Hi Alf, You are on the right track in checking the power supply voltages.  Follow those voltages to where they stop.  Is the +5 VDC reaching PCB 2 ?  What is the output voltages of the regulators for +5 V, +15 V and -15 V ? Check the PCB 1 connector pins where +5 V and +15 V connect from the chassis. -John

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    

Hi Alf, P2-2 should be close to +5 V, which you say you have. P2-9 should be close to +15 V 1TR21 controls power on/off from the uC.  Check the voltages around 1TR21 and if they are not good then check for broken traces. That PCB 1 board is very susceptible to breaks in the traces.  Especially at the bend in the board.  Every Beogram 8000/8002 PCB 1 board I have seen is bent (curved) from the way it mounts on the frame.  More than once I have had to jumper traces around the bend because of breaks in the trace. This was a Beogram you had previously restored to working condition, right? -John

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  

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

Hi again, so far I spend probably a couple of hours (incl. some needed breaks ) with various magnifiers to scan across the main board in search of broken tracks…….nothing to see ! going back to the elusive -/+15VDC search: At the anode junction of 1D21/D24 I get about -25.3VDC, at the cathode junction of 1D22/D23 I get about +25.3VDC. after having tested the involved TRs and Diodes to produce the 15V lines without any adverse findings I really have arrived  at a dead end …….! what kind of AC voltage  should I see at the junctions 1D21/D222 and 1D23/D24  ??? unless the board has suffered a particular nasty almost invisible hairline fracture  it looks even more like another shelving exercise ? so far only once very briefly have I been able to see  the -/+15 VDC by giving P2 a serious wiggle - that was when I suspected a connection issue but…., that is only good if it can be reproduced which I can’t , no matter what. the usual question, where from here  -Shelf of Multimeter ?? ALF

I would focus on the fact that you were able to get it working, briefly, by wiggling P2. You won't always be able to see a broken trace.  Check continuity between the related P2 wires/traces for where they came from and where they are going to. In other words, see that the output of 0TR1 reaches P2-9 on the board. On the board side check continuity from P2-9 to 1D25, 1C28 and other +15 V destinations. Also check continuity around 1TR21 (wiring/traces to and from 1TR21). Check that the grounds are good but it seems like the problem involves P2-9. John

Well John, this one looks like a very tricky rescue. Frankly, I am running out of idea what else to measure or check. sadly a repeated wiggling of P2 did not delivery a desired result. The connection between P2 and 0TR1 is fine, all grounds checked fine as well as continuity between points of -/+15VDC and their involved TRs, Ds and Cs. i understand there has to be a reason/source of the missing -/+15VDC lines. i even lifted the uP to make sure it sits properly in its socket - no impact. whether the voltage of +/- 25VDC after the rectifier is fishy I am not sure. fact is I have the 5VDC supply, P6-1 gets 5.06VDC which should make the uP happy. a long distance analysis is always tricky and I really appreciate your input……just -/+15 V would be nice to start ? ALF  

Your +-25 V off of your bridge rectifier is good.  That is what you should see at those nodes. How about continuity from 0TR1 collector all the way to  1C28 (instead of 0TR1 to P2-9 and P2-9 to 1C28) ? Have you connected up a scope and monitored what is happening at P6-4 (the on/off control signal) or right at 1TR21 base? John