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This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
This post is about my 89 year old Uncle's Beomaster 4400. By way of background, my Uncle loves classical music and splurged when he purchased the 4400 for himself around 1979. As a child at that time, the 4400 was really a wonder to me. I loved the design and sliders... and of course its wonderful sound. This 4400 is a family heirloom.
My Uncle used the 4400 for about 15 years until retiring it. I was never sure why he stopped using it (until recently), but he still kept it positioned in a prominent location because he loved it so much.
I was delivering my Uncle a meal during the pandemic a few weeks ago when he told me that he stopped using the Beomaster because one channel had stopped working. He was still hoping that he could get it fixed and I wanted to try to help him. I would appreciate any help you can offer in terms of troubleshooting.
On a positive note, the 4400 powers right up and works (sort of). It plays music well out of the left channel, but only very lightly on the right side (the same is true whether with headphones or speakers). All of the sliders on the front work smoothly and without noise except the balance - which works, but has some cracks and pops as you slide it.
All of the switches on the front panel work except the very first switch (stereo speakers). The first switch next to the headphone socket is stuck in the on position (which doesn't seem like a harmful problem). I tried a little deoxit on the switch and it made no difference. I assume its broken rather than stuck.
Interestingly, if I use the mono switch... most of the time the right side speaker will turn on and I can hear both speakers playing pretty evenly. Operation seems more or less normal with the mono switch activated except that I am only receiving mono playback versus stereo. I am not sure why activating the mono button causes both channels to work fairly evenly.
The only other items that don't appear to function normally are the back light for the FM signal level meter and two red indicator lights for correct tuning. While it would be nice to have them working, I am not sure they are essential to have operating.
I would sincerely appreciate any help you could offer to help me troubleshoot these issues. I recognize these machines are quite technical and I know enough to not get in over my head. I have a multimeter, oscilloscope, and can solder. However, I will bring it in for service as needed if it proves to complicated. O have removed the wooden cover and my initial look over the inside of the 4400 shows nothing obviously out of place. I will try to post pictures later if that would help.
Again, much thanks for any suggestions you might have for me to try to track down why the right channel isn't working well.
-Marc
As promised, some pictures attached.
Another picture.
Hi Marc,
Having restored several Beomaster 4400 receivers and as the owner of one myself I can tell you that there is not one particular issue to troubleshoot and fix.The problem is with aging components inside the Beomaster 4400. The primary culprits are electrolytic capacitors which are designed to control the workings of the electronic circuits. Electrolytic capacitors have an age limit where they start to deteriorate to the point where they become way out of the 20% tolerance range they were designed for. The result of this failure causes various types of operational faults in the amplifier.The good news is that electrolytic capacitors can all be replaced with new electrolytic capacitors and in most cases the amplifier will return to like new operating condition again. There are a number of threads here on the Beoworld Forum that show some Beomaster 4400 restoration projects. My personal Beomaster 4400 restoration I posted over on the Beolover Blog. The link to those posts go from the final, completion post backwards but if you take a look you can get an idea about the scope of the restoration tasks. I did a couple of extra things on mine but I can tell you that I use my Beomaster 4400 almost every day and it sounds really great. I use a pair of B&O Beovox MS150.2 speakers with mine along with a Beogram 4002 turntable.
I hope that information is of some help to you.
-sonavor
I see you have a scope and can use a soldering iron.....thats a good start, the manual for this is available here on the site, a signal generator would help you trace the signal through from the input to the potential problem. I would pull out and clean the internal plugs and sockets first as I have had a problem with bad connections in those.....has the machine had a knock causing the speaker 1 switch to stick in the ON position? if so check around for cracks in the circuit board.....these can cause open circuits on the tracks causing problems too.
From the sounds of it your power amp circuit is working fine....so the output transistors are ok, these often fail and prevent the whole machine from functioning by operating the cut out relay......enjoy ;¬)
UPDATE and ADDITIONAL QUESTIONS:
BALANCE POTENTIOMETER: A friend of mine who repairs vintage AM radios came over yesterday and helped me troubleshoot the 4400 a little further. It appears my balance (potentiometer) slider could be the primary culprit. Using a non-conductive tool, if we press gently on the back of the balance slider it causes the speakers to alternate getting sound and at times when we push just right... both speakers work perfectly in stereo (the 4400 literally sounds perfect too). We were able to repeat this over and over by pushing on the back corners of the balance slider plate (which appears to have some play on one side). Additionally, my balance slider makes terrible pops and cracks when moving it from side to side. We think it makes sense to at least try to start by repairing/cleaning the balance slider.
I have seen Sanovar's blog where I think he removes the front plate of the 4400, but any instructions and tips would be helpful. Craig - you mentioned the service manual available on the site, correct? I have the large blow up of the wiring diagram that is several pages for the 4400. Is that the service manual (I thought it was, but wanted to confirm)? Or, is there an actual (more complete) service repair manual with written instructions?
Again, I would appreciate thoughts on how to repair the balance slider. I would imagine another alternative could be trying to order one from Beoparts.com. A final alternative, although not ideal or optimal would be to try bypassing the balance slider completely, since it is rarely used. I realize that isn't the right thing to do, but it could allow me to further troubleshoot.
Many thanks to Sanovar and Craig for your responses.
Marc
Good to hear you making progress.....it sounds like you have the correct service manual that is available on the site, its not the best as the diagrams are cut in half in some places but its suitable for most work.....be carefull with the Balance Potentiometer, its very different from the other slider pots.....it works in a "mysterious way" in my view, you cant replace this slider with one of the others.....Dillen tried to explain the operation of this component to me, its sort of counter intuitive in my mind........however he may be able to supply a replacement. Be careful if your sourcing one elswhere.
Craig
Update: I have been in touch with Dillen several times and unfortunately he wasn't able to locate a replacement balance potentiometer for my Beomaster 4400. If anyone might have a replacement balance potentiometer, please let me know or send me a direct message.
I removed the balance potentiometer this past weekend and did a little more testing. It seems to be reading the Ohms properly. I also applied DeOxit to the slider which improved its performance by 80-90%. In fact, after the application of DeOxit the Beomaster worked nearly flawlessly, without the loss of either channel. Every so often it would still act up, but this was only if I applied pressure to certain soldered tabs on the back of the unit. However, when I left it alone, it continued to work well. I will continue testing and using the Beomaster to make sure if it is working properly and... (assuming it is working well) then may close it back up and consider this a success.
If the problems with dropping one channel persist, I think I will need to take apart the balance potentiometer and look for further clues inside it. I appreciate the comments and assistance I have received.
Much thanks.
Good work.......keep an eye on ebay, you may find a damaged unit sold for spares/repair, I dont think I have come across one with a failed balance pot. Hopefully a member on here can help you out.
Regards Craig