Philips 4307 - Playback issue

[eddfriz]

Hi all,

I've been working on a Philips 4307 and have replaced all the belts, cleaned out as much of the goo etc and have reassembled. The issue I'm having is the right spool is not moving when it has a tape on. Fast forward, rewind all work fine and the right spool moves when there is not a tape connected via the supply spool.

Any suggestions on what might be causing it? It feels like it's trying to spin but can't quite manage it.

Cheers!

[eddfriz]

Had a bit more of a play about and looks like the head is not engaging properly when in play mode. If I push up on the arm it does connect and the spools start moving (albeit at a slower speed).

Any tips on getting the head to engage properly and to run at the correct speed would be most welcome, and apologies if I'm getting the terminology wrong I'm very much a novice at this!

[DMcMahon]

Not sure what you mean by head in this case, a photo would help to better understand.

David

[eddfriz]

Sorry, I meant the wheel that pushes the tape to the smaller spindle when play is pressed. I've attached a photo of me pushing it in place using a pen to mak

[DMcMahon]

OK that is the rubber Pinch Wheel/Roller, called Pressure Roller in the Philips service manual (item 70) when Play is selected it pushes the tape up against the rotating capstan shaft.

On some machines the amount of travel and/or the pressure can be adjusted so that the roller makes proper contact with the capstan shaft.

Looking at the Philips drawing I cannot easily see if there is any adjustment on this machine.

Have a close look at the mechanism to see how the roller mounting bracket is moved forward when Play is selected to determine if there any adjustment or any way to put more tension on the associated spring.

Also wondering if there might be an issue with the Take Up spool friction clutch and also if the take up spool brake shoes are being released properly.

Maybe someone familiar with this model or similar will be able to comment more.

David

[DMcMahon]

You can download the purchasable service manual from the "Instant Downloads" available from the Downloads section at top right of Forum screen.

The Philips N4307 Manufacturers Service Data service manual has some information on the pressure roller adjustment and also some brake info.

David

[Cobaltblue]

As David said available top right but in case your not familiar a direct link here:

https://www.service-data.com/product...13/6162/m20713

Cheers

Mike T

[eddfriz]

Amazing, thank you both for your help. I've downloaded the manual so will have a read through and see if I can make the necessary adjustments to get it working properly.

Thanks again.

[TIMTAPE]

Its also possible the pinch roller rubber has hardened so that it can no longer conform to "wrap" enough of the tape area evenly over the spinning capstan shaft for positive drive. It's a common problem especially these days. Extra pressure may temporarily gets things going but the best solution is a new pinch roller or at least new rubber tyre. Not saying this is the only problem but it may be a factor. These days some sellers are offering new pinch roller wheels or tyres for some models but they may no longer have access to the hardness specifications for the original factory rubber part. But that's another story. Sometimes if the correct replacement is no longer available, the outer layer of hardened rubber can be carefully sanded or lathed off , revealing a better surface underneath, but it can be tricky to do well and not always successful.

[Lucien Nunes]

It feels like it's trying to spin but can't quite manage it.

This is what you would expect with the pinch-roller not gripping the tape against the capstan. During playback, the tape is pulled off the supply (L/H) reel and across the heads exclusively by the capstan and pinch roller. The takeup (R/H) reel is driven at low torque via a slipping clutch, so that it takes up the available tape as it leaves the capstan, but doesn't itself pull it through the machine.

I have recently worked on one of these and although I didn't have this problem, I did think the pinch-roller condition was a bit marginal. Don't butcher the mechanism to make up for a bad roller!

[DMcMahon]

If it does turn out to be a bad Pinch Roller and you are not able to improve the roller rubber condition, then you maybe able to get a replacement online such as eBay.

Be aware though that Used and NOS parts may not be any better than your old part, although they could be fine.

I see there is one German seller selling Philips Pinch rollers which are described as brand new.

David

[eddfriz]

I've now managed to get the pinch roller to meet the capstan and I'm getting sound. I've checked the brakes and they seem to be fine but it's still running very slow.
Any ideas of what might be causing that? The fast forward and rewind functions appear to be running at the right speed, it's on playback that speed issues are apparent.

[DMcMahon]

Try a new recording and see if that plays back slow.

It also is possible that the tape/tapes that sound slow on playback were recorded (on another machine) at a slower speed that the 3 3/4 ips of the N4307.

David

[eddfriz]

I've tried a few different tapes and all are running slow unfortunately.
With my (very) limited knowledge of electronics and these machines I think I may be beaten.
I don't suppose anyone knows of someone who resotres these types of players? Preferably in the Nottingham area but can post it. It's my mums machine and I was hoping to get it fixed for her 70th birthday later this year.
Thanks to everyone for their input thus far, it's been very much appreciated.

[DMcMahon]

Suggest you Post the request by starting a new Thread to this part of the Forum :-

https://www.vintage-radio.net/forum/...play.php?f=145

David

[eddfriz]

Originally Posted by DMcMahon

Suggest you Post the request by starting a new Thread to this part of the Forum :-

https://www.vintage-radio.net/forum/...play.php?f=145

David

Apologies, I didn't realise there was a separate place for posting repair requests. I have started a new thread there as suggested.

[ben]

Check the drive belt is on the correct step on the motor pulley - you may have it on the one for 60hz mains.

I have never replaced a pinch roller in one of these Philips units and I have worked on dozens.

[ben]

You might also want to check the backtension on the supply side. Did you replace the rubber clutch inserts inside the spool carriers? You will get tape spilling when stopping in fast wind if this is not done, or you will get very sluggish winding and slow playback if they're fitted wrongly giving too much drag.

[eddfriz]

Originally Posted by ben

Check the drive belt is on the correct step on the motor pulley - you may have it on the one for 60hz mains.

I have never replaced a pinch roller in one of these Philips units and I have worked on dozens.

That's exactly what I had done as I realised when watching a video on YouTube.

The volume is now my main issue as it's intermittent to say the least and very cracklely when adjusting the volume control. Not sure what I can do about that though.

[DMcMahon]

If the volume potentiometer (pot) is not a sealed pot and has any gaps around the 3 connection legs (or elsewhere on the pot body) then a spray of electrical contact cleaner will normally resolve crackling, unless the pot track is badly damaged/worn.

Also make sure that the heads are really clean using IPA/Methalated spirits and a cotton bud, water or spittle also will do a good job if the heads are not too dirty.

David