June 14, 2022 at 6:51 pm #5884
Just a few weeks ago, came across a Craigslist ad here in California for a B&O MX5500, including the motorized stand and the VCR for $500. I’m really into vintage TVs and retro gaming, so when I saw the ad I was definitely excited. My console RCA had just failed, and I was looking for an interesting replacement.
When I came to check it out, I found that it had been stored in a landscaping company’s shed for the past 15 years. We couldn’t get it to power on, and the remote was missing, so the seller gave it to me for free.
I got it home in one piece, cleaned it up, and found that I could get it into standby mode with the power button in the front, but the step button did nothing.
So, it sat in the spare room, waiting for a remote. I found a Beolink 5000 for dirt cheap, sold as not working, and that arrived just yesterday.
Of course, it came in pieces, but after soldering the battery compartment back together and cleaning the contacts, we got it to output a signal! Hitting the TV button caused the TV to turn off immediately. The next step is opening up the system, and starting with the power supply, testing and replacing components.
It’s in pretty decent shape, so hopefully I won’t need to replace every single cap. I’ll document the progress, and hopefully, add some interesting information into the public record to help out anyone else trying to get their 32 year old TV working again.June 15, 2022 at 3:50 pm #5900Die_BogenerBRONZE Member
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Interesting project 🙂
This is a US MX5500?
The European modell is complete different.
June 15, 2022 at 4:09 pm #5903
- This reply was modified 2 weeks, 5 days ago by Die_Bogener.
Oh wow, that is totally different. Yes, it’s the US model.June 22, 2022 at 6:53 pm #6078
Yesterday’s project was removing all the individual boards for full capacitor inspection. The service manual shows all the boards in this map, and to make it make sense, they have swung out the boards shown on the right as they are all connected together on a rail that unclips from the back.
The only tricky part in removing the boards was that PCB 2 has an RF cable soldered to its connection, so you just need to heat it gently and pull it off with some needle nose pliers. The rest are just connected by an incredible hydra of wiring, but thankfully, each connector is labeled with the port it connects to, so as long as you go in order, reassembly shouldn’t be too difficult.
PCB 1 – Power Supply and Deflection
This pic actually shows PCB 1 – the main board, PCB 12 – Switch mode power supply, and PCB 10 – Video Output, as they are all interconnected. When I removed the Anode cap, I got no spark at all from a grounded screwdriver, so it’s likely that we aren’t getting power to the flyback at all. The main fuse is intact and shows continuity, and no obviously bad caps present themselves, so we may have a dead transistor or maybe even the flyback. The caps will all get replaced regardless, and then further testing can progress.
PCB 2 – Tuner, IF and Sound Processing
Here’s where I find the first obviously bad cap. C4030, in the middle above the two transformers has a rusty top.
PCB 4 – System Control
PCB 4, 6 and 7 are all screwed and clipped together. There is an orange wire that goes between them that has to be desoldered.
System control contains the CPU, BIOS and the rest of the chipset, all connected to a 3.6V battery that miraculously is not dead and leaky, but also is still running at 3.3V! Quite a few bad caps in here, especially in the little processor village. On the opposite side of this board is a steel cover that has been soldered, so that will need to be desoldered to reach bottom of the board for the cap replacement.
PCB 6 – AV Switch
The only thing to address on this one will be to make sure the discoloration at the top is not trace corrosion. If it is, some bodge wire will need to be run after the caps are replaced.
PCB 7 – Video Processing
This little guy attaches to the top of PCB 4 & 6, and only has a few caps.
PCB 9 – Standby Power Supply
Because the TV turns on into standby mode, it’s assumed that this guy is fine. The fuses check out, and the transistor passes diags as well.
PCB 12 – Switch Mode Power Supply
This is the back of the PCB, attached to PCB 1.
A few PCB pics were omitted, like the power and step button board, since there’s really nothing to it, but it was tested for continuity and confirmed working. I don’t have a pic of PCB 5 – IR Receiver, because I forgot it at home. Visually, it looks fine, and just has 3 caps.
The next step is to make a capacitor map based on the pics here, put an order in to mouser, and see where we’re at after that.
Coming soon will be scans of the American Service Manual and the regular manual, unless you guys have that stuff already.
Also, if anyone has any advice or sees something I don’t see, by all means, please let me know. I’ve repaired a few arcade game PCBs and some old consoles, but there’s a lot here that I’m learning for the first time, so any tips would be appreciated.June 28, 2022 at 9:53 pm #6268
Finally finished the cap map for all the PCBs. Caps have been ordered, and I’ll be able to get started replacing all these little guys next week. Here are the maps for your enjoyment.
Still working on scanning the service manuals. Will get those uploaded soon.July 5, 2022 at 2:50 am #6529jvezinaBeoworld Member
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I owned a US MX 5000 (the previous model) for about 30 years. For the time, it had an excellent picture. Unfortunately, I damaged it when reassembling it by accidentally dropping a screwdriver on the case a few years ago. The picture tube shorted. It required another massive capacitor replacement, so it was not catastrophic.
In your case, the first thing is to replace all capacitors branded Rubycon. There may be 100 or more. You should also get an ESR meter to check all remaining ones. If the set was stored for 15 years, expect to see most of the capacitors dried.
On PCB 6 be very careful when removing capacitors. The black Rubycon caps leaks and damage the traces on the component side.
I have prepared a long time ago a repair guide for the MX 5000. It should be on the service manual section.
Capacitor replacement is also required for the VX 5000.
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