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BRONZE MemberI would start by leaving the supply disconnected and measuring resistance on the board side between each pair of windings pins looking for a short. Ex: P7 pins 2 and 4. Then you can desolder to find the shorted part.
To add one advisory to the excellent advice already posted, if you have put in one or more of the electrolytic caps backwards and tried to turn it on, you’ll need to check the fuses, transistors and regulators prior to that as you have effectively shorted them. This is likely why you have not made progress.
1 October 2024 at 06:44 in reply to: Beogram 2402 arm skating and recommendation for good companies to fix #59648It’s likely a missing diamond or mis-calibrated tracking force. I doubt its a cueing mechanism issue.
You can get that one to work by removing the top platter and belt.
The proper fluids will not leave a residue especially if you dry them. Just keep the liquid off the labels.
The sound issues you are describing are not likely due to a dirty stylus or record Bass distortion is more likely to be caused by improper stylus force or a failing stylus cantilever suspension. I would recalibrate your tracking force to 1.2g for your MMC4 and 1.5g for your MMC5 first and then evaluate. As to cleaning the stylus, I prefer the gel-based ones such as from DS Audio as they leave no residue. Finally, a Spin-Clean Record washer will be a significant step up from your brush cleaner
Since, you found a shorted cap replaced all of them, it is likely the culprit for the burnt resistor. OpAmps usually work fine or simply fail by their nature. If the sound is now clean without noise and distortion, I would just button it up and enjoy.
If R121 burned, I would replace IC 10 & 11 as they are connected to the same resister. I would also change out C103 & 107 which I believe you are doing.
There are actually 2 dual opamps IC10 and 11. You may be referring to the 100 μF caps on the 15v -/+ rails that help smooth the DC. However, their failure, assuming they opened versus shorted, would not cause white noise in my experience. It is also not likely that both channels would fail together since each has its own dual opamp. If in fact both channels exhibit the same white noise your problem is likely in the 15v dual power supply section. This regulation was done discretely back then and is where I would start.
You haven’t mention what component/system it is connected to. If both channels have the same distortion you may be overdriving the input to your receiver as the diigital side sounds fine and once the signal leaves the DAC chip it flows in discrete L/R circuits which are unlikely to both distort unless you have problems with either the +15v or -15v supplies to their opamps.
As far as the coils go those readings should be fine. Hope your restoration goes well.
I don’t see the video; however, you should take a look at the service manual and follow the adjustments in Section 5.1. While doing that take note if it also needs cleaning and lubrication which is covered in 4-8.
15 June 2024 at 00:34 in reply to: Beogram CD 50 – How to Select Proper Setting For ‘Master Voltage Switch’? #56503You need to use the 120v position AND need to ensure that the fuse in 500mA. If you are unsure of switch end positioning, use an ohm meter between the two AC pins and the 120v one will have about half the resistance of the 240v one.
I would not bother turning it off at the mains daily or even a few days as this stresses components that were intended to have power on continuously such as the those in the power supply. I would only do it for extended vacations of weeks to protect from power surges. Using the 4002/4 models for almost 50 years this way without an issue.
Actually the marks are a wearing away of the matte finish. Some have simply removed the finish entirely or you can check out Rudy’s excellent blog entry at https://beolover.blogspot.com/2022/04/beogram-40024004-keypad-restoration.html.
The tweeter section is on one side of the woofer section, so you ca place a stereo pair with them on the inside or outside as they are mirrored. If doubling up I would have each channel in a WTTW configuration and angled at the listener as you’d want to stay on axis.
The damping cylinder only slows lowering. Raising should be quick. You can turn it more to slow it further. It simply won’t lower if too much.
The screw in the black bottom of the damping cylinder controls the rate of descent.
I have seen the braided cable rise up out of the curved channel as approaching the spindle if it is twisted. Also the bearing height is adjustable. The brass bearing is threaded and with a large locking nut on top. However, that rarely ever is the problem.
I believe that bearing is part of the arm assembly and is not available separately. You will need to replace the entire are or find a parts unit. Most B&O tonearms were a single part number.
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