Philips DCC 175 rewind issue: gear grinding noise at tape start/end after new belt

Recorders, Players, etc.
1

I am looking for some advice about a Philips DCC 175.

Recently I replaced the belt, the SMD capacitors, and the capstan rollers/wheels. In general, the deck is working well again, but there is still one issue I cannot explain. ( i will try to upload a video of it)

When I rewind all the way to the beginning or the end of a tape, I hear a strange noise that sounds like a squeal, grinding, or mechanical resistance somewhere in the gear train. It almost sounds as if a gear is being forced too hard.

What is confusing is that I did not have this exact noise with a previous belt I installed (from MFBfreaks), but with that belt the deck had a different problem: it could not always rewind properly all the way to the end of the tape. That is solved with this new belt.
With the current belt (from the DCC Museum), rewinding does reach the beginning/end correctly, but this unpleasant grinding/cracking gear noise appears. The current belt is slightly thicker: 0.7 mm instead of 0.6 mm i used earlier.

My suspicion is that the belt may be slightly too tight, causing extra load on the mechanism during fast winding and forcing the gears, which then creates this destructive-sounding noise. I am worried that over time this could damage the transport or even break internal gears, especially since replacements are not easy to find without a donor machine.

Another thing I noticed: this seems to happen only with non pre-recorded tapes that contain an older recording and that I want to record over again.
With pre-recorded tapes, the deck slows down properly during the last part of the rewind and then stops normally at the beginning of the tape.

I have two DCC 175 machines, and the other one does not have this issue, which makes me think this is not normal behavior.

So my questions are:

  • Could a slightly thicker/tighter belt cause this kind of noise?

  • Could this point to a problem in the gearing, clutch, idler, or tape-end detection? Where is the issue located most propably?

  • Why would this mainly happen with non pre-recorded tapes, but not with pre-recorded tapes? Because of the tracking information so it knows where it is when spooling the tape?

  • Is this something that could damage the mechanism if I keep using it like this? Which gear is most vulnerable causing this sound?

I would really like to understand the exact cause before continuing to use the deck. I have several players here, so I can compare parts and test suggestions if needed.

Any ideas are very welcome.

Thanks in advance!

2

Due to the age of the machine and different specs, every machine ideally needs a 64mm x 0.6 mm belt. In practice this no longer works. We have repaired over 250 portables and with most 0.6mm belts the belt stretches immediately, because of the heavy lifting that one belts need to do.

When changing to a 0.7mm belt, that problem is gone.

The other problem is the slip mechanism, that has aged.

That mechanism makes the machine stop when rewinding to the beginning.

With original tapes, the player can determine very easily that it is near the beginning and will slow down and stop correctly. With empty or home recording it does not always work.

When the slip mechanism fails to work correctly, sometimes a bigger or smaller belt might help. Sometimes there is no ideal combination.

Ralf

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Thanks for your reply, Ralf. That does indeed seem to be the cause of this issue. Not meant in a derogatory way (I have great respect for all your work), but I’m also curious about the experiences of hobbyists and the things they’ve run into, which might help contribute to a solution or at least point us in the right direction.

The annoying part is that one DCC 175 has this issue while another doesn’t Although the same changes are made to the internal mechanism (Capstan wheels, belt and capacitors). You would expect that to be something that could be addressed somewhere in the mechanism, although I do of course understand that these players go out of spec over the years.

Very curious to hear others’ experiences and any possible clues toward a solution.

P.S. Where is the slip mechanism located? Maybe the cause can be found somewhere around there.

4

I looked at the service manual and can’t find a specific mention how it is to be located and how it operates. You can clearly hear the “slip” when it works fine. Sometimes it slips 4-5 times before it stops. I have a DCC170 here that also rattles when rewinding normally. FFW but always REW.

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Thank you for your reply Ralf. Are there other forum members who are familiar with the ratlle issue issue and solved it maybe? There must be a way hopefully.

6

After I installed a slightly different type of belt, the spooling issue at the beginning or end of the tape has been resolved, but now I have this sound problem. It sounds like gears are slipping over each other. It’s not constant — it sometimes happens during fast forward or rewind, and sometimes it doesn’t. During normal playing you don’t hear the issue.

What I did to fix the initial issue was remove all the gears and reapply lubrication to them. Unfortunately the players makes More overall noise during playback maybe because i need to lubricatie some parts more than i have done

Fast forwarding and rewinding otherwise work fine, and all other functions like recording and playback are working properly as well.

Does anyone have an idea which gear this could be? It’s very difficult to locate the source of the sound because of the soldered board.

7

Any help. Somebody? :face_blowing_a_kiss:

8

The noise seems to be from a toothwheel loosing contact to its counterpart at the end of the tape travel. There could be several reasons to check:

There is a spring under the big curve wheel. Pls check position against the drawing in the service manual. Move mechanics as shown in the manual and video and check if actuator follows exactly its curved way.

There could be something disturbing the movement of the mechanic from left to right and back at the end of its way. When repair attempts were made sometimes I found the lacking of axial play at the axles of turning parts.

Too short too thight too thick belt …. I had various bad experience with part dealers Maybe look for panasonic belts.

Some people took the mech apart and relubricated and adjusted it. The mechanics are similar to the Panasonic AR90 walkman drive. There is a youtube video showing the dis- .. and assembling. Maybe you could find the location of a clutch in this video

If nothing helps and you need the computer interface you can use the complete drive, heads and lower board of a DCC170 and combine with your upper board and case.

Good Luck !

Michael

9

Thank you for your answers, Michael. I have continued troubleshooting and have now run into the following issue.
The right pinch roller was stuck in its housing, which also caused problems with rewinding. I have since replaced it with the pinch rollers from the DCC Museum, but unfortunately the issue still persists.
Is this a known issue, and is there any idea how to resolve it? Rewinding sometimes works (better than with the old pinch rollers), but it fails more often than it works. When you move the pinch roller by hand, you can feel that it rotates freely at certain points, but sometimes it gets stuck.
I have removed the pinch roller again, but I cannot see any visible defects. I assume it’s not the intention to sand down the pinch roller to make it slightly smaller so it fits, so I hope there is another solution.
I’ve added a couple of photo’s for reference.

New pinch roller but still not smoothly running like the left one.

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10

Der Jurjen,

The problem with your rattling when rewinding:

I am more and more convinced that you have a too short belt. It may be that the thicker belt runs with many drives better than the original size but I have used the same sources as You and have received non working belts. Maybe due to this there is a timing glitch when stopping: The thinner belt stretches and there is enough time for the optoelectonics to shut off and with the higher torgue of the stronger or too short belt it does not stretch and before the optoelectronic shuts off it slides over some of the toothwheel and that is what your hear.

The new problem may have its source in a bent pinch roller axle due to too strong spring force on one side or bad luck when assembling. Please read all the available repair guides about the Panasonic AR90 drive at sources for example fixyouraudio.com or keyword search at youtube. I think if you have a second chance don,t try to change the pinch rollers as long as you can clean and sharpen it with alcohol. I use Contact WL with good results. Capstans must be cleaned as well but make sure nothing runs into the bearing.

There is little chance the replacement pinch rollers are exactly the same as the originals as we see with the belts.

I am now a little at the border of my knowledge and foreign language but I hope you will fix or replace the drive unit !

Good Luck !

Michael

11

In addition to last message:

Have you checked the axial play of capstans. I think there must be a little play in axial direction. The lower part under the axle has to be removed when changing the belt and maybe there is no axial play now.

In your first photo it looks like the axle with the spring is bent and not in paralell but I hope this is only due to bad optics of the photo unit or phone.

Assembling video of AR90 Panasonic https://www.youtube.com/watch?v=-tkSRDPsMFA

Have fun !

Michael

12

Thank you for all the information. I will check. This is a pretty time consuming experience though but will will make it. I am still curious if there is a cause why some players have stuck wheels and others don’t. :upside_down_face:

13

We have had around 10 portables here with this problem. If it was fixable, it needed a different belt. If it was not fixable (50%) we had no other option, but using it for donor parts.

It was always a 134,170 or 175. The 130 range never had this problem. There was never a constant fix. Sometimes it needed a 67mm belt, sometimes a 63mm to not make it rattle.

The 0.6mm belt for fixyouraudio only partly works. It is the correct size, technically, but stretches out really quick and will not rewind longer tapes at all. Jurjen had a similar problem.

The problem is finding a consistent belt supplier as the quality varies. We had 0.6mm, 0.8mm and find the “in between” version of 0.7mm the best. The supplier we once had, disappeared and the search started all over again. Some belts are just too stretchy when pulling the tape. I have send Jurjen a test package, to get him going and hope one of the belts will do the trick.

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Thank you for your answer, Ralf. I will let you know the outcome of my tests wit the belts.:wink:

Please note that I removed and cleaned the gears because the player was completely stuck at first.

It is also possible that some misalignment has occurred during reassembly. Unfortunately, it is difficult to pinpoint the exact location.

What about the stuck pinchs rollers. Een with a replacement purchased from the DCC Museum shop the roller is still stuck

In the photo, it looks like the mechanism is bent, but fortunately that is not the case.

The part where you have to insert the pinch roller is just too tight it looks like. When i put the roller in the left side there is no problem. Never had this issue earlier.