Tandberg 2041 (series 2000) Erase Head Problem.

[scottie_UK]

Originally Posted by DOFFERY

Scottie,
It is rather difficult to see the faces of the heads to determine the state of same. However as you state you get a signal exerting some pressure on the head/s, check the reverse torque on the feed spool, there should be some slight backwards movement(check on pause) to retain the tape path. Also check the pressure pad on the bracket (erase head)is in contact & is "clean & not worn away, this contact also assists the tape path. As for the head/s alignment, difficult to tell from the pics. I have seen worse heads give a signal & your comment on applied pressure, points me to the above.

Difficult to be precise Scottie without sight of the head block but do ensure the heads , in particular the record head you mention is perfectly clean , sometime ingrained deposits require more than the cotton bud treatment, remember nothing abrasive or metal.

Colin.

I have some Audio Technica Stylus cleaning fluid, would that be good to clean the heads with?

[scottie_UK]

Some further information. I have taken a futther look at the pad next to the erase head is clean and fresh looking (looks a bit like velour). When I press this gently the channel comes in (when monitoring record). Also when I put my finger gently on the left reel the sound comes in.

Could this be an issue relating to a tired drive belt?

[ricard]

If adding some pressure to the pressure pad brings the sound back, it sounds like there's too little tension in the tape path to keep the tapes firmly pressed against the heads. In these machines the tension is maintained solely by the pressure pad. It could be maladjusted, or the tension spring has broken or become dislodged. I've noticed that with more or less complete loss of tension one of the channels will often sound fairly ok, but the other one gets very weak. This can be due to head wear causing the surface of the heads not to be parallel to the tape, so that one track makes contact with the tape but not the other.

The service manual I think specifies the required tension on the pressure pad. Note that if the pad has been replaced with a non-original part or has become soiled, the friction coefficient can change. But as you describe it as velour-like, it sounds like it's original (it should be white in color if so).

It's definitely not the drive belt at any rate. The belts only provide the drive, not any back tension. The first symptom of a worn belt is that the machine doesn't wind properly, although the most likely cause for this symptom is degraded friction pads between the reel tables and the underlying pulleys.

BTW, the heads do look worn, but the wear pattern is even and symmetrical. With heads that worn, the tape tension might have to be increased over its recommended value to maintain good head contact. Still, I wouldn't expect it to be as bad as you're describing because of this.

[scottie_UK]

Originally Posted by ricard

If adding some pressure to the pressure pad brings the sound back, it sounds like there's too little tension in the tape path to keep the tapes firmly pressed against the heads. In these machines the tension is maintained solely by the pressure pad. It could be maladjusted, or the tension spring has broken or become dislodged. I've noticed that with more or less complete loss of tension one of the channels will often sound fairly ok, but the other one gets very weak. This can be due to head wear causing the surface of the heads not to be parallel to the tape, so that one track makes contact with the tape but not the other.

The service manual I think specifies the required tension on the pressure pad. Note that if the pad has been replaced with a non-original part or has become soiled, the friction coefficient can change. But as you describe it as velour-like, it sounds like it's original (it should be white in color if so).

It's definitely not the drive belt at any rate. The belts only provide the drive, not any back tension. The first symptom of a worn belt is that the machine doesn't wind properly, although the most likely cause for this symptom is degraded friction pads between the reel tables and the underlying pulleys.

BTW, the heads do look worn, but the wear pattern is even and symmetrical. With heads that worn, the tape tension might have to be increased over its recommended value to maintain good head contact. Still, I wouldn't expect it to be as bad as you're describing because of this.

The velour is brownish, probably due to tape residue, some other parts in the head bay have brown dust next to them.

As for the worn friction pads on the underlying pulleys I believe this is the case, as the cork looking things are crumbling away, infarct one fell off. A few times I have had to refit the belt as it came off. What is a suitable replacement for the pulley friction pads?

[scottie_UK]

I'm getting the feeling that the problems are created by the lack of functioning cluch pads. I suspect this due to the crumbling clutch pads but also the belt looks good, but it does have trouble rewinding or fast forwarding when the right spool is near full. I have been reading about how to make diy replacements with a leather belt. I have an old leather belt of approximate thickness and will cut some pads to size and fit them.

I've opened this machine a couple of times, both the facaia and the back and can see that the tables are not so straight forward to remove (I have also read this too). Any recommendations in how to get the tables off safely and quickly?

[ricard]

Basically there is a plastic nut on the back of the feed reel table, and a pulley on the back of the take-up reel table, which is unscrewed and the table is then simply pulled up with its shaft. In many machines the nut on the feed reel table is hard to get at, you need a long-nosed plier or similar to reach it. Not sure exactly what it looks like on the 2041. Also, there is a fibre washer which is easy to loose and can be awkward to get into place when remounting.

So, a bit fiddly, but definitely not that hard.

When remounting, tighten the nut so much so that there is about half a millimeter of play when pressing the reel tables down in stop mode. Or, put another way, enough to give a clearly audible 'clunk' when pressing them. If you tighten the nut too much, there will be too much friction for the drive to work properly, if they are too loose, the difference in height between stop and run modes will cause the tape to run against the flange(s) of the reel(s).

A good replacement for the belt is a rubber o-ring with a diameter of 180mm, with the actual material being 3mm in diameter. Available from places that stock hydraulic components.

[scottie_UK]

Originally Posted by ricard

Basically there is a plastic nut on the back of the feed reel table, and a pulley on the back of the take-up reel table, which is unscrewed and the table is then simply pulled up with its shaft. In many machines the nut on the feed reel table is hard to get at, you need a long-nosed plier or similar to reach it. Not sure exactly what it looks like on the 2041. Also, there is a fibre washer which is easy to loose and can be awkward to get into place when remounting.

So, a bit fiddly, but definitely not that hard.

When remounting, tighten the nut so much so that there is about half a millimeter of play when pressing the reel tables down in stop mode. Or, put another way, enough to give a clearly audible 'clunk' when pressing them. If you tighten the nut too much, there will be too much friction for the drive to work properly, if they are too loose, the difference in height between stop and run modes will cause the tape to run against the flange(s) of the reel(s).

A good replacement for the belt is a rubber o-ring with a diameter of 180mm, with the actual material being 3mm in diameter. Available from places that stock hydraulic components.

I fitted the new pads last night made of a black leather belt (of similar thickness to the original pads) and cut to the approximate shape. Taking the reel tables off was simple. I was expecting a metal nut, and because I could not see one, expected there to me some other non obvious method.

Anyhow it looks like I have not got the reel frictions right. The left side table is not to pad, but the right side one is a little stiff and causes the motor to labour. I've tried loosening the pulley, but it goes far to lose before commig within acceptable level of friction.

[DOFFERY]

Did you obtain the service manual as given above, if so we can start to explain the various functions.

The tables have to be adjusted correctly to enable the machine to function . You say you have removed the tables & fitted new clutch pads, were the clutches you took apart using the two small springs between the upper/lower halves, or the type with the metal spring fitted under the lower half? If the former did you replace the loose springs correctly.?

As the take up table is stiff, it is more than likely that there is need for adjustment by the black plastic screw near the table mounting,(assuming the clutch was assembled correctly) if you have the manual it would be easier to assist in the process.

If we can get the clutches working , the rest would be much easier to resolve.

Regarding your earlier problem re. one ch. being low in volume, this could be lack of reverse torque on the feed spool plus the pressure pad being in poor condition . From your description of the pad & the amount of "rust" you mention do ensure the heads are thoroughly clean.

Colin.

[scottie_UK]

I have a manual. I only removed the tables not the cluches.

I adjusted the lower central most black screw, but it did not seem to have much effect.

As for the springs I'm not sure what you mean?

[scottie_UK]

I cant seem to get these settings right, its like a rubiks cube problem to get all the settings in the right place.

Either the rewind works, or the ff works, but I cant get both to work. Even with this when they do work, there fast but not very fast. I'm not expecting woosh either.

[scottie_UK]

Ok so a partly successful fix of mixed blessings. It now records both channels and plays. However, I could not get rewind and FF to behave as one would like, both ff and rw grind to a halt depending on the amount of tape on each spool. I noticed that if I pinch the belt against the motor pulley, things start running as they should. My diagnosis is that belt needs changing, looks in great shape but is possibly a little slack

Also during my fix, I broke the braking mechanism on the left reel. There is a plastic piece that slides under the brake mechanism to engage the brake when the joystick is in certain positions. However,a small plastic nipple that acts as a retainer for a tension spring to keep said plastic bit in place has broken away. (parts numbers 263601a, and 260512 on page 22 of the tandberg series 2000 service manual. Any reconsiderations on how to fix this?

[ricard]

Firstly, yes, the belt needs to be in reasonably good condition, there's not a lot of contact area between the belt and the motor pulley, so that's the first place it will slip. At least if it slips here it indicates that you've got sufficient friction in your replacement clutch pads.

Adjusting the clutches is not rocket science, if you can look between the reel tables and pulleys, you should see that in FREE mode the friction pads should lift about 0.5-1mm from the pulleys when not engaged, compared to stop mode where both clutches are engaged; that's what the black screw in front of each reel table adjusts.

Colin, isn't the back tension on these machines provided solely by the friction pad in the tape path? There's a slight amount of tension supplied on the supply reel, but it's only there to take up any slack when going into pause mode, so that the sudden stop doesn't create a loop to the left of the head cover. Granted, it does have an effect, but the main source of tension is the friction pad I would have thought.

Regarding fixing the broken piece, if it's some sort of a nipple that's broken away, perhaps a hole can be drilled in the plastic, and something else, like a small screw, fitted? Try not to stress the plastic by actually screwing it in, as I would expect it would crack somewhere else, instead, aim for a loose fit and superglue it into place.

[scottie_UK]

Originally Posted by ricard

Firstly, yes, the belt needs to be in reasonably good condition, there's not a lot of contact area between the belt and the motor pulley, so that's the first place it will slip. At least if it slips here it indicates that you've got sufficient friction in your replacement clutch pads.

Adjusting the clutches is not rocket science, if you can look between the reel tables and pulleys, you should see that in FREE mode the friction pads should lift about 0.5-1mm from the pulleys when not engaged, compared to stop mode where both clutches are engaged; that's what the black screw in front of each reel table adjusts.

Colin, isn't the back tension on these machines provided solely by the friction pad in the tape path? There's a slight amount of tension supplied on the supply reel, but it's only there to take up any slack when going into pause mode, so that the sudden stop doesn't create a loop to the left of the head cover. Granted, it does have an effect, but the main source of tension is the friction pad I would have thought.

Regarding fixing the broken piece, if it's some sort of a nipple that's broken away, perhaps a hole can be drilled in the plastic, and something else, like a small screw, fitted? Try not to stress the plastic by actually screwing it in, as I would expect it would crack somewhere else, instead, aim for a loose fit and superglue it into place.

Yes I realise now that I'd actually got the tension right earlier in the night, but the issues with the belt were making me think I'd got it wrong. Still every day is a school day. Right then next to Ebay fora new belt.

[DOFFERY]

Scottie,
If you email me I can supply the fig 8 belt.

Colin.

[DOFFERY]

Ricard,
Regret we must disagree again, there is reverse torque on the supply spool.

Colin.

[ricard]

I agree Colin, there is, but the principal tensioning for the tape I would think comes from the felt pad, whereas the reverse torque on the left hand reel is mainly for taking up slack in pause mode, even though of course it does have a slight effect on tape tension too.

Or to put it another way, the service manual specifies a certain pressure on the felt pad in order to maintain tape tension, whereas the specification for adjusting the torque on the left hand reel (by adjusting the springs under the reel table) is that it should be as small as possible but still enough to cause the reel to rotate and take up slack even when a full 7" reel is used.

The later 3-motor machines don't have the felt pad at all and all tension comes from the left hand reel (which has a brake which is more elaborately designed and coupled to the left hand tension arm on those machines).

I guess it could be that in practice the torque on the left hand reel provides a substaintial amount of tension, although if so it must vary quite a bit throughout a reel owing to the differing diameter the tape pack.

[scottie_UK]

I've had an idea regarding the broken nipple. What I will do is use one of these lego studs, and glue it in place to hold the spring in position.

http://www.tyovov.com/shop/images/614123.gif

[scottie_UK]

Gaaah, I'm almost thinking of throwing in the towel giving it up as a lost cause. This tape recorder is taking over my life. Maybe I should get another one or just give up on reel to reels altogether

I've put good tape in. I'm playing a straight sine wave generated by my computer. When I play back the recording what I get is the left channel playing up (quiet and distorted with previous recording comming though) again and the sound really gravelly from both channels. I'm being carfull that the sound source and the record volume arn't to high.

[TIMTAPE]

Originally Posted by ricard

I agree Colin, there is, but the principal tensioning for the tape I would think comes from the felt pad, whereas the reverse torque on the left hand reel is mainly for taking up slack in pause mode, even though of course it does have a slight effect on tape tension too.

Or to put it another way, the service manual specifies a certain pressure on the felt pad in order to maintain tape tension, whereas the specification for adjusting the torque on the left hand reel (by adjusting the springs under the reel table) is that it should be as small as possible but still enough to cause the reel to rotate and take up slack even when a full 7" reel is used.

The later 3-motor machines don't have the felt pad at all and all tension comes from the left hand reel (which has a brake which is more elaborately designed and coupled to the left hand tension arm on those machines).

I guess it could be that in practice the torque on the left hand reel provides a substaintial amount of tension, although if so it must vary quite a bit throughout a reel owing to the differing diameter the tape pack.

Ricard, I tend to agree. In fact this is a problem with machines such as 3 motor types which is not always appreciated. The effective diameter of the supply reel can change radically from start to finish of a reel. So the effective back tension gets higher and higher as the reel progresses. A Revox A77 or B77 for example is not even rated to play a standard 5" reel of tape, even at low reel tension setting, as with the small inner hub diameter, the back tension at the end of the supply reel is too great for reliable tape speed. Unless the capstan and pinch roller are in top shape there is the risk of slippage and slowing. The best the A77 and B77 can do is a standard 7" reel or larger.

The Tandberg's pressure pad feature, though a bit cheap, primitive and liable to failure is at least closer to a true constant back tension. I personally like the Tandberg setup for small core tape reels with double play or thinner tapes. Far less likely to damage the fragile tapes than say a 3 motor machine like the A77 or B77 with no servo tape tension feature.

When playing delicate tapes on a B77 I rewind the fragile tape onto a large core 5" , 7" or even 10" reel for more constant back tension.

Tim

[ricard]

Originally Posted by scottie_UK

Gaaah, I'm almost thinking of throwing in the towel giving it up as a lost cause. This tape recorder is taking over my life. Maybe I should get another one or just give up on reel to reels altogether

I've put good tape in. I'm playing a straight sine wave generated by my computer. When I play back the recording what I get is the left channel playing up (quiet and distorted with previous recording comming though) again and the sound really gravelly from both channels. I'm being carfull that the sound source and the record volume arn't to high.

Well, quite frankly, these recorders are approaching 40 years of age, and they were probably not designed for that lifespan. So as a whole or at least individual recorders are bound to have issues after this time.

As I think someone might have mentioned, a dodgy record/playback switch due to oxide or dirt could cause a reduction in recording bias, or complete lack of high-frequency erase/bias signal, and intermittently at that.

It can be very frustrating to get a machine like this to work properly if there are intermittent problems. But given time - and rest - you'll get there in the end. The road is just not as direct as one hopes at each step of the way.

The lego stud idea sounds like something that would be worth trying.