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Leinster Lad

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  1. this is how it will look when on the board. About 10 mm clearance to the top of the case
  2. Hey folks a bit of an update. Substituted the bc550’a for bc546’s (higher voltage rating) , matched them real good ( ON semi from element14). And they made no difference to the output offset voltage. So now to the VAS. I’ve got some 2sa1142 and 2sc2682 which some folk over on diyaudio recommended as substitutes. Matched them up to within a bees dick. Currently making suitable heatsink for them. Lots of drilling and tapping and measuring and filing. Should work a treat !
  3. Depends on the circuit, but in 99% of cases it absolutely DOES matter where active and neutral go. Active(brown) - fuse - switch - transformer (or motor if AC synchronous) Neutral (Blue) - transformer (or motor if AC synchronous) REMEMBER, neutral and earth are equipotential at the M.E.N. which should be at the fuse box. Meaning that neutral conductors are referenced to earth. If you swap the active and neutral wires, something does wrong and the internal fuse blows, the chassis of the device will still be active !!! If you are not confiden
  4. No worries Andy, no need to buy 1000 of them as I can get them individually at Element14
  5. Thanks Suzy, that part number at mouser is in 1000 piece lots !
  6. Hi Suzy, I must be having an old bloke look, but for the life of me I cannot find the Faston 110 terminals that go into the board. Would it be possible to trouble you for the part number please ?? Thanks heaps David
  7. Thanks heaps Suzy, now to start planning ! ( well I am a between jobs (SAP) planner )
  8. Hiya Suzy, was wondering when this bigger version would show up 🤐 Really great that you decided to share with the DIY community Just one quick question please. The connectors used for the pwr and speakers ?? I've looked on mouser but there are so many that are similar, but not quite the same. I've measured with calipers and get 2.8mm x 0.9mm x 10.4mm long. I cannot for the life of me find the connector to suit ( the female one that would have the cables connected to it ) Could I trouble you for a part number please ? The l
  9. Also built a dummy load, switchable between 50 and 100 ohms ( 2 channels) to load test the pwr supply. Got a fan for cooling as well. @ 50 volts, it pulls 0.5 or 1 amp
  10. Just having a play with the scope, looking at the pwr supplies. Roughly 55mV RMS on each rail with about 180mV P-P. I also check my “rebuild” series 5000 and that was 35mV and 130mV P-P
  11. L R R11, 10.67V and 10.88V L R R10, 30.9V & 31.3V R13, 30.5V & 30.8V L R R7, 1.61V & 1.60V R18, 1.64V & 1.63V So, close but there is a bit of difference. I'm going to wait until the BC546's arrive and fit them. Then I'll check the voltages again. Measured the Vce on the BC550's installed and Q1 & Q2 are all around 49.5V = way too high, possibly causing a bit of breakdown ? (max = 45V)
  12. Did that and tried the other. Matched both hfe and Vbe to within a poofteenth of each other. hfe within 1 and Vbe exactly the same. Even with waiting for temp stabilisation. Managed to get the offset down from around 80mV to around 50mV The trimpot idea did basically nothing until the wiper dropped off the end of the track and went to zero ohms. That saw the offset drop to 18mV
  13. Thanks Alan, I did measure volt drops across those resistors that you mentioned when I first started investigating this offset voltage issue. From memory there was nothing of note to concern me. I will measure ( and record ) these figures again once I've replaced the BC550's with BC546's The offset that I have is 53mV and 62mV. It was around the 80mV range when I first got it. The 25mV is what DT specified would be realistic to achieve from the kit. I have had a bit of a look for alternative transistors for the diff pair, and the BC546 are t
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