Beogram 4000 woes

[Stephen Farmery]

Believe me everything I am about to write is totally true. My trusty 4000 was playing happily one evening and then stopped mid record. Arm returned manually, re started and played all the way normally for a while and did the same. I traced this issue to a faulty reed relay so repaired that, all well. Then after a while I pressed play and nothing, nada. Traced that to the 6V line at the fuse broken away from the board, re soldered that, put a record on, played until record end no problem, then after a few days arm lifted but no return. Just sat there with platter running. Started fault finding and general cleaning of all contacts on start/stop board and arm slider. Put all back together runs /plays until record end and lifts without returning. Now the fun starts… Tried the deck the next day to start fault finding and it starts immediately, drops at record start but at 45 RPM. I press return, arm lifts but wont return. Manually wind the arm back and try again without record, arm moves in, stops and drops at correct place but at 45 RPM. Do it again, this time it runs at 33 RPM, still won’t return after stop and return is selected. Next day WITHOUT touching a thing, try the deck it starts, arm moves 1/4 inch toward the record, before the switch under the slider is actuated, and drops to play, at 33 or 45 RPM depending on how it feels. Try again today, WITHOUT altering a thing and it now moves into the record and stops without dropping at all by half the distance than before. It will manually go FWD when selected until runout without record and not return manually or automatically. How on this gods earth can it get progressivly WORSE without me actually changing ANYTHING except cleaning all the selector switches, which I did at start and never touched or altered anything since. I blame brexit. On a more serious note these are the most elegant if most frustrating peices of equipment I have ever owned. Luckily my 4002 is still going strong with no issues, but given the history of my 4000 I daren’t even LOOK at the damn thing.

[hcraig244]

With all due respect I found the above very funny….it’s typical behaviour for one of these decks! they can be so frustrating…I have spent many hours going over and over a fault finding exercise and getting nowhere, and as you say things can seem to get worse despite your best efforts….your issue sounds like more than one problem, possibly both being intermittent which are the worst kind.

My advice, for what its worth, would be to confirm the p0wer supply levels for 6 and 24 volts at the voltage regulators….unstable supplies can wreak havoc on the logic board, a failing/leaking smoothing capacitor will cause this as will a failing voltage regulator transistor, I have suffered all of these failings. The logic board itself and the associated IC chips are very reliable and seldom fail, my experience has been most issues can be traced to power supplies dropping below the specified threshold and faults associated with the switches and the small plastic spigots that can stick and hold the leaf switch in the wrong position…and also there is the real possibility of a bad connection between the wiring loom and the control panel….I have had one case which was resolved by resoldering all the connections from the wiring loom to the control panel connection terminals….I have no idea which connection was poor or dry but on completion everything came good…..

Stick with it…..send pics and updates as there are lots of very capable members in here who will advise/help you ;¬)

Regards Craig

[Stephen Farmery]

Thanks so much Craig, I have no issue with you finding it funny at all, so no probs there. I appreciate you taking the time and will start again with your recommendations. Will start with a few piccies later on. Have a good weekend there.

[Stephen Farmery]

Just a quick question, can anyone point me to information regarding either the correct transistors for my beogram 4000 mainboard or equivalents please. The numbers, such as 8320232 bring up nothing on a google search. Thanks people. 🙂

[Stephen Farmery]

No worries, I found it all on page 3-3 of the service manual. Me being the village idiot today I think.

[Stephen Farmery]

Can someone point me to a supplier of the logic chips used on my Beogram 4000 deck please? In particular the FCH 131/ FCH 111 and FCY 101. My google search pulls up data sheets and not much else. Thanks.

• This reply was modified 1 week ago by Stephen Farmery.

[Mark-sf]

I believe you can find Millard equivalents as FCH111 for the 131/111 chips and FCH191 for the 101. I have not tried these but they are listed. It’s very rare for these to fail in normal use.

[hcraig244]

I agree with Mark…

Been down that rabbit hole myself, those IC’s are very reliable, I did source some originals at the time which where expensive and as it turned out not required….this followed the removal of a number of them for testing and they all worked as designed, there is a post in the archives of this site detailing that particular journey but I cant seem to get to the archived files and pictures, anyone know the secret to accessing them?..

The IC’s provide OR and AND gates making up the very complex boolean logic control board that the early engineers decided was required to drop a stylus onto a rotating platter ;¬)  and other safeguards it has to be said. Seems that back in the day these engineers where in competition to devise the most complex solutions for decks and amplifiers ie the BM6000 Quad……..I love them and the associated complexities. In my case the cause I discovered to my issue, the deck regularly started up in 45rpm speed as soon as the deck was powered up, was that the carriage slider switch plastic actuator for the 45rpm position was sticking intermittently giving a out of sequence signal to the control logic which was playing hell with everything…. SolderRon advised at the time to confirm the 6vdc supply to the IC’s as if that drops too low the logic goes to rat shit just the same…..

Enjoy

[Stephen Farmery]

Hi Craig, and Mark if you are reading this, thank you so much for the imput.

I know that the logic CCTS are very reliable but the problem is that the logic board is, as you say extremley complicated to understand as a whole. I have tried for a few months now to work it all out. The issue I have is that for some reason the fault gets worse every time I simply re start the deck to fault find. I have cleaned ALL switches on the ctrl panel and all work as they should. ALL of the switches under the arm travel board work as they should, cleaned and checked. The initial problem was that the arm would play normally, lift at record end and then nothing, no arm return. When I re started the deck after manually re winding the arm back it went almost to the record and stopped before actuating any of the switches. Then again after doing it all again the arm simply went fwd about a few cm and stopped with the motor running and no drop or anything. The situation now is this: I have the control panel set with ALL of the switches in their ‘pre start mode’ with bits of cable between the springs and the switches, the board is out of the deck and panel switches removed. I removed the arm drive belt to watch the arm motor. When I plug the deck in and press start with a screwdriver blade to initiate, the motor runs for about a second and stops with no drop. If I unplug the deck and do it again it does exactly the same thing. The fact that the motor runs tells me the fwd drive all works, the fact that the motor stops on its own without any switch actuation tells me that something is stopping the arm drive motor on its own without any switch driven command. I really am having trouble totally understanding that logic CCT to competently fault find in this complex maze. I do understand how NAND gates work, just not this logic board.

[hcraig244]

I can see your a bronze member….upgrade to silver and download the Beogram_4000_training_course_notes.pdf which where gifted to the site by a former B&O service engineer, they are very helpful and informative…a little clipped in places but mostly complete…..

Can you confirm that the platter still spins and the control panel indicates a start at 33rpm ? …..also measure the 24vdc and 6vdc power supplies as the unit starts up and look for a drop in voltage…often the voltage regulator 2TR6 can read good but can be pulled down on load…..Have you changed out the power supply capacitors? these should be replaced as a matter of course in any event.

craig

[Stephen Farmery]

Hi Craig,

Thanks so much for the reply. I can only usually answer intermittently as I am not very well, put that down to old age. Anyhow, so far I will upgrade as you suggested. I used to be a fully paid up member of the previous edition of this site and also helped many people in my younger and more adept past. So far I have the following: The 6v live shows 4.7 volts, the 24 V line shows 24V at all times. On start the platter motor spins, the record dector lights up as expected. Now comes the silly part. If I have the arm/motor belt connected and manually drive the arm to the extreme right (as it wont drive there electrically) it does as it should on power up (the arm moves a few mm left to the rest position as I observed it to do when working correctly, it used to go all the way to the right, stop and move a few mm left to stop). If I the press ‘on’ it moves a few mm more to the left and then stops without making any contact to tell it to.. If I remove the arm drive belt and rewind the arm mechanism back far right then re-connect the power the arm movement motor will sit spinning happily until I manually move the arm to the ‘SO’ contact position. The motor then stops as it should. Then I press ON and the motor runs for a second and simply stops on its own. Also the 4.7 V (6V) line has been 4.7 V since I fixed an old issue of the arm movement/ record detector lamp intermittently stopping (this was a reed realy issue and after a poor connection on the 6V line to the board), now fixed.

• This reply was modified 3 days, 8 hours ago by Stephen Farmery.
• This reply was modified 3 days, 8 hours ago by Stephen Farmery.

[Stephen Farmery]

Hi Craig,

Now I have re done the checks all Power Supply Voltages are as they should be. In fact the 6V line is a little above, so quite robust. I have upgraded my membership to silver and will down load the full service info you recommended. Thanks for your help thus far. Regards, Steve F

[hcraig244]

No worries Steve…..we like a bit of a challenge in here, 4.7vdc is very low for the supply to the logic IC’s I can’t remember the actual min voltage for them but 5.something comes to mind for reliable operation send pics 👍

[Author]

Posts