Beogram 8002 (5633): Full Functional Restoration and a Test Spin with Oscar Peterson and Milt Jackson

This post describes the functional restoration of the Beogram 8002 (Type 5633) that I recently put on the bench. My initial assessment of this unit is posted here. 

This shows the Beogram in 'service position', i.e., with all functional parts removed from the enclosure. I usually put everything on my Lazy Susan, which lets me work on it from all sides without moving the delicate setup:

I started by rebuilding the main PCB. I unplugged it from the wire harnesses:

Next I removed the microprocessor can:

Here is a detail shot of the large reservoir capacitors:

I exchanged all the electrolytic capacitors:

The main reservoir capacitor on these boards has a 'historic' 4-pin package, which is no longer manufactured. I replaced it with the Beolover 4-Pin 2200uF Reservoir Capacitor for Beogram 8000 and 8002. This shows it in comparison with the original part:

This shows the rebuilt reservoir capacitor section:

I also resoldered all the board headers. They tend to develop intermittent solder joints due to mechanical and thermal stresses.

There is one important capacitor inside the microcontroller can. It is responsible for decoupling the processor power supply from the motor noise on the power rails. This shows the can with the top lid removed:

The capacitor is located under the small piggybacked board. Pulling the board up usually reveals some insulating tape:

The capacitor is located under the tape:

The interesting aspect of this capacitor is that the negative lead is soldered to the board on both sides, i.e., it acts as a via. In the 1980s, they did not yet have through-plated vias on PCBs, and so they used through-hole component leads as 'convenience vias'. Since one cannot get to the top solder of the negative lead without doing some damage, it is best to unsolder the positive lead first

followed by breaking off the other lead from the capacitor can by rotating it until the wire breaks.

This is how the board looks from the bottom after removing the other lid from the can:

It is best to remove the tacked-on shielded wire before removing the capacitor:

After removing the broken off wire stump, the new capacitor can be soldered in with the negative lead first

This shows it with the positive lead soldered in, too:

After tacking the wire back on and putting the lids back, I installed the assembly on the board:

If you do this at home, make sure that the wire leads of the ribbon cables are properly inserted into the header underneath the board. It is easy to get adjacent wires into the same female header position. If this happens, 'interesting' effects on the turntable operation occur!...;-).

After completing my work on the main PCB, I exchanged the capacitors on the voltage regulator board next to the sub-platter. This shows the original capacitors still in place:

And with the new capacitors in place:

It is a good idea to remove the tacked-on wires before replacing the caps. This prevents potential damage to the wire insulation with the soldering iron.

Next came the replacement of the output relay. This shows the bottom side of the DIN7 jack output assembly. The relay is concealed by a clamped-on shield:

Pulling off the shield reveals the relay:

I replaced the relay with a new one:

The new one has the same form factor as the original one, so the shield clamps back on without problem:

I usually also install a (red) switch that allows connecting the signal and system grounds:

Connecting both grounds usually quenches any hum when connecting the Beogram to an amplifier.

The last capacitor that needed replacement was the phase-shift capacitor in the transformer block. This shows the block without its lid:

The grey capacitor is a non-polar electrolytic capacitor, i.e., it has two back-to-back polar capacitors of double capacitance inside. This makes it a bulky component. The Beolover replacement part shown next to the bloc uses modern multi-layer ceramic capacitor arrays, which are 'natively' non-polar. A much better solution for use as a phase capacitor! The part fits neatly next to the fuse and contact terminals assembly:

The Beolover part can be used for both 50 Hz and 60 Hz versions of the transformer block. Depending on the frequency, the phase capacitor has a different value. Simply solder one of the two wires to the appropriate capacitance terminal and the other to the COM pad. 

This concluded my capacitor replacements. The next step was to replace the incandescent light bulb in the <</>> button assembly on the PCB that is clipped to the back of the keypad. This shows the keypad with the PCB still installed:

The light bulb is in the black box mounted to the board. Its replacement requires the removal of the board from the keypad. After lifting up the board with a suitable screwdriver on the right side that it can clear the locking plastic feature, it can be slid out to the right.

I usually take this moment as an opportunity for cleaning the keys and their recesses in the plastic panel. The keys come off easily after the PCB has been removed:

Make sure the keys are in the right order when reassembling the keypad after cleaning everything.

I usually clean the keys with a moist Mr. Clean eraser pad:

Don't use the pad on the LED display cover. It can scratch the plastic! A lens cleaning cloth is perfect for cleaning the LED cover.

The plastic panel is best cleaned with some warm water and dishwashing soap. Never use alcohol on Beogram 8000/8002 components.

After this cleaning excursion, it was time to replace the bulb. This shows the black box with its lid removed:

The bulb is in the center of the assembly. The two whitish components, left and right, are photo resistors. When pressing the << or >> buttons, the amount of light impinging on the resistors changes by means of two apertures that are moved with the buttons. This allows the gradual adjustment of the carriage speed depending on how hard the </>> buttons are pressed. Nifty!...;-).

The bulb leads are soldered to pads on the solder side of the board underneath the black box:

This shows the white light 5 mm LED together with the extracted bulb:

The LED needs to be Dremeled a bit to roughen up the surface of its plastic bulb and to reduce its diameter slightly. This ensures the LED fits and that the light is dispersed homogeneously onto the photoresistors. LEDs emit a more directed light pattern compared to incandescent bulbs.

This shows the LED installed:

The light bulb runs from 15V. Therefore, a suitable current-limiting resistor needs to be connected in series with the LED. I usually solder it in on the high side: 

If you try this at home, make sure the resistor is approximately in the location shown in the photo above. Otherwise, it is possible that it will interfere with the plastic panel when the board is reinstalled behind the keypad.

After replacing the cover of the black box, I focused on the carriage. I removed the carriage rods and spindle parts for cleaning. As usual, they were encrusted with old, hardened lubricants:

While they enjoyed a bit of ultrasonic cleaning, I replaced the light bulb in the tracking sensor with the Beolover Tracking Sensor LED Light Source for Beogram 8000 and 8002.

The bulb sits in a small compartment under the arms, which is covered with a piece of sheet metal:

The cover can be slid out to the left after it is lifted a bit up with a screwdriver to clear the locking feature:

This reveals the whitish photo resistor on the upper side of the grey tracking aperture and the light bulb below. Both parts are mounted on a small PCB. The exchange of the bulb requires the extraction of the PCB. The PCB is connected to four leads that come in from the bottom of the tracking sensor compartment. This shows the bottom view with the wiring. The wires are held in place with a small rubber ring stuck onto a plastic nipple:

Removal of the rubber ring allows pulling the wires out of their conduit:

This is necessary to give the wiring some slack so that the small PCB can be pulled out a bit to access the solder pads of the bulb.:

This is how the board looks from the component side:

I removed the bulb. This shows it together with the Beolover LED assembly:

This shows the LED assembly soldered to the bulb pads:

The board is in the correct position when the end of its narrow part is flush with the solder side of the PCB. Also, make sure the LED is facing the photoresistor if you try this at home:

I pushed the board back into place:

Then I pushed the wires back into their conduit and replaced the small rubber ring:

While the carriage is 'up', it is the only moment the vertical arm can be adjusted. The screw can only be accessed when the carriage is liberated from the rods

Turn the screw until the arms are parallel:

In the meantime, the carriage components came back from the ultrasonic cleaner:

I put everything back together. It seems the best way is to first put the longer rod in place together with the plastic 'fork' that connects the white nut on the spindle with the carriage, and then insert the spindle with the nut approximately in the center as shown here:

Then simply tilt the carriage towards its horizontal position while inserting the other end of the spindle into its ‘bearing’. Once the spindle is in place, the shorter rod can be inserted and locked into its cradles.

At this point everything was back together and I adjusted the 'idle voltages' of the <</>> assembly. Both left and right voltages need to be ~650mV when the buttons are not pressed:

This voltage is adjusted by turning the screws on the black <</>> box on the keypad PCB in or out.

After this adjustment, I adjusted the tracking feedback, and then it was finally time to give this functionally restored Beogram 8002 a first spin!

I selected one of my favorite records, 'Very Tall', which was released by Oscar Peterson and Milt Jackson in 1962. I have a 1982 Japan pressing (UMV 2026), which sounds very nice. This shows the album playing on the Beogram:

I will now play this Beogram a bit to see if there are any intermittent issues. While I do that, co-Beolover Beomazed is working to transfer the original 8002-labeled hood trim to a new reproduction hood to give this Beogram a sharp 'like-new' look! Beomazed has figured out how to remove the original trim without damaging it. At this point, the only way to preserve the original look when exchanging the hood is to use the original trim.