Beogram 4004 Type 5526 - Restoration Project - SyncDrive and Remote Commander Installation

Continuing on from this project's previous post, I needed to install a Beolover SyncDrive platter motor and a Beo4 Remote Commander.

However, there were still some other follow-up tasks like checking the 21V supply voltage (to make sure it doesn't have any noise), adjusting the TR3 collector voltage with the new R26 trimmer, installing a Beolover platter detector lamp replacement, installing Beolover RPM indicator LEDs and running the platter speed calibration.

Here is the 21V measurement check.  The inset oscilloscope screenshot is zoomed in on the 21 V line so I could check the ripple. The measurement looks very good.

Next, I installed a Beolover platter detector lamp module so I could check (and adjust) the platter detection signal with the 1TR6 trimmer I installed (in an earlier post).
Once the 1TR6 trimmer was properly set, I moved it over to the component side of PCB1.

I changed the speed indicator lamps in the Beogram 4004 RPM indicator panel to Beolover LED modules.

Now I could install the SyncDrive platter motor, run its speed calibration and test the platter detection functionality of this Beogram 4004.

SyncDrive speed calibration...

At this point I was able to calibrate the Beogram 4004 record tracking.

I removed the platter belt for this calibration procedure so I could rotate the platter by hand and check the Beogram 4004 servo motor performance when advancing the tonearm.

While this procedure is usually a repetitive adjustment and measure series of steps, I was pleasantly surprised that I was able to lock in the correct setting only using the coarse screw adjustment shown in the picture above.

Usually I get the setting close using the coarse adjustment, then dial in the final setting with the Beogram 4004 eccentric screw adjustment and/or the Beolover tracking lamp trimmer.

Now for a quick check of the platter detection signal and the position sensor run-out groove detection.

The empty platter detector signal looks good.

Previously I had adjusted the position sensor to output 5V when the clear part of the position scale was in front of the detector.  Note that when the blacked out part of the scale is blocking the sensor, the voltage is around 10 V.  Those can be checked and adjusted (using PCB1 trimmer 1R88) without the platter motor if desired.

The last section of the position scale has a series of narrow black bars.  This is so the position sensor will generate a series of pulses that the detection circuit on PCB1 can interpret as the run-out groove of a record. Each run-out pulse adds to the voltage level that capacitor 1C33 charges up to in the detection circuit until the detection threshold is reached. At that point, the run-out detection circuit initiates a stop and return to end the record play.

This picture shows the position scale bars entering the position sensor area. The inset oscilloscope screenshot shows what the run-out sensor signal looks like when the tonearm is moving through the run-out groove.  In this case the run-out detection circuit triggered on the third pulse.
Note: My measurement point here was at the node for 1D41, 1D42, 1C33 and 1R82 on PCB1.

Last, but not least, was to install the Remote Commander...but first, I still had to clean the old oxidation off the Beogram 4004 control panel button contacts.  I applied some Deoxit fluid on the cleaned contacts.

While checking the button panel I discovered that one of the buttons was badly damaged and would not work.  I replaced the plastic button with a spare.

With the button panel restored and tested, I install the Beolover Remote Commander.
This version of the Remote Commander is designed to operate using a Bang & Olufsen Beo4 remote control.

Also...note that the Remote Commander installation is using the Beogram 4004 options.

Using the Beolover Remote Commander with a Bang & Olufsen Beo4 remote control can be a little bit tricky.  That is because the Beo4 remote control is configurable and may not be ready to work with controlling a Beogram right out of the box.

This was the case I ran into with this Beo4.  It did not have the Phono option in its list of supported components.  Adding that to the Beo4 menu list is not difficult but it wasn't intuitively obvious.
Beolover describes the setup in this video.

This Beo4 had one additional wrinkle however.  It did not have a Phono named function in its memory to add to the list of components.  It did have "N. Radio" which, it turns out, is another function name that works as a phono selection.

My next step will be to reassemble the rest of this Beogram 4004 and do some record play testing.

Beogram 4002 (5513): Another Beogram From Houston - Electrical Work

Continuing the Houston Beogram 4002 restoration with the electrical work, here is the reworked main PCB.

Before

After

Some details to point out are the replacement of the speed select relay and the trimmers for the platter speeds (33.33 and 45).

The old trimmers for the platter speed adjustment have trimmer adjustment slots on the top and bottom.
The Beogram 4002 main board mounts where its trace side faces up so the speed adjustment is made from the underside of the board.  That is why the new trimmers are mounted upside down...so their adjustment screw can be accessed from the trace side of the board.

Here is the trace side of the main board.  You can see the speed trimmer adjustment screws.

Next are the replacements of the Beogram 4002 main board Darlington transistors IC1 and IC4.
Other Beolover Blog posts show the replacement of these two transistors with new transistors as a precaution against the aging Darlington transistors the Beogram 4002 uses for its power supply (IC1 21V) and the solenoid actuation (IC4 30V).

Another possible transistor replacement is 1TR3.  It is in the arm detector circuit the Beogram 4002 uses to determine if a record is on the platter or not. On the Beolover Blog restorations of Beogram 4002 (and 4004) turntables we check the 1TR3 transistor Hfe value to make sure it is good (typically, above 500).  If it is not, we change the transistor.  

Regardless whether 1TR3 is replaced and whether the lamp in the Fixed Arm (Detector Arm) is replaced, we do change resistor 1R26 from a fixed value (1Mohm) to a trimmer (usually a 2Mohm or 5Mohm trimmer).

This photo shows a 5Mohm trimmer for 1R26 installed on the trace side of PCB1.

The new trimmer will remain there for a while until I finish the rest of the electrical restoration work and am ready to test the Beogram.

The Beogram output board is next.
Here is the before photo of the output board.

Here is the after photo.

The only changed components on the output board are the Beolover replacement muting relay, a new electrolytic capacitor for C1 and the addition of a toggle switch to select whether the Beogram chassis ground is connected to the signal ground.  We have found that different grounding conditions can exist with various preamplifiers that result in ground loops.  Those cause hum in the phono signal and is noticeable during record play.  The grounding switch provides another option to handle that scenario.

Next, I replaced the incandescent lamps for the platter speed indicator panel.

Here is a little bit closer look at the original lamps...

...and the Beolover replacement lamps.  

The incandescent lamp in the Fixed Arm for the Detector Arm circuit was also replaced with a Beolover replacement LED assembly.

I changed out the Beogram 4002 control button panel with a refinished one.  The old panel was in bad shape.

The button panel contacts were oxidized pretty good so I cleaned them up to a nice shiny finish again.

Here is the button panel and contacts reassembled.

As I started installing the floating chassis components back into the Beogram 4002 cabinet, I replaced the original reservoir capacitor with a new Beolover capacitor assembly.  This new Beolover replacement component is very easy to install.

I also replaced the original DC Platter Motor with one that Beolover had refurbished for me.

Now I could install the circuit boards back into the Beogram 4002 cabinet and make some electrical adjustments.

With the electronic components re-installed in the Beogram cabinet it was time to tackle the adjustment of the Detector Arm Circuit.  The new 1R26, 5Mohm trimmer needed adjustment so the DC voltage measured at the 1TR3 collector is 4 VDC.

With the steady state voltage adjusted on 1TR3 the new 1R26 trimmer can be moved to its final position on the component side of PCB1.

Another PCB1 adjustment is with trimmer 1R88.  This trimmer adjusts the voltage at the collector of 4IC1 which is the sensor for tangential arm position. That is the sensor that receives the infrared light from 4D1 as the position slide moves between light and sensor during arm movement.  The light, sensor and position slide detect the arm set down points for various size records as well as the run-out groove detection.

The 4IC1 collection should be set to 5 VDC when the clear portion of the position slide is between the sensor and lamp.

So far all of the adjustments and measurements have worked out as called for in the service manual.

I continued on with the calibration of the tone arm groove tracking.
For this adjustment I like to make a crude adjustment with the bracket connected to the base of the tonearm which holds the aperture slot controlling light to the tracking sensor.

Note that I also make this crude adjustment with the eccentric tracking adjustment screw in its center position.  That is so I have room to make the fine adjustment in either direction.

I adjust that bracket so the arm can be lowered and it just stays put (it doesn't try to move forward on its own).

After that is achieved I loosen the set screw for the eccentric (fine) adjustment screw.

A test record can now be placed on the platter (without a platter belt).
The tonearm is advanced to a center track on the test record and lowered.

The arm should not try to advance.

Manually rotating the platter with the test record should result in the Beogram servo motor turning to advance the arm within one revolution of the platter.  It should advance the arm every platter revolution after that.

The eccentric adjustment screw is used to dial in that calibration.  
Extra fine adjustment can be made with the small trimmer on top of the Beolover tracking sensor lamp assembly.  Those adjustments increase or decrease the intensity of the LED used as the sensor light source.

This photo shows an adjustment with the eccentric screw.

Using an oscilloscope I measured the empty platter signal at the 1TR3 collector to check the health of the sensor output.

Two last measurements before actual record play are to re-install the platter belt and adjust the 33.33 RPM and 45 RPM platter speeds.

For these adjustments I use the Beolover RPM Tool as the measurement instrument and the two speed trimmers on the main, PCB1 board.

The owner of this Beogram 4002 also would like the Beolover Remote Commander installed as part of the restoration.

My next steps will be to first, finish reassembling the Beogram 4002, then some quick test play of some vinyl records.  

After that I will install the Beolover Remote Commander and resume testing record play on this Beogram (the real fun part).