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  • Re: Beomaster 8000 restoration #3

    Hi ALF, Is the distortion in one channel or both? 2IC6 is a good place to start. What are the DC voltages on the chip? I had a TL072 fail on the filter board 4IC2 on a BM8000 for no apparent reason, it was distorting badly. It failed after I'd changed all the caps, I replaced it with no other changes and it was all good. Regards Lonnie
    Posted to Vintage Products (Forum) by Lonnie on Fri, Jun 7 2019
  • Re: Beomaster8000 repair/resoration

    Hi ALF, Well done, mystery solved. I agree with you, the people on this group are a fantastic resource and I've learnt a lot from their words of wisdom. So... please don't keep us in suspense..... what is the next project??? Regards Lonnie
    Posted to Vintage Products (Forum) by Lonnie on Wed, May 22 2019
  • Re: Beomaster8000 repair/resoration

    Hi ALF, I'd go back to basics to see where you lose the signal. Starting at the obvious, do you have the external filter links in place? Using the FM as a source do you have an AC signal at R250 on the preamp board? You can used the leg of R250 that is common to R249 as the measurement point and the other leg of R250 as signal ground. If so, do you have an AC signal at R258? Use the leg that is common with connector P16(5) and the collector of TR203/204. If so, do you have an AC signal at R236
    Posted to Vintage Products (Forum) by Lonnie on Wed, May 22 2019
  • Re: Beomaster8000 repair/resoration

    Hi ALF, The replacement relay I used was: SPST, Coil: 24VDC, Switching Current: 10A@240VAC, Coil resistance: 880ohm. I found some 5A relays with a max current rating of 7A but decided to go with the 10A instead. The 5A is probably ok for the 240V version of the amp given that the fuse F2 is spec'd at 4A. You can buy it here: https://www.ebay.com.au/itm/24V-10A-RELAY-SPST-TYCO-EBERLE-SHRACK-AUS-STOCK-/180538893095 I've had a look at the power supply ON sequence and realised that the -23v is
    Posted to Vintage Products (Forum) by Lonnie on Mon, Mar 25 2019
  • Re: Beomaster8000 repair/resoration

    Hi ALF, The measurement on 7R1 should be an AC voltage measurement, can you confirm if that was the case? The anode of the diode 7D2 should always be at -23v or thereabouts. The cathode should be -23v in STANDBY and -02v (approx) during ON. Do you still have the -15v while in STANDBY? If you do do you have -23v at P51(2)? Regards Lonnie
    Posted to Vintage Products (Forum) by Lonnie on Sun, Mar 24 2019
  • Re: Beomaster8000 repair/resoration

    Hi ALF, I agree with a previous post of John's about faulty relays, I've also had to replace RL2 on a BM8000 I recapped a couple of years ago. I'd measure the collector voltage of 6TR18 after you plug the unit in and it's gone into Standby. It should be around -24v. When you try to power the unit on the collector voltage should increase to around -0.2v. If this happens and if you measure 0v at 7R1 then then I'd replace RL2. If the voltage doesn't change at the collector then
    Posted to Vintage Products (Forum) by Lonnie on Sat, Mar 23 2019
  • Re: Beogram 8000 main drive issues

    Hi ALF, John is correct, you can't have voltage at the emitter of 1TR20 if the collector of 1TR21 is properly grounded. Instead of just using a link between C&E of 1TR21 why don't you try a link between C of 1TR21 and another earth point like the negative terminal of C40. I'd try measuring the +/-15V supply with R82 added back, 1TR21 removed and adding a link from C 1TR21 to C40 earth. Regards Lonnie
    Posted to BeoGram (Forum) by Lonnie on Thu, Jul 26 2018
  • Re: Beogram 8000 main drive issues

    Hi ALF, Sorry, I thought you were indicating that the LED in the arm was on all the time. Re-reading you post you clearly say servo bulb. As Dillen indicated 1TR6 is fine so no need to remove and check. Regards Lonnie
    Posted to BeoGram (Forum) by Lonnie on Wed, Jul 18 2018
  • Re: Beogram 8000 main drive issues

    Hi ALF, Was the LED in the tonearm on during both measurements? Assuming it is, then 1TR6 is not being biased on properly and the only way for the LED to be on is for 1TR6 to be faulty. I'd pull it and test it. Regards Lonnie
    Posted to BeoGram (Forum) by Lonnie on Wed, Jul 18 2018
  • Re: Beogram 8000 main drive issues

    Hi ALF, John's explanation is correct, you'd have to take the switch out of circuit and re-measure it to see an open reading. You previously gave readings at P6-10 to confirm the voltage when the switch was open and when it was closed. Those voltages were fine so the switch is operating as it should. I'd be interested for you to measure the voltages around 1TR6 which controls the LED in the tonearm. What are CBE voltages during Stby and Play? I'd like to know if the uC is biasing
    Posted to BeoGram (Forum) by Lonnie on Wed, Jul 18 2018
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