked top section faces outwards rather than inwards which makes threading the tape very difficult. So I guess the next step will be to remove the assembly and look at drifting the pins out from the underside. I can then hopefully source some hard steel rod of the same diameter. Are they made of a special non-magnetic material? The inner section of the assembly is formed of a threaded rod that attaches to the solenoid - this end will just unhook from the yoke. However, the other (pivot) end has a tiny circlip that is very hard to dislodge - I think I may need a special tool for this. Once this is free, it looks like the whole assembly (including pinch roller arm and felt pad arm) should just lift out. The machine operates well on playback with a pre-recorded tape, but when I tried recording last night, I got absolutely no movement on the meters. When I ran the tape afterwards, there was just the faintest impression of a recording. So it looks like I'll have to go through the recording circuit as well! I've got a demagnetizer and I'm prepared to use it! I'll keep you posted. Best wishes, Colin.

18th May 2016, 10:12 am	#6
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Philips N4506 J have 2 4506 machines, do you mean the rollers on the tension arms. on mine the tape tends to run tight. i cleaned mine with duraglit and it improved things, faster wind speed. but for really quick winding i pull the tape off the arms. the tape winds neatly on the spools even though back tension is disabled during winding

18th May 2016, 11:58 am	#7
Chindit Tetrode Join Date: Feb 2011 Location: Bishop Auckland, County Durham, UK. Posts: 97	Re: Philips N4506 Hello Tony, Do your tension arms have rollers? Mine just appear to be smooth metal bollards on which the tape rubs. They might well be worth a polish if that improves the transport of the tape - good tip regarding running directly from reel to reel when winding/ rewinding - thanks! The bits with the most wear that I am seeking to possibly replace are actually the thin metal lifter pins that move the tape clear of the heads when winding/ rewinding they are attached to the pinch roller operating linkage. Best wishes, Colin.

18th May 2016, 7:04 pm	#8
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Philips N4506 thats an odd question, i always thought that a roller rotated. when you remove the small end pieces by unscrewing them the so called rollers come off but they have a flat on the inside, so you cant rotate them to use a fresh area of the "roller". i dont know why philips made them like that. as the tape goes past i would have thought it kinder to the tape to make the rollers able to rotate on their shaft. but thats philips for you. oddities! they once made a transformerless audio output stage , again odd. one day ill machine my own bits that enable the rollers to rotate on the shafts. surely it would cut tape friction, good luck with yours, ill watch this post, cheers

18th May 2016, 7:07 pm	#9
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Philips N4506 as an addition, where on earth did you get your mfb speakers, DO NOT POST YOUR ADDRESS ON HERE, you might get a visitor when you go out, jesting!!!!!!

19th May 2016, 8:02 am	#10
Chindit Tetrode Join Date: Feb 2011 Location: Bishop Auckland, County Durham, UK. Posts: 97	Re: Philips N4506 Well, yes a roller should do just that - roll! Do other manufacturers' machines do this? I can foresee the problem that would result if they did! Being such a small diameter, there would never be enough friction between the tape and the roller to ensure the roller kept up with the tape. So I guess Philips for one, just decided to have them as fixed, smooth polished bollards over which the tape slides. I've seen a few pairs of MFBs on Ebay over the past months although naturally, most of them seem to be in Holland. Mine came from a chap in Clitheroe, not a million miles from you and even closer to where I was brought up (Wilpshire). They stank to high heaven of smoke - I had to keep them in plastic bags until I could get around to dismantling them and cleaning up all the parts one by one. Everything inside was filthy brown. I recapped them using the kits supplied by Thomas at mfb freaks - expensive I know, but it was a convenient way to start for someone who has only ever previously messed with valve stuff. I never knew there were so many electrolytics in solid state electronics! Still, it was an easy and pleasant job as all the Philips stuff is beautifully laid out and easy to work on. They are the common 22RH541 speakers - I'd LOVE a pair of 545s though! I'll post more as I get round to looking in greater depth - as mentioned, I have a recording fault to find now, so its back to printing out circuit diagrams and pasting them together so that I can colour them in! Best wishes, Colin.

19th May 2016, 8:43 am	#11
ricard Octode Join Date: Mar 2006 Location: Lund, Sweden Posts: 1,632	Re: Philips N4506 The tension arms on the Tandberg 9100X are not rollers but simply machined pieces, just to mention another machine that doesn't have rollers. The old Beocords do have rollers though.

19th May 2016, 11:16 am	#12
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Philips N4506 Thanks for not assuming my last post regarding a nocturnal visit was serious. Being from Yorkshire originally can get me into bother, (warped sense of humour) I still think you were fortunate getting them though. From my days at tech. college I remember the speakers, and wanted a pair then. I know there are very clever souls on here conversant with reel to reel, but both of mine have been stripped down and rebuilt, and apart from the plasticy feel about them I like the way they play, hope you are as pleased with yours as I am, LOCK YOUR DOORS! What is your recording issue Colin.

19th May 2016, 2:18 pm	#13
Chindit Tetrode Join Date: Feb 2011 Location: Bishop Auckland, County Durham, UK. Posts: 97	Re: Philips N4506 Hello Tony, I've spent long enough around Yorks and Lancs folk to know their sense of humour so don't worry on that score! The recording issue was alluded to in an earlier post on this thread - basically, almost zero impression is made on the tape when recording. You can just hear the faintest sound on playback. I know there are no issues with the Tuner/pre-amp which was used as the source, because a Philips N2511 cassette deck records and plays back perfectly when substitued for the N4506. Anyway, I've printed off the schematic and stuck the pages together so I guess I have a bit of signal tracing to do when I get chance. Colin.

19th May 2016, 2:22 pm	#14
Chindit Tetrode Join Date: Feb 2011 Location: Bishop Auckland, County Durham, UK. Posts: 97	Re: Philips N4506 Hello ricard, I guess the Tandberg is unusual in having actual moving rollers on the end of the tension arms? Colin.

19th May 2016, 3:47 pm	#15
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Philips N4506 Thanks Colin, I assume the needles are moving OK whilst recording, I got caught out by not selecting the appropriate input whilst recording. A silly mistake as I have been in the trade 45 years.

20th May 2016, 8:34 am	#16
Chindit Tetrode Join Date: Feb 2011 Location: Bishop Auckland, County Durham, UK. Posts: 97	Re: Philips N4506 Hello Tony, Well, come to think of it, they WEREN'T! Perhaps I need to look at the inputs again although I did try moving all the various input switches up and down. I may have done something stupid along these lines as its strange that the problem affects both channels. Colin.

20th May 2016, 9:03 am	#18
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Philips N4506 Hello Colin, Well I have been in the trade 45 years, had 4 strokes and was recently taken into hospital with a brain issue, and before you say "impossible, he's from Yorkshire" it's true. But I was caught out with this, and I'm still working, with LG and they class me among the brighter people!!!! I will have a pint on you if I'm right, sounds favourite to me, can you believe I work on the newest tv's by LG and things are not what they used to be, don't forget, A PINT!!!!!!!!!! Tony

22nd May 2016, 7:43 pm	#19
Chindit Tetrode Join Date: Feb 2011 Location: Bishop Auckland, County Durham, UK. Posts: 97	Re: Philips N4506 Oh dear! How STUPID am I (Don't answer that question!)...it is even worse than you surmised - I HADN'T set the recording level - it was on ZERO!!! Looks like you can have that pint on me as you suggested. Still, it does us all good to hold up our hands now and again and say 'I'm an ass!' The recorder now appears to work very well on both record and playback; all I need to do is sort out the worn lifters - might swap them with the ones on my other N4506 (the Italian one) which currently doesn't run. You mentioned that you completely stripped yours; what did you do, change the electrolytics? Best wishes, Colin.