ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hello B&O lovers. This is my first post here: I hope I would be accepted in this community, since I found a beautiful (and cheap) Beogram 4004 on eBay and I didn't resist to its charm… When I was a young boy and couldn't afford a proper hi-fi system, it was one of my dreams, so I decided to make myself a gift :-)
The eBay seller told me the turntable wasn't working properly, but after I fixed some false contacts and replaced some capacitors, it started up… but the arm assembly travelled toward the center and back, without lowering on the record. I found that the main board relay wasn't working (broken winding) and I replaced it with its twin from the second board. Then I managed to install a different relay on that board, much less cluttered.
I should have test the turntable at this point… but I decided to replace all the capacitors instead. It was a big mistake… now there's a short circuit somewhere and the Start button doesn't work anymore :-(
I'm sure I'll find the fault, but it won't be an easy task and it'll take time. Before discovering this forum, I downloaded a 4002 service manual with an addendum for 4004: unfortunately the print quality is terrible and the board pictures (completely different from 4002) are missing. Could anybody tell me about the quality of the service manual available here? I'll probably upgrade my membership anyway, but I would be glad to get the right 4004 service manual: my job would become much easier.
Thanks in advance for your collaboration. Any suggestion is appreciated.
B&O Beogram 4004, Revox B790/Audio Technica VM520EB, Yamaha CX1000/YSTA5/TX350, Philips CDP400/BDP3100,Technics RS-B965, Infinity Qbx, Audio Pro 4/40 MkII
Hi. One of the new tantalum cap was faulty (shorted)
I don't know if it was defective or if I toasted it replacing the relay… But now the turntable is working
Now it's time for alignment, but first I'm gonna find a new belt.
Can anybody suggest me where to buy the right belt for the 4004?
Many thanks in advance.
Contact user Dillen (Martin) on here using private message, he sells belt kits for the Beograms. Best to get a new platter belt and a belt for the arm servo.
Drew
As Drew mentioned Dillen for belts, he sells the rights ones, welcome to the forum, and nice to see something happening in the vintage forum, please keep us updated when you have got your belts.
Collecting Vintage B&O is not a hobby, its a lifestyle.
Thank you guys. I already replaced the arm motor belt and I sent a message to Dillen, I'm waiting for his answer…
PMs are called "Conversations", correct? I didn't find nothing else about Private Messages on this forum.
They used to be called "Private Messages" or PM's for short on a previous version of the BeoWorld forum software.
Now called "Conversations"
Regards Graham
I just bought the drive belt. Dillen wrote he'll send it out tomorrow. I can't wait...
The turntable has a strange behavior, by the way: when I press Start, the arm travels to the right position (30 or 17 cm) then returns to home. If I press another key to stop the "auto-return" movement and I use the Up/Down key to lower the arm, the turntable plays… although sometimes it stops all of a sudden and the arm returns home
I'll wait for the new belt, before to check adjustments and fine tunings. In the meantime, does anybody have any suggestions or advices?
Thanks a lot, guys.
Hmmm. I just upgraded my membership to Silver and downloaded the service manual for my BG4004. Unfortunately, it's the one I got already… the BG4002 manual with an addendum about the differences from 4002 and 4004. No schematic diagrams and PC board drawings.
Anybody could help me ? Thanks in advance.
Can you give us the 4-digit type number (53xx or 55xx) ?
Martin
T5525
Thanks for upgrading your membership. We appreciate your support.You have email.
Thanks to Martin, who sent me the schematic diagram, my 4004 is slowly improving
I noticed that the arm transport was slow and impossible to align with the trimmers, so I replaced all 4 transistors that drive the arm motor.
Now the transport is smooth and steady, and the automatic start seems to work too, although there are still random errors, especially with automatic stop: most of the times, the arm raises and returns way before the end of the record. But sometimes it plays the record from start to end… maybe it's a matter of taste
Time to stop and wait for the new belt. I'm getting closer…
Thanks again to Martin and Keith for their help.
Finally the new belt arrived (thanks Martin) and now everything seems to work…
I thoroughly cleaned the arm assembly and I've been able to play some records from start to end. I keep my finger crossed while I'm writing this… not an easy task by the way
I still need some time to check all the alignments, but I'm positive I'm almost there. Yay!
Hi guys. It's been a long time... I had a lot of work and I didn't find much time for my Beogram: I had to fix some of my musical instrument first. But last week I took it off the shelf and put my full attention on it - or should I write her?
I couldn't get rid of a random fault: sometimes the arm rises up during play and returns home. I had the impression that it happens in certain spots, corresponding at 12" and 7" record diameter, but at times the whole record plays without stopping. I HATE random faults...
Reading service manuals and tech descriptions, I focused on LED 4D1 and photo-transistor 4IC1. After checking out solder joints on transistors 1TR16, 1TR17 and 1TR18 and cleaning the ruler, I removed the LED and found a broken leg... Of course I don't know if I broke it or it was already, but I believe it was a good idea trying to replace it, so no regrets
On Menahem's PDF about 4002 restoration I found this quote:
I replaced the 24V 25mA lamp (IL1) with an opaque white medium-intensity 3V LED. This light from this LED is highly directional, and much more intense than the original lamp. So the Photo-transistor, on my unit a Motorola 2N5779, should be able to sense the light more precisely now.
I guess I can apply it to my BG4004 too, but I'm not sure: is it possible that 4D1 was an infrared LED?
Any suggestion is highly appreciated. Thanks in advance.
Oh, I got another important question for you guys.
The sound of my MMC20EN is pretty dark... no high end at all. Could it be a bad symptom ?
I'm using my old Marantz 1040 for testing, and I know the RIAA preamp is fairly cheap, but I tried another amp - a '90s Onkyo - without noticing any difference. Of course I'll wait until the restoration job is complete, then I'll connect the BG4004 to my Yamaha preamp and I'll run some A/B tests with my Thorens/Shure couple. But I feel something's missing above 8000 Khz or so... Such a pity I don't have a frequencies test record anymore
In any case, last night I spotted on eBay this pair: BG8000 & BC8000 for 250 euros. Needless to say, I contacted the seller and I'm waiting for his mail. Guess I've been severely infected by the B&O collector's disease
Finally I've made it. It works. It's been a long, hard battle but I won.
Replacing the broken LED with a new one fixed the random thing... the arm didn't lower any more
I knew for sure there was some bad contact somewhere on the main board, but it was hard to find. Trouble was, I had to take off the plates and the belt every time: then I thought about the "extender boards" I was using back in the studio days to fix mixers and tape recorders, and I got the idea...
As you can see, I removed all boards from the chassis. I had to "extend" only the motor and the arm board connectors: the other plugs were long enough to reach the board without extensions.
Then I was ready to check the main board... It took a couple of hours, but finally I got lucky, hitting the weak spot: a bad contact on R62, in parallel with C28, where the low pulse is sent to the electronic switch. When I heard the solenoid "click" I couldn't believe it...
I played a couple of records without problems, then I put everything back in place and I started listening to my old LPs...
Time to sleep now: tomorrow I'll check the mechanical adjustments.
Many thanks to Martin-DIllen, for the schematic diagrams, the service manual addendum and of course the belt.
Good job and thank you for posting, The follow ups often are missing. Lets "hear" how it sounds tomorrow
Perfectly possible that 4D1 was an IR led. It was on model that I once had.
Søren Mexico: Good job and thank you for posting, The follow ups often are missing. Lets "hear" how it sounds tomorrow
You can hear it and watch it downloading a short movie from this link
https://dl.dropboxusercontent.com/u/793661/beogram2.m4v
Actually the lab is my favorite listening place: I guess I'll keep it there for a while, though the main hi-fi system is upstairs.
I still believe that the cartridge sounds "too" warm... On certain records it's ok, but sometimes I really miss the high end. I'm a musician and I spent years in recording studios, nevertheless my ears are still working well
joeyboygolf: Perfectly possible that 4D1 was an IR led. It was on model that I once had.
Yes, it's possible. The new LED is very bright, I don't remember seeing such a light from under the arm.
Maybe I'll try to replace it, sooner or later. But it's working, and that's what really matters (I'm crossing my fingers and touching wood while I'm writing it).