[alf]

Thise measurements are as follows:

C3+ = 28.8 VDC

IC1 In=112 mVDC, G=0, Out=0

3TR5. E=0.130 VDC , C=0.220 unsteady jumping, B= 0

just an observation:

looking at the PS board of BC5500 I see a jumper in series connecting the track coming from rectifier to Input of IC1 instead of a resistor (R11?)

this board looks exactly the same as the one for the BC7000 except no jumper but R11?

ALF

 

 

[alf]

Sorry about the double reply – the last one is the one that should be there.

ALF

[alf]

Had another look at the PS to see why the 5V regulator isn’t getting enough voltage at its input.

there is a resistor R11 about 1MOhm (?) which can’t be found in any of the circuit diagrams listed and I begin to wonder if that resistor is actually out of spec, showing about 6VDC on the entry side and next to nothing at the lead up to the regulator input?

was the circuit diagram altered for the BC7000 model ? Martin might know ?!

looking at the IC7805 spec sheet its input voltage should be 7 – 25 V, so R11 would act as a input voltage limiter for IC7805 , correct ?

ALF

[alf]

Had another look at the PS to see why the 5V regulator isn’t getting enough voltage at its input.

there is a resistor R11 = 22MOhm (?) which can’t be found in any of the circuit diagrams listed and I begin to wonder if that resistor is actually out of spec, showing about 6VDC on the entry side and next to nothing at the lead up to the regulator input?

was the circuit diagram altered for the BC7000 model ? Martin might know ?!

ALF

[alf]

Ok, strange things but:

I replaced the 5V regulator for good measure but it does not get any decent voltage input nor would it then deliver the required 5V.

the 1.5ohm resistor at the transformer measures spot on.
The voltage at D3/D4 is about 28.8VDC and D6/D8 is about 6.1VDC which is a new development.

I also checked for injured tracks – all seem fine but I can’t work out why the 5V regulator isn’t getting enough ??

ALF

[alf]

Ok, time for a confession ?

i do remember the marking on C3 = 2200uF was confusing but I thought I read it correctly…..no, I did not as it turned out and put it in the wrong way. That was the reason of many blown fuses in the power-pack. That is ow rectified after going over the whole board once again.

measuring on the power-pack across pin 1-2 = 6 VAC and pin 3-4 = 22 VAC.

at D3-D4= 29.8 VDC but at D6-D8 = 0.7 VDC which can’t be right ?!?!
Could this point to a leaky diode ??

I tested D5 to D8 but all tested ok quasi off-board. Well, in the end I had a nice day !

still, I am getting basically nothing at the pins on P2 or P3…..in other words, more help

is badly needed…..definitely no StandBy dot visible.

ALF

[alf]

i used the deck for years mostly with cassettes, recorded from a radio program.

during those years I owned the deck which is part of my 7000 system.

i say it AGAIN:

every component has been tested off-board from the PS-board…no adverse findings.

C3 has been replaced just recently and meets its spec.

don’t have the circuit diagram in front of me but I presume C6 is on the PS board – yes, tested at 9.1uF. and dto all rectifier diodes………

don’t i need two different DC voltages -two rectifiers, remember !!

ALF

[alf]

The PSU does not see the drive as P2 and P3 are disconnected as the link to

the rest of the deck – in other words it should not matter

ALF

[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

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