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
Hello out all you fellow B&O enthusiasts :)
Thank you for this amazing board, and all there is to learn here
I post this, because I have this problem with my newly bought beomaster 5500.
Everything works flawlessly and the sound is absolutely amazing with my beovox 4702! But recently at has begun to degenerate the sound over a matter of 5-10 seconds, until an almost complete silence at the end. The degeneration at first sounds like a bit of distortion, then it gets worse and worse until it only sounds like a lazy dog farting (sorry for my language use here)
I can keep the degeneration away by adjusting the volume up and down 1 step at a time, adjusting balance, adjusting bass or treble setting. but the same moment I lay the remote to rest, the sound starts to degenerate.The exact same failure occur in the head-phones when plugged, and with the exact same sound-degeneration.
What I have done so far:
- Checked the cooling ribs, and they are fine. Not heated.
- I measured resistors in the amp-section, and they are within specs.
- I changed the 22nF and two 10nF caps placed at the power-supply to new ones.
- I have unmounted the accessplate under the beomaster and visually inspected everery soldering
None of this gave any results nor hints of what to do!
Could it be the mute-relay/phone-relay?
No-one has ever described this kind of failure in a beomaster, so I am in a bit of a confused state right now...
Please, any advice is welcome
Best regard, TheDane
Hi again,
Any ideas, guys?
You can rule out the mute relay by connecting your speakers to the Speaker 2 sockets, as these are not fed via the relay.
My only other suggestion is adjusting (or replacing) the idle current trimmers - but that is very much a guess based on reading about the problem of other 5500s!
Thank you for reply. Forgot to say, that the mute-relay works like a charm. Everything works, output 1 and 2 and also the headphones output. All input works aswll and also the radio and so on.
Only Thing is, that All output (speaker 1 and 2 and headphone) play sound which start out perfekt only to distort more and more, until it after appr. 10sec. sound like a farting dog, regardless which input/output I choose.
My Best guess is some caps om the preamp board, since I changed caps around the mainpower.
Any ideas?
Check the voltages around the preamp i.c's IC4(TC9177)and IC5(4558)particulary the +12/-12 lines(pins 4 and 8 on IC5)
The fact that both channel's are affected suggests something in common such as psu?
TC9177 could be faulty,I have seen this.Do you have any freezer spray to try,to see if temperature shifts will provoke a return to normal service?
C9 and C10 (near IC5)can be troublesome too.
Nick
Thanks solderon
C9 and C10 I have replaced as My first effort. I Will try following your instructions and reply when I'm done.
OK, Im back. I have cooled All ICs on the board to appr. - 30 degrees celcius, and the problem persists. I have noticed, that the backup battery may need to be replaced, because it cant memorise when unplugged from 240V. Can this be the problem? It would be Nice if you know, because otherwise I will need to re-cap the entire preamp soon, to be able to seek-n-destroy the fault.
Did the voltage checks around IC4 and 5 reveal anything?
Hi again
So I made a "diode-test" on every pin on each IC on the preamp. IC 1, 2, 3, 4 and 5 are in perfectly good and operational condition. But-but-but, IC nr. 6 (the TC9184p from Toshiba) was in poor condition indeed. L/R bass-control aswell as L/R treble-control aswell as some other pins seemed to be shorted, when connected to the GND-pin.
I think the TC9184p IC is burned, and this could explain the particular habit of the reciever, that when it plays parts of music, where there might be extra bass or treble, then the sound starts to deteriorate/degenerate even faster. Maybe...
I still cant figure out, why it plays so well the first 2-4 seconds (some times longer), when/if the IC is faulty (even when cooled down to minus 30 degress celcius).
Ok, I think that I will wait re-capping the preamp for now, because if the failure is the TC9184p IC, then I will not obtain better sound quality from my beomaster, before I have replaced the faulty IC either way.
Maybe I can find my sparepart in China somewhere, so it may take awhile before I can write you the result.
TheDane
Buying from China = risk of receiving counterfeit components.Ask Littlediode in the UK - or me.
Martin
Yes, Im not happy either to buy in China, but it seemed like the only way. All my searches led to China... until you wrote😊 can we PM on this board?
Re-capped the entire pre-amp board anyways. The problem is still there, but I already had a clue that the caps werent the problem, so HEY, COULD ANYBODY SEND ME A NEW TC9184P IC? if you please🤩😋
Sincerely your truly fan forever if you provide me with a Tc9184p IC
The Dane
TheDane: Re-capped the entire pre-amp board anyways. The problem is still there, but I already had a clue that the caps werent the problem, so HEY, COULD ANYBODY SEND ME A NEW TC9184P IC? if you please🤩😋 Sincerely your truly fan forever if you provide me with a Tc9184p IC The Dane
You have email.
Update: I have now replaced the tc9184 (thank you Martin) along with mcp8554 (ic3 and 5), I have Re-capped the entire preamp, Re-capped the powersupply-board completely, teste idel current (10mV both sides), cooling ribs fine, change backup battery.
Problem persists🙄
However, I may suspect the IC4 (Tc9177p) could be faulty, because I found out, that sometimes I can eliminate the problem for 2-3 minuts by turning loudness on and off. And a New fault (which relates to the Tc9177p) has occured, that the bm5500 always powers on at 42 volume and without loudness, No matter how often I set the memory otherwise.
COULD anyone provide me with the Toshiba chip TC9177p?
Best regards
Hi again, forum :)
So after waiting for appr. 2 month, I recieved the tc9177p loudness/volume IC, and replaced it... *drum sound*...............................NO CHANGE
Well, next component I will replace is now the TC9164N switch IC. Lets see, if that works.
Eventually, when I have replaced all components in the beomaster 5500, it may work
Otherwise, it may react to threats, such as the force of gravity (when held 10 meters over concrete pavement)
It's difficult to sit miles away and take a guess at what could possibly have gone wrong.It's the kind of case I would prefer to have on the workbench.
Yes, I know. Well, to be honest, I actually enjoy the process in locating the fault. I definately learn something in the process
Only yesterday, it was a bit annoying. I will post when I solve the problem, may it take years
Backup battery OK?
I'm intrigued by this problem,and you have certainly been patient with it so far sir!
The odd behaviour when you operate the loudness function,suggests that the problem is around 2IC4(TC9177)as that's where that function is carried out.Replacing the chip seems to have ruled out the most likely culprit though?
All three chips in the signal path there are "intelligent"and controlled by the main microprocessor of course,so you may have a problem there?You would need a sophisticated data analyser to interrogate the three data lines,but I wonder if you see any changes on those lines (pins 10,11,12)there between fault/no fault,just using a digital meter?
I use a simple(cheap) logic probe for this type of problem which sometimes throws up a clue too!
I come back to checking the +12/-12v supply voltages at IC4 also.Can you monitor the voltages (fault/no fault)using IC4 pin 9 as negative reference,rather than clipping neg meter lead to chassis?Perhaps there is a hair line crack in pcb,or dry joint at loom connector P22,pin2,or P5 pin 2?These are the grounding returns for the pcb2.
Keep at it,there will be a great sense of achievement when you crack this problem,and it will be another entry for all of us in the gremlin book too!
Yes, I replaced the battery with a new one.
I promise I will continue fighting, Nick
I have now replaced all IC on the preamp-PCB, but IC 1 and 2. I will replace the IC 1 during today, so lets see how that turns out. If it doesnt work, I will try your suggestions, because if I countinue replacing components in this rate, I will soon have replaced every single component in the BM5500
On the positive side is, that I have made no fault/human error during my replacing, which means that the BM5500 plays exactly as well and beautiful as when the fault occured, but I can still only operate it for max 10 seconds before the sound starts degenerating.
I will keep you updated outthere.
Muting signal dropping (TR203/TR403)?8V present and stabile?
It measures 6.58v stable. Is that within specs?
Where do you measure that?
Good point Martin.
Measure at the base of eg Tr203,and it should be about negative 7 volt for normal un-muted operation,and positive 0.7 volt when muting.
I did meassure that way :)
GOOD NEWS GENTLEMEN: PROBLEM SOLVED!!!
I replaced the tc9164n switch array IC, and tada....
Seems like there were a series of faults:
1) The TC9184p was faulty, causing the left and right side to un-allign everytime BM was shut off (fault gone)
2) The TC9177p was faulty, causing the loudness to distort sometimes, and turning off the BM unexpectedly (fault gone)
3) The TC9184n was faulty, causing the sound to generally distort after 5-10 seconds, especially when handling peak-bass signals.
Now I will concentrate on the next 2 faults:
BM always turning on at level 42 (ain´t the meening of life and a rock-band? :-D) and the humming PSU. I will start with the pcb at the front of the BM.
Gentlemen, thank you for your cooperation :)
Good new's indeed!!Break out the beer's?
There was a danger of teeth marks appearing along the edge of your workbench?
For humming,look at C8,9,11 and 15 on the main pcb 2.
Switch on memory prob's could be due as Martin suggests,to a failing battery,or reset cap 4C10(33uf)or simply a need to clear the RAM etc,as detailed in the manual?
You bet, Nick :D And yes, I think that the BM felt my rage and thought I might be a worthy opponent, so it eventually gave up, :D haha
By the way, the humming is coming for the PSU rubber-washers, which carry the weight of the coils, so I will replace them.
I already replaced the battery twice (seems to discharge extremely quick, so maybe I must look for a bleeding-spot somewhere). Even with a fresh out-of-the-box battery, it doesnt memorise the settings. I try some of your suggestions (ram, cap and so on....)
I will write, when I win the next battle(s)
Kind regardsLars
Hi again forum,
This morning I went to the basement and my workshop, where my newly overhauled beomaster 5500 was waiting for me to be powered up. I was in pure joy, because I was looking forward to listen to the beautiful sound of it paired with my s35 speakers, like I did yesterday.
Powered it on..... remote didnt work. Tried another beolink1000 and my beo4, but no response.
So, Im sorry to tell you, that a new problem has occured, as I cannot communicate with the BM in no usable way.
I will start with the caps, and work my way in on the pcb4, and I already ordered a couple of 8031 intel micro-processor chips, to play with. They will arrive in appr. 2 month, so I will be back then with my little adventure :-)
Kind regards
Backup battery OK?The Beomaster can do all kinds of strange things, if the backup battery is bad.It can also lose or mess up settings - also option settings (remote control = option 1).
Yes, its brandnew, measuring 3.05V. It all worked the whole day, yesterday, after my rapair on the preamp was overhaued and the new battery was installed. No problems. I also unplugged the BM, and plugged it again yesterday, and evereything worked (all but the memory-settings, which I planned on looking after today)
Do you think it could help replacing the 8031 IC? Or could it be the eeprom?
Hey Martin (and other capable tech-oracles )
While I am waiting for my spareparts for the microprocessorboard in the BM5500 to arrive, I wondered:
Question: If the change of backup battery messed up some things e.g. the option setting, so that settings switched to "no remote", will I then ever be able to recover the microprocessorboard (You know when I replaced caps, microprocessor i.a.)? And will I ever be able to use a beolink with this particular pcb4 again?
Or am I fooling myself here?
Humble questionsLars
Yes, the Beomaster still listens to remote commands, it just doesn't respond to anything but option changes.Press Sound-1-Store on the remote.
Ok, I Will try that, when i replaced some parts. For now, that trick doesnt work, either in stdby, nor powered on. Also the Tp4 doesnt work, the display only keeps flickering when shorted, which could indicate a worn out 33uf cap, or a fried microprocessor (I guess?)
What was the end of this story?
/Pindsen