ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Well......as requested by Peter from Minnesota I have decided to chronicle the events associated with this adventure in pictures for everyone's entertainment! In order not to Shanghai Peters post I have elected to start a new thread...so here goes, this is the unit pre surgery.
Unit with the top removed.....cleaned up a bit, but still needs more dust removing
Now a shot of the bottom, again some of the grime removed.....
The unit works quite well as is however on power up it issues some crackling noises, and when the sliders are operated it hisses somewhat....when the MONO switch is operated to select STEREO/MONO one channel drops in and out until eventually settling down. The transformer is mercifully quiet....didn't fancy the cost of replacing this with a toroid unit as Rudy did recently. I have cleaned things up a little and sprayed some servisol 10 onto what I believe is the right location for the selector switches and given them all a good workout...mechanically all seems well.
Having received a bag of bits from Dillen so I'm going to make a start on the Pre amp board
I have taken Rudy's advice and started on this board leaving it wired to the chassis as opposed to removing it, it's a little tricky and may well end in a wire or two ending up accidently removed due to pulling and tugging....but hey nothing ventured nothing gained!
It's been a long time since I last wielded a soldering iron and solder sucker, however a faint heart never won a fair lady (so I'm told) having cleaned the board up I picked an awkward one first, one with a wire connected on the underside as well as the printed circuit connection, and applied my long lost skill, to my astonishment it came away very easily and what's more the new one was happy to take its place, top left of pic.
and the underside......the joint looks reasonable and shows no signs of being dry, I'm quite pleased with that for a first attempt
Encouraged by this early success the soldering iron was re applied and in what seemed like a short time I had all the electrolytic cans installed without incident, and was actually enjoying myself.........
Being somewhat fearful of the trim pots I decided to tackle the Tantal capacitors next, I could use some advice on these trim pots (can they be reset using a multimeter? is there a procedure for this?) However this was where the wheels came off........the capacitors are rather small, the values printed on them is even smaller and at cracking on 62 my eyes are not what they where..so I will take the whole lot into the office where I work and get one of the "young bucks" to tell me which is which, bloody embarrassing. (to be continued)
Cheers Peter
This was not what I had envisioned when I bought this machine, It was an impulse purchase based on a memory of a similar amp a friend purchased back in the 70's.....I always envied him the system and seeing one so cheap was hard to resist.....a little digging on the internet brought me to this point, and quite frankly I am really enjoying this challenge
I made mine some years ago here the thread
Collecting Vintage B&O is not a hobby, its a lifestyle.
Ok....finished replacing all the capacitors on the Pre Amp, as was feared a couple of the connecting wires became detached in the process...as I expected given the age of the conductors and the repeated turning over and back for each de soldering and re soldering operation...still the photos I took will make this easy to correct. Still not clear on the way forward for all the pots though......
Well done so far. Please bin those old trimpots!
This is my Beocenter after restoration.
Jacques
Chartz
Thanks for your words of encouragement....I appreciate them, I would love to change the trim pots for the new ones Dillen sent me, thing is I'm unsure as to the procedure for setting up the replacement ones.....what procedure did you use to achieve this?
Craig: Thanks for your words of encouragement....I appreciate them, I would love to change the trim pots for the new ones Dillen sent me, thing is I'm unsure as to the procedure for setting up the replacement ones.....what procedure did you use to achieve this?
The name's Jacques. Dillen is Martin.
I simply used the procedure shown in the service manual, pure and simple. Have you got it?
It is available here but you have to be at least a Silver Member to be able to download it.
As for the ones on the preamp module, just preset them on the 12 o'clock position and adjust according to your sources, so that the volume remains the same on all sources.
Thank you......I do have a service manual and its very useful regarding the circuit diagrams/schematics but I find it a little light on the description side of things, however I'm sure I can adjust the Pre Amp trim Pots following your explanation above, that will be my next exercise.....thanks again for your help.
Craig: I do have a service manual and its very useful regarding the circuit diagrams/schematics but I find it a little light on the description side of things, however I'm sure I can adjust the Pre Amp trim Pots following your explanation above, that will be my next exercise.....thanks again for your help.
I do have a service manual and its very useful regarding the circuit diagrams/schematics but I find it a little light on the description side of things, however I'm sure I can adjust the Pre Amp trim Pots following your explanation above, that will be my next exercise.....thanks again for your help.
-sonavor
Sonavor....Thank you for that, the description of how to set up the DC idle voltage will be very useful once I have completed the re cap exercise, however your thread identifies resetting the left and right channel trimmers to the prescribed 12mv Idle voltage....what about the additional 4 trimmers commented on by Martin, did you replace those and reset them, the reason I would like to change these 4 extra ones is that the 6 I have just replaced in the Pre Amp almost fell apart when I removed them, this suggests the rest of the trimmers in the unit may well be in a similar condition.
Another worrying discovery has been this Capacitor on the Power Supply side......5000uF @ 80VDC looks like it has suffered a leak, seems to have been weeping resin of some sort, strange how its dripped over the connections though....could this be flux from the solder job on the capacitor, lots of connections onto this device and I imagine it would take a fair amount of heat to connect up......is it possibly flux? the capacitor looks the odd man out suggesting a replacement of either this one or its counterparts....any ideas on this?
I would change all 3 of them, the middle one is leaking
Craig: Sonavor....Thank you for that, the description of how to set up the DC idle voltage will be very useful once I have completed the re cap exercise, however your thread identifies resetting the left and right channel trimmers to the prescribed 12mv Idle voltage....what about the additional 4 trimmers commented on by Martin, did you replace those and reset them, the reason I would like to change these 4 extra ones is that the 6 I have just replaced in the Pre Amp almost fell apart when I removed them, this suggests the rest of the trimmers in the unit may well be in a similar condition.
That archived Beoworld thread was from 2011. It was one of my first projects as I was just catching the Beovirus and learning how to restore audio equipment. For that reason and the fact that my Beomaster 4000 trimmers were still operating, I didn't replace mine on that unit. If I go back in I will replace them. Maybe Martin can provide some instruction on readjusting the additional trimmers.-sonavor
When I have to replace trimmer where I dont know how to adjust them I measure them before desoldering and then after desoldering, I set the new ones to the same value, if the old trimmers are so bad that I cant measure, I set the new ones to the same visible adjustment, if posible. checking against another unit same type if available, or get a pic from a another member which shows the trimmers and adjustment position
Søren Mexico: I would change all 3 of them, the middle one is leaking
Good advice Soren......looking at these in the service manual the manufacturer is ELCO 5000uf 80vdc, does anyone know the best equivalent manufacturer and distributer for these three bad boys?
I used 4700 uF 100V
I used Nichicon capacitors for my power supply. Here is my archived pictures for that first Beomaster 4000 project (way back in 2011). The new caps were smaller in size so I installed rubber spacers.
This is the other side.
Ok.....3 off 4700uf 80v power supply caps on order, should be with me today. Meanwhile set about changing the trimmers on the mail board, on Martins advice I did one at a time starting with the left channel emmiter idle voltage adjustment, following removal and measurement of old trimmer I set the new one in place having adjusted it to the old trimmer value, and tweeked it to the prescribed 12mv....I then replaced each of the mystery trimmers using the same measurement and replace method above and checked the emitter idle volts after each activity and the voltage remained at 12mv.....so repeated the same on the right channel. This seems to have went well.
I'm starting to see the finishing post with only a couple of troublesome caps to winkle out and replace, the one behind the power switch and the two behind the transformer...and a handful of trimmers, along with the power supply caps and I will be done.
Steve of Soundsheavenly kindly let me have his old 4000 for a very reasonable price, which I received yesterday (thanks steve), this was intended to be a "doner" unit to be canibalised for parts as and when required, however if I can source a replacement rosewood outer enclosure I may well purchase another bag of "magic beans" from Martin and restore it......so if anyone knows of such an item gathering dust I would be interested ;¬)
Hi Jacques,
These are PIHER trimpots right? Would you mind sharing part # please? Are they rear adjust? I need that for my project.
Thanks!
chartz: Well done so far. Please bin those old trimpots! This is my Beocenter after restoration.
go mouser, Piher trimmer resistor, this one 100 ohms PTC10 is 10mm round, L is through hole screw driver adjustment, H is horizontal adjustment, check the data sheet , adjustable from both sides
Data sheet
Thanks a lot Soren!
I was sur they were PIHER but wasn't sure about the rest.
Thanks a lot!
Søren Mexico: go mouser, Piher trimmer resistor, this one 100 ohms PTC10 is 10mm round, L is through hole screw driver adjustment, H is horizontal adjustment, check the data sheet , adjustable from both sides PTC10LH01-101A2020
Well.....finally received the replacement power supply capacitors from HiFicollective, took them over a week to deliver and I was not impressed. However fitted them and boxed everything up.....I have to confess I gave up on the 2 capacitors hidden alongside the transformer...just couldn't get to them!.......hooked up an IPad to tape 1 and had a listen, sounds incredible! it's easy to see why people paid so much for this kit back in the day. I know this will sound a bit glib, but I feel as if I have joined some sort of exclusive club having completed this....and I have enjoyed every minute of it ;¬)
chartz:You did an excellent job and I am glad you should be rewarded with great sound! Now there is no turning back - you have contracted the Beovirus.
Now there is no turning back - you have contracted the Beovirus.
Agree with Jacques, enjoy
Hmmmmmmm............that may be the reason I've just bought another unit from eBay! Will be needing some parts from Martin shortly ;-)