January 7, 201511 yr turning the pot to max is the same This. I didn't notice that my 717 had a bypass switch.
January 7, 201511 yr This. I didn't notice that my 717 had a bypass switch. I didn't notice that your 717 had such thing... Lux Aeterna. Edited January 7, 201511 yr by Sr Marqués
January 7, 201511 yr I now have practically all the bits and a half populated power supply board. I have a question about Q9,10, 13 and 14 in the power supply. In the BOM I have, this is a 2N3904, and the bom I have gives a mouser part number 863-2N3904G, but this was not available, so I ordered a 2N4401G instead. This has similar technical data, except max voltage collector emitter (3904=0.3V, 4401=0.75v), collector dc current (3904=0.2A, 4401=0.6A, and probably most importantly, hfe min (3904=60, 4401=20). As there is a large variation in hfe, am I OK, or will it be mucking up the biasing to use the 4401? (I have probably already answered my own question, as I have decided not to risk it, and to order 3904). I also have a question about the caps on the +-15v supplies (C11, 12, 13,14)– in the BOM these are 4700uF 25v and 100uF 50V – on the PCB of 3300uF. I am assuming that it won’t make much difference; I am just wondering if there is reason why the PCB states 3300uF (other than those parts were available) Finally, the BOM lists 2 x 3900pF, with no circuit reference, and no voltage, and states they are “optional”. Where do they do and what should the voltage rating be? There are quite a lot of errors in the BoM I have, for example, some quantities are incorrect (which I failed to spot before ordering), and the Mouser number for the fast switching diodes is the uninsulated (incorrect) package. I’m just sending these back in exchange for insulated ones. I’ll set out an errata list and where I got the BoM from Any comments will be much appreciated! PS – I have some 4% silver solder, but am using standard 37%PB from Balver. I was thinking of using the silber only on the connections. Should I steer clear of using it on the boards?
January 7, 201511 yr I used 4401g without issue You can look at different revisions of the boards, those cap values are all over the place. Use whatever fits, or stuff that is fancy. I think I had leftover fine golds from the krell that I stuffed there. I think I had 1kv for those 3900 pf spots, but my memory is a bit fuzzy I've used the board as a "golden" reference and it hasn't steered me wrong for 95% of the time. The remaining 5% is usually quickly sorted out by Kevin and/or Birgir.
January 7, 201511 yr Board is always correct, the BOM probably isn't. I moved to smaller caps in the LV supply to save space when I did the KGSSHVk boards. A 500V 3900pf will work especially with the 270V zener in place.
January 8, 201511 yr This. I didn't notice that my 717 had a bypass switch. You take off the cover and there's a switch on the right hand side of the outer case, it's marked.
January 9, 201511 yr I am having some difficulty setting the offset. I have the v0.6 PSU (450v) and v0.6 offboard amp boards. - Power supply outputs +/-453v and +/-16.3v - I've been able to zero the balance on both boards - all 3 of the LEDs on each amp board light up - the offset hovers around +443V. Occasionally it will drop to +230V and go back up to +443. Adjusting the offset trimpot doesn't seem to affect the offset. This happens on both boards.
January 9, 201511 yr Something is blown or shorted. Also the LV supply is kinda high, the 7x15 regulators should never be that much out of spec.
January 9, 201511 yr Do you have a picture of your amp board? Make sure you don't have anything reversed. Also, is your psu still reading 453v when connected to the amp boards?
January 9, 201511 yr I noticed the nice NKK push button switches have functions that are either ON-ON or ON-(momentary ON). I'm not sure what it means to be ON-ON, I thought it should be ON-OFF? The data sheet also indicates ON-ON. http://au.mouser.com/ProductDetail/NKK-Switches/UB16KKW01N-F/?qs=sGAEpiMZZMufv8JNQ5fVHaG9l0kRAbB%252bJnaW9ZKhTy0%3d
January 10, 201511 yr The low voltage power supply output I stated previously was without amp boards connected. With 1 amp board connected (forgot to check before I started taking everything apart) is +/-452v and +14.7v/-14.89v I've attached pictures of one of my amp boards. I've looked it over and there aren't any obvious shorts.
January 10, 201511 yr I noticed the nice NKK push button switches have functions that are either ON-ON or ON-(momentary ON). I'm not sure what it means to be ON-ON, I thought it should be ON-OFF? The data sheet also indicates ON-ON. http://au.mouser.com/ProductDetail/NKK-Switches/UB16KKW01N-F/?qs=sGAEpiMZZMufv8JNQ5fVHaG9l0kRAbB%252bJnaW9ZKhTy0%3d ON-ON is SPDT. ON-OFF would be SPST.
January 10, 201511 yr Indeed, the CCS isn't active as the LED is missing. Also the soldering on the feedback selector is suspect and with the local resistors also in place that could short and cause problems.
January 10, 201511 yr Try it with the LED in place. Also, you should use steel screws on those transistors since they are insulated.
January 10, 201511 yr Sorry, I meant switch it over to ohms mode. I hope you manage to get it working.
January 10, 201511 yr Can you check for shorts with a volt meter? you probably could. measure a 9v battery and then check for shorts by measuring in parallel with the battery and see if your DC volt reading drops?
January 11, 201511 yr May be a silly question, but, did you run the amp board without the heatsink connected?
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