Mark-sf
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The platter lifts off to replace the drive belt. You need the right one which is available from beoparts.com.
It’s easiest to remove the power supply whole as it’s carrier is secured with screws from the bottom.
It appears you are not getting DC voltage from the regulator on PC Bd #2. I would disconnect connector P3 and measure the DC voltage on the input and output of the regulator, IC1. Either C3 or C4 could be a problem but id the fuse is not blowing, I would expect the regulator has opened. It’s not likely the solenoid unless you hear it activate when simply plugging in the power cord. Then either TR4 or 5 could be shorted.
If you are getting 12v at the anode of D1 then pressing Play should cause pin 10 to go high and turn it on. Please confirm you see 5v on that pin.
You should also reflow the connector’s solder joints as these are notorious for developing fractured connections.
Thanks for the video. Some of what you are observing is normal. For example, the 33 button record clean function ONLY works when the arm has not left its home position. Also, the single arrow buttons do NOT work until the tonearm has left the home position. Finally, the >> and << and >> do not need to be held down.
The two major problems I see are the following:
- The return servo motor direction is not functional as it should not only engage when you press and hold > or press >> but also when it gets to the center endpoint.
- Your solenoid is engaging but not holding as it’s there to keep the tonearm lowered. This means that there is an insufficient voltage on the coil when it switches to its “hold” mode.
These are likely independent, and you have multiple issues. Go back to the servo motor circuit for #1 and the Solenoid circuit made up of TR9,10 and IC4 and its caps.
Quite frankly as long as the female connector is also clean, I would not worry about it coming back. You likely didn’t have rust but oxidation and the connections should be fine.
You will need to open the top and remove the front panel as if I remember the switch assemblies are board mounted. Once you have access, you can see what is hanging up the interlock mechanism.
Diodes like transistors typically cannot be measured without being removed as you are measuring resistance of their circuit.
When I have painted aluminum I’ve used a self-etching primer. However, you obviously are going to need to remove the old paint first which may need to be sanded. Given the dings, that’s probably required along with a filler If you have a paint booth for your air sprayer that’s how I’d try. Nice DIY project if you take your time.
Glad it worked out. I don’t know about a new string but belts and other spare parts are reliably available from https://www.beoparts-shop.com/. If you can’t find the “string” you can make a new one using tuning dial cord.
It’s likely that the tensioned string that moves the arm has broken or come untracked. There are instructions at the end of the service manual at https://beomanuals.com/manuals/Beogram/Beogram%209500/Beogram_9500-Service_Manual-version2.pdf
on replacing and adjusting.
I am having trouble parsing the symptoms you are reporting. In normal operation, simply pressing start momentarily will cause the tonearm to move to the edge of the record and lower. If you press and hold then it will continue past that point until you release. Pressing 33 should just cause the turntable to spin for cleaning without the arm moving. If it is then you may have a shorted transistor in the servo motor control section. You can see a table of voltages on the schematic available at https://beomanuals.com/manuals/Beogram/Beogram%204004/Bang-Olufsen-Beogram_4002-4004-Schematic-2.pdf.
If you are referring to the resisters in the lower right where the board is darkened, those are 1/4w resistors which are typically 6.5mm in length. You will not find a replacement parts kit that includes standard resistors. I would check their values with a meter as even though the board is discolored most are probably fine when the resistor itself is not blackened in the middle.
There are small knurled knobs under the black trim aligned with the speed indicators.
From your picture it is missing the veneer. Quite frankly I was never a fan of that motor but you have nothing to loose in trying to relubricate it. Cannot comment on how long it will last. I would also have the stylus checked for wear as you don’t want to be damaging your records.
To answer that we are going to need a bit more information.
- Does the noise vary with volume and turn off when muted?
- Putting your ear to each driver (tweeter and woofer), do you hear the noise only from one or both? Note that the tone will be different.
IC1 is a voltage regulator and the operation is the same in that it is being turned off by the SO switch grounding the anode of D5. I would confirm that is occurring.
If the 1200 has the phono preamp then you would connect to an AUX/CD/Tape input on your Marantz. If not you go into Phono making sure MM is selected versus MC if your Marantz has this. Either the stylus or its suspension may have worn out which is not surprising after 40+ years. Finding a replacement will be costly or lucky.
