[Gravity Graham]

Having given up on my 4000, I have decided to work on the BG6000 which I have.
It runs well, and drops when it should, and can be run forwards and backwards with no problems.
The silent cct works OK, because sound comes out of the t/t when in play.
However, it is not tracking and requires the motor to be moved manually, in order to prevent it getting stuck in one groove.
I’m probably missing something, but I can’t seem to find any guidance in the manual ???
Any advice will be appreciated !!

[Mark-sf]

There is a bulb ? n a plastic housing at the tonearm base that burns out and we replace with an LED kit. You can see if it’s lit. If it is there is a shutter adjustment in the manual. It’s the same for the 4xxx series.

[Gravity Graham]

Mark-sf wrote:

There is a bulb n a plastic housing at the tonearm base that burns out and we replace with an LED kit. You can see if it’s lit. If it is there is a shutter adjustment in the manual. It’s the same for the 4xxx series.

Silly question - What is the identity number on the circuit diagram ?
Regards - Gravity G.

[Mark-sf]

It is OIL1; however, that is not as important as its location which can’t be determined by the schematic since it is not board mounted. It is under a black plastic cover held by two brass screws directly to the right of the damping cylinder.

[Gravity Graham]

Thanks Mark – found it ! Will check it later today !

[Gravity Graham]

OK Mark – checked it and it’s lit. However I now have a different problem, with motor control….
It does everything except return or Stop !
I suppose the next thing is to remove the main board, and check the Darlington pairs & diodes !! Onwards and upwards as they say !!
Any known problems with this model ??

[Mark-sf]

When you say “return and stop” do you mean if you press Stop during play it does not return or only at the end of the record? If the later that is typically a leaf switch problem as these easily corrode or get out of adjustment. Do either the “>” or “>>” work when the are is cued up? If they don’t then I would look at the electronics focusing on the caps first.

[Gravity Graham]

Hi Mark, I can cue forward (< or <<), but not return (> or >>).
If I press STOP, it does stop – but does not return.
When it reaches the centre of the TT, it stops, but again refuses to return.
At least on this the electronics can be unplugged for testing, unlike the 4000 !
I think you may be right about the caps – might start by replacing all electrolytics as they are a good 30 years old !!
Tks – Graham

[Mark-sf]

Actually, those caps are almost 50yrs old so they definitely are a recommended starting point! I would then check closely for the listed voltages on the transistors in the servo motor circuit as it could be a bad transistor, diode or simply a broken solder joint or trace.

[Gravity Graham]

Work is progressing slowly ! The power supply electrolytics have been replaced, but still awaiting delivery of electrolytics to replace all the Tantalum capacitors on the PCB’s, before I proceed any further. I may take the time to remove and check the transistors and diodes in the motor circuit…

[hcraig244]

Some pics would be good Graham….

 

[Gravity Graham]

Sorry guys – been a bit busy, working a different turntable (65 ft diameter)..
I’ll post a couple of pix, hopefully tomorrow (Monday)

[hcraig244]

Gravity….

Martin (the oracle of all BG4000 knowledge) would frown on replacing the tantalum capacitors with electrolytics, he did explain the reason for this in a previous post of mine when I performed a similar restoration on a BG5000, I do know there are advocates of the replacement with electrolytics (Rudi) however I went with Martins advice and put new tantalums in. You should replace the old electrolytic capacitors with new as they will have dried out and as Christian says change out the skeleton trimmers for new piher sealed trimmers, do this one at a time measuring the settings of the existing one (as best you can) and run the deck, adjusting the trimmer if required, to ensure all is well before moving on to the next one….that way you will know just where to look if things stop working (poor solder joint etc)……so far so good ;¬)

Craig

[Gravity Graham]

Here are some pictures ! TR22 was u/s, so changed it out while replacing the Tantalum capacitors.
I also switched out the supply filter capacitors (old electrolytic) – for 2 separate new electrolytics (The 4000uF was replaced with a 4700uF at this point).
All back together and working (ish) – Still need to fix my BeoMaster 1900 !!

[spassmaker]

Congrats!

“WISE GUY MOD ON”:

When you used shrinking tube at the reservoir caps, why did you not put it over the soldering?

It’s a 4700 uF, keeps a lot of power inside when you touch chassis ZAPP!, don’t ask me why I know ;-))

I’m missing the clamp for the cap, maybe with some feltpad underneath to get it tight fit.

I would have mounted new pots on the mainboard while I have the unit already open. The speed trimmers could be precize spindle trimmers so it’s easy to get the right speed at 33/44.

“WISE GUY MOD OFF”

Kind regards

Christian

[Gravity Graham]

Hi Spassmaker – it’s not shown in the photos, but the terminals of the reservoir capacitors have been masked with ‘black-tack’ which will keep them well insulated. Thanks for your concern. They are also held in place by ‘black-tack’.
and to hcraig244, while working on field survey equipment in Houston, if a PCB came in with ANY fault, we always changed out any tantalum capacitors for electrolytics as a matter of course before sending it back out. Even though opinion is divided, I decided to go with that rationale. And as regards the trimmers, on that point I personally like to go with the adage of “if it ain’t broke – don’t fix it” as they are working fine.

Gravity G.

[hcraig244]

Best if you dont apply that adage to the cam belt on your car ;¬)

Craig

[Gravity Graham]

I’ll give you that one Craig ! 😀

[hcraig244]

this is the adjustment for a BG4000……..

[Mark-sf]

The section hcraig244 posted is correct.

[Author]

Posts