[alf]

Hi again,

i have tested all previously mentioned transistors inc. D25/26…..all tested fine – that’s the good news but still no +/-15 supply.

P2-9 sees about 25VDC. That kind if voltage I see at 0TR1 as well, no surprise here.

I am afraid John your worst “fears” seem obvious: I found 1 cracked track so far but it is a very tedious undertaking to find more.

there is definitely a connection issue after fiddling with P2 the table suddenly sprang into action.

i tried to minimise the degree of bent in the PCB by slightly shifting the uP box backwards but sadly that didn’t have an impact in terms of restoring function.

looks very much like getting the magnifier glued to the eye ball again……..

there is no point replacing 0TR1 as it tested ok – i also did check for OL but nothing showed up so far……

will get back shortly

ALF

[alf]

Hi John,

its been quite a while but from memory(?)  this was probably one I eventually shelved to be looked at again as other (easier) projects came in……

i know, that PCB is pretty terrible and not that flexible as it showed in various examples.

all those transistors I mentioned must have been tested off-board before but will be looked at again after I have taken out the board again plus without the Standby Dot present I would not expect to be able to turn on the Beogram anyhow.

will get back with further findings – thanks again for helping ?

ALF

 

[alf]

Hi John,

thanks for your input.

Looking at the circuit diagram, the +15VDC should be taken care of 0TR1/1TR18/1D25 and the -15VDC by 1TR19/1TR20/1D26.

the 5V regulator produces 5.06VDC which is also present at P6-1, so that’s ok.

As for the -\+15VDC I am only getting about +/-25.06VDC which is also present at P2.

it looks as I have to dig out TR18/19/20 and D25/26 for testing ?!

0TR1 = TIP32 tested ok with hfe=138.

ALF

 

 

[alf]

I am trying to follow the 12V entry for the drive, which I should measure at p16-4…..

but nothing anywhere near it.

I should also see 12V at the “emitter crosspoint” of TR37 and TR38…..nothing again.

both Transistors have been tested off-board as ok which made me believe I should actually see the 12VDC at that crossing or shouldn’t I ?!

i can see the entry voltages – 14.1V & 15.5V – at R171 and R172 …..so, what is it that I am missing here and why isn’t the capstan getting the 12V either.

the drive unit looks like being hard-wired to the control board #2.

ALF

 

 

 

[alf]

Is your glass cover broken or just scratched ?

i still have the glass cover  – it is good but not mint.

please send a PM so I can mail a photo and you decide them.

ALF

[alf]

i will have a second look at the colour rings of that resistor but the 4…..? could

indeed be right ?!

lots of other corners to check – the drive itself could have issues as well, although the capstan runs if fed by the benchtop dc power supply.

ALF

[alf]

Some minor development:

after the previous measurements it all made no sense. I took out that mysterious R11

and measured it…..OL !! Which explains why IC1 did not deliver the 5V.

i can not identify that resistors value as its colour markings made no sense – discoloured ??

I decided to replace the dead resistor with a 690 Ohm one for now which seemed ok as the BC5500 board just has a jumper in that position.

the display lights up, the drawer closes but shortly after the deck shuts off again.

the drive does not engage……meaning there is still lots more to check….☹️

ALF

 

[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

[Author]

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