BeoGram

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

Andre — Thu, 17 Nov 2011 17:21:01 GMT

Hello Gents

I'm sorry I missed all your valuable posts (it seems my auto notification got switched-off).

Yes, I'm still busy troubleshooting and must admit I'm getting a bit depressed about the situation as more symptoms are manifesting - the arm no longer returns, let alone drag the needle across the record etc. The keypad has all new switches and tests perfectly on all 7 controls out of the turntable etc and so on.

Anyway, I'm now looking at the possibility of non-functioning sensors. Menahem's LED + 1KOhm resistor mod works as the turntable operated perfectly with it. Although I don't suspect any of the sensor devices to be faulty, I must find ways to test to see if they work. The paddle (is that the slotted plate?) and the sensor device below - how would one test this?

I have already removed this device from the turntable and tested for continuity but this must have been an incorrect test. Instead, if my multimeter is set to Ohms and one touches the two leads, there is a resistance reading. If one shields the lamp? from light, the resistance reading changes.

The 3 other similar devices I retrieved from the scrap 4000's behave exactly the same. Can I therefore assume this sensor can be eliminated from troubleshooting?

Next, earlier this evening, I switched off all lighting in my workshop and photographed a LED-like device which appears to be a UV lamp.

The attached pic shows the lamp lights up if start is pressed. Do you think this checks out OK, looking at the attached pic?

The paddle/slotted plate and its mountings have not been disturbed and is tightly clamped to the arm base. However, it is possible that the plate may have been disturbed slighly upwards when I removed the sensor below. I will re-check this now and check its position according to the manual.

The oil there has been cleaned up completely. No longer an issue.

Thankyou once more for your valuable tips and input. I will follow them all until the problem is solved.

Regards

andre/dauphine

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

joeyboygolf — Mon, 14 Nov 2011 02:53:34 GMT

I am sure that this problem is a badly adjusted paddle and or detector at the base of the carriage tube.

It does not need to be far out for the arm to travel continuosly inward once the stylus hits the record.

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

chartz — Mon, 14 Nov 2011 01:53:28 GMT

Hi,

A couple of innocent questions:

1) are both arms parallel and at right angles to the deck?

2) how long does the pickup arm take to lower?

It seems to me that a bad sensor lamp would just bring the pickup arm close to the sensor arm and skip the same groove over and over again...

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

Dillen — Sun, 13 Nov 2011 16:37:31 GMT

Correct.
Those are the sensors. (The ones with four leads will track both ways!).
The lamp is a wedge socket type and should be very easy to replace.
It sits right above the interrupter (where the sensors sit below).

I often find a little oil around the screws holding the assembly and also between the
two plastic halfes. Nothing to worry about, unless it's really soaked.

Martin

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

Step1 — Sun, 13 Nov 2011 16:29:05 GMT

Your pictures show the light sensors not a lamp! The two above belong to a gram4000.

Also a blown bulb should not result in a the sled responding as you suggest, and oil should not conduct BUT if there was enough it could have acted as a light gathering lens in front of the sensor or something equally strange!

Put everything carefully and meticulously back and test again then if problems still persist start some proper troubleshooting or you will cause far more serious problems in my opinion!

What I would do in your position - remove platter, disconnect shutter lamp (the glass bit above the sensors), press start let arm go to play then see if the problem persists if not reconnect bulb and go from there, if it does disconnect sensor etc...

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

Andre — Sun, 13 Nov 2011 15:48:25 GMT

Hi Martin,

Thank you. I found these from the scrap decks. The lefthand lamps in each are still OK so I will use one of these. There could have been a bit of vibration or shocks over the months I worked on the 4002 as I used a very small plastic mallet on occasion to tap some of the top plates into position. I will avoid this from now.

I will also check the voltage which I think should be between 21.5 and 24Vdc.

Regards

andre/dauphine

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

Dillen — Sun, 13 Nov 2011 15:39:27 GMT

Lamps can blow and break for any reason, even from mere vibrations but with another lamp fitted
I suggest you check the voltage across the lamp, just to make sure it didn't blow
from overvoltage.

Martin

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

Andre — Sun, 13 Nov 2011 15:19:16 GMT

Hi Martin

Thanks

I've just checked. No continuity I will have to check the two scrap decks for a replacement.

Regards

andre/dauphine

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

Dillen — Sun, 13 Nov 2011 15:08:35 GMT

Put an ohmmeter across its leads and check for continuity.

Martin

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

Andre — Sun, 13 Nov 2011 14:56:06 GMT

Hello Gents

I am still troubleshooting the arm dragging problem and have been delving deeper into the heart of the 4002. I have removed this lamp? and found it and the surrounding area drenched in sewing machine oil. My fault as I am unused to lubricating turntables with Elna oil which is almost as thin as water (the dispenser belongs to my wife and she cut the nozzle far too much)! and the stuff ran everywhere it shouldn't have

I have just cleaned-up the mess and vacuumed and used compressed air to get the stuff out of the black box in the pic.

Is there any way I can test the lamp to see if it still works?

Regards

andre/dauphine

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

Andre — Sat, 12 Nov 2011 10:19:48 GMT

Hi Martin

Thanks, I know about ambient. The plates at one stage was completely fitted and the problem still showed up. Initial tests after fixing the 45rpm speed was done with the covers fitted. I was working in my workshop and with bright fluorescent directly above. I also had a 100W worklamp above which I switched off as soon as I saw what was happening.

During the weeks I played without problems, the plates were first just loose on top, then fitted properly and the light above were from 5 40W incandescent lamps. At this time, the platter was still not properly level and flush with the plates.

So after the 3 weeks or so while I 'rested' before tackling the 45rpm speed problem, all worked OK, despite the platter dipping slightly at 12 o'clock.

The other change I made was to insert the coil of brass shimstock and changed to another lubricant in the spindle bearing.

Therefore, 3 parameters changed. The 45rpm speed got restored, the platter is now perfectly level and flush with the top plates and, the bearing hole has been shimmed.

There must undeniably be a little more spindle bearing friction because of the shim. With the belt and top platter off, I can still spin the platter with a finger flick although I had to make small + adjustments to the speed pots.

After receiving your earlier comment about the original spindle bearing tolerance where I could move the platter say at 3 o'clock and 9 o'clock and observed (perhaps wrongly) excessive bearing sideplay as compared to my other turntables (Micro, Micro Seiki and Garrard 301's) - I think I will also remove the shim incase this could be causing a problem.

Except for the 45rpm repair, I think I will restore all revised settings to as close as possible to what it was when everything worked.

And of course look and double-check all the other possibilities you mentioned.

I'll let you know what I find.

Regards

andre/dauphine

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

Dillen — Sat, 12 Nov 2011 09:49:44 GMT

Ambient light may confuse the sensor (at least the original sensor - I am not sure what is in there now).
Have you tried with all surface panels fitted ?

Martin

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

Andre — Sat, 12 Nov 2011 09:06:00 GMT

Hi Martin

I really appreciate the advice and clues as to where to look. I got the same advice about the board I showed in the pic from a friend more qualified than I am. He advised those little bubbles on the 2 caps are just wax - nothing to worry about.

The present symptoms are dragging of the arm to the left and the tonearm traversing much too fast.

I had to take a short break but will return to the problem this evening and tomorrow.

I already had a thorough look at the interrupter which is held with a clamp to the arm base spindle? and everything is tight and clean there.

The cover plates are still off so I think I will take a close look at the main board incase I see a broken track or anything else under a 60X stereoscope I have.

The sensor arm's lamp is OK and I've got Menahem's LED + resistor installed inside the black cover. That also worked after installation and there's another UV? LED-like device with bent wires somewhere around this area which I'm not sure how to test.

I understand one can photograph it in the dark with a digital camera to see if it is emitting light, which I will also check this evening.

What is so strange about this problem is that absolutely everything except the 45rpm speed worked fine for weeks after I installed the main board after getting it back from Menahem.

I'll post here if I have news.

Regards & a fine weekend.

andre/dauphine

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

Dillen — Sat, 12 Nov 2011 07:51:21 GMT

I wouldn't worry too much about anything on that board.
I suggest you check the tracking circuit and related mech. as mentioned earlier.
It drags towards the left because it is fed a wrong signal from the tracking sensor, either
the interrupter has become lose from the tonearm base spindle, something went wrong with
the sensor or lamp assembly or the electronics are somehow misbehaving.
The tracking electronics are on the main board.

Martin

Re: Beogram 4002 Series 5511: Arm Drags Cartridge Across Record

Andre — Tue, 08 Nov 2011 06:09:23 GMT

Hi Martin

Both of the parts on the underside of the board shown above have signs of 'bubbling'. I take it then these have nothing to do with the arm dragging problem? I will have to re-study the manual and familiarise myself with the tracking circuit.

Regards

andre/dauphine