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  #1  
Old 07-17-2011, 03:47 AM
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stratobird stratobird is offline
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Philips N4308 Reel to Reel refurb

I am new to this site so may I introduce myself as a recent convert to the joys of restoring and running vintage Philips 43xx and 44xx series reel-to-reel tape recorders. Yes I know they are not hi-fi by any means but I like them.

In February 2011 I bought a non-working Philips N4308 tape recorder off eBay, because I had one in the 1970s when I was a teenager. I felt that if I could get it going, it would be interesting to play back a small pile of tapes I had recorded back then. Call it sentiment if you like.

The machine cost only a few pounds plus p&p so I reckoned that even if my attempts at restoration came to nothing, I could write it off to experience which is itself worth a lot.

As a long-term Meccano modeller I'm quite confident with mechanics and electrics and I can use a soldering iron, but I know very little about electronics. Even so, I was determined to give the project my best efforts.

On receiving the machine I took the top plate off and saw that the belts had turned to black goo. But, with patience, isopropyl alcohol and 300 cotton buds I was able to clean it out, and with a kit of replacement drive bands, etc. I was able to get it working. I was delighted to be able to play once again, tapes I had recorded 35 years before. Memories came flooding back - Suzi Quattro, Status Quo - wonderful.

Having greatly enjoyed fixing that machine up, I found myself buying another, then another, just for the fun of restoring them. Now I have three N4308s plus an N4404, fully restored and jostling for storage space in my spare room. These machines mostly only needed cleaning up, replacement chassis mounts/pause brake/clutch rubbers/drive belts and a careful lube. I had to replace a germanium transistor AC187/01 on the first of them though. This cured crackling on playback.

Another (fourth) N4308 85/WT03 has no playback at all, although the speaker is working because I can hear crackle when I adjust the volume. Is there a "tick list" of things to check for in order to identify the problem?

Yet another (fifth) N4308 plays back louder than any of the others. This is the oldest one, a 55/WR02 with the early take-up spool belt layout. Unusually, it has a dual cone speaker (the others all have a single cone). It records fine but has excessive hiss on playback. Again, are there any things to check for in order to reduce the hiss?

Thanks in advance to anyone who may be able to assist with some advice.
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Old 07-17-2011, 03:33 PM
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shotwell shotwell is offline
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Welcome to Tapeheads!

Plenty of help around here.
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  #3  
Old 07-17-2011, 04:35 PM
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Lance Lawson Lance Lawson is offline
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Welcome to Tapeheads. Rare is the tapehead that doesn't become an expert in some way shape or form. Everything that I figured wouldn't happen to me with this stuff has indeed happened. So I'm learning all kinds of new things. It's great fun!
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Old 07-18-2011, 04:26 PM
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stratobird stratobird is offline
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Philips N4308 refurbishment

Thank you Shotwell and Lance Lawson for your kind greetings and making me feel welcome in the forum.

As an update to my earlier posting you may recall that I wrote:-

Yet another (fifth) N4308 plays back louder than any of the others. This is the oldest one, a 55/WR02 with the early take-up spool belt layout. Unusually, it has a dual cone speaker (the others all have a single cone). It records fine but has excessive hiss on playback. Again, are there any things to check for in order to reduce the hiss?

To my surprise, I seem to have solved this problem by simply defluxing the record/playback head. Some weeks ago I bought an old Ferrograph defluxer which seemed dead on arrival. When I plugged it in and pressed the little red button, nothing happened - not even a humming noise. However I tested it on a section of junk cassette tape and it did create a noticeable dropout (nothing more) on playback, so I concluded that it did work but rather weakly. I attributed this lacklustre performance to its age and put it back in its box.

Today I thought I would try the defluxer on the "hissy" tape recorder on the principle that it would do no harm even if it did no good, and even a weak deflux would be better than nothing.

So, following the enclosed instructions to the letter, I plugged it in and carefully brought the tip into close proximity to the recording/playback head. On pressing the little red button on the defluxer, I was astonished at the sudden unexpected strength of the response. Wow - that little old defluxer really woke up when it got near to that tape head and I had some difficulty in holding it steady.

When I next played back the tape, there wasn't any of the hiss that was previously spoiling the performance of that machine.

So now my only problem is the N4308 that is "dead" on playback, although I am sure the loudspeaker on that machine is OK because I can hear crackling when I adjust the volume control.

May I ask you experts out there if there is a set sequence of checks to make in order to narrow down the cause of the problem? Or could anyone point me to a part of this site where this problem (of no playback) is addressed?
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Old 08-11-2011, 03:55 AM
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kelvinmunson kelvinmunson is offline
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Hi, I am awaiting delivery of a Philips N4308; a fully working freeby

You have done quite a bit renovation on your machines and, in anticipation of having to service mine when it arrives, I wondered if you could point me in the direction of decent suppliers you've found who can still provide parts such as belts, rubber parts etc ?

Kelvin

Last edited by kelvinmunson; 08-11-2011 at 03:59 AM.
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  #6  
Old 08-12-2011, 08:26 AM
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stratobird stratobird is offline
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Philips N4308 spares

Hello Kelvin,

Thank you for your interest in the Philips N4308 tape recorder thread which I started.

Of course I would be pleased to point the way to where spare parts may be obtained.

There is a seller on eBay called bigdave-h who routinely sells kits of parts required to refurbish these tape recorders. The UK price is 24.99 plus 1.29 delivery in the UK, but he will ship to anywhere in the world.

The kit comprises the correct size of drive belts for the main drive, the take-up spool drive, the counter pulley drive and the capstan/flywheel drive. In addition to the drive belts, you get four new rubber grommets to replace the existing worn-out chassis mounts, and a length of rubber strip of the correct thickness for you to make new clutch rubbers and a pause brake.

All the components are supplied in their own separate, clearly labelled polythene bags, so you really can't go wrong.

But best of all is the instructions manual which is supplied as part of the kit. Within the pages of this manual are contained many years' of experience and good practice in actually carrying out the refurbishment work. You get to know the exact correct sequence in which everything should be done, and you also find out what not to do.

To make things better still, Dave is a real tape recorder enthusiast who will reply to any queries you have. The guide book is most comprehensive but there's always the possibility that you may encounter something a bit unusual. If you do, Dave will help you out. He can supply other components for the N4308 but this depends on what is available. Sometimes the little lamp below the VU meter may need replacing, or the germanium transistor. Both of these spare parts can be obtained from Dave.

The worst job in refurbishing the N4308, (or many similar Philips machines) is clearing out the "goo" that the original drive belts disintegrate into over time. This "goo" is a real nuisance and can get everywhere if you're not careful. Thankfully, the manual has many helpful tips on how best to clean it up.

Important: At the back of your N4308 you will find a DIN socket marked "Stereo". Do not connect this to your stereo! One of the pins carries 24 volt DC which was intended to power the optional EL 3787A pre-amp module, allowing for stereo reproduction from a pre-recorded stereo tape. If you connect this "Stereo" socket to an external audio setup, that 24v DC is going to fry something in no time!

To record or play back via an external stereo audio system, you need to use the "Phono" DIN socket - never the "Stereo" DIN socket.

I wish you every success with refurbishing and operating your Philips N4308.
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Old 08-31-2013, 04:05 AM
RagnarAT RagnarAT is offline
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Since this seems to be one of the very few online resources on the 4308 I'd like to resurrect this thread.

My 4308 had the same speaker issue and was therefore taken out of service in the late 90s. Now I decided to either fix or scrap it and went hunting for the fault.

A likely culprit is the mute switch on the DIN headphone socket. This is Sch 5 in the schematics (page 9)
http://forum.electronicwerkstatt.de/.../4308/4308.htm

The headphone socket is quite haphazardly wired through a flying 1.5 kΩ resistor wrapped around the socket. If the chassis is carelessly dropped into the casing the soldering tab can rip clean off the socket, putting both the internal speaker and the speaker socket forever on mute. As a temporary solution I simply jumpered the mute switch. I have yet to find a permanent solution short of replacing the entire socket (where to find a panel-mount 5-pin DIN headphone socket?) as the tab is broken flush with the socket's plastic body.

If the external speaker connector still works but the internal speaker doesn't, the likely culprit is the speaker socket mute switch, Sch6.

Hope I could help!
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Old 10-02-2013, 01:14 AM
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stratobird stratobird is offline
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Thank you RagnarAT for your information relating to the possible cause of the N4308 internal speaker failure. As this seems to be a vulnerability in the design of that particular Philips tape recorder model, I will keep it in mind as a possible cause if I encounter the issue in future.

The specific machine I was referring to was eventually fixed by Colin Braddock of the Tape Recorder Centre, Blackpool. Apparently I had incorrectly reassembled the sliding switch contacts in that machine, after cleaning it out.
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Old 10-02-2013, 09:49 AM
RagnarAT RagnarAT is offline
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Glad I could help!

Just realised that the link to the service manual is garbage, here's the correct one:
tonbandwelt.magnetofon.de/philips/4308/4308.htm

It does make sense that the rec/play switch causes trouble when assembled the wrong way.

Unfortunately my 4308 needs a full set of new rubber parts (belts, brakes, clutches and for a full restoration both idler wheels). I'd probably buy the kit you mentioned, but it doesn't seem to contain the idler wheels.
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Old 07-08-2014, 04:52 PM
Jimmyhaflinger Jimmyhaflinger is offline
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i'm a big fan of these Philips 4308 recorders!

i have 4 of them, all "made in Holland", two from 1971, one from 1970 and one from 1969, i also had an Austrian made MK2 model from 1974 which i scrapped for parts as the cabinet was heavily damaged

apparently both 1971 machines are still running fine on their original belts and rubber parts, while the 1969 machine had a melted capstan belt under the chassis but was otherwise perfect

the 1970 machine needed all new belts but the clutch rubber elements are still perfect.

the worst was the 1974 machine, everything made of rubber had melted in this one.

also they all have dual cone speaker except the one from 1974 which had a single cone speaker
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Old 07-09-2014, 05:13 AM
RagnarAT RagnarAT is offline
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Mine is a 1969 Austrian model IIRC and needs everything. The idler wheels still work but one of them already looked a bit suspicious the last time I had the machine open (glossy spots like the rubber was softening as well) and the plastic body is very brittle.

BTW, with the help of some fellow enthusiasts I discovered one issue with all service kits I've found so far: the instructions always mention a takeup reel clutch (under the reel table) but in fact there is a supply reel clutch as well that provides back-tension. It's identical to the other one and therefore prone to melting as well.
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Old 07-09-2014, 05:23 AM
Jimmyhaflinger Jimmyhaflinger is offline
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the plastic cabinets of my 4308s seem to hold up well, the lid latches are extremely brittle and have broken in two of my machines though

Also, my 1969 machine has a different takeup clutch belt arrangement and has an additional groove on the motor pulley to enable it to run on 60Hz, all other machines run on 50hz only

the fact that some had the 60hz pulley groove makes me wonder if Philips ever attempted to sell a Norelco version of the 4308 in the US, i've never seen one though
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Old 07-09-2014, 10:23 AM
RagnarAT RagnarAT is offline
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Quote:
the plastic cabinets of my 4308s seem to hold up well, the lid latches are extremely brittle and have broken in two of my machines though
I was referring to the plastic body of the idler wheel, not the entire machine. Cosmetically my recorder is still in very good shape and the electronics are fine as well. Only the rubber parts are completely gone.
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Old 07-14-2014, 07:21 AM
Jimmyhaflinger Jimmyhaflinger is offline
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the idler wheels show some small cracks on their hubs but are apparently still solid in my machines

now i'm having a problem with the 1969 machine, i tried to play a Philips LP18 black oxide tape from 1970 and the head gap for the 3-2 track got dirty fast enough to force me to stop the recorder and clean the head between each song.

the gap for the 1-4 track instead stays clean much longer.

the head is an exact replacement from another scrap 4308, as the original one was totally worn out and had poor treble reproduction, the replacement is a bit worn too but much less than the original head and still sounds fine.

are these black oxide Philips tape notorious for oxide shedding or maybe there's something wrong with the head, the pressure pad or the tape path?
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Old 07-14-2014, 09:33 AM
RagnarAT RagnarAT is offline
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A former user from the Netherlands claimed that these tapes are indeed known as shedders. Mine are all ok-ish but I can see how they could cause trouble. Maybe try a different tape before you jump to any conclusions!
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Old 07-23-2014, 04:25 PM
Jimmyhaflinger Jimmyhaflinger is offline
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update: i replaced the head with another one in almost new conditions taken from a scrap 4308 i bought a few days ago (badly abused and modified)

now the LP18 tape is clogging up the track 1-4 (upper) gap within a few minutes of playback, other red oxide tapes i have tend to leave some residues too

could this be due to the head's zenith angle adjustment not being set correctly? i tried to adjust it as best as i could so that the tape wasn't pushing visibly against the head's guides but i don't know if this is accurate enough
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