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Glitch, I do have an oscilloscope, will try to probe the signals, not sure what to look for though. Tested all of the grounds, all good. At this point, it might be best if i find a proper remote
Checking the DATA should be pretty straightforward (if you want to poke around while waiting for your remote to arrive). The diagrams below are from the cTC9177P datasheet.
Connect the scope to DATA, CK, and STROBE signals and “single trigger” the scope off the STROBE.
Once you have a data packet captured it can be decoded with the info above. There is also a more detailed description in the datasheet. It looks like two DATA packets will need to be captured, one for the L command and one for the R command, to debug possible balance issues.
Glitch
Here is a picture of the connections on a BG8002.
Hope this helps (and you don’t have to deal with the same glue on the solder).
Glitch
I’m so glad you discovered a way around using a Dremel. That will same a bunch of time and effort.
It also avoids creating metal dust around the motor magnet. This kind of contamination is very difficult to remove.
Can you go into detail of what you did for your performance measurements?
I tried many different things. I did the obvious stuff like measuring motor current. I also added an encoder to measure motor speed. The brass encoder adapter is also machined to attach to the capstan shaft. For the motor vibration, the simplest setup was a mechanics stethoscope coupled to a microphone.
The data from the various sensors is logged and post-processed offline. I tried to run a variety of experiments, like comparing the “drop of oil” method against the “vacuum oiling” method. Unfortunately, my number of samples is statistically insignificant so it is hard to make truly conclusive statements without caveats.
I can go into a lot more detail, but it would be helpful if you had specific questions. It is hard to provide the appropriate level of detail without understanding someone’s interests and technical background.
Glitch
I ended up buying a couple of dead Beocord 8000’s. I want to experiment on something appropriate before tearing into my beloved Beocord 9000. I learned quite a bit in the process. I won’t go into the whole story since there are a lot of details. However, I thought that people might be interested in a few highlights…
1) I found it is not necessary to do any Dremeling to get the motor lid off. I used a pair of snap ring expansion pliers to pop off the lid. The lid can be pressed back on without leaving any indication that work was done.
2) My motors were the same as in sonavor’s pictures. The motors themselves were surprisingly easy to take apart. The only things to be careful with are to not break the plastic clips holding the motor together and to pay attention to the white plastic spacer on the armature shaft. The motor tachometer is nothing like a Beogram 400x motor. The wire arrangement is such that one would have to try hard to break the thin wires.
3) The motor bearings are not like the Beogram bearings. They are different sizes. The bearing retention is similar. Making a tool for crimping the bearing retainer is easier than what is shown on the Beolover site. A simple piece of wooden dowel will work.
4) The windings in one of the motors were burnt up. Rewinding the armature is possible.
5) Bearing cleaning in preparation for vacuum oiling isn’t critical. I tried to thoroughly clean one set of bearings and skipped the prep work on another. Either way, the before/after of the oil bath was the same. I attribute the change of color to the old amber colored oil coming out of the bearings.
6) I ran a some experiments to refine the process for vacuum oiling. This is beyond what I would want to describe in this post. One thing that I will mention is that I’m skeptical about being able to a good job at vacuum oiling without a proper vacuum pump.
7) I measured the performance of the motors using several methods. The plots above are FFT’s of the motor vibration. The motor in the first plot was obviously noisy. The motor in the second plot was the one with the burnt armature, but was quiet. The third plot was from my BC9000 which started in very good condition. The light blue is before, the dark blue is after vacuum oiling. All three motors are now performing more similarly. I have a more data, but I assume that I’m the only one that geeks out on data analysis.
8) I also vacuum oiled other sintered bearings from the tape transport. I weighed all the bearings before and after to get a feel for how much oil that I added to the bearings. There were things that I found very interesting in the data analysis, but the bottom line is that a well done vacuum oiling is worth the effort. …but you already knew that!
I was able to repair both of the broken Beocord 8000’s and get them 100% working. I did the normal stuff like replace a few bad caps, new belts, rubber tires, LED display rebuild, reflowed solder joints, etc. Now the hard part… figuring out what to do with extra tape players ;-).
Glitch
