hcraig244
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Martin aka Dillen will sell you a complete set of capacitors and lamps for this unit, not sure what he charges these days so you need to send him a post…….however replacing capacitors may be just the start………first thing would be to determine if it actually works prior to replacing anything, most problems can be resolved without spending a fortune and these amplifiers are well worth restoring
Craig
Ok……so what did you replace? I’m guessing capacitors and maybe trimmers, double check the polarities of the caps you changed, it’s easy to get one in the wrong way around
Did you replace the tuning lamps?…..I haven’t worked on a BM2000 but I do know that if one changes the lamps on BM4000 they must be the correct mA rating or it causes issues with the rest of the circuit….Dillen (Martin) from the site may be able to supply the correct lamps if thats the case…
Craig
Looks like the nozzle from a windscreen wash, I bought a wine bottle vacuum pump when I was considering infusing one of my BG4000 motors….however when i put it on test and mapped it using one of Rudi’s tachometer devices, downloaded the readings to Excel to produce a graph I found the speed was very consistent so haven’t tried it yet. It’s something I will do when the time comes more out of interest than anything else…
Best if you dont apply that adage to the cam belt on your car ;¬)
Craig
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
Sounds like a problem with the servo…..the shutter adjustment could need adjusting. Silver members can access the service manuals which describe how this can be carried out, I haven’t done much work on the 4002 many in here have….im sure someone will advise you further, my advice is to go silver and download the service manuals
Craig
Dave
I will run it periodically before you come and collect….if it happens during those tests I will document it here ;¬)
Craig
Never use WD40 for anything other than blinding burglars ;¬) deoxit seems to be the solvent of choice in this forum….I used to use servisol until I converted…….
Craig
“The first is at the base of 1TR14 and the collector of 1TR17”
Looking at the schematic I dont see a point showing a scope reading at the collector of 1TR17 ?
The main forum product section contains manuals for the BG4000 and also some training notes donated by a member who was a one time repair engineer who went on a training course and reatained the course notes…..these notes identify the abbreviations and are a very usefull guide…..they are available to silver members and above, take a look…..do you have a transistor tester available?…….seems like your machine is only a short way from being sorted…..
Is the platter spinning with the tone arm over the rotating ribs in the scope readings?…..looks like it is….so the photovoltaic cell looks like its still working, good news.
Are you sure the readings are taken at the points you identify above? and as the tone arm will drop under some conditions then the solenoid and associated linkages/damper pot etc are all working, more good news.
I think the potentiometer you refer is the one installed to enable playing transparent disks? does the tone arm stop at the correct place when a disk is played….or just run to the left side then run back to the rest point?
Craig
All reassembled and functioning flawlessly………very odd. However I will fire her up again from time to time and see if the issue returns…..I still suspect a sticking switch or switch nipple on the control panel.
Craig
Had a look at the leaf spring contacts and they look clean, gave them a squirt of Deoxit non the less…..once dry I will re install the control panel and try it again….I do recall having issues in the past once the panel screws are tightened down, i think if they are not evenly tightened they flex the PCB causing erroneous signals…….
Well……..got to this today, removed the control panel for a visual inspection and all looked fine, ran her up and she works perfectly?…….
Alf
The service notes say “speed switching (33-45rpm) is performed by altering the values of R1 and R2 so that the oscillator frequency will be approx 42 and 59hz respectively” seems to me if everything works fine on 33rpm that the oscillator is working fine, could be wrong of course…….have you checked the trimmers and associated solder connections?
Craig
