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    Need a new multimeter - any thoughts

    I'm afraid I agree with you. The last meter was from the local hobby electronics chain and lasted me very well with only a minor repair on the main terminal soldering. Its finally died with the screen showing only a few bars and defying attempts to reseat the contacts. Im amazed at whats...
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    Need a new multimeter - any thoughts

    So as a hobbyist i use the multimeter all the time. Unfortunately the display on my relatively cheap (then) Maplin sourced meter is giving up. I've been amazed just how cheap digital meters are nowadays. Does anyone have experience of Angeng meters - they are selling an amazingly low priced...
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    Pure Oasis DAB radio switches itself back on..

    So with decent battery voltage the Pure Oasis digital radio will switch off....then with a modest delay will switch itself back on. The switch itself is a momentary push to connect and appears to be working correctly. Although a trained electronics engineer I last practised in the era of TTL so...
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    Swingline nail gun semi ideas please

    Absolutely brilliant. Yes id found a patent application but you found the key one. Working my way through the circuit - so far replaced the cap and Q1 with no success but its not far now, looking at the SCR and Q2 - I suspect the gate circuit of the SCR got zapped. Many thansk, Julian
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    Swingline nail gun semi ideas please

    While the gun has no label remaining it appears to be the same as the 34201. Although it is stated as 110v the patent application from where the circuit diagram came states the circuit works 110-240v though with the addition of what appears to be the first capacitor as shown in section 12a to...
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    Swingline nail gun semi ideas please

    Unfortunately in good mass production style they have a thick varnish that obscures the markings.....
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    Swingline nail gun semi ideas please

    So had a bug in the system - literally. My nail gun shorted across the thyristor (a S6010L) to Q1 via a bug that took out the electrolytic C1 (50uf) and Q1 - amazingly despite fireworks everything else tests OK. The clue that the cap is gone is one half blasted out (!) and half of Q1 no longer...
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    Bang & olufsen Penta amp repair - circuit diagram needed

    Hi Martaine2005. No its none of those. I've messaged Beomanuals to see if they could help but no reply. If you go into those manuals you will see the circuit diagram relating to board 2 (marked 2-4) has a number at the top left....either 8002831 or 800165....my circuit appears to be a mid-life...
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    Bang & olufsen Penta amp repair - circuit diagram needed

    4 years ago I started the repair of a B&O Penta 6602 amplifier from the base of a speaker. Got the main circuit behaving but found a problem in the input board. Unfortunately having just dug the circuit board out from the heap of other projects I realise I don't have the right diagram. The...
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    B & O Penta amplifier repair and Tr equivalents

    Hi 73's de Edd. No its not those. On the original circuit diagram there's another board. On your schematic there is a heavy black line that B&O use to identify the boards. The main amp is board 1. The smaller input selection and sensitivity board is no.1 and has three slide switches. On the...
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    B & O Penta amplifier repair and Tr equivalents

    Situatio report. After a long break i'm back trying to sort out the penta amp. The amp section appear to be working nicely - but for a few seconds at best. I finally bit the bullet and took aprt the input control board - its labelled as section 2 in the diagrams. Unfortunately - the trs and the...
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    B & O Penta amplifier repair and Tr equivalents

    Hi Guys, sitrep. Replaced the semis and powered the amp up, Found the early stages of the amp performing correctly and the first pot adjusted voltages correctly. The power stages were a different matter with the voltages around MPSA 13 wildly out and the last pot having no impact on voltages...
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    B & O Penta amplifier repair and Tr equivalents

    Hi Dorke, should have said I did check for shorts between the rails, earth and output - all tested OK. The 0.5ohm power resistors tested OK. Those final (power) transistors fitted with insulation underneath had clear plastic tabs with thermal paste (not all). Construction of the back of the...
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    B & O Penta amplifier repair and Tr equivalents

    Have now installed all the semis excluding the final 3 pairs of power transistors. Am I right in underrstanding the feedback circuits via R83 & R88 from the emitters of the first pair of power transistors is to balance the circuit - so will not be upset without them (TR 25 & 30) being installed?.
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    B & O Penta amplifier repair and Tr equivalents

    Hi guys, apologies for the radio silence, thought I would wait till I had new replacement semis to test against. At this point I have to hold my head in shame....finger trouble and not checking the multimeter....so I was a tad surprised when having removed the semis then tested them they came...
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    B & O Penta amplifier repair and Tr equivalents

    So stripped out the semis back to TR3 (MPF4392). ALL THE SEMIS WERE BLOWN ! Would like to know how to test TR3 - not sure if the test meter on diode setting will work on this type (n-channel JFET). Once I know the fate of TR3 I will get the replacements ordered. Once D5 & D6 are replaced I'm...
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    B & O Penta amplifier repair and Tr equivalents

    Many thanks for the schematic - it immediately solved one problem of a seemingly mismatched pair of driver transistors. Looking further back down the circuit it seems only the bf423 and bf858 are going to be hard to source. More on Monday hopefully. By the way did your schematic have a parts...
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    B & O Penta amplifier repair and Tr equivalents

    Will check the stores to see what I have in terms of good kit to check against. Will probably get back after the weekend - might as well tear it down now and keep going back till I find a good semi !!. Shows the problem of not knowing the background to it. Next few days are getting busy - not...
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    B & O Penta amplifier repair and Tr equivalents

    Haven't measured out of circuit yet as bench space at a premium and the amp is a nightmare built into a hexagonal aluminiumheat sink. Bad news is I checked the next series of Trs (15,16,17,18) - all >200 ohms in each of the six measurements.Similarly the diodes (D18, D19) and the IC1 at the...
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    B & O Penta amplifier repair and Tr equivalents

    These are the values from the trs in the circuit board. The meter on diode setting shows O/L when over 200 ohms is detected.
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