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
Hi - I put this under a separate thread so it would be easier to find if someone else needed to reference this.
So my 4004 is now turning, it has had new trimmer pots on the main board, the relay was causing speed fluctuations and has been by passed pending a new one being installed (as per someone elses suggestion in another thread) However I am still getting speed fluctuations - tapping the fine speed trimmer seems to cause the fluctuation in just the same way as the relay unit did. Searching the forums this part is no longer available and in another thread someone suggested disconnecting it or bypassing it - does anyone know how to do this?
For the BG400X types with the DC motor, you can install two 470 ohm resistors, one between P6 pin 4- 5 and one between P6 pin 4-6 , disconnect the original wiring going to pins 5&6 from the front panel speed trimmers. (This will roughly simulate the front panels being set in the middle position as they are 1K ohm devices.) You'll need to re tweak your speed trimmers on the main board slightly to zero the speeds.
You could also probably just jumper pins 4-5-6 together, there will _probably_ be enough adjustment range in the main board trimmers to still allow you to zero the speeds.
If it's the fingeroperated one on the panel, you can clean it.Give it a shot of contact cleaner and work it back and forth a couple of times.
Martin
Hi both
Many thanks for this, I tried the above, but still have some fluctuations, changed the belt back for the original and this stabilised things much more, but it is still there
I think I have got as far as I can and don't want to risk messing it up - considering now seeing if someone wants to swap it or p/x and a few other bits for another decent non b&o turntable as the condition is excellent, just needs the electronics sorting!
Thanks again, really frustrating and may well come back to it again.
The motor bearings will be next. Clean and relubricate.
Thanks Martin, you've inspired me to persevere - I shall look at the motor this weekend
Regards
Andrew