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
Hi,
My MCP 5000 had been working fine till recently.
After using the last set of batteries for a few months, was time to change them as per routine.
With the new batteries, the MCP would only work properly after insertion of the new batteries. Subsequent use of the MCP will not work. The above would be repeated if I wanted to use the BM5000???
Initially though the batteries maybe a bad batch, so bought a few set of replacements and it was the same issue every time.
Has anyone experience the same?
Thank you in-advance for any assistance in the matter!
Dom
2x BeoSystem 3, BeoSystem 5000, BeoSystem 6500, 2x BeoMaster 7000, 2 pair of BeoLab Penta mk2, AV 7000, Beolab 4000, BeoSound 4000, Playmaker, BeoLab 2500, S-45, S-45.2, RL-140, CX-50, C-75, 3x CX-100, 3x MCL2 link rooms, 3x Beolab 2000, M3, P2, Earset, A8 earphones, A3, 2x 4001 relay, H3, H3 ANC, H6, 2014 Audi S5 with B&O sound, and ambio
I'm not sure I understood the problem statement... you mean that new batteries only last for a short while, or that you need to remove the batteries and reinsert them to make the MCP work again?
--mika
Have you checked for a bad capacitor in the MCP?
Jacques
Yes need to remove the batteries and re-insert them to make the MCP usable. Need to do so more or less for every command to be entered via the MCP 5000
Only a large Philips cap near the IC, in the MCP 5000. Have not substitue it yet but tested via connecting another cap of equal value in-parallel and the same issue still there.
hew128:Have not substitue it yet but tested via connecting another cap of equal value in-parallel and the same issue still there.
That's not a conclusive test, if the old cap is very leaky and loading the circuit, adding another in parallel isn't going to improve the situation.
I never worked on an MCP 5000 (mine worked fine for the duration I had it), but this sounds like a power supply failure, or a problem in the reset circuitry of the processor, which could be caused by a tired cap... There's a good schematic in the service manual, but I'm afraid I'm not able to start guessing over it without having the unit at hand. C30 and C34 seem like the most suspect candidates. Or just a plain old dry solder.
Better start with the simple things, like does the battery holder make good contact? Don't just believe how it looks, put a multimeter on the circuit board where the wires enter and see if the voltage remains stable when the MCP lights up. The next point to check will be the stabilized +4.75V rail after the power supply. The power supply circuit is rather complex because it has very little headroom to stabilize 4.75V from just four battery cells.
I have MCP behaving exactly the same. Have changed caps, resolder and everything I can think of, no solution. If I reset uP manually, it works for a while until it goes stand-by, but never wakes up, only with reset or batterys off. So maybe there is something in circuity that raises it from sleep.
Really annoying. Hope someone knows the answer to this
blah-blah and photographs as needed
Here's an even better one!
After posting this on the forum. I left the batteries in the MCP w/o the battery cover. Initially the issue persists.
Left for it for about a week and decided to depress the buttons when I saw the replies to my original post.
Eureka, it works again???
Am theorising if the new battery's are too "strong" for it as I measured over 6V during the initial dis&re-assembly of the MCP??? Or maybe it will decide to go into a coma again when I next change the batteries ...
Lucky you Mine have been lying around self for a while now, and I do not have Any attempt to pick it up for a try
Hi.
Did it continue to work, or did it only last a shot time?I've got the same problem, the previously owner said he used it fine for a whole evening, just a couple of days before i purchased it, which was yesterday. I've checked the battery supply and the connection is fine, but I'm also measuring over 6 volts. Did you find out how many volts it should have?
Best regards Rune Rasmussen
I had the same issue with one of my Master Control Panels. I wasn't able to fix it so ended up buying another one which worked fine.
The over voltage idea is interesting...
Lee
Hello,
So did anyone reach any satisfying conclusions with this kind of problem on the MCP 5000? I have the same issues.
Reading 6V+ off the power supply which drops to 3.9V when buttons are pressed.Some corrosion on the lower half of the underside of the main board, but not to bad. Some dry-looking solder joints too. I've not attempted re-soldering just yet.
Looking to see if anyone has anything further to help steer me in the right direction.
Thanks in advance,
Julian
Solved! With qualifications, and a little help from a German website.
I just repaired a MCP5000 with this issue.. Works OK immediately after batteries are installed, but after the processor goes to sleep in a few seconds, it would not re-awaken.
It seems that the MCP5000 processor stops "strobing" the keyboard when it sleeps. Instead, it applies a set voltage to the keyboard through resistor R149, and detects a keypress with this voltage. If this voltage is too low, no keypress is detected, and the system does not wake up.
This, by the way, is not mentioned in the repair manual, but it does offer an excellent schematic of the MCP5000.
It seems that the circuit boards used in the MCP 5000, especially the keypad switch boards, absorb moisture and deteriorate. This causes discoloration of the boards, and the copper traces to corrode under the solder mask coating, leading to circuit-to-circuit bridging. This is also accompanied by a pungent vinegar / burnt smell.
Steps taken:
Replaced the electrolytic capacitors, with no effect. (some are inside the metal "can".)
Set the regulated voltage to 4.75v, according to the service manual.
Verified the system works after applying a positive-going pulse to reset pin of IC1 (pin 7), This simulates installing batteries.
Verified the oscillator is running happily at around 400khz, both with the system running and sleeping.
Noted that resistor R149 had a significant voltage drop across it. This seemed odd for a system in sleep mode. This is what lead me to the German-language thread, where someone else had noted it, combined with the pungent smell inside the MCP5000, similar to a vinegar or burning smell. Their deduction was that the solder mask on the circuit boards, particularly the switch contact boards was causing current flow through the keyboard. My deduction is that the solder mask is OK, but the board itself is deteriorated.
De-soldered and removed the two ribbon cables connecting the main circuit board from the keyboard switch circuit boards. Checking for resistance found the culprit - 100k ohms resistance between two terminals, which was "jittery" and varied if the ohmmeter leads were reversed.
Removed both keyboard circuit boards (don't lose the keys!) and separated them by desoldering the three ribbon cables joining them together. A further continuity check revealed the circuit-to-circuit short to be in the lower board.
Removed the protective black plastic tape from the keypad switches, (don't lose the switch contacts!) and inspected the circuit traces under the solder mask coating by shining a powerful flashlight through the circuit board from underneath... There it was, a big dark spot near the center of the board bridging 3-4 circuit traces. Oddly, this was not near any of the dark brown discolorations of the board itself.
OK, at this point, I have a defunct 35-year old circuit board made of unobtainium. How to best repair it?
Here are the steps I took to repair it. Please note that this risks completely destroying the irreplaceable circuit board!!!
1- Cleaned the board with 99% isopropyl alcohol, allowing to dry. Also cleaned the non-shorted upper board, after removing the protective tape.
2- carefully abraded the solder mask coating from the affected area with a brass wire brush in a dremel tool (high speed handheld grinder). this revealed 2 corroded circuit traces. I continued removing the solder mask from the area, exposing 4 traces, and stripping it back until reaching non-corroded areas of all traces. The bare area is maybe 15mm wide and 10mm high.
3- with the corroded traces exposed, the dark corrosion and deteriorated circuit board bridging the traces is visible. Keeping the powerful flashlight underneath the board, I scraped out the damage between traces with a hobby knife, until all the bridging was gone. Some had extended deep into the board material, perhaps 0.2mm-0.4mm. A continuity check at this point reveals that the circuit-to-circuit short is gene.
4- with the damaged area exposed to atmosphere. I placed the stinky, discolored and deteriorated lower keyboard circuit board in an oven set to 120C for a couple of hours. My though here is to drive off any remaining moisture and kill any growing organisms within the board material.
5- After baking the damaged board, I sealed the repaired are with a few coats of nail polish which I had previously tested for continuity when dry. (make sure not to use conductive paint!) After the nail polish is dry, I re-checked continuity, still at infinite ohms. (OK)
6- as a precaution, I also baked the upper keyboard circuit board for an hour at 100C. It also has discolored spots and smells bad. The main circuit board also shows signs of deterioration, but since it is loaded with electronics, I only cleaned it off with spray flux cleaner,
7- reassemble, and viola! MCP5000 now wakes from sleep upon keypress!
Caveat:
As all three circuit boards are deteriorated, I can expect future further degradation and failures. But for now, the poor battered MCP5000 is back in operation!
Good luck with yours,
Keri
¡No entiendo Español!
NEIN! Nicht Versteh!
Я немного говорю по-русскии но не очень хорошо... и
I'm not very good at English either! Maybe someday I'll find a language I'm good at?
Very clever! Impressed! Luckily my mcp5500 has never given problems but if it does...
Thanks for taking the time to post this.
Peter