[alf]

Absolutely correct Martin as it was before !

thanks for asking…..

ALF

[alf]

ok, here it goes:

the PS board is isolated from the rest of the deck incl the tape drive.

just a side issue:

i checked the capstan motor function with a benchtop ps independent of the

powerpack and is was running fine.

i can guarantee the bulbs would come on – so far I blew at least 5 fuses, and they were the correct ones.

ALF

[alf]

Ok,

i am back on the BC7000 after receiving a replacement powerpack……sorry to say,

but Glitch was right in assuming the powerpack is ok…..and as far as I can tell it is !

here is what happens:

if I plug in the naked powerpack I measure about 6VAC across pin 1-2 and about

22VAC across pin 3-4.

the moment I connect the powerpack to the PS board its fuse blows – p2 and p3 are still disconnected.

so far I have not found a faulty component on that board nor a broken track that may be responsible for  the constant  blown fuse in the powerpack ???

every single component I tested was fine which begs the question ‘where from here’ ?

Obviously there is a problem I can not see nor measure.

ALF

[alf]

Ok,

transistor 2TR6 has been relocated as recommended. Sorry, I would have posted a picture but I do not have the appropriate photo software compatible with this forum.

my ipad takes excellent photos but they are all too big for uploading.

The erratic issue seemed to have been related to the switch next to the solenoid.

as mentioned, the contact must have been insufficient between the pin and the leaf spring (closest to the spindle) so I adjusted the pin.

so far the Beogram hasn’t missed a beat and I begin to feel cautiously optimistic it may have fixed the erratic behaviour ???

ALF

 

 

[alf]

I will have another check at those set of contacts (as I have done before).

the BC119 transistor is on order, heatsink I got – that should not be too hard, only takes time until it arrives.

fairly confident the 0TR4 = Tip41 is ok. I had another good run, basically no problems

until the sequence came to an end with the carriage moving in, stops -as described- but no lowering…..

ALF

[alf]

Many thanks for the picture – I will do that.

the unit’s most prominent issue seem to be that the carriage is moving in after ON is activated, stops at the drop down point but nothing is happening.

in that case I can “finger-operate” the solenoid and everything is fine. The lowering can’t be blocked as the solenoid would otherwise not click in.
Does that mean the 24VDC is not getting to the solenoid when the automatic lowering (drop down) should occur ?

ALF

[alf]

Hi Nick,

thank you for replying. The BG is plugged into mains constantly. The main board has been recapped as far as I remember but will double check. Most morning I just activate play and it works but as said: most times, not all the time.

I got some reed switches and may consider replacing the existing ones if that indeed could cause those issues.

just drives me mad, every time I put the alu decking back on it is playing up….meaning

the BG has its “bonnet” open at all times for now.

i shall report back once I found something fishy. The last post quoted Martin, having suggested to move the voltage regulator (2TR6)  from board 2 because of heat issues?!

ALF

[alf]

No silly Q at all Nick, yes the servo belt is fine. I am just questioning the mentioned issues caused by silicon spray ??

i have never observed any issues with it like sticking on plastics etc.?? What I will do is getting all the plastic nipples out and wash them including their holders.

the reason I am sceptic is the BG works fine for a number of records and then all of a sudden something is happening and I wish I’d know what ?

ALF

[alf]

Well, two ways to interprete:

on its way out = about to die

on its way out (in) = approaching the drop down point, drop and play a record.

just today I played about 6 or 7 record sides in succession over the course of the day

and the BG hasn’t missed a beat…….?!

which means precisely nothing as it is just as likely to fail at the 8th records.

that is exactly the issue here.

of course I can keep taking transistors off the board and checking, cleaning switches but i do not believe that will cure it. Simply put: some component isn’t playing ball !

all I wish for is a consistent fault.

ALF

[alf]

That is a interesting point – I actually used silicone spray for those plastic nipples not just at the carriage switches but on the keyboard switches as well….but I never had that trouble with other Bg4000 tables ??!

ALF

[alf]

Hi,

i am not quite sure what exactly you mean – please go to the service manual, check the explosion drawing and tell me the part number.

ALF

[alf]

I sense you are a sceptic in regards to the transformer being all but dead….but a transformer that gets 244 VAC input and basically nothing coming out I would at least call “a problem” notwithstanding the presence of possible other faults ?
I only repeat myself when stating that no other suspect components on the power supply board have been detected……

the promise of reporting back is a certain once the replacement powerpack has arrived.

many thanks for getting on board to help – very much appreciated ?

ALF

[alf]

Sorry but the multimeter does not lie !

I measure incoming mains voltage which is  244 VAC .

what I can measure across P1 pin 1 to 2 and pin 3 to 4

are about 0.015 to 0.020 VAC and that is the sad fact.

I still believe that powerpack (transformer) is not working as it should, in fact

It probably died a slow death ?!

luck had it that I was able to purchase a replacement one from the UK….so it will take a while till Work can resume.

ALF

[alf]

well, I believe my last measurements were measured correctly.

I can not imagine the deck to work with these kind of voltages, can you ?

there is still the unanswered Q :

is the powerpack (transformer) working according to its specification ?

i checked basically all components on that power supply board (3) without any

further defects.

ALF

[alf]

The AC voltages as you suggested are around 0.018 VAC  P1 1 to 2 and P1 3 to 4

when the transformer is disconnected from board 3

does that make sense ! Sorry about the confusion

ALF

[alf]

Ok, another voltage check:

looking at the disconnected transformer and its Plug1 voltages

Pin1/2/3/4 = 42 VAC

looking at the connected to board3 via Plug1 – Plug2 and 3 were disconnected !

pin1 = 5.6 VAC, pin2 = 5.5 VAC, pin3 = pin4 = 0.08 VAC

I do not get  5 VDC  nor 22 VDC

grounding Plug2 pin2 via neg of C3 delivers nothing (unless I misunderstood you)

are you still quite confident the transformer is ok ?

ALF

 

 

[alf]

Thank you very much for trying to help – much appreciated !

i really don’t know what the current draw is or should be in that circumstance.

the way I tested or checked was to isolate a possible transformer issue from the rest of

the deck by unplugging P2 & P3 which are supplying the rest of the deck, in other

words the only connection from the power supply to the main deck.

so, it is really only the power-pack (transformer) connected to board 3 which should

deliver the 5V, 14.8 V and 15.5V supplies for the deck but it doesn’t.

there one last thing I will try and report back.

ALF

all main components involved have been tested off-board.

[alf]

As another check I disconnected P2 and P3, which are the supply lines to the deck.

so I must ask again:

what makes the transformer secondary AV voltages almost “evaporate” when

that transformer is connected to board 3 where its AC voltages are getting

rectified to DC ?  Which load exactly is there ?

just like to understand – thank you

ALF

[alf]

Well amongst many things I do not understand this is certainly amongst them:

the transformers secondary delivers AC voltage to the rectifier diodes….so how can that be this AC voltages can be lower before DC voltage is supplied to the rest of the circuit?

so, lets assume there are 40VAC delivered to the rectifier, turns into 5 VAC before getting rectified ?? Sorry, don’t get it.

the transformer’s fuse blew as well.

looks like I am missing something here, or do I ?

ALF

[alf]

I had another check at the transformer and its connection to board 3:

It secondary pins show AC voltages  of up to 40VAC when disconnected from board 3, but all those voltages seem to break down to levels of 5 VAC  and less the moment the transformer is connected to board 3 via P1.

so, is this transformer faulty or is it a plausible reaction because of a problem elsewhere?

bottom line is : the deck does not work

ALF

 

[Author]

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