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Latest post 02-20-2012 4:42 PM by sonavor. 215 replies.
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  • 01-07-2012 4:58 PM

    Beomaster 6000 Refurbish

    I have an update kit from Dillen for my Beogram 6000 and am ready to begin work on it.  I really wasn't familiar with this receiver and it wasn't on my list of vintage audio equipment to own.  It came along with a Beocord CDX unit.  The two came as a package deal for practically nothing so that is how I got to this point with it.  It wasn't supposed to be working but when I brought power up on it slowly with my variac I could here a click inside the receiver.  When I got to 120 VAC power was on and the unit worked.  You can see in the picture that it has the problem where the FM tuner display is stuck on 74.8.  Dillen has supplied me with an IC that should fix that.  The controls need deoxing but they do function.  While waiting on Dillen's parts to arrive I probably shouldn't have used the receiver but I wanted to get familiar with it prior to upgrading it.  I played it through some RL 140 speakers and it sounded really good (I only used an ipod as an input source though).  I started to like it.  All of a sudden, last week, while playing some music through it, the receiver just shut down.  Power would not come on at all ... no stand-by light or anything.  I tried unplugging it for a while and still nothing.  I thought I really screwed up and likely damaged the unit before even starting with the upgrade kit.  As I am now starting the upgrade I decided to see how the unit looked on my dim bulb tester (while bringing up the voltage from zero to 120).  Again, as I applied power I heard a click inside the receiver and then noticed the standby light was on again. Power is restored!  This time I will not use the receiver until after the recap. I am wondering if the lost power is due to some kind of fault in the protection circuitry?  I can see a protection circuit should shut down the output but it should be able to reset after being unplugged for a period of time.  It seems like the variac forced the reset by bringing up power slowly.


  • 01-07-2012 5:07 PM In reply to

    Re: Beomaster 6000 Refurbish

    The Beomaster 6000 opens up really easy for maintenance. It's like opening the hood of a vehicle.  This is quite a change from the Beomaster 4000 I just finished.


  • 01-07-2012 5:15 PM In reply to

    The PCBs look like they are all connected via connectors instead of hard-wired like the older BM 4000.  Side note: With my second BM 4000 unit I worked on I am seriously considering making the board connections by installing high quality connectors.  That would allow me to experiment with some my spare BM 4000 PCBs. 

    Anyway, continuing on...this picture of the Beomaster 6000 FM PCB shows the wiring to the board connectors I am talking about.


  • 01-07-2012 5:31 PM In reply to

    Here is a picture of the parts from Dillen's kit - electrolytic caps, trimmer pots, volume control belt and the IC for the tuner display problem.  He also provides instructions for where the parts go.  Very handy.


  • 01-07-2012 7:02 PM In reply to

    • Step1
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    Re: Beomaster 6000 Refurbish

    This model is one of my all time favorites! I have restored a few now, and enjoy doing so every time :) They all suffer from similar faults / weaknesses but one thing worth noting is don't go in all gung-ho those LED displays are very delicate (can be repaired with SMT leds but fidly) other things to watch for are connectors coming loose when jiggling things about which can cause much head scratching!

    Also, be very careful with the switch panel when lifting off, it unclips from the front with three clips but do not lift up any further than is nesesary to pull the lifted clips forward beyond the front veneer. The rear of the switch panel has three clips clamping to the chassis (switch panel slides forward to release) and these can snap very easily!

    You will need to to access the processor unit - and you will want to get to those pop buttons as well to clean as they can become quite badly oxidised. This results in the user pressing harder to activate the buttons which in turn puts stress on the clips holding the board to the panel, resulting in failure of the clips (usually the standby button!).

    Worth stripping every last bit of this hifi (I even pull the speaker switches apart as the contacts are nearly always black with oxidation! might not make a lot of difference sound quality wise but I have had a switch fail to work, for this reason..

    For the fault mentioned you could try dissconnecting the power to the amp. This will allow you to rule out fault detection. I am sure at least the standby led should remain lit though!

    Will be interesting watching this thread :) Good luck!

    Olly.

  • 01-07-2012 7:37 PM In reply to

    Re: Beomaster 6000 Refurbish

    Thanks for the tips.  I'll contact you when I get to some specific items you mention.  About that power fault...I did completely disconnect power to the amp when I first encountered the fault.  I let it set a bit, then plugged it back in.  The standby light wouldn't light and the unit was completely dead.  It was only when I plugged the power into my variac and brought power up slowly that it worked.  And when that worked I could hear a distinct click as I was dialing up the voltage.  There is an RL1 relay in the power protection circuit (PC11 module).  I am guessing that is the click I hear.   

  • 01-07-2012 9:25 PM In reply to

    Re: Beomaster 6000 Refurbish

    I decided to start with Module 16 - Power Supply PCB because it has two electrolytic caps that are part of the kit that I have questions on.  In the following sequence of pictures you can see module 16 installed, removed and the trace side (with electrolytic caps C1 and C10 removed).  These two caps (C1 & C10) are packaged differently from usual electrolytic caps.  The positive terminal is at the bottom in the center.  The negative terminal is connected to the three mounting prongs of the case. 

    For C1, the mounting prongs (negative leads) mount to three points on the PCB.  When I replace that with a typical two-lead electrolytic cap it appears from Dillen's instructions that I will have to make sure and jumper from the locations on the PCB I have shown with a yellow line.

    For C10, the PCB marking for the negative terminal of the cap is not a hole in the PCB. So for that recap the instructions say to use the old cap case mounting hole I have marked with the negative sign (in a white circle).

    Does that sound right?


  • 01-07-2012 9:36 PM In reply to

    Re: Beomaster 6000 Refurbish

    Here is a measurement of the existing module 16 PCB C1 cap (3300uF) and the new, replacement cap.


  • 01-07-2012 11:27 PM In reply to

    Re: Beomaster 6000 Refurbish

    Here is the finished module 16 PCB recap.  Note that there are three old cap mounting points that are no longer used.


  • 01-08-2012 2:21 AM In reply to

    Re: Beomaster 6000 Refurbish

    The next board is Module 06 - Standby Power Supply and Volume Preset

    In the picture, the large 10000uF capacitor is easily replaced and is the only one for this board in Dillen's kit.  The 22uF electrolytic cap is not in the kit and is not in the Beomaster 6000 service manual.  I have drawn on the inset picture of the schematic where this unknown cap is wired to - between +15VDC and ground near the IC5 chip.  I pulled the capacitor and measured it.  It currently measures 8.78uF. Is this capacitor a factory service bulletin type mod to the circuit or is this some mod someone that worked on the receiver added?  Do I put a new, good 22uF capacitor in its place?  The bottom part of the cap near its leads looks a little dark like maybe it got too much heat.  8.78uF seems to indicate this cap is bad.


  • 01-08-2012 4:23 AM In reply to

    Re: Beomaster 6000 Refurbish

    Completed Module 06 recap.  I talked to Dillen and concluded that the 22uF (unknown designator) electrolytic cap should be there.  I had an extra (new) Nichicon 22uF, 50V cap in my electrolytic supply box so I used it.  In the following picture of the completed 06 module it is the little round can below the big C9 capacitor.  The little 22uF cap negative lead goes between R48 and R49 (ground) and the positive lead to pin 1 of IC5 (+15V).


  • 01-08-2012 7:26 AM In reply to

    • Step1
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    Re: Beomaster 6000 Refurbish

    Doing well so far :) Regarding Module 16, did you check all the joints as it is rather prone to drys especially round the sockets and the transistors!

     

    BTW Very nice choice regarding the ESR meter :) I gave up on my home brew meter a while back and as I live down the road from Peak, went to pick one of these up from their 'factory'! Really nice folks these devices are pretty much hand built in a small office in Buxton, Derbyshire! Superb little machines and very good for measuring low resistances too! Also got their transistor checker which I need to take back for an upgrade soon, so that it will measure leakage. Now that thing is indispensable!

    Olly.

  • 01-08-2012 8:37 AM In reply to

    • chartz
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    Re: Beomaster 6000 Refurbish

    Excellent work, nice pictures and a great how to. Smile

    As Olly says, check ALL the joints! And use a magnifying glass too!

    Your Beomaster looks very good, no dust or oxidation, wow. Mine is absolutely mint outside, but much less so inside!

    Jacques

  • 01-08-2012 2:50 PM In reply to

    Re: Beomaster 6000 Refurbish

    Before I started I did use an air compressor (at low air flow) to get rid of loose dust inside the unit.  But overall the unit is extremely clean.  I bought the receiver and a couple of other B&O pieces from the seller in person.  He was a nice guy and I found out was the original owner.  The pieces were always kept in a house so they weren't exposed to big changes in temperature. 

    I will go over all of the solder joints on the boards as you suggest.  A couple of months ago I bought this little LED illuminated 45X mini-microscope off Amazon for around $3. - http://www.amazon.com/gp/product/B002E0MU70/ref=oh_o00_s00_i00_details

     It is just a toy but works really great for checking out solder joints. 


  • 01-08-2012 6:22 PM In reply to

    Re: Beomaster 6000 Refurbish

    The next board is the 09 Module - Output Amplifier.  This picture shows the board installed, then removed and the trace side (with the transistors on the heat sink.  While doing the recap I measured each capacitor I removed.  Unfortunately I first removed the two 47uF bipolar caps as a pair. One of them was bad - measured open circuit but I can't say for certain which one.  The remainder of the caps I tested as I removed each one.  There were two 100uF, 16V polarized caps that measure bad.  Those are marked in the picture.


  • 01-08-2012 6:27 PM In reply to

    Re: Beomaster 6000 Refurbish

    Here is a picture of the bad 47uF bipolar cap.


  • 01-08-2012 6:30 PM In reply to

    Re: Beomaster 6000 Refurbish

    Here is a picture of one of the bad 100uF polarized caps.  They measured too low to check out on my ESR meter so I used the LCR meter and it shows the measured capacitance of close to 2nF ... way off.


  • 01-08-2012 6:33 PM In reply to

    Re: Beomaster 6000 Refurbish

    Here is a picture of the recapped 09 module. Next for this board is the four trimmers.


  • 01-08-2012 6:35 PM In reply to

    • Step1
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    Re: Beomaster 6000 Refurbish

    Those Rodenstien caps are about 75% faulty usually. The orange capacitors tend to be well behaved and generally good I find.

    That Faulty bipolar will more likely be the reason the amp kept going into standby, as it is a major part of the protection circuit. Have you actually got an operational decimal point on the display?

    Olly.

  • 01-08-2012 10:04 PM In reply to

    Re: Beomaster 6000 Refurbish

    Before I started the recap and after I restored power to the unit using the variac, I did have the decimal point on the display.

    I am trying to decide if I need to replace the four trimmer pots on the 09 Module PCB.  The four that are there are nice and shiny (still look new).  Of course that doesn't mean they are good but compared to the BM4000 I just recapped....those old trimmers looked old.  I guess I'll pull one off and measure what the current setting is and check out the range.

  • 01-09-2012 12:19 AM In reply to

    I pulled the old trimmers (R110, R134, R210, R234) and checked them.  They initially measured a higher ohm value across their contacts than what should be valid for 100 ohm variable resistors.  If I moved the pots back and forth the measured ohm values looked much better.  So I take that as meaning they are oxidized.  Since I have four new ones in Dillen's kit and intended on changing them, I went ahead and swapped out the trimmers with the new ones.  I just have to remember to do the no-load current and DC offset adjustments first thing when I finish putting the receiver back together.


  • 01-09-2012 2:49 AM In reply to

    Re: Beomaster 6000 Refurbish

    The 08 Module is the FM tuner board.  It takes a little more care getting out than the others so far because it has a big wire bundle going across one side (you can see that in the earlier picture of this board when it was still in the chassis).  Once out here is the front and back.


  • 01-09-2012 3:18 AM In reply to

    Here is the 08 Module after the recap.  I noted the one bipolar cap.  I also noted the two orange 0.47uF electrolytic caps that were not recapped.  Those weren't in the kit.  I was wondering if those are a small enough capacitance where they could be replaced by a polypropylene film capacitor?


  • 01-09-2012 4:01 AM In reply to

    • Step1
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    Re: Beomaster 6000 Refurbish

    I would leave them tbh, it is very unlikely they will be causing any issues which is why Martin won't have sent you replacements. If you want to replace then anything that isn't physically too big will be fine, but why not electros?

    You were right in replacing all those trimmers in the amp, they would have been ready to cause no end of trouble!

    Olly.

  • 01-09-2012 12:36 PM In reply to

    • Rich
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    Re: Beomaster 6000 Refurbish

    sonavor:

    The Beomaster 6000 opens up really easy for maintenance. It's like opening the hood of a vehicle.  This is quite a change from the Beomaster 4000 I just finished.

    How freaking cool is that?

    Current primary listening:  SMMC20EN -> BG4002 -> BM4000 -> Beovox M70

     

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