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I have a model 2000 that I have been working onm replacing caps and checking resistors erc, getting rid of 2sc458 transistors. On the main amps I also replaced the 4 diodes with 1n4148...After getting the thing together I find that the center voltage can only be brought up to apprx 21 volts. The...

I am working on another 555a main amp board, the board is recapped, all resistors are in spec, transistors are ztx795, ztx694b, 2n3904, for t05's there are mj15003's. Initially I could not get the center voltage below around 33 volts, and the bias would not go below 18mV, the B+ is 58V. I...

Thanks Bourvil for replying. I should have said that both of these amps have been recapped, in fact the tone board in the bad amp is totally new, metal film resistors, electrolytic caps, transistors as well as film caps and ceramics. It seems to me that because the problem persists when I put in...

I have been working on a 555A and finally got the main amp to show good voltages, no fuse blowing and correct bias. I currently have another 555A that I rebuilt and which plays very well. The amp with the problems, I have coupled with the good amp in the following ways: Pre out on the good amp...

Alienz, yes I have replaced the trim pots w/ Bourns, this is the third 555a I have done, but I am not a technician, so really have no troublshooting skills. Today I replaced R843,845,844 and 846 with metal film .5 ohm 2w resistors, and since I had them I also stripped all the carbon comp...

Jon many thanks, this morning I got info from a friend who has a working 555a, his 813/814 base is .2 and the emitter is zero. I will look at that..

Thanks stereofun, I will give that a go today..

Hello I have been working on a 555A for sometime now, this included a recap of all boards and on the main amp replacement of the transistors using ztx 694 (8002-1) and 795 (9002-1), ksa 992 (xa495g) and 2n3904 (2sc281). Output transistors and TR815 are original and test good on an Atlas. All...

many thanks, I will use cap coupled

The switch on the AU517 which separates the pre amp from the power amp has 2 options, direct coupled and capacitor coupled. I have tried to find an owners manual which would explain this option, but have had no luck. What is the significance of this option?

AU519 F-2915 power supply and protector circuit problems. Initially I powered up this 519 without the output boards in place, after recapping and checking all components. The protector circuit worked fine and I was able to make the flat amp and equalizer board adjustments with no problem. I then...

Hello all, I have been working on an AU-505 and discovered some variations between the amplifier and the schematic. I am as certain as one can get that no one was ever inside this this, and thus certain this was a configuration delivered to customers, or at least one customer. First there is no...

Yes AU-505, I should proof read before posting I guess

I picked up one of these for less than shipping costs on fleabay. First off I have downloaded a service manual but it has no alignment instructions, so I was wondering does anyone know the bias current value, or alternatively the voltage across R843? Second issue is the output TO3 transistors...

Anyone know where I can find a service manual?

I haven't seen many posts about the 519. I purchased last winter a number of Sansui integrated amps intending to rebuild them when I became redundant..So I have now rebuilt 2 555A's, am working on a 317 and have finished a 517. A lack of parts lead me to finally open up the 519 and begin the...

OK will do, thanks. When digi key parts get here..

I reassembled my 517 for the second time, this time after replacing all the diodes, the transistor which drives the relay, and all fuse resistors and resistors out of spec. The amp is also completely re capped. When I turned it in I was able adjust both output boards to correct vales, and the...

OK, no I have not replaced the trimmers as of this date, I am a bit in the dark here. I am not sure what the wattage rating S/B and of course there is the issue of where the thru holes are on the board relative to the pins on the trimmer. So in essence I have no idea what Bourns part to order...

The amplifier is now working, replacement of TR805 and 806 did it. I want to thanks all that provided support technical and moral, this is a great place. Listening to this amp I find it particularly good with saxaphone and upright bass, much more to these sounds than the amp I removed (a Music...

Update, this AM I replaced the 4 transistors on the tone board, replaced the board, now the right channel is missing, yesterday it was the left channel missing. Only change was the replacement of 4 transistors on the tone board. I think I am going to inspect the socket which connects to the tone...

The main amp board is now configured with tr801 and 803 xa495g's are now ksa992fbu the 8002-1 are now ztx649b tr 805 and 806 2sc281 are original tr 809 and 810 9002-1 are now ztx795a tr 815 original The amp was able to be aligned using the voltage drop across r843. The main voltage is 61.6...

I checked the smaller fuse in the meter and it was blown. I guess from now on I will start in the 20A range. The bias current reads 1.4A and the pots have no effect. I guess for me the real question is why would it be so high? Would TR801, 802 809 810 and TR 803 804 807 808 cause this if they...

Many thanks to all. I think I will first install the ztx 795a and ztx 649b substitues and then revisit the alignment procedure. I have to say this is a wonderful board.

I am close to giving up on this amplifier. The main board alignment is not possible. I can set the voltage, currently I have 51V, so I adjusted the voltage to 24V, slightly less than half (using the ratio of 57V to 27V I assume the voltage adjustment should be a bit less the 1/2). However I have...