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yachadm wrote:

I do know that as long as the machine is used every now and then, causing the belts to expand and contract, that reduces the chances of “gooing”.

I’d like to learn more about this. Can you provide any further details about why this would be the case?

I’ve always assumed that the belts degrade due to a process (like oxidation) that either causes the polymers to break down (into “goo”) or form a “new/modified” substance that is less elastic (cracked, brittle belts).

My motivation for having a better understanding of this is to help with a long term preservation plan for the equipment. For example, if it is inevitable that belts will turn to “goo”, it might be prudent to remove them before placing the equipment into storage. An analogy would be removing the alkaline batteries from a vintage toy, draining the gas from an antique car that won’t be driven for a while (or the swapping out the foam inside certain active speakers). I recently pulled apart a vintage computer where the CMOS battery leaked and corroded the nearby circuit board traces into green dust. Had I foreseen this, I’d still have a working computer.

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Beobuddy wrote:

The pentagon form would give the option to use 2 penta’s at the both sides of the original Penta

Something like this?

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Check out MiniDSP.com. They likely sell something that would get you to where you want to go. You may find out that when you consider the cost of the speaker equipment (DSP’s, amps, new enclosures, etc.), the necessary test equipment, and the value of your time, that it would be cheaper to just buy the ’50’s  ;-). However, I suspect that, in this case, the journey is more important than the destination.

Have you considered doing the project in stages (with each stage having very specific goals)? For example, you could multi-amp and DSP crossover one set of Pentas to make them ultra-linear frequency response. You could also leave the Pentas untouched and do an 6-speaker room correction. At some point you would combine all that you learned in the earlier stages.

I’m looking forward to hearing about whatever you decide to do.

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I’m certainly not questioning the suitability or performance of the beoparts-shop (now: Danish Sound Parts) belts. My assumption is that they are the highest quality part that is available.

My question was related to a design choice. Material science has made great progress in the decades between when the belts were originally designed and now. The new belts could have been specified using the original rubber formulation or something newer. I wouldn’t consider either choice to be “wrong”. I’m just curious about which choice was made.

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• This reply was modified 1 month, 1 week ago by Dillen.

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chartz wrote:

I did mine ten years ago and it just needed a new set of belts and a drop of oil here and there, always a good idea while it’s in bits and pieces.

How is it working now?  Was the “drop of oil” added to the sintered bearings?

chartz wrote:

The motor does look similar to the Beocord 6000/8000 one but is it the same? How are the two speeds obtained?

Two speeds could be obtained by varying the voltage to the motor.

hcraig244 wrote:

It’s something I will do when the time comes more out of interest than anything else…

It seems like the tricky part is figuring out how long it can be run before any permanent damage is done. Wouldn’t it be “too late” if the issue was found during some sort of performance testing?

sonavor wrote:

If you decide to go that route I would be interested in hearing your results.

My plan is to buy another Beocord to experiment with. BC800x’s that need some TLC are readily available. I’d rather make any mistakes on a something that is already broken and less rare/collectable than the BC9000. I’ll post results when I make progress.

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I just finished a refresh of this Beomaster 4000. This receiver was a good example of why one shouldn’t just grab a spray can of “contact cleaner/lubricant” and spray indeterminately to fix a noisy potentiometer or switch. Whatever product the previous owner used seeped everywhere inside the receiver then turned into a hard waxy substance. Fortunately, I was able to fully disassemble the receiver and clean the “gunk” out of the chassis, sliders and switches.

My plan for the receiver is to pair it with four Braun speakers from the same era. Braun speakers are actually somewhat rare in the US. I like to assemble systems with a theme. This will be my “70’s Euro-system”. I’m guessing that most of the forum members would just call it a “70’s system”   😉

I’m looking forward to experiencing the Ambiophonic feature. Does anyone have suggestions for era-appropriate recordings that highlight this feature?

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sonavor wrote:

I found some more pictures where I took a Beocord 8002 motor assembly apart and photographed it next to the Beocord 9000.

Thank you very much for posting the pictures. Based on your pictures and some other information posted by Beolover, it looks like this is a reasonably straightforward job.

I wonder if any of the Beogram bearings sold at beoparts-shop are the same size? The motors certainly look similar. Has anyone measured/checked this already? Obviously, new bearings would be better than refurbished bearings if they are available.

quattttro wrote:

Here is my pressure lubricator, if you need some ideas.

Here is what I came up with using what I had on-hand.

I can pull a very good vacuum and hold it for a few days. The blue hose goes to a HVAC vacuum pump. I plan to heat the bearings and oil. I don’t know if this will make a significant difference, but it couldn’t hurt.

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sonavor wrote:

Option 2, running the motor by continually trying to keep it wet doesn’t sound like a good idea to me.

sonavor wrote:

I haven’t done anything with those parts other than treating them with some synthetic oil.

We may be talking about the same process here. What I’m calling “wet” simply means adding a small amount of oil to the shaft/bearing interface. “Dry” would be relying exclusively on the oil that is impregnated in the bearing. I would consider a mechanism that is maintained by adding oil to a felt washer to be “wet”.

Many say that the downside to running a bearing “wet” is that it attracts contaminants that cause extra bearing wear. This might be a necessary evil compared to running a bearing with a worn/damaged surface that might not be getting oil from the reserves in the bearing. Neither choice is appealing.

I do have a concern about damaging the motor when disassembling it. For me, it is a hard decision because the motor seems to be operating very well. I try to avoid the self-inflicted injuries/problems whenever possible. Also, I try to not leave “technician tracks” when I work on something.

The motor cover is held in place with three bent tabs. I’ve tried to remove it, but it quickly became apparent that I wouldn’t be able to do so without damaging the case.

I haven’t seen any videos/pictures of this particular motor being disassembled. My next thought is to buy a “parts machine” to experiment on.

Do the Beocord 8000’s use the same motor as the the BC9000?

You make an interesting point about testing the motor. I’ll have to think about how to do this. I have a precision encoder left over from a robotics project that might be perfect for this.

You talked about testing your motor rebuilds. Have you gone back from time to time to check to see how well your rebuilds are aging?

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sonavor wrote:

I was thinking motor bearings as I read it but I see that you are talking about the bearings on the capstan bearing.

I was considering ALL of the sintered bearings, but didn’t convey it very well. The first part of the question had to do with the best way, in general, to lubricate the bearings. I planned to ask a follow-up question on how to get the bearings out of the motor if it was deemed necessary. I also referred to the clutch bearings incorrectly as “idler shaft” bearings.

I am hoping to learn about other’s experience with various lubrication methods. I suspect that many of these machines were serviced/restored 15, or so, years ago. By now it should be clear what worked and what didn’t.

I assume that most everything that I’m doing to my machines is old news and was discussed decades ago. I’ve tried searching the archives of this (and other) forums for info. What I didn’t find much info on is: 1) the long term performance of the fixes and 2) the idea to swap the higher load bearing with the lower load bearing.

I’ve started working on cobbling together a small vacuum chamber. I think I figured out how to make a good connection to my vacuum pump with parts that I have on-hand.

My gut feel is to try option #3 above for the capstan/clutch and #2 for the motor unless someone has a compelling argument for one of the other options.

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Based on the info above, I decided to revisit the lubrication of the supply and take-up reels on my BC9000. Here is a close-up of the cap and spindle.

I noticed that the original lubrication was an amber colored, medium density grease. The grease on the shaft itself was hard to identify, but there was a small amount of grease in the groove of the cap that looks original and is not between moving parts. This is a bit odd since the service manual calls for Floil on the shaft. In researching this, others have also described grease at this location.

I wonder if the difference in lubrication was a running change, an oversight in the manual, or something else. I doubt that it really matters as long as the tape deck works reliably.

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I’m glad to hear that you figured out the issue. I wouldn’t have guessed that particular thing was your problem.

The markings on those Piher pots is difficult to read. One tip that I have is to place the components in a block of foam that is marked for the value.

I like to test all of the new components before I install them. After they are tested, I stick them in the foam. This makes the re-cap/re-pot procedure go faster. I’ve also found new parts that are technically “in spec”, but are so marginal that I wouldn’t want to use them.

I also mark and stick the old components in the foam when I remove them. This makes it easy to test the old components to get an idea of how well they have aged.

BTW, the adjustment for the signal strength is one that you could get away with adjusting without instruments. Tune between strong and weak stations and adjust until the display gives a behavior that you like.

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In general, it is not a good idea. If you are stuck, use two polarized caps in series to make a non-polarized equivalent. You could also use a different value non-polarized cap. I’ve tried both of these solutions as a stop-gap until the correct part arrived.

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Did you test the amp separately on a bench setup? Was the amp working OK before the recap?

Posting some high resolution pictures of your board might be helpful.

You were on the right track comparing the properly operating channel to the channel with the issue.

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Now that I think about it, it isn’t too much of a shame since I’ve already had fun working on it and learned some new things in the process. Also, I now have a solid machine on which to experiment with my crazy ideas. Hacking this into something unique may provide more entertainment than doing a restoration.

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chartz: Thanks for the info. This is the kind of thing that makes this website great!

chilibt: Thanks for this picture! It makes it clear what is going on.

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5TR1 is listed as a BD534 in the Beocord 9000 service manual. Is what you have a TO-92 or TO-220 package?

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I had a very similar issue. Unfortunately, I wasn’t able to figure out how to get it apart for proper cleaning and lubrication. It seems logical that, if it was assembled, it could be disassembled. I didn’t want to risk permanently damaging the part either.

Mine wasn’t that bad and I got it to run free by adding a very small amount of plastic safe oil and spinning it until it ran free. I would have rather restored it properly.

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chilibt: Is your question about the plastic part not spinning easily on the metal shaft when that sub-assembly is removed from the main-assembly? (sorry if my description isn’t very good)

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kingside wrote:

You are saying however that the clip is preventing an upward motion and that is what needs to be released while applying a gentile upward pressure

Yes. The clip is part of (or attached to) the button panel. It will move up with the panel when it is released.

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That panel is easier. With the top in normal (non-service) position, I’ll position the Beocord on the edge on a table with the front edge of the Beocord overhanging. There are three rectangular holes in the bottom to get access to the clips. I start with the rightmost one. First put the screwdriver between the clip and the front of the deck. The first time you do this you’ll probably need to visually locate the clip.  Put upwards pressure on the right edge of the switch panel and twist the screwdriver just enough to release the clip. Once the the first clip is released, repeat for the middle and left clips, all while lifting up on the switch panel. After the front is free, lift it just enough the clear the front clips, then pull forward.

After you’ve done this a few times, it can be done strictly by feel in about 10 seconds ;-).

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