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Post by Deleted on Dec 21, 2011 20:59:53 GMT
Hi Chaps, With my PSU pcb, does anybody want want a wirepad adding to where all the 0v meet (nestled between the tank caps), and does anybody want provision for an LED 'on' indicator? Finished work for Christmas now - what a feeling!!! Hi Will A LED 'on'indicator is a good idea, as the front panel LED for the amplifier in it's separate case, will come on several seconds later if supplied via the Loudspeaker Protector PCB. My present PSU case used a nice looking rocker switch with a neon, but as with all neons, they don't last forever.  Regards Alex |
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Post by Deleted on Dec 21, 2011 22:48:24 GMT
Hi Chaps, With my PSU pcb, does anybody want want a wirepad adding to where all the 0v meet (nestled between the tank caps), and does anybody want provision for an LED 'on' indicator? Finished work for Christmas now - what a feeling!!! Hi Will, Yes please, yes please.  Syd |
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Will
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Post by Will on Dec 22, 2011 0:09:18 GMT
 okey dokey, led (plus current limiting resistor) in place, along with a pad for a 1mm pcb pin smack on the star. The led will be fed from the 'raw' dc after the rectifiers, so a half watt resistor would be a good idea, as it'll be coping with a high voltage drop. The pad for a pcb pin on 0v allows the easy use of 3 wire cable for supplying the 20-0-20 Vdc to the amp, although you could use one of the two middle terminals marked CT if you wished. I've used a 4 terminal connector so that if using a normal dual secondary winding traffo, the two leads you would connect for the CT have there own terminal, and perhaps looks neater. Other points to mention are 0v connections on the +/- outputs, so you can use 4 individual wires for +/0v and -/0v. There is also a resistor in parallel with the trimpot. You can use 5k (?) here that Alex mentioned earlier in the thread, or not use a trimpot and go straight for a fixed value resistor to set the dc outputs. This is the same thing that I did on my 'other' reg pcbs that some of you have. Most of these things are to give as much choice to you guys building it, as everyone likes a choice. If there are any other things that you'd like to see on the psu pcb, please do post, and as long as it doesn't cause a complete re-jig, i'll do what I can. |
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Post by Deleted on Dec 22, 2011 2:25:21 GMT
Hi Will
Where you have made provision for the LED, it may be better to
dimension it so that a couple of .9mm PCB pins can also be used for extending the LED wiring to the front panel.
Regards
Alex
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Post by Deleted on Dec 22, 2011 7:58:59 GMT
...or even re-dimension to squeeze in another terminal block for said use?
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Post by Deleted on Dec 22, 2011 8:57:05 GMT
okey dokey, led (plus current limiting resistor) in place, along with a pad for a 1mm pcb pin smack on the star. The led will be fed from the 'raw' dc after the rectifiers, so a half watt resistor would be a good idea, as it'll be coping with a high voltage drop. The pad for a pcb pin on 0v allows the easy use of 3 wire cable for supplying the 20-0-20 Vdc to the amp, although you could use one of the two middle terminals marked CT if you wished. I've used a 4 terminal connector so that if using a normal dual secondary winding traffo, the two leads you would connect for the CT have there own terminal, and perhaps looks neater. Other points to mention are 0v connections on the +/- outputs, so you can use 4 individual wires for +/0v and -/0v. There is also a resistor in parallel with the trimpot. You can use 5k (?) here that Alex mentioned earlier in the thread, or not use a trimpot and go straight for a fixed value resistor to set the dc outputs. This is the same thing that I did on my 'other' reg pcbs that some of you have. Most of these things are to give as much choice to you guys building it, as everyone likes a choice. If there are any other things that you'd like to see on the psu pcb, please do post, and as long as it doesn't cause a complete re-jig, i'll do what I can. Hi Will good work i think that an led is going to be a pretty useful way of ensuring that the amp is not inadvertently left switched on. I'm not usually a big fan of LED's as i usually leave my kit switched on permanently. but with the Class A I'd probably go for switching it on when music is required. with the two PSU arrangement it could be nice to have one LED on the PSU front panel and one mounted on the other PSU internally just to give a nice clear reminder that it's powered up if we need to test. i usually go for that sort of arrangement to avoid those ouch moments. great work on the PSU it keeps the good parts of the original but improves things size and layout wise. take care |
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Post by jeffc on Dec 22, 2011 12:15:02 GMT
Hi Will, Nice work on the PSU PCB  . Can I ask whether there might be some value in adding a couple of extra holes/pads for TO-201 type SBYV28 diodes. Easy to do in the track joining the left pair but for the right pair each track would need to be extended inwards 5 mm or so to accommodate these. Would save mounting them vertically. Just a thought  . cheers.. jeffc |
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Will
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Post by Will on Dec 22, 2011 22:04:58 GMT
no problem on a terminal on the led, and a good idea on the other diodes, Jeff.
Are these the same size case that other are using when not using the to220 diodes? Just want to make sure that it's suitable for all.
OT, I've had a mare of a day today, even though I'm in holiday mode. Woke up to no heating and hot water, with the heating pump hot enough to solder with. One new pump, and a few hours of re-doing pipework to suit the new pump and back to heat and hot water. I shudder to think how much that would have cost if it'd been a call-out.
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Post by jeffc on Dec 23, 2011 6:44:25 GMT
Hi Will, Just as well you're handy with soldering as I'm sure it would be tricky finding a tradesperson ATM. Fortunately my older son did 3 years of a plumbing apprenticeship so I have problems like yours covered. The TO-201 diode case is specified to be 7.2-9.5 mm long so your PCB might/might not quite have enough space for them if laid flat. docs-asia.electrocomponents.com/webdocs/0928/0900766b809285fc.pdfSill if extra pads were added to the inside for each diode and separated by approx 3 mm it would provide options. cheers.. jeffc |
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Post by Deleted on Jan 8, 2012 11:11:25 GMT
Hi All
just to keep this available.
for the LS device GB so far i have
Will 2x LS352 and 2X LS313
Phil 2x LS352 and 2X LS313 (provisional)
Me 2x LS352 and 2X LS313
Syd 2x LS352 and 2X LS313
Alan 2X LS352 and 2X LS313
Alex 2X LS352 and 2X LS313
Mark 2X LS352 and 2X LS313 (cyteen)
Jeff 2X LS352 and 2X LS313
Jon C 2X LS352 and 2X LS313
Kits GB
Chris
Syd
Phil
Will
mark (cyteen)
Jon C
me
Boards only GB
Alex
Alan
Jeff
anyone else?
take care
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Post by Deleted on Jan 8, 2012 11:57:25 GMT
Shaun
Surely Jeff wants the PCBs too, UNLESS he has chickened out of the build , preferring that crappy Clarse D instead ?
Perhaps he is frightened that Phil might show him up ? ;D
Regards
Alex
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Post by jeffc on Jan 9, 2012 10:53:22 GMT
Thank you "Grandad" for looking out for me, not, and for feeling pity on this poor sole who only has a crappy Class D Audio amp to try and listen too with hands over ears  . You know I'm going to have to hand in my Greenpeace membership once I build this amp as I'll be included on their blacklist as a greenhouse gas generating environmental terrorist.  Unwritten rule that all members must use highly efficient Class D amps to save the planet. Shaun, please count me in for amp and PSU PCBs thank you. I think I have most other parts, might just need to check for BC337 and BC327 matched for hfe's and possibly output transistors if bulk buying of these is required also to get pairs closely matching in hfe. cheers.. jeffc |
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Post by Deleted on Jan 9, 2012 11:04:09 GMT
Unwritten rule that Cl D manufacturers sand off the designations of the I.C.s used, and that as they are switchmode, that the low ESR electros used will have limited life spans. Save the Planet , my arse !  It's all about limited lifespan, throwing them on the tip and buying another one. They make it so the DIYer can't readily repair them. If the truth be known, Greenpeace probably tracks the Japanese whaling fleet by the RF emissions from their Class D amplifiers ! ;D |
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Post by Deleted on Jan 9, 2012 15:03:37 GMT
Shaun Surely Jeff wants the PCBs too, UNLESS he has chickened out of the build , preferring that crappy Cl arse D instead ? Perhaps he is frightened that Phil might show him up ? ;D Regards Alex Hi Alex I've updated the list Hi Jeff I'll be letting people know closer to the time we start the GB rolling. that way i can include people who only want parts from the kit. sorry i mist your name from the board GB but it's now included. take care |
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Post by Deleted on Jan 10, 2012 23:52:45 GMT
Hi Guys, any pointers as to why I'm blowing caps in this circuit.  Negative section is OK and giving out an adjusted -20v but the positive side has blown C1. I had the DMM on the neg side JLH out, it came up with -18v and a few turns of VR1 negative took it to -20v and seemed to be OK. I switched off and attached the DMM to the JLH out positive side, voltage was 7.9 I then adjusted VR1 positive but no voltage movement then cap C1 blew it's top. Probably ran about 3/4 mins before blowing. I had a good look at all traces connections and layout and they all looked OK, so I stuck in a new C1 switched on again and voltage was around 8v so I hung back a bit and guess what C2 blew it's top so switched off I'm a bit hesitant about the cheapo LT1085s from Florida they don't look like the ones from Farnell and RS. I've changed the LT1085 for a new Florida one and replaced C2 but am waiting to see if anyone has any suggestions as to where I'm adrift with this one. Alan |
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Post by Deleted on Jan 11, 2012 0:13:49 GMT
Alan
The only thing I can think of at this stage is to remove the 1 ohm current limiter resistor, and see what you get out of the +VE regulator. Do you have a link between the +VE regulator and the JLH section that can be removed, so as to check out the JLH separately ?
The CL diodes should be 1N4148 GP silicon diodes, as the forward voltage of the SF12 is a little low for this application.
Good Luck
Alex
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Post by Deleted on Jan 11, 2012 0:45:18 GMT
Hi Alex,
Diodes are UF4002 , I'll put in the 1N4148s and change the LT1085 Florida flavour for one from RS known to be good. I'll also try a Florida LT1085 in an ADDJLH which is also a working model.
Yes I can break out the positive JLH and try the Reg on it's own also feed the JLH section from another small LT1086 board and see if it works ok there.
Perhaps keeping the Reg and JLH boards separate would be better. The combined board looks good and is neater so I'll persevere with it for a bit.
Thanks
Alan
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Post by Deleted on Jan 11, 2012 6:22:42 GMT
my best guess is you made the bridge rectifier wrong (D1, D2) or have a diode that conducts in both directions.
Has nothing to do with regs or anything behind the cap.
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Post by Deleted on Jan 11, 2012 6:37:26 GMT
my best guess is you made the bridge rectifier wrong (D1, D2) or have a diode that conducts in both directions. Has nothing to do with regs or anything behind the cap. That seems a likely scenario, although I expect that should have been already checked ? D8 should be across the +VE regulator, not as drawn ? Alex |
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Post by Deleted on Jan 11, 2012 7:52:10 GMT
Alex,
I think Alan is running strictly to the application notes, the LT1033 requires D8 as shown on the neg rail which Alan said is working but not required on the LT1085 pos rail where the fault lies?
Going purely on problems I've had in the past I'd be looking at the D5 & 6 area as already pointed out. A long shot is also double checking the value of the VR, I've blindly taken one "as supplied" to find it of the wrong value later!
Alan you have PM
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Post by Deleted on Jan 11, 2012 8:37:29 GMT
Alex,
Correct of course.
I and I think Shaun, have had this discussion with Alan before, pointing out the protection diodes and Alan pointing out to us that they are "optional" due to internal protection.
That's what I meant by
Choices!
Chris
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Post by Deleted on Jan 11, 2012 8:45:28 GMT
Chris
As Alan is using the CL section of the JLH this time around, we can stop worrying about the optional diode. Without the CL in the JLH,
it would definitely be a good idea to use it because of the huge possible startup current referred to by JLH.
Alex
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Post by Deleted on Jan 11, 2012 10:49:14 GMT
Thank guys,
I'm free this morning to explore all your suggestions and appreciate your input.
Regards,
Alan
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Post by Deleted on Jan 11, 2012 11:06:33 GMT
Thank guys, I'm free this morning to explore all your suggestions and appreciate your input. Regards, Alan Alan I would double check the bridge rectifier area first, as Frans suggested.Make sure by resistance measurements in case of a tiny bridge between tracks. Regards Alex |
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Post by Deleted on Jan 11, 2012 15:11:02 GMT
Hi Alex, Frans and Chris,
I now have a working board no bangs or pops and steady 20v pos/neg on both JLH out and
straight off the reg.
So what did I do.................
First took out D1 D2 and they measured OK however I replaced them with new anyway since they were out.
Replaced the diodes on CL with 1N4148
Found a solder bridge between pin 1 adj pad on the Reg LT1085 and the pad with pin 3 vin
D1 D2 cathodes and C1+ C2+.
I think that bridge was made when removing D1 D2 it was too obvious for me to have missed before.
Cleaned out all milled breaks between pads again to make sure all bridges were gone.
So many thanks for your advice as I can now move on and cut the revised final PSU boards.
Also looks like those Florida Regs are OK.
Regards,
Alan
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. 
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. You know I'm going to have to hand in my Greenpeace membership once I build this amp as I'll be included on their blacklist as a greenhouse gas generating environmental terrorist. 
Unwritten rule that all members must use highly efficient Class D amps to save the planet. 
It's all about limited lifespan, throwing them on the tip and buying another one. They make it so the DIYer can't readily repair them.