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Old 27th Jan 2018, 3:35 pm   #1
SiriusHardware
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Default Philips D8334/05R - Toothless gears

This much loved (and heavily used) Philips twin-deck portable radio cassette has been my partner's since new. I last had direct contact with it about five years ago when the drive belts snapped and were replaced. She was still using it up until very recently when it started to chew tapes.

Aparently, the take-up spools on first one deck and then the other started to turn first intermittently and then not at all. On taking a look and removing the flywheel from one deck I was greeted with the sad sight of a yellow plastic gear minus a number of its teeth. Those of you who know these Philips decks will undoubtedly know exactly which gear I mean.

Although it might be possible to impress the broken gear into clay or something similar, extract it and pour plastic resin in to make a replacement gear, instinct tells me that actually doing this requires more precise physical / machine skills than I possess.

Instead, I'm hoping that the obviously all too common occurrence of this failure means that someone, somewhere in the world, has either stockpiled some of these gears, made a good mould from which they can produce reliable replacements, or is able to 3D print them?

I've taken some pictures which I will upload in due course.
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Old 27th Jan 2018, 4:02 pm   #2
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Default Re: Philips D8334/05R - Toothless gears

Once you've established diameter and number of teeth, search eBay for plastic gears. You may find something you can adapt.
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Old 27th Jan 2018, 4:33 pm   #3
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Default Re: Philips D8334/05R - Toothless gears

Unfortunately this is a 'dual layer' gear with a large diameter main disc and a smaller diameter 'hub' both of which have teeth, so I would be fortunate indeed to find a general purpose gear with both diameters, overall thickness, number of teeth on each section and internal shaft diameter all present and correct.

I've found that someone in the USA (where the unit was branded 'Magnavox' rather than 'Philips') designed a 3D printed replacement, but only made and sold them in small batches and has not made or sold any since last year. I've messaged him to see if he has plans to make (or will consider making) some more.
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Old 27th Jan 2018, 7:30 pm   #4
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Default Re: Philips D8334/05R - Toothless gears

Many Philips deck's share the same problem mainly with ff/rewind there is is chap in Holland who used to make the years I will see if I can get hold of him .
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Old 28th Jan 2018, 9:59 am   #5
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Default Re: Philips D8334/05R - Toothless gears

Deliverance, if you can do that or provide me with any clues that would enable me to track him down myself, that would be appreciated.

The gear in this case is involved in driving the take-up spool in Play mode, possibly in FF mode as well.
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Old 28th Jan 2018, 12:45 pm   #6
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Default Re: Philips D8334/05R - Toothless gears

Quote:
Originally Posted by SiriusHardware View Post
Unfortunately this is a 'dual layer' gear with a large diameter main disc and a smaller diameter 'hub' both of which have teeth.
You could bond two gears together to make it dual layer.
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Old 28th Jan 2018, 9:40 pm   #7
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Default Re: Philips D8334/05R - Toothless gears

Hi the guy in question is on boomboxery member Michiel .
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Old 29th Jan 2018, 1:18 am   #8
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Default Re: Philips D8334/05R - Toothless gears

Thanks deliverance, I'll follow that up.

I did get a response from the gentleman that I mentioned had designed a 3D printed replacement but it turned out I had misread the model number - 8443, which he has designed a new gear for, as against 8334, the model number of the unit I'm trying to source gears for.

As mentioned earlier, I took some pictures, now attached.
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Old 29th Jan 2018, 2:46 am   #9
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Default Re: Philips D8334/05R - Toothless gears

Looks fairly easy to replace the large cog with a standard gear and graft the small cog and the centre pivot onto it? Provided you could get them truly concentric.
Agreed though if you can get a complete item it would be the simple solution.
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Old 2nd Feb 2018, 6:20 pm   #10
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Default Re: Philips D8334/05R - Toothless gears

Before I realised I had my numbers crossed (8443 / 8334) I had already ordered a pair of the 3D-printed 8443 gears.

- I could have cancelled the order but on looking around, found one post in another forum which suggested that the rogue gear - the one which is prone to failure in the 8334 - is interchangeable with the one which fails in the 8443.

To put it another way - Philips (apparently) used this same gear in the decks on both units and of course it fails in both models.

So I've let the order stand, and we'll see just how similar they are / are not when they arrive (from the USA).

If they don't fit my partner's unit I will put them carefully to one side and keep them - bound to be someone here who will eventually need a replacement gear for a Philips 8443.
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Old 3rd Feb 2018, 11:35 am   #11
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Default Re: Philips D8334/05R - Toothless gears

There is the same problem too with Grundig cassette machines
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Old 4th Feb 2018, 11:39 am   #12
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Default Re: Philips D8334/05R - Toothless gears

Remembered I have a bag of mixed gears, bought from ebay. They are not mounted on shafts. What are the diameters and teeth numbers for each section and I will have a look if you wish. As boater sam says, you maybe able to mount two gears together.

Ken
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Old 4th Feb 2018, 12:04 pm   #13
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Default Re: Philips D8334/05R - Toothless gears

Ken, thanks for the offer. As stated in #10, I have a pair of 3D-printed gears on the way to me which may or my not fit, as they are actually for a different model, due to a mix up on my part. I'll see how they work out first.

Given the sort of slippy / low friction material that these gears are typically made from, I would have thought it would be extremely difficult to bond them together with the required degree of strength.

By the nature of their use, there will be a constant 'shear' force being exerted on the joint between the two layers when the gear is doing its main job, which is to drive the take-up spool in play mode.
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Old 4th Feb 2018, 1:26 pm   #14
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Default Re: Philips D8334/05R - Toothless gears

A few of those in the bag are tandem types but lets see how you get on with the order.

Ken
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Old 4th Feb 2018, 9:09 pm   #15
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Default Re: Philips D8334/05R - Toothless gears

Funnily enough, only yesterday I found that my 40 year old Philips N2501 has suffered exactly the same fate: when the take-up stopped taking up I thought it was just the drive belt that had gone soggy and needed replacing, but its a yellow plastic gear with stripped teeth. I have the Philips service manual and on looking up its part number (4882 522 10138) I did get one hit from a site in Poland, but it was "out of stock". It is at present in pieces on the dining room table and I have not yet removed the head slide assembly to remove the gear to measure its size and tooth pitch. I was thinking of fitting a rubber ring around it as was suggested in a post last year as mine is only functioning as an idler, but it would be better to get a proper replacement.
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Old 5th Feb 2018, 12:00 am   #16
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Default Re: Philips D8334/05R - Toothless gears

Emeritus, the gears have arrived although to be frank the quality is a bit rough. This is not the fault of the person who CAD designed them but the 3D printing company which prints them. Only after I've cleaned one up will I be able to say whether it will work in the machine which I haven't taken apart again yet (I left the original gears in there, so I can't make an immediate comparison).

Take a few clear pictures of your stripped gear and either post them here or start you own specific thread about that unit and post them there, and I may be able to judge whether one of these 3D printed gears might solve your problem, even if they don't solve mine.
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Old 5th Feb 2018, 7:31 pm   #17
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Default Re: Philips D8334/05R - Toothless gears

Slow progress - I can only work on the unit about 15 minutes at a time so I have one of the decks out, but taking anything further apart looks perilous indeed because the whole thing seems to be a plasticy, clipped together affair. One false move and... snap.

To get the white cam wheel off to allow access to the dead gear (see pictures in post #8) it looks as though I have to spread three incredibly delicate looking 'latches' away from the spindle the cam sits on and then lift it off. But I can't do that either until I lift off the white arm, one end of which rides in the groove in the cam, and it looks as though I may need to remove the head carrier bar on the front of the deck (as per emeritus's post #15) in order to release the arm before I can release the cam.

When I realised I would have to do that, I parked the job for the night.

I'm going to have to completely unwire the deck (the wires to the motor, the wires to the deck switches and the head wiring, which I'll unwire at the PCB end) in order to be able to handle it and look around it properly in good light under a magnifier. The restricted access / movement due to the attached cables is driving me mad at the moment..

The (possibly) good news is that the 3D printed gears appear to be quite a close match, although unfortunately not very precisely printed. The gaps between the teeth on the small cog are shallower and less well defined than they are on the original gear, so I don't know how well they are going to work.
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Old 6th Feb 2018, 1:45 am   #18
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Default Re: Philips D8334/05R - Toothless gears

Well I finally managed to get the gear out, having broken a very stubborn circlip (bottom RHS of the first picture, at the pinch roller pivot) in the process rather than damaging the plastic pillar it was attached to. Although I do have the official Philips service manual, it only mentioned two of the three springs that I needed to release to gain access, and the number of one of them was wrong! I thought I was going to have to do more dismantling to get the gear off its shaft, but on levering up the plastic circlip to release it, the circlip stayed put and tha shaft pulled out of its socket, so that was a relief. All the various springs (all different) and screws are now safely packed in individually-numbered plastic bags and I can see about looking for a gear tomorrow.

The stripped idler gear is 25mm diameter over teeth, 2mm bore, 1.6mm thick at the teeth, about 4.3 mm over boss. There are 12 teeth in 90°, making 48 teeth in all. From looking for replacement gears for something else last year, it seems that metric gears are specified in terms of "Module", but further investigations can wait until tomorrow.
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Old 6th Feb 2018, 2:17 am   #19
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Default Re: Philips D8334/05R - Toothless gears

You have far more patience than I.
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Old 6th Feb 2018, 12:15 pm   #20
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Default Re: Philips D8334/05R - Toothless gears

Emeritus, in a bag of gears, I have one 48 teeth, 24.8 mm dia, 1.5 mm teeth thickness. It has a tandem gear making it 5.8 mm thick but guess this could be taken down to give you a correct boss. Think it's 2 mm bore.

Ken
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