Studer B67 faults initial inspection. - UK Vintage Radio Repair and Restoration Discussion Forum

Nickuk99 · 19th Mar 2017, 8:28 am

This is the beginning of my Studer restoration story, having recently acquired a B67 MK1 serial 35## with 3/78 on one of the large caps, so I'm assuming 1978.

I was told that the Studer had the 'spinning away' issue with the take up spool, so having got it home I decided to resist the temptation to power on and take a good look up inside before removing it from the trolley and investigating further. So at first inspection...

1. F7 -12V 2 amp fuse is blown.

2. Signs of heat (slight blackening) to the tips of the blue pair of wires where they connect to the connecting block on the PSU. I'm assuming this pair is something to do with the -12V rail ?

3. One of the motor control boards is more visible than the other, and on the more visible board, there are heavy signs of yellowing on the 0.47uf caps on the board (were they black before), the middle of the three 0.47uf caps is totally cracked and split and looks to have completely failed, I'm thinking this will have caused F7 to blow? The other board is more difficult to see but I can see the 0.47uf caps are yellowed so I'm assuming they will have failed also. I can not see the capstan motor control board at the moment due to the trolley obscuring most of the underside.

4. The take up spool (right) tension arm positively returns back to its home position when lifted and released and I can hear the microswitch engage when it reaches the home position, however the feeder spool (left) tension arm is more sluggish when lifted, almost feels like it is missing its spring or certainly much weaker. When lifted and released it does not return fully to its home position and so the microswitch does not engage. In this scenario I'm thinking the feeder (left) tension arm is telling the take up (right) spool motor that there is still tape on the feeder reel? Should they be equal in operation? I'm thinking they should be.

I am in need of a manual, is there one available on-line? However in the meantime can anyone tell me how to remove the top cover plate, the head block and switch rail, so I can clean them properly and take a little look at the left tension arm.

Any comments, observations and advice would be most welcome.

Thank you.

Ted Kendall · 19th Mar 2017, 3:00 pm

OK - first thing to note is that you should replace ALL the Rifa 0.47uF capacitors before you apply power. Those which haven't already gone pop will be on the point of doing so and you can do without the the smoke, smell and general corruption. There are about five, from memory, including one on the capstan card, and RS do a drop-in replacement.

Disrobing is as follows. Unscrew the the pinch roller and tension arm roller caps and remove rollers. Undo three hex bolts which hold the headblock and remove - carefully. The clearance around the capstan shaft is small and you don't want to scratch it. Undo the five hex screws through the top plate and remove. If you have a monitor speaker in the top plate look out for the connecting plug and remove. The switch rail is retained by one hex screw at either end and then lifts out.

Each tension arm has two springs - one for return and one for limiting - and both are needed for correct operation. Damping is also present and the dashposts may need replenishing, but don't dive into this without reason.

There is a service manual available free on the Studer ftp site.

Michael Maurice · 19th Mar 2017, 7:51 pm

There are a lot more than 5 of those capacitors, there are three on each of the motor drive boards and about 9 on the relay board. There is also one across the mains on the transformer.

Use good quality X class capacitors.

Nickuk99 · 21st Mar 2017, 12:43 pm

Hi,

Many thanks for the response.

Re the caps, can anyone recommend which make to use and where to get them?, there seems to be several vendors out there selling "kits", however I read somewhere that these kits don't use the best quality caps, I want to buy the best quality I can find. I think I would like to replace all the Rifa 0.47uF capacitors, is there a list of how many I need?

The removing the top cover, the head block and the switch rail. I removed the head block cover first, 2 screws, and then the 3 screws holding the head block in place, it was a loose after removing the screws but a little stiff and did not want to lift off. I didn't want to apply too much pressure, is it really just a case of working the head block and pulling it up when the three screws are removed?

The same situation with the switch rail. I removed the 2 screws, one at each end of the rail, and it didn't want to lift off, and again I didn't want to apply too much pressure if there was something else holding it down. So the same here? just need to apply more pressure to lift it off, it has probably been on there for many or even 39 years...

Many thanks.

Ted Kendall · 21st Mar 2017, 3:50 pm

The headblock connections are via a 37-way D connector, and it is just a matter of a careful upward pull with slight rocking to get this parted. The switch rail sits quite snugly between the side pieces, so may need a little winnowing out.

I have used the caps from RS (414 8459) - Farnell have a suitable component as well. Also, I have found the stuff sold by Nagravox of Australia to be of good quality.

The shortest cut to finding out how many you need is to download the manual - when I trip over mine I'll do a quick head-count. Certainly five - the related A700 has many more. RS sell in packs of ten...

Ted Kendall · 21st Mar 2017, 4:37 pm

I forgot to mention that the headblock comes off first, then the top panel and then the switch rail.

Michael Maurice · 21st Mar 2017, 10:40 pm

I think you mean these Ted, these have a 22.5mm pitch, whereas the ones you suggested had 27mm pitch

These tape recorders are very complex if you are a novice, then tread very carefully.

Ted Kendall · 21st Mar 2017, 11:13 pm

Brain fade...

Nickuk99 · 22nd Mar 2017, 12:16 am

Many thanks for the replies

I'll get some 0.47uf caps ordered and make a start.

Also take a careful look at why the supply tension arm is sluggish and not returning to its home position, causing the micro switch not to be operated.

Ted Kendall · 22nd Mar 2017, 8:48 am

The RS listing for the smaller form factor now shows the Rifa "fox's glacier mint" component - might be better to look elsewhere...

Nickuk99 · 22nd Mar 2017, 8:51 pm

Hi,

Is the suggestion that the cap listed below is not the one to go for?

RS Stock No.414-8437

KEMET 470nF Polypropylene Capacitor PP 275 V ac ±20% Tolerance Through Hole PHE840 Series

If it is, can anyone suggest another option?, I would like to buy the best quality caps I can find to repair the B67.

Many thanks.

Ted Kendall · 22nd Mar 2017, 10:34 pm

Sorry, as you were. That one will be fine - the ones to avoid are the aforementioned translucent yellow things which, confusingly, RS also now sell. See the "Rifa capacitors" thread elsewhere on this forum for dozens of almost identical tales of their misdeeds.

Michael Maurice · 23rd Mar 2017, 12:15 am

The problem with the 'rifa' capacitors is that they are now 40 years + old and were never designed or expected to last as long as this.

Replacing these with Rifa capacitors will not cause a problem except perhaps in 30 -40 years time so if we are still around, we can worry about them then.

RS do not sell cheap unreliable brands and if they sell these capacitors then they expect them to work well and last well.

Nickuk99 · 23rd Mar 2017, 12:25 am

Okay. I'll go with these. RS Stock No. 414-8437

Ted Kendall · 23rd Mar 2017, 1:25 am

This brings to mind the old joke about the watch with a lifetime guarantee - when the mainspring breaks it slashes your wrist.

I have been fixing Revoxes and Studers for decades rather than years. I have seen enough "glacier mint" failures under power (and had to clear up the

mess resulting from such failures) to make me swear off the things for good.

Every piece of kit discussed on this forum is, by definition, beyond its design life. Even professional kit, when I worked for the BBC, qualified for RWOP after ten years.

RS, in common with the other well-known component suppliers, stock stuff for which there is demand. No doubt all the due diligences are observed, but the fact remains that these components fail so much sooner than the rest of the machine that to persist with them when there is a better alternative is perverse.

To put the matter beyond doubt, RS 414-8437 or equivalent is the preferred choice.

Nickuk99 · 23rd Mar 2017, 1:32 am

So what is the better alternative? If you don't mind saying. I'd like the best, only want to repair it once.. well the caps once in any case

Ted Kendall · 23rd Mar 2017, 8:32 am

Quote:

Originally Posted by Nickuk99

only want to repair it once.. well the caps once in any case

Couldn't agree more - that currently available as RS 414-8437 is what I fit and what I suggest you use.

Nickuk99 · 17th May 2017, 4:37 pm

Hi,

I am pleased to report that following a recap of the power supply (C3 had gone short circuit) and replacement of all rifà caps in the 3 motor control boards.. The machine is actually running okay.. All logic functions respond as they should. I have replaced some lamps in the logic and speed control board.. I'll continue to recap other parts as I go starting with the large motor caps bolted to the upper part of the chassis. Any recommendations of where to source these??.. There is an eBay seller in Germany selling the set of 5 for 38 euros plus delivery. .are these okay or should they be avoided??

A couple of question's if anyone can help...

1. Does anyone know how to change the lamps in the VU meters? Mine are all out. . I read somewhere that you pull the acrylic covers off the front of the VU meters.... but I don't want to force anything. The manual says open the VU meters...

2. The capstan is pretty much silent in 3 3/4 ips and 7 1/2 ips. .. I can hear it slightly in 15 ips. . Is this normal or should I be considering replacing the capstan motor bearings?

Any help gratefully received..

Many thanks

John Caswell · 18th May 2017, 5:21 pm

Hi Niku
Are you sure it is the capstan motor? I have just changed the pinch wheel on a B77 hi speed as it was noisy on 38cms.

John

Nickuk99 · 18th May 2017, 5:31 pm

Hi,

Yes. . I am talking about the capstan motor when running without the pinch roller being engaged... It is not noisy but it can be heard. .i e. If you listen..... you are aware it is running, however at the two lower speeds it is all but silent. . I'm just wondering whether I should consider looking to change the capstan motor bearings. ..

19th Mar 2017, 8:28 am	#1
Nickuk99 Triode Join Date: Mar 2017 Location: Reading, Berks, UK. Posts: 23	Studer B67 faults initial inspection. This is the beginning of my Studer restoration story, having recently acquired a B67 MK1 serial 35## with 3/78 on one of the large caps, so I'm assuming 1978. I was told that the Studer had the 'spinning away' issue with the take up spool, so having got it home I decided to resist the temptation to power on and take a good look up inside before removing it from the trolley and investigating further. So at first inspection... 1. F7 -12V 2 amp fuse is blown. 2. Signs of heat (slight blackening) to the tips of the blue pair of wires where they connect to the connecting block on the PSU. I'm assuming this pair is something to do with the -12V rail ? 3. One of the motor control boards is more visible than the other, and on the more visible board, there are heavy signs of yellowing on the 0.47uf caps on the board (were they black before), the middle of the three 0.47uf caps is totally cracked and split and looks to have completely failed, I'm thinking this will have caused F7 to blow? The other board is more difficult to see but I can see the 0.47uf caps are yellowed so I'm assuming they will have failed also. I can not see the capstan motor control board at the moment due to the trolley obscuring most of the underside. 4. The take up spool (right) tension arm positively returns back to its home position when lifted and released and I can hear the microswitch engage when it reaches the home position, however the feeder spool (left) tension arm is more sluggish when lifted, almost feels like it is missing its spring or certainly much weaker. When lifted and released it does not return fully to its home position and so the microswitch does not engage. In this scenario I'm thinking the feeder (left) tension arm is telling the take up (right) spool motor that there is still tape on the feeder reel? Should they be equal in operation? I'm thinking they should be. I am in need of a manual, is there one available on-line? However in the meantime can anyone tell me how to remove the top cover plate, the head block and switch rail, so I can clean them properly and take a little look at the left tension arm. Any comments, observations and advice would be most welcome. Thank you.

19th Mar 2017, 3:00 pm	#2
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,670	Re: B67 faults initial inspection OK - first thing to note is that you should replace ALL the Rifa 0.47uF capacitors before you apply power. Those which haven't already gone pop will be on the point of doing so and you can do without the the smoke, smell and general corruption. There are about five, from memory, including one on the capstan card, and RS do a drop-in replacement. Disrobing is as follows. Unscrew the the pinch roller and tension arm roller caps and remove rollers. Undo three hex bolts which hold the headblock and remove - carefully. The clearance around the capstan shaft is small and you don't want to scratch it. Undo the five hex screws through the top plate and remove. If you have a monitor speaker in the top plate look out for the connecting plug and remove. The switch rail is retained by one hex screw at either end and then lifts out. Each tension arm has two springs - one for return and one for limiting - and both are needed for correct operation. Damping is also present and the dashposts may need replenishing, but don't dive into this without reason. There is a service manual available free on the Studer ftp site.

19th Mar 2017, 7:51 pm	#3
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,224	Re: B67 faults initial inspection There are a lot more than 5 of those capacitors, there are three on each of the motor drive boards and about 9 on the relay board. There is also one across the mains on the transformer. Use good quality X class capacitors. __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/

21st Mar 2017, 12:43 pm	#4
Nickuk99 Triode Join Date: Mar 2017 Location: Reading, Berks, UK. Posts: 23	Re: B67 faults initial inspection Hi, Many thanks for the response. Re the caps, can anyone recommend which make to use and where to get them?, there seems to be several vendors out there selling "kits", however I read somewhere that these kits don't use the best quality caps, I want to buy the best quality I can find. I think I would like to replace all the Rifa 0.47uF capacitors, is there a list of how many I need? The removing the top cover, the head block and the switch rail. I removed the head block cover first, 2 screws, and then the 3 screws holding the head block in place, it was a loose after removing the screws but a little stiff and did not want to lift off. I didn't want to apply too much pressure, is it really just a case of working the head block and pulling it up when the three screws are removed? The same situation with the switch rail. I removed the 2 screws, one at each end of the rail, and it didn't want to lift off, and again I didn't want to apply too much pressure if there was something else holding it down. So the same here? just need to apply more pressure to lift it off, it has probably been on there for many or even 39 years... Many thanks.

21st Mar 2017, 3:50 pm	#5
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,670	Re: B67 faults initial inspection The headblock connections are via a 37-way D connector, and it is just a matter of a careful upward pull with slight rocking to get this parted. The switch rail sits quite snugly between the side pieces, so may need a little winnowing out. I have used the caps from RS (414 8459) - Farnell have a suitable component as well. Also, I have found the stuff sold by Nagravox of Australia to be of good quality. The shortest cut to finding out how many you need is to download the manual - when I trip over mine I'll do a quick head-count. Certainly five - the related A700 has many more. RS sell in packs of ten...

21st Mar 2017, 4:37 pm	#6
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,670	Re: B67 faults initial inspection I forgot to mention that the headblock comes off first, then the top panel and then the switch rail.

21st Mar 2017, 10:40 pm	#7
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,224	I think you mean these Ted, these have a 22.5mm pitch, whereas the ones you suggested had 27mm pitch These tape recorders are very complex if you are a novice, then tread very carefully. __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/

21st Mar 2017, 11:13 pm	#8
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,670	Re: B67 faults initial inspection Brain fade...

22nd Mar 2017, 12:16 am	#9
Nickuk99 Triode Join Date: Mar 2017 Location: Reading, Berks, UK. Posts: 23	Re: B67 faults initial inspection Many thanks for the replies I'll get some 0.47uf caps ordered and make a start. Also take a careful look at why the supply tension arm is sluggish and not returning to its home position, causing the micro switch not to be operated.

22nd Mar 2017, 8:48 am	#10
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,670	Re: B67 faults initial inspection The RS listing for the smaller form factor now shows the Rifa "fox's glacier mint" component - might be better to look elsewhere...

22nd Mar 2017, 8:51 pm	#11
Nickuk99 Triode Join Date: Mar 2017 Location: Reading, Berks, UK. Posts: 23	Re: B67 faults initial inspection Hi, Is the suggestion that the cap listed below is not the one to go for? RS Stock No.414-8437 KEMET 470nF Polypropylene Capacitor PP 275 V ac ±20% Tolerance Through Hole PHE840 Series If it is, can anyone suggest another option?, I would like to buy the best quality caps I can find to repair the B67. Many thanks.

22nd Mar 2017, 10:34 pm	#12
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,670	Re: B67 faults initial inspection Sorry, as you were. That one will be fine - the ones to avoid are the aforementioned translucent yellow things which, confusingly, RS also now sell. See the "Rifa capacitors" thread elsewhere on this forum for dozens of almost identical tales of their misdeeds.

23rd Mar 2017, 12:15 am	#13
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,224	Re: B67 faults initial inspection The problem with the 'rifa' capacitors is that they are now 40 years + old and were never designed or expected to last as long as this. Replacing these with Rifa capacitors will not cause a problem except perhaps in 30 -40 years time so if we are still around, we can worry about them then. RS do not sell cheap unreliable brands and if they sell these capacitors then they expect them to work well and last well. __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/

23rd Mar 2017, 12:25 am	#14
Nickuk99 Triode Join Date: Mar 2017 Location: Reading, Berks, UK. Posts: 23	Re: B67 faults initial inspection Okay. I'll go with these. RS Stock No. 414-8437

23rd Mar 2017, 1:25 am	#15
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,670	Re: B67 faults initial inspection This brings to mind the old joke about the watch with a lifetime guarantee - when the mainspring breaks it slashes your wrist. I have been fixing Revoxes and Studers for decades rather than years. I have seen enough "glacier mint" failures under power (and had to clear up the mess resulting from such failures) to make me swear off the things for good. Every piece of kit discussed on this forum is, by definition, beyond its design life. Even professional kit, when I worked for the BBC, qualified for RWOP after ten years. RS, in common with the other well-known component suppliers, stock stuff for which there is demand. No doubt all the due diligences are observed, but the fact remains that these components fail so much sooner than the rest of the machine that to persist with them when there is a better alternative is perverse. To put the matter beyond doubt, RS 414-8437 or equivalent is the preferred choice.

23rd Mar 2017, 1:32 am	#16
Nickuk99 Triode Join Date: Mar 2017 Location: Reading, Berks, UK. Posts: 23	Re: B67 faults initial inspection So what is the better alternative? If you don't mind saying. I'd like the best, only want to repair it once.. well the caps once in any case

17th May 2017, 4:37 pm	#18
Nickuk99 Triode Join Date: Mar 2017 Location: Reading, Berks, UK. Posts: 23	Re: B67 faults initial inspection Hi, I am pleased to report that following a recap of the power supply (C3 had gone short circuit) and replacement of all rifà caps in the 3 motor control boards.. The machine is actually running okay.. All logic functions respond as they should. I have replaced some lamps in the logic and speed control board.. I'll continue to recap other parts as I go starting with the large motor caps bolted to the upper part of the chassis. Any recommendations of where to source these??.. There is an eBay seller in Germany selling the set of 5 for 38 euros plus delivery. .are these okay or should they be avoided?? A couple of question's if anyone can help... 1. Does anyone know how to change the lamps in the VU meters? Mine are all out. . I read somewhere that you pull the acrylic covers off the front of the VU meters.... but I don't want to force anything. The manual says open the VU meters... 2. The capstan is pretty much silent in 3 3/4 ips and 7 1/2 ips. .. I can hear it slightly in 15 ips. . Is this normal or should I be considering replacing the capstan motor bearings? Any help gratefully received.. Many thanks

18th May 2017, 5:21 pm	#19
John Caswell Hexode Join Date: Jul 2009 Location: Wokingham, Berkshire, UK. Posts: 437	Re: B67 faults initial inspection Hi Niku Are you sure it is the capstan motor? I have just changed the pinch wheel on a B77 hi speed as it was noisy on 38cms. John

18th May 2017, 5:31 pm	#20
Nickuk99 Triode Join Date: Mar 2017 Location: Reading, Berks, UK. Posts: 23	Re: B67 faults initial inspection Hi, Yes. . I am talking about the capstan motor when running without the pinch roller being engaged... It is not noisy but it can be heard. .i e. If you listen..... you are aware it is running, however at the two lower speeds it is all but silent. . I'm just wondering whether I should consider looking to change the capstan motor bearings. ..