The Workbench

Re: Workshop VX7000 How to repair this recorder, common faults

Die_Bogener — Mon, 23 Feb 2009 12:35:19 GMT

Inside the VX

What is the main problem around these VX recorders?

It's pretty simple, it's time and heat. The VX becomes pretty hot during operation, they are now 12-18 years old and B&O used some of the worst caps on this planet. My experience with the black RUBYCON and the blue NICHICON is sooooo bad, i cant tell you...

Take a look at this picture, it's a detail from the CPU board and you know what i'm talking about...

If the board has turned it's colour to dark brown, it was used a lot of time. Usually the board a bright brown, like honey.

Look at the small chip, the acid of the caps was spread all over the board, the pins of the chip are black, there is a black oxide on it's connectors... and the acid conducts currents.

Hmmm, boards like this are scrap, usually they cannot be really repaired. The acid of the caps is spread all over it and is now also under the copper on the solder side. If you try to solder new parts in such a board, it stinks awfully and the copper contacts of the board seperate from the substrate. The copper is black oxidated...

Some more: Clean the boards. The acid causes short cuts and will be working all the time, causing more and more oxide on the copper and other parts. I clean these boards with hot water and a bath cleaner. Yes, these boards can be washed! But take care that they are dry before using... i let them dry for several days in a warm room. Turn them arounf that no water stays inside steel or cabinet parts.

Or should i say HITACHI? Yes, this VX7000 and the older VX5000/5500 were not produced in Denmark, they were produced in Japan. And most of the parts are identical to Hitachi parts, the drive deck, the loading unit and maybe some parts more. You wont find any label inside stating produced by Hitachi... only the service numbers can tell you the story, that these parts have the same number like Hitachi ;)

What is what?

The Power Supply

This is the power supply of the VX7000. It's an evolution of the VX5000/5500 linear regulated supply to a switched power supply. The power consumption especially in standby dropped from around 20W (!) to around 5W, also in operation from 60W to 32W. That's really nice.

And it became more durable, at least a little bit since to less parts and better parts... and less heat.

For a complete rebuild of this power supply you need only 6 caps:

C854, C865 (on the small board) = 10uF 16V standard and miniature or both miniature

C851 = 2200uF 50V

C856 = 3300uF 25V

C853 = 1500uF 35V, diameter 12mm, hight 38mm, RM5, that's something very rare.

C858 = 2200uF 25V, diameter 12mm, hight 38mm, RM5

Note: There are also versions of the VX7000 where C858 is a 2200uF 25V type or a 1500uF 35V. I can confirm this, i have seen now both versions. In this case use the same values again. The 1500uF caps are very, very hard to get, the others are standard 105 degree low esr types. Take a close look at them, sometimes they are still ok.

Note: There is some brown stuff around these caps, this is epoxy or a special type of glue to protect these caps against vibrations. You may think that this brown stuff could be acid, but this is quite normal. But... if you see drops you can wipe off or this typical smell when you solder on it, it could be really a defect cap.

But what you should replace is the blue 10uf Nichicon cap. You will probably see the black acid around his feet... nasty.

And one WARNING: NEVER RUN THIS POWER SUPPLY WITHOUT LOAD! IT MUST ALWAYS BE CONNECTED TO THE VX! Otherwise 2 zenerdiodes for protection will blow, followed by the other fuses.

Here is a provisoric picture of the power supply, my camera got damaged...

The power supply can be tested, look "the lower mainboard"

The Upper Mainboard

The Lower Mainboard

This is the lower mainboard. On this board are:

- Power Regulators

- the HiFi Audio Decoder

- Linear Audio

- System Control

- Servo and Motor Control

Please note, that there a several different versions of this board. I know of 3 versions, there are some minor changes of the components.

OK, a lot of parts... but here it is always quite the same problem: caps. B&O ( or should i say: HITACHI? ) used a lot of the worst caps on this planet, the black RUBYCON and the blue NICHICON. They are prone to fail.

This board becomes pretty hot around the power regulators, the heat damages also the CPU board above.

Sorry, it's a lot of work to do here, replace them all. Even if you dont see acid or black feet on the caps, they will fail, sooner or later.

Part List:

....

...

....

Some interesting part is the fuse QF1601 on this board. It is a chip fuse, looking like a 2-pin transistor. If there is a problem with overload or overvoltage it will blow... but almost nobody knows about this fuse. The VX will be almost completely dead.

QF1601 is in grid section 2C. Either you use the orignal type ICPN20= 800mA or you use one of the small round standard fuses with RM5.

QF1601 = N20 is specified as a 800mA medium-slow type. You can replace it by a standard MINI MTR 0.8A type. This one here will fit perfectly for this job. It has the same size and the same spec. And it can be socketed in 2 standard pins of a chip socket. Nice and clean, and B&O uses this type of fuse also... so it's almost "original" ;)

Note: There is also a second chip fuse QF901 = N5 = 0.250A, section 3C, right between a large blue and white socket. On a different board the same fuse is called QF902, next is a print on the board for QF901 which is bridged by a wire. So, here is the proof that B&O used several version of this board. Interesting is also, that neither QF901 nor QF902 are documented in the circuit plans or in the part list... but they are on the boards.

Here is a picture of the other mainboard version from Friedmett.

http://i114.photobucket.com/albums/n277/Friedmett/Anderz/VX7000022.jpg

http://i114.photobucket.com/albums/n277/Friedmett/Anderz/VX7000024.jpg

Testing the Power Supply and the Power regulators

OK, let's test the power supply. You need access to the lower mainboard, section 2B, there is a 8-pin connector PG1623, the pins are numbered 1-8. It is directly connected to the outputs of the power supply. Since it is not possible to operate the power supply outside the VX, use the connector PG1623 instead. All boards are correctly mounted and connected inside the VX, nothing is missing. You can use the steel cabinet of the VX for ground.

Pin 1: 5,4V regulated

Pin 2 + 4 + 6 + 7= ground (take care... there are several ground connections on the power supply, they split on the lower mainboard to 4)

Pin 3: 13,5V regulated

Pin 5: 50Hz clock signal

Pin 8: 27V unregulated

Check these voltages.

If 27V is missing, the Fuse F853 = 2A or the rectifier D851 is dead.

If 13,5V is missing (probably around 0.4-0,5V), then the zener diode ZD1605 (16,3V, grid 2C) is dead and makes a shortcut. This happens if the power supply failed to overvoltage.

If 5,4V is missing, then the power supply was used outside the VX without load. ZD855=6,2V on the power supply makes a shortcut.

If these 3 voltages are ok, then the power supply is ok.

The power regulators on the lower mainboard:

There are 6 more tests for the power regulators on the lower mainboard.

Check the fuse QF1601=800mA grid 2c. There must be 13.5V on both pins. (Sometimes there is a glued black rubber block... the text is hard to find)

Check C1614 grid 1c or the output of Q1603, there must be 9V if the VX powers up.

Check C1603 grid 1d or the output of Q1601, there must be also 9V if not in standby. Used for the tuner.

Check C1607 grid 1D or the output of Q1605, there must be 12V if not in standby.

Check Q1614 grid 2c, there must be 5.4V if not in standby. Used for the tuner.

Check the output of Q1611 grid 2c, there must be 11.3V during operation for the capstan motor

If one of the voltages is missing, the fuse QF1601 is blown or the according transistor is defect or overloaded.

The parts to be checked are marked red.

The CPU and AV-Switch Board

The Modulator

The AV Connector

Re: Workshop VX7000 How to repair this recorder, common faults

Die_Bogener — Tue, 10 Feb 2009 14:11:51 GMT

The broken loading unit:

If you see something like this, then the loading unit is broken. This picture is from a VX5000, but the loading unit is identical to the VX7000, all parts are compatible.

http://img405.imageshack.us/img405/7349/p1060018sm9.jpg

The reason is a defect capstan motor or a defect motor control. The motor did not reverse and has broken the gearbox. Maybe a very rude owner can also cause this defect by pushing the tape inside fighting against the crazy VX...

To repair the broken loading unit, you must dismantle the VX completly, also the front cover must be removed.

You need a spare part from B&O, it is still available, costs around 20 Euro, has the part number 2700082 Gear Wheel. VX5000,5500 and 7000 have the same part. But there seems to be a number change, the box says part number 2700011 Gearweel VX7000... but it fits perfectly.

http://img249.imageshack.us/img249/2196/p1090013gz7.jpg

Ok, here we are, this is the broken loading unit... the gear wheel is broken Quite normal after 20 years. B&O has noticed this defect on the VX5000/5500 series and has improved/changed the material of the plastic. The newer VX7000 has almost no problem with this part.

It is mounted with 2 bolts and is hooked to the frame in the front.

http://img338.imageshack.us/img338/1026/p1090009hy0.jpg

It cannot be fixed with glue or anything like that... at least not for a long time.

http://img249.imageshack.us/img249/8452/p1090012bj0.jpg

To open it, open these small plastic hooks veeeeery carefully, they break off easily. Then you can pull out the gear wheel.

Mount the cassette holder and assemble the unit again. Watch for the alignment of the gear wheels, it must look like that:

http://img249.imageshack.us/img249/9215/p1090015rt0.jpg

The 2 gearwheels and the frame of the gearbox must fit together like shown on this picture and must be aligned like this.

http://img168.imageshack.us/img168/5087/p1090011ox5.jpg

If there is a problem to mount the axle and the gearbox, press the left button, inside the gear is a nose on the gearwheel....

http://img168.imageshack.us/img168/2333/p1090017gq3.jpg

Insert the 2 bolts in the holes and mount it into the VX again. On the front there are only 2 hooks, in the back the 2 bolts. Check wether it's horizontal and then tighten the bolts.

Broken time and adjustments:

A defect lithium cell is sometimes very difficult to see. Sometimes the VX works quite normal, the picture is good, but if you disconnect mains, then the logon (tv set and VX are talking when connected by scart, the tv makes a download of channel data to the VX) is very slow.

Sometimes the VX disappears from the AV-menu. Also the operation is very slow, commands of the Beolink are not executed, the keyboard does not work.... a lot of very strange errors.

Usually its lifespan is around 15-20 years in a VX, pretty long... but not long enough. This VX here has a defect lithium cell.

The lithium cell is located here:

http://img503.imageshack.us/img503/870/p1080007lu9.jpg

The lithium cell has 3.6Volt. If it is less than 3.3V it should be replaced. I dont know what this part cost in a B&O shop... and i dont want to know. Probably around 30-40 Euro...

This battery can be bought in any good shop, costs around 3-10 Euro. VX5000-7000 use the same lithium cell.

Here it is:

http://img211.imageshack.us/img211/2447/p1080006hl0.jpg

Cut the foil, and replace it carefully. Take care not to shortcut anything, this battery has a lot of power and can explode.

DO NOT SOLDER DIRECT ON THE BATTERY! THEY DONT LIKE HEAT!

Workshop VX7000 How to repair this recorder, common faults

Die_Bogener — Mon, 09 Feb 2009 14:23:25 GMT

PLEASE do not post any answers, i'm still working.... i know this is a copy of the VX5000 workshop. I will copy and paste first and then modify the article.....

Hi B&O fans,

this is a little guide how to test and repair this VX7000 video deck. The VX7000 is a direct evolution of the older VX5000/5500 recorders, some the most advanced and also most expensive decks ever built. 12kg high tech in a small cabinet, very stylish ... and still very complicated.

The VX7000 is already a pretty old machine today, most of them are now 16 years old and have a lot of bigger and smaller defects. All have problems, i have had a lot of them (several hundred incl. the older models...) and 99% could be repaired.

OK, first the defects which you can see on the tv.

1.) Noisy Picture with horizontal bars, sometimes distortions, black and white horizontal bars

This is a typical symptom of bad caps on the cpu board and... sorry, the cylinder head can be worn. The older VX5000 does not suffer to worn cylinder heads, but the newer VX7000 has some problems here.

2.) Sometimes very strong humming sound, shutdown after some minutes or it's impossible to load or unload the tape

Bad caps near the voltage regulators on the lower mainboard, bad caps on the cpu board

3.) It is impossible to load or unload the tape, the loading unit is broken

Sometimes the control unit for capstan motor fails, it's a cap problem

4.) the internal tuner shows bars, noisy picture, the sound is dull or just a grey/black picture

The tuner unit is defect... caps.

5.) the recorder is dead, no further reaction

Power supply defect, fuse blown, probably thermo fuse on the lower mainboard destroyed

6.) recorder is working, but the sound is missing, speed is not ok.

There is a small mechanical part broken or missing near the audio heads.

7.) lost time, forgotten adjustments, strange behaviour, slow or no operation when connected to mains

Lithium cell defect

8.) The VX rewinds very slow, has no power to rewind and stops sometimes

This is a very common defect, the reason is almost unknown ... i think it has something to do with noise in the digital state switch, repair is still almost impossible

9.) The VX goes into "STOP" mode without any reason

The tacho unit fails, power supply defect, lower mainboard regulator unit defect, defect caps

10.) some more? Tell me ;)

The Self Test of the VX7000:

Yes, there is a very nice feature implemented on this VX7000, a selftest. And it is very easy to use, just press on your remote control (BL1000...)

MENU - 0 - 0 - Play

and you enter a service mode menu. Very nice!

- Software Version

- After Repair Check

- Picture Adjust

- Center Tracking

- Total Reset

Software Version:

Known software versions are: 1.2 1.3 1.37 2.3 3.1

1.2, 1.3, 2.3 and 1.37 are two-way version, the 3.1 is one-way

1.3 and 2.3 are almost identical, the 2.3 was made for the built-in Version of the AV9000, some colours of the menus are differnt.

1.37 uses a different decoder for the VPS Timer signal, so this Version cannot be downgraded. Sometimes especially this newer v1.37 has trouble with timer recordings.

3.1 was used with the newer Beo4.

In V1.3 and V2.3 is a bug: after you selected Software Version, the VX will will not react to any command. Unplug it from mains.

After Repair Check:

This is a very nice test, here you can test your drive almost complete. Insert a cassette and start the test. The VX will play, rewind forward and reverse, record and test the drive. It takes some time, around 5 minutes, then the test begins again.

Dont use a cassette with a movie or records you like, the VX will try to make some records and destroy your old record! Make sure, that the VX is connected to an antenna, since it will try to tune to a tv station. Without antenna the test can fail.

If anything fails, the VX will show "FAIL" on the display.

Picture Adjust:

Here you can adjust the sharpness of the picture. Soft - Medium - Hard. I would recommend medium

Center Tracking:

Here you adjust where the 0-mark of the tracking should be. Use a good old record and adjust the center. There will be distortions on the top and the bottom of your screen, try the arrows to center the good picture in the middle of your screen.

Reset All:

That's pretty clear what it's doing ;) Clear all counters, timers, clock, date, tv stations and so on. Also the center of the tracking will be deleted. Do it when the cpu board was disconnected from the lithium cell or removed to clear strange settings.

MMI type:

In V3.1 you can select the type of Beolink for control. Beo4 or BL1000

How to dismantle the VX:

OK, here we are, a quite normal black VX5000. There is no difference to VX5500 or VX7000. The steel cabinet, top-, bottom- and the side- covers are quite the same, just the front is different. The cabinet and all steel parts of the VX 5000/5500/7000 are interchangeable, they are all the same.

So i use the same fotos again...

http://img164.imageshack.us/img164/5321/p1060009sw2.jpg

Put some thick newspaper or a towel on the desk and flip it over.

These are the 7 bolts on the black steel bottom cover. Open them. Pull off the cover, watch for the noses on the front cover, they can break off. If some are broken off, then i know at once, that this unit was opened

http://img263.imageshack.us/img263/6209/p1060010xv3.jpg

To remove the sidepanels, use only your hands, nothing else! Pull the corner a little bit outwards, around 5mm.

http://img215.imageshack.us/img215/8242/p1060011gl4.jpg

Push it backwards, around 10mm.....

http://img406.imageshack.us/img406/9738/p1060012df9.jpg

and pull upwards and the sidepanel is disassembled without any scratch. Most of the VX decks were treated with a screwdriver... nasty [:'(]

http://img406.imageshack.us/img406/2335/p1060013eu1.jpg

Remove 2 bolts on each side, these here...

http://img137.imageshack.us/img137/7816/p1060014zh4.jpg

and 2 on the rear side...

http://img137.imageshack.us/img137/5851/p1060015ug3.jpg

Then you can remove the top cover.

To remove the front cover remove 6 bolts, 3 on the top, 3 on the bottom. Pull on the left side here...

http://img407.imageshack.us/img407/9049/p1070001uj2.jpg

Now you can remove the the frontcover.

When you assemble the front cover, take care for this hook. Open the cassette flap when mounting the front cover. If you forget it, you can load a tape, but unloading is impossible. It will break the flap, the front cover or the gear wheel !!! The hook must be in a guide rail inside the flap.

NEW FOTO.....

http://img184.imageshack.us/img184/1530/p1070006dy2.jpg

The defect Capstan Motor:

In the older VX5000 series, the capstan motor had very serious trouble with some bad caps. B&O has probably noticed this problem with this motor and made an evolution of the motor. The all new VX7000 capstan has no electrolyth caps at all, just small tantal smd caps, they last almost forever.

But: it still has almost the same controller on the board and this chip does not like heat. Usually it will not fail, i think 99% of these new motors will never fail, but some do. You can hear it and feel it, the chip becomes really hot and the motor does not run smooth at all. There is a humming noise, the motor can not reverse. If this happens, the cassette load mechanism is also broken.

The capstan is located here. Just open the black metal cover on the underside of the VX, just 7 bolts. Watch for the small noses on the front cover, dont break them off.

The motor itself is mounted with 3 bolts and a fourth one for the power transistor. Just pull off the cable and disassemble the motor. Thats really easy.

NEW FOTO.................

http://img521.imageshack.us/img521/229/p3050001xw8.jpg