Wow and flutter

Contact cleaner from maplins on all switches and sliders and most importantly the record bar for the tape deck. Spray and work them thoroughly.
You can do this while powered to see if it affects what you are hearing.
Failing that and you still have issues check speaker cones are in good order and test on all functions including line in.

Thanks Docs, servisol super 10 was used on all switches, sliders and connections with special attention to the record bar, everything works really well, listen to my Ipod (£1in swear box) through the line in, it is only on playback of tapes I get the problem, it's as though the tape speed isn't constant!

Have you checked the firmness and smoothness of the pinch roller ?

Open the cassette door, press play and shine a light inside and check the pinch roller smoothness on the flywheel.

It's a new pinch roller but yes I will check...

 

checked it and all seems ok, this leads me to think it may be the deck it was recorded on, will check that out next...

Yes try a different tape.

Also when you look at the above you are checking the flywheel is straight.

Alternatively, the motor could be the problem but I'm not convinced. Usually the tape path causes this which is down to the flywheel/pinch roller. Or perhaps the grommet on the flywheel is uneven.

Thanks, I did place some model car fuel line on this after cleaning but I can feel another strip down coming on

a drop of oil under that white capstan washer might be it 

 

some of the problem can be the tapes themselves shane as i have found out over and over...even with origional cassettes...just a thought buddy and thanks for your pm very nice of you...cheerz lad

 

Advice from the Sharp corp.

(in the owners manual)

 

Often over looked check the spring tension against the body of the pinch roller if weak it will drag the tape .

This would be to stop the general public from gettig in there and oiling the wrong thing! The manual also states "No User servicable parts inside" For us enthusiast folk, some 30 years on, we have to diss obey these rules in order to keep these machines  going! A little drop of light oil on the bottom capstan bearing will do no harm and may help cure the problem.

That is an excellent point del!

A massive thanks to you all, I am away with work this week but have the box strip planned for this coming weekend.

 

cheers all

 

But not for this type of mechanism. This is why there are so many GF 9*9* with melted capstan pulleys. Because of the service by "general public". This little drop of the light oil, applied on the bearing, will go onto the pulley, and melts the rubber with time.

 

Wow and flutter may caused by worn motor brushes, or worn/glazed idler tyre, etc, etc.

So, the better way to fix - is to find out, what's the problem,  

and only then - to act.

This GF-9191 had huge wow and flutter.

You can see completely worn motor brushes.

 

 

 

 

 

 

Hi Shane, I reduced a 'wow' problem on my GF-9191 by lubricating the motor's spindle so it ran a bit more easily when twisting the pulley between finger and thumb. I also ended up fitting a slightly tighter flywheel belt. I noticed on mine that the flywheel to motor belt was not always running central on the motor's pulley - it tended to ride to outermost side of the pulley and then back central again as the motor rotated. Swapping it for a slightly tighter belt kept it central. Either one or both of these tweaks resulted in a much more stable tape playback - I wouldn't call it 100% perfect but a great deal better than when it started out. Anyway, food for some thought and experimentation :-)

Okay I will clear up what I meant by the lower capstan bearing. It is on the bottom of the flywheel. It is nowhere near the capstan pully. If you put oil anywhere near the capstan pully it would slip and cause tapes to be chewed up a long time before melting rubber became an issue! I stand by what I said, oil in the lower capstan bearing area will do no harm. Oil in the upper bearing area is bad. When doing the lower bearing, remove the flywheel retaining bracket and carefully clean the bearing then apply a tiny drop of fine oil with the end of a cocktail stick, job done. I agree that motors can cause problems along with worn/ glased idler tyres, and i agree that it is better to find out what the problem is before you act, but these are suggestions, based on many years of expearience and many succesful repairs, so please, bear with me.

Well, the oil on the lower bearing will do no harm- you're right. But that bearing already has pretty thick lube, looks like a graphite oil. I have never seen a dried lower bearing on this type of mechanism. Even after 30 years it looks fresh.
And one more thing - the lower bearing of this mechanism, is like an adjusting screw, and person who has no experience may will do harm, while cleaning this bearing, cause it's a precise part, and requires an exact clearance.

Of course, the better way is to dismantle the whole mechanism to the bits, remove old oil, and white grease, clean all of gears and axels, replace all of rubber parts, and lube it with new oils. That will guarantee another 10-20 years of flawless work.

I have had the lower bearing lube dry out on a GF-9191. It caused some subtle but unpleasent effects on the spead. I used some high quality light oil and had another 5 years of good service out of the machine until I sold it! (I regret doing that!) I am not trying to suggestthat this is a common problem but it worked for me.

 I was trying to say, that is not enough to pay attention for one specific part of the mechanism. There is a dozen (at least) points in this mechanism, that may cause the wow and flutter. The whole mechanism has to be serviced, not just some particular parts

 

Yes, I agree with you, I was just lucky enough to pin point the problem on that particular machine early! I like to work through the different areas of the deck one by one; sometimes it can be one area causing the issue, and sometimes it a combination of problems as you say. I have worked on several of these mechanisms; some have required more work than others. All had problems with the capstan pulley but this was a long time ago and spares were still available from Sharp which made life a little easier……. Now I come to remember it; one machine, a GF-9090, had a problem with the sprung metal tongue at the bottom of the deck on which the cassette sits. This had been bent out of shape (possibly by an abusive previous owner!) The result was that not enough upward pressure was being applied to the cassette; effectively the cassette was sitting loosely in the deck. This played absolute havoc with the speed, wow and flutter issues were severe! Bending this gently back into place was the cure, until after a few hours use other issues became apparent; this maybe another thing to look at.

Seb, what happened to the font, it's too small  

 

You know, I've seen two units with good capstan pulley. And they looked like never been serviced, even never been opened before. It's not enough for statistic, but it shows that there are several different factors, not just the ages - that cause problem with this rubber part. But as I know, almost everyone who was trying to repair cassette mechanism - lube capstan, and capstan bearing/bushing

 

 

Sorry about the font, I coppied it out of a word document (I wanted to check my spelling as it is pretty dreadfull!!) Forgot to re-size the font! Okay, you win this one!