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
Taking Sonavors advice Justin (Bulldog) asked if I would take a look at this.......I cant resist a challenge and I'm not doing much just now so have agreed to take it on..... when I say "me" I mean the forum of course ;¬)
It comes with a couple of kits from Rudi.......Capacitors and laser printed bracket along with two sets of LED conversions for the control panel
Along with a list of issues as follows:
* only playing in one channel right now * from time to time tracking arm drops before it reaches the platter * sometimes starts in 45rpm automatically even when 12” is on the platter * drive belt rubs agains the guides making noise * low level hum from unit someone has changed out a couple of capacitors already
Using the variac powered the unit up.......pulled very little current
running at 33rpm with no platter or drive belt I cannot hear any low humming noise, everything seems to be operating within pre defined parameters.....as I have a a couple of drive belts spare I tried one and run it back up.......no rubbing against the guides either.
There is a little scorching on the fuse sleeve of the power supply PCB...I've seen this before, the only real issue I can find is there is very little damping on the pickup arm....it drops onto the disk with an alarming clatter....and when playing a 45 disk it misses the start altogether and falls short, fortunately the pickup adjustment is good and the stylus doesn't hit the platter ribs. I have yet to check out if both left and right signals are present, I will look into that next...Its looking like a good clean of all the switches will sort out a lot of the intermittent issues.
Craig:running at 33rpm with no platter or drive belt I cannot hear any low humming noise, everything seems to be operating within pre defined parameters.....as I have a a couple of drive belts spare I tried one and run it back up.......no rubbing against the guides either.
Regarding Justin's report of only receiving a single channel from his unit I have checked continuity from the 5 pin din plug back to the pick up arm, had to operate the solenoid manually to this due to the grounding of ths output signals when the solenoid is de energised.....to my surprise I found this inside the pick up.....not seen this arrangement before.....my previous repairs have involved individual wires from the entry point to the stylus connector?
The continuity from the 5 pin din to the brass tracers on the underside of the connector shown is good....I'm suspecting a poor connection on the female side of this arrangement deep inside the pick up arm.
Having cleaned and re assembled the pick up arm I have proved the continuity from the 5 pin DIN through to the stylus connector on the end of the pick up arm.....so I did what I should have done at the beginning and tried the stylus on one of my 4000's and it performed flawlessly.....
A little befuddled I turned my attention to the 5 pin DIN plug, the clear wire loops perilously close to being proud of the plastic pin mounting assembly, making me think that when assembled the wire may be touching the outer case thus sending the signal to ground.....diffucult to get a good picture of it.
This said I went ahead and replaced the stylus back into the pick up arm and with the 5 pin DIN cover still removed hooked the deck up to my Beolab and gave it a go.....I was rewarded with both channels operational, however the hum reported by Justin accompanied the output to the amp, grounding issue.....
So...I have insulated the suspect terminals within the 5 pin DIN plug and re assembled it, soldered a link to connect the signal ground and system ground together and had another go...works perfectly now with no hum and both channels functional...I'm very happy the hum wasn't down to the transformer. Let it run for half an album and I'm thinking once I have sorted the pick up arm damping I will be ready to start replacing the aging components.
Martin
Do you have a kit for the 4000....caps and trimmers etc to include new belts? I think the belt rubbing on the guides was probably down to the wrong drive belt fitted (too long). Justin has sent me a kit for the big capacitors so I dont require those.
Moving on to the tone arm damper I have dismantled the assembly and discovered there is no adjustment on the valve that controls the flow of air into the cylinder.....the adjuster screw is screwed all the way in and wont come out.....someone has had a pop at this in the past, thought it looked a bit far in on first inspection.
However.....all is not lost as I happen to have a spare cylinder sitting in a 4004 assembly I acquired some time ago....I'm confident it will fit.
Identical.....
Installed the replacement into Justins machine, set up the switches and gave it a go.....works perfectly now, arm lowers in a controlled manner.....its still falling short on a 45rpm disk however, so that will be addressed at the same time I clean the slider switch contacts.
Time to unravel this lot and replace them with Rudi custom made mounting assembly.
All gone...
Here's Rudi's parts ready to go in....
Rudi's brackets are a very good solution and a good fit.......
I like to run a test after each of these steps, it makes it easier to go back and identify any blunders if you know the points at which everything worked fine following surgery......so far all is well
Next up Rudi's LED conversions for the control panel.....straight forward enough, chose to use the wire connectors as opposed to the pins as I thought the pins would be more fiddly
And powered up....
Control panel switches followed......for most of these I left the leaf in place and just un soldered the saddle, I decided to try out a glass fibre pen to do the cleaning after seeing a video by Rudi.....nice and gentle and very effective.
However three of the leaf's had to be removed due to the contact side being underneath or in the case of two of them double throw....
Finished panel ready for re assembly and testing....
Tested good....all switch functions are working well.......
New belts arrived yesterday....compliments of Dillen.
Slide contact switches next up........
i noticed these switches where quite sticky, not as free as they should be....this has caused me problems in the past when i used silicone grease on the buttons thinking it would lubricate them and make for better operation, it actually made them stick....so I have given these a clean with alcohol and will leave it at that.
As with the control panel I have removed the saddles and cleaned the brass strips in-situ, with the exception of the one NC contact that has to be unsoldered...one down four to go
Re installed the slide switch assembly and set up the switch (B) that controls the 17cm drop position as it was missing slightly when dropping......all good now. Moved onto the main PCB and replaced the 33 and 45 rpm trim pots with bourne 25 turn pots for better adjustment....always a bit fiddly these, added some heat shrink sleeve too.
Craig:Re installed the slide switch assembly and set up the switch (B) that controls the 17cm drop position as it was missing slightly when dropping......all good now. Moved onto the main PCB and replaced the 33 and 45 rpm trim pots with bourne 25 turn pots for better adjustment....always a bit fiddly these, added some heat shrink sleeve too.
No I only use the 25 turn pots on the RPM trimmers, it's something I picked up from Rudi (beolover)...stands to reason that a 25 turn pot will be more sensitive than a single turn pot, I do however use them for the quiet current trimmers in Beomaster amplifiers...I seem to remember Rudi stating that they are less likely to go open circuit due to the mechanical design than the single turn components......i dont know how this works but it always sounded like a good idea to me......
Craig
Replaced the suspect ROE capacitors.....tantals next while I wait for the piher pots to be delivered, seems to be a bit of a shortage of some values recently.
Good job!
However, I for one hate those multi-turn pots.
I never know where the central position is. Plus you have to adapt them to the PCB's which is plain ugly.
I always go for quality potted cermet Pihers for example (the white ones) which are very stable. And at least I know the cursor's position!
Raplacing electrolytics and tantalums (tantala? ) is a must do, but honestly on Beograms they keep their value and ESR, I find. I always measure the old caps out of curiosity and they are usually perfectly okay.
In amps, however, that's another story...
Jacques
Yes, good work as usual. I like the multi-turn trimmers for no-load current adjustments on amplifiers and for the Beogram speed adjustments. The fine dialing in of the value is really nice. I use single turn trimmers for adjustments that should only need to be set once.
-sonavor
New single turn trimmers delivered and installed.......I haven't seen white piher trimmers for sale anywhere in the UK?
Craig: New single turn trimmers delivered and installed.......I haven't seen white piher trimmers for sale anywhere in the UK?
I don’t know. I buy them here in France. Digikey have them.
I just love this gadget I acquired from Rudi.....bit of an extravagance I know, but I do like it