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Upgrading a Beogram TX-2 to Beogram 7000 specification
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I took delivery of another late-model PCB1 control board (with the discreet Play/Off hookup), so I decided to replace PCB1 on my 5005, and do a bit more analysis of this late-model feature.
This additional feature basically provides continuity over the component range, as compared to the earlier Beograms where the button was a mere extension of the "Play/Repeat" button located inside of the cover. The original Datalink status sent by the original Beogram 5005 thru 5500 was "Play/Repeat" is a single Datalink command "Beogram.Status.Playing" when first pressed. Subsequent presses of the "Play" button put the Beogram in 'Repeat' mode, and were handled without sending any additional information back to the Beomaster. In fact, this was a missed opportunity by B&O to send a 'Status.Counter' to update to the MCP on any 'Status' request, showing the number of queued repeats - for example, the Beogram could easily have been coded to send "Beogram.Status.Counter 'C 03' ", reporting back to the MCP screen the number of record plays remaining - a trivial code addition which could have provided some visual feedback to the listener as to the number of repeats remaining.
Conversely on the late PCB1 board, the pressing of the front button while the Beogram is playing sends two Datalink commands: "Beogram.Status.Standby", followed a few seconds later by "Beogram.Status.Stopped" when the platter stops spinning. Sending the Standby command will cause the Beomaster to act accordingly.
If I ever find the time to create a replacement microcontroller for the Beogram, I'd like to add a feature-set which provides more status reporting to the listener. Repeats, song count (based on 3 seconds of silence, for example), 33/45 selection via the MCP, and things of this nature would make excellent upgrades to the base system.
This additional feature basically provides continuity over the component range, as compared to the earlier Beograms where the button was a mere extension of the "Play/Repeat" button located inside of the cover. The original Datalink status sent by the original Beogram 5005 thru 5500 was "Play/Repeat" is a single Datalink command "Beogram.Status.Playing" when first pressed. Subsequent presses of the "Play" button put the Beogram in 'Repeat' mode, and were handled without sending any additional information back to the Beomaster. In fact, this was a missed opportunity by B&O to send a 'Status.Counter' to update to the MCP on any 'Status' request, showing the number of queued repeats - for example, the Beogram could easily have been coded to send "Beogram.Status.Counter 'C 03' ", reporting back to the MCP screen the number of record plays remaining - a trivial code addition which could have provided some visual feedback to the listener as to the number of repeats remaining.
Conversely on the late PCB1 board, the pressing of the front button while the Beogram is playing sends two Datalink commands: "Beogram.Status.Standby", followed a few seconds later by "Beogram.Status.Stopped" when the platter stops spinning. Sending the Standby command will cause the Beomaster to act accordingly.
If I ever find the time to create a replacement microcontroller for the Beogram, I'd like to add a feature-set which provides more status reporting to the listener. Repeats, song count (based on 3 seconds of silence, for example), 33/45 selection via the MCP, and things of this nature would make excellent upgrades to the base system.
Just to document the needed changes to add discreet "Play/Off" function to an early Beogram, these are the steps.
The "Play" button is fixed in place with a black bracket, which holds the button in the appropriate place on the front panel.
It's wired directly to the "Play" button on the top surface, so it only can perform the same function as the "Play" button under the cover. The large PCB3 is removed by carefully moving the 4 black tabs that hold it firmly in place, and wiggling the PCB up and back out of its mount.
I was surprised to see that these buttons were exposed - typically, they are covered with black tape to help hold them in place (and probably also to keep moisture and debris out from them - they are a slightly cheap design, and can easily be made inoperable with a bit of contaminant). I fixed the vulnerability by adding a bit of electricians tape myself. Next, I severed the connections of the small PCB, and added two additional wires to it, per the new design specification.
Last, I ran these new wires back through the cover, using the same clamps used for the existing wires. A bit of trimming later, and everything was hooked up per the late-model specifications. A fairly straightforward modification.
I've elected to not add an RIAA to this unit, as I need something I can use to test with earlier variants of Beomasters with built-in RIAA. So this unit is upgraded as much as it can be, and ready for work.
I'm restoring another 5005, and I elected to try another technique for retrofitting a TR11 BC547 transistor into the datalink path of PCB1.
I started with a new BC547 transistor I bought from Mouser. When looking at the flat face, the pins from left to right arre (C) Collector (B) Base and (E) Emitter.
I unsoldered R42 on the side nearest the I/O cable, and drilled a small hole 2-3cm from it, taking care not to pierce any existing traces, or the adjacent R45 resistor.
Next, I took the BC547 and placed the (C) pin through the vacant R42 hole, and the (B) pin through the newly drilled hole. I bent the (E) pin towards the R42 resistor.
Turning the board over, I unsoldered the jumper adjacent to R30, and squeezed a 10K resistor through the hole. Theere was just enough room to have both the resistor and jumper in the same hole, which I resoldered in order to make a permanent connection.
I covered the resistor lead with heat shrink, and soldered the end to the (E) pin of TR11. This heat shrink is just a security blanket to prevent future shorts on the board.
I finished with attaching the TR11 (E) pin to the R42 resistor, and covered the end with a piece of heat shrink. IMHO, this looks much nicer than the other solution.
Impressive work I must say 😊
Im sorry I was not paying attention in my electronics class in school 😏
Im sorry I was not paying attention in my electronics class in school 😏
Location: Sweden
My B&O Icons:
Another day, another upgrade. This time I'm taking a Beogram 3000 and upgrading it to Beogram 4500 specification. I got this unit because I thought it would fit in stylistically better with the black 7000 series that I have. My first thought was to simply replace the 5500 shell with the 3000 shell, but I decided to leave well enough alone - the 5500 had the latest motherboard with the discrete standby function, which the 3000/4500 could not make use of, because it lacks a front face.
I started with the chassis. Some new feet and touch-up paint to cover up the deep scratches.
I'm using graphite-infused black paint, in order to keep all areas of the base conductive. It's not a perfect match, but IMHO better than exposed bare metal. My hope was to eventually use this conductive paint as a new semi-black coating for the platter, but that will be a bit later when I've experimented a bit with it.
This go-around, I thought I'd take a stab at creating a plug for the RIAA right on PCB2, like the original. After checking all the caps and diodes for function, I drilled 2 small holes with a 1.0mm bit using a hand drill. It's a tight squeeze on a US-Spec power supply, due to the long fuse which occupies the space normally reserved for the plug. Thankfully theres an adequate space over the PCB label, where there are no traces to damage.
I added a dab of crazy glue to the backside of the plug, and placed it in the hole. So far, so good!
The rear side required 2 wires. I decided to stick to my convention of keeping the red wire at 12V, and the black wire at 25V.
After checking all connections for connectivity and shorts, I was ready to insert the power supply back into the chassis. I replaced the regulator IC for good measure, as the installed one was reading 11.7 volts - it probably would have worked fine, but the new one was bang-on 12V. Although I have a few NOS barrel capacitors, I elected to keep the original in place, as it was reading a healthy 1100uF / 0.47 ISR, with no signs of leaking. Another step complete.
I also came up with a better version of the motherboard upgrade for early 5005 and TX-2 boards to prepare them for Datalink use, by placing the 10K resistor in the same location that it appears on the 5500 and newer boards.
I first drilled a hole for the resistor.
Next, I placed the resistor and transistor in their proper locations, taking care to leave the legs long, so I could connect them later under the board. I didn't make any changes to the transistor placement from the last iteration.
Last, I connected the legs of the resistor and the transistor base, followed by a protective heat shrink cover to prevent shorting.
Here's a solution that no one really was asking a question about. The tiny tab that holds the thread ends which move the tone arm sled tends to snap when things bind up. This morning I took a stab at a remedy.
For starters, the bottom of the sled appears to contain an extra tab that does not appear to be used for anything, so my first thought was to carefully slice this off and find a way to graft it in place of the missing one.
I decided to forego that option, and opted instead to head to the hardware store to purchase a few 1.6mm bolts with nuts. This would provide a bit more holding surface and friction. The idea is to place the string and spring in place, and thread the nut onto the rod as a "keeper", which would prevent the string from falling off. This new plan of action involved generously epoxying over the holes, and drilling a pilot hole I could thread with the bolt, which I thought would be stiff enough to provide a robust holding point to the thread. Alas, laziness prevailed- I went with super glue, and simply positioned the bolts during the curing phase.
We'll see if this provides enough durability to create a lasting solution to the problem.
I have a black Beosystem 7000 which lacked a turntable, and instead of spending $1000+ to find a matching Beogram 7000, I set about retrofitting a old BG 3000 to match the look, using available parts I could buy online.
The original 3000 lid was cracked, so I opted for a clear replacement from DK Sound Parts, along with a black metal decorative top plate. In the end, IMHO it's an 'ok' match with the BM7000, but not perfect - I give it a 7/10. Perhaps if I had selected the dark grey lid option, it would bland a bit better, especially since the platter is not black.
Here are my costs, including delivery:
Beogram 3000 - $75
RIAA card - $125
4500 lid - $120
Top Plate - $20
Misc parts - $40
----------------------
Total: $380
I think I got a bit fortunate on the purchase price of the BG 3000, so I'd venture to say that a more typical budget would be in the $450-500 range. In the end, I'm pleased with the results, although I'm not sure I'm really saving all that much in comparison to buying a good-condition stock 4500. All that being said, I'm a bit of a purist, so if a black Beogram 7000 comes up for less than $1000 delivered, I'll probably still look to acquire it.
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