I'm comparing my PSU board to the pic of Ben's board that Colin put together. Originally I had populated more parts than were required on the PSU and I thought I'd removed them all, but I can see at least one difference. Q8 for example is populated on my board but blank on Ben's. I'll remove that and check rest of board for differences.

Edit: Found more differences. I'll update my PSU board and try again.

Good spot Kieth but I think that the DC should pass through those Diodes. I'd prefer those bypassed though all the same.

15V is a little low and dropping down further indicates that something may need a little attention.

Don't forget to isolate the Regs with top hats between the IC and bolt and check between tabs and chassis for continuity which you should NOT have.

Hold off on switching on until you have the regulator IC's located to the heatsink. You don't want those babies to get to toasty.

And then

Maybe disconnect your SECA board from the PSU and measure the PSU output unloaded just to be sure which board the fault ''may'' be on.

Another suggestion but not a must would be to change out the wires from PSU to SECA so that you can clearly identify +ve ,-ve and OV rails. I tend to be a little forgetful and colour coding helps stop me going ouch as often. Likewise for the return lines for the speaker output. maybe white for the + and blue for the grounds.

Not important but helps my OCD stay calm under fire.

Nice work though and with another little push you'll have a superb sounding amp.

Thanks Shoom. With the amp disconnected I have +15.6v and -15.7v on the PSU output. To avoid toasting the regulator IC's I only left it on a short while, but the voltages remained constant. I'm going to check over my amp build now - can't see anything else different compared to Ben's PSU board...not checked the SMD part values admittedly.

EDIT: Resistors at R1 and R2 look different on my PSU board compared to Ben's. I'll check my BoM.

Just a quick note the relay contact must be linked on the relay.

As shown here.

Next if one PSU PCB is shutting down to 6.5V then this could be a hot bit somewhere, please check build, There has also been a few mods and this may help to find the info I will spend the day tidying it up and reposting.

Also I see the REG chip are not on heat sinks, they do have internal temp shut down so I suspect they are getting hot and causing the shut down. Please fix them insulated to the heat sink.

I can't help with technical advice (tho I'm taking some unjustified satisfaction from the fact that photos I posted have acted to help somewhat ;-) ), but I would like to provide some moral support here... I'm cheering you on from the sidelines Brumjam! =D>

Yikes now we have sparks 8-X. All I did was fit the pads behind both IC's. None of the fuses went and can't see any parts that have obviously been fried. With hindsight I should have asked Colin to build these boards for me

I can't help with technical advice (tho I'm taking some unjustified satisfaction from the fact that photos I posted have acted to help somewhat ;-) ), but I would like to provide some moral support here... I'm cheering you on from the sidelines Brumjam! =D>

(It will get sorted! >:D< )

Thanks Ben. I won't be defeated.....electrocuted maybe but not defeated

I can't help with technical advice (tho I'm taking some unjustified satisfaction from the fact that photos I posted have acted to help somewhat ;-) ), but I would like to provide some moral support here... I'm cheering you on from the sidelines Brumjam! =D>

(It will get sorted! >:D< )

Thanks Ben. I won't be defeated.....electrocuted maybe but not defeated

That is exactly the sort of response that we (and probably especially Colin) are looking for. =D>

It is possible that you have a short between the small transistors where you fitted the isolation pads and the chassis. Sometimes those top hats just do not fit correctly.

I think I've made a mistake with RL1 - last night I soldered a piece of wire on the top of the board to join two points as advised by Colin. Now I've had a look under the board and can see I put a piece of wire on the opposing side as well. Not sure if this would cause fireworks but it needs fixing anyway.

But as Alan said the TOP hats are a pain and need care when fitting , oh why are there sparks is the power on whilst you fit it to heat sink, I do hope not.

It must have been a short as I've turned it on now and no more fireworks. Voltages are +16v and -15.4v. Still going after five mins of being on.
I'm going to check my soldering now on the current adjustment pot. Getting closer to music.

That sounds like good news. Waiting for further news...

Some of these parts had different values on original BoM, so I had to remove some of these resistors and solder in the new values - I only mention this because my soldering wasn't brilliant given proximity to other parts. Should I focus on checking the solder on these parts?

A quick clean with isopropyl alcohol and a check with a magnifying glass can save a problem down the line. And a bulb tester is worth making for when you first switch on although you can't set the bias with one connected in the mains line other than to turn the bias trimmer and watch if the bulb starts to glow assuming it isn't already.

A quick clean with isopropyl alcohol and a check with a magnifying glass can save a problem down the line. And a bulb tester is worth making for when you first switch on although you can't set the bias with one connected in the mains line other than to turn the bias trimmer and watch if the bulb starts to glow assuming it isn't already.

Great Advice

I usually use a 10x watch makers Loop for checking my SMD work.

I was referring to DS1/2 in my previous post but I think its most likely not an issue.

I'd still recommend testing the PSU unconnected to the SECA board just in case.

A nice close up of your SMD work may be useful.

just as an aside

''Some of these parts had different values on original BoM''

Is there a place where the current Booms and schematics are kept?

Hi Shaun I've been testing the PSU unconnected. The voltage readings on the output are the same. If I get time today I'm going to try my other PSU.....if it measures the same then this would point to me installing wrong parts as opposed to an SMD soldering mishap. I'll post a pick of DS1 and 2 later - no harm in checking I've got these installed correctly.

A quick clean with isopropyl alcohol and a check with a magnifying glass can save a problem down the line. And a bulb tester is worth making for when you first switch on although you can't set the bias with one connected in the mains line other than to turn the bias trimmer and watch if the bulb starts to glow assuming it isn't already.

Great Advice

I usually use a 10x watch makers Loop for checking my SMD work.

I was referring to DS1/2 in my previous post but I think its most likely not an issue.

I'd still recommend testing the PSU unconnected to the SECA board just in case.

A nice close up of your SMD work may be useful.

just as an aside

''Some of these parts had different values on original BoM''

Is there a place where the current Booms and schematics are kept?

Could be useful.

As new parts better parts and nice heatsinks I improved the amp so some parts did change also if you use large heatsinks you can up the power, so the voltage on the PSU needs to change and the transformer.

The idea of this kits was to help others understand and have confidence in there hidden skills like Alan B and Ben, now it is Uncle Dave,s turn others like Alan E. and Quickie and the incredible James did great jobs based on learning curves they collected from past DIY.

Me it just a shame my Dyslexia screws my ability to write it all down but thank god for this community or liked minded nut cases.

A quick clean with isopropyl alcohol and a check with a magnifying glass can save a problem down the line. And a bulb tester is worth making for when you first switch on although you can't set the bias with one connected in the mains line other than to turn the bias trimmer and watch if the bulb starts to glow assuming it isn't already.

Great Advice

I usually use a 10x watch makers Loop for checking my SMD work.

I was referring to DS1/2 in my previous post but I think its most likely not an issue.

I'd still recommend testing the PSU unconnected to the SECA board just in case.

A nice close up of your SMD work may be useful.

just as an aside

''Some of these parts had different values on original BoM''

Is there a place where the current Booms and schematics are kept?

Could be useful.

As new parts better parts and nice heatsinks I improved the amp so some parts did change also if you use large heatsinks you can up the power, so the voltage on the PSU needs to change and the transformer.

The idea of this kits was to help others understand and have confidence in there hidden skills like Alan B and Ben, now it is Uncle Dave,s turn others like Alan E. and Quickie and the incredible James did great jobs based on learning curves they collected from past DIY.

Me it just a shame my Dyslexia screws my ability to write it all down but thank god for this community or liked minded nut cases.

I've noticed that on a couple of builds that folks have taken the speaker connections from the amp board and not the connections on the p/s board. Does this make a difference?

How do I choose and use an Avatar? Showing my computer illiteracy here.

''The idea of this kits was to help others understand and have confidence in there hidden skills like Alan B and Ben, now it is Uncle Dave,s turn others like Alan E. and Quickie and the incredible James did great jobs based on learning curves they collected from past DIY.''

and it's worked out very nicely in that respect. Puts me in mind of the ''good old days'' when people where actually encouraged to have a go.

the resulting builds speak for themselves.

''shame my Dyslexia''

No shame as it makes two of us. Richard Branson manages pretty well on his.

I use MS word to sort out my gibberish.

Brumjam

''The result will be all the more satisfying when I sit down and listen to music through it''

And the really cool thing is that you'll have some idea of how to make repairs should they be needed. true longevity.

''Second PSU reading +17.8v and -17.9v when connected to the amp''.

Looking good and gives you something to compare PSU 1 with.

Really good work and total commitment.

just a small push further needed :-)

Keith

''I've noticed that on a couple of builds that folks have taken the speaker connections from the amp board and not the connections on the p/s board. Does this make a difference?''

I did notice that but was thinking that the Speaker return taken directly back to the PSU common 0V without the added impedance of the added connector may be more elegant. but I'm sure that in real life operation it matters very little IMHO.

## Comments

Have you fitted the diodes on the amp board?

Any chance of posting a couple of pics?

PS thanks for all the help so far. With the amount of support here I'm confident my amp will be playing sweet music soon.

I'm cheering you on from the sidelines Brumjam!

=D>

(It will get sorted! >:D< )

=D>

8-X

I'm going to check my soldering now on the current adjustment pot. Getting closer to music.

Waiting for further news...

Family has stopped play for time being. To quote Arnie 'I'll be back'.

Make the most of the company. :-)

R3 = 240R

R4 = 2K7

R16 = 470R

R5 = 240R

R6 = 2K7

R16 = 470R

Some of these parts had different values on original BoM, so I had to remove some of these resistors and solder in the new values - I only mention this because my soldering wasn't brilliant given proximity to other parts. Should I focus on checking the solder on these parts?

Thanks, James

## Sorted List of Output Voltages with R3/R5 and R4/R6+R15/R16

1.43VR1 = 470, R2 = 681.47VR1 = 470, R2 = 821.48VR1 = 370, R2 = 681.51VR1 = 330, R2 = 681.51VR1 = 390, R2 = 821.52VR1 = 470, R2 = 1001.53VR1 = 370, R2 = 821.56VR1 = 330, R2 = 821.57VR1 = 270, R2 = 681.57VR1 = 470, R2 = 1201.57VR1 = 390, R2 = 1001.59VR1 = 370, R2 = 1001.60VR1 = 240, R2 = 681.63VR1 = 330, R2 = 1001.63VR1 = 270, R2 = 821.64VR1 = 390, R2 = 1201.64VR1 = 220, R2 = 681.65VR1 = 470, R2 = 1501.66VR1 = 370, R2 = 1201.68VR1 = 240, R2 = 821.71VR1 = 330, R2 = 1201.71VR1 = 270, R2 = 1001.72VR1 = 220, R2 = 821.72VR1 = 180, R2 = 681.73VR1 = 470, R2 = 1801.73VR1 = 390, R2 = 1501.76VR1 = 370, R2 = 1501.77VR1 = 240, R2 = 1001.81VR1 = 270, R2 = 1201.82VR1 = 150, R2 = 681.82VR1 = 330, R2 = 1501.82VR1 = 180, R2 = 821.83VR1 = 390, R2 = 1801.84VR1 = 470, R2 = 2201.86VR1 = 370, R2 = 1801.88VR1 = 240, R2 = 1201.89VR1 = 470, R2 = 2401.93VR1 = 330, R2 = 1801.93VR1 = 150, R2 = 821.94VR1 = 270, R2 = 1501.96VR1 = 390, R2 = 2201.97VR1 = 470, R2 = 2701.99VR1 = 370, R2 = 2202.02VR1 = 390, R2 = 2402.03VR1 = 240, R2 = 1502.06VR1 = 370, R2 = 2402.08VR1 = 330, R2 = 2202.10VR1 = 220, R2 = 1502.12VR1 = 390, R2 = 2702.13VR1 = 470, R2 = 3302.16VR1 = 330, R2 = 2402.16VR1 = 370, R2 = 2702.19VR1 = 240, R2 = 1802.23VR1 = 470, R2 = 3702.25VR1 = 150, R2 = 1202.27VR1 = 270, R2 = 2202.27VR1 = 330, R2 = 2702.29VR1 = 470, R2 = 3902.29VR1 = 180, R2 = 1502.31VR1 = 390, R2 = 3302.36VR1 = 270, R2 = 2402.37VR1 = 370, R2 = 3302.40VR1 = 240, R2 = 2202.44VR1 = 390, R2 = 3702.50VR1 = 470, R2 = 4702.57VR1 = 370, R2 = 3902.61VR1 = 220, R2 = 2402.65VR1 = 330, R2 = 3702.66VR1 = 240, R2 = 2702.73VR1 = 330, R2 = 3902.74VR1 = 470, R2 = 5602.75VR1 = 150, R2 = 1802.76VR1 = 390, R2 = 4702.78VR1 = 270, R2 = 3302.78VR1 = 220, R2 = 2702.84VR1 = 370, R2 = 4702.92VR1 = 180, R2 = 2402.96VR1 = 270, R2 = 3702.97VR1 = 240, R2 = 3303.03VR1 = 330, R2 = 4703.05VR1 = 390, R2 = 5603.06VR1 = 270, R2 = 3903.06VR1 = 470, R2 = 6803.08VR1 = 150, R2 = 2203.13VR1 = 220, R2 = 3303.14VR1 = 370, R2 = 5603.18VR1 = 240, R2 = 3703.25VR1 = 150, R2 = 2403.28VR1 = 240, R2 = 3903.35VR1 = 220, R2 = 3703.37VR1 = 330, R2 = 5603.43VR1 = 270, R2 = 4703.43VR1 = 390, R2 = 6803.43VR1 = 470, R2 = 8203.47VR1 = 220, R2 = 3903.50VR1 = 150, R2 = 2703.54VR1 = 180, R2 = 3303.55VR1 = 370, R2 = 6803.70VR1 = 240, R2 = 4703.82VR1 = 180, R2 = 3703.83VR1 = 330, R2 = 6803.84VR1 = 270, R2 = 5603.88VR1 = 390, R2 = 8203.91VR1 = 470, R2 = 10003.92VR1 = 220, R2 = 4703.96VR1 = 180, R2 = 3904.00VR1 = 150, R2 = 3304.02VR1 = 370, R2 = 8204.17VR1 = 240, R2 = 5604.33VR1 = 150, R2 = 3704.36VR1 = 330, R2 = 8204.40VR1 = 270, R2 = 6804.43VR1 = 220, R2 = 5604.44VR1 = 470, R2 = 12004.46VR1 = 390, R2 = 10004.50VR1 = 150, R2 = 3904.51VR1 = 180, R2 = 4704.63VR1 = 370, R2 = 10004.79VR1 = 240, R2 = 6805.04VR1 = 330, R2 = 10005.05VR1 = 270, R2 = 8205.10VR1 = 390, R2 = 12005.11VR1 = 220, R2 = 6805.14VR1 = 180, R2 = 5605.17VR1 = 150, R2 = 4705.24VR1 = 470, R2 = 15005.30VR1 = 370, R2 = 12005.52VR1 = 240, R2 = 8205.80VR1 = 330, R2 = 12005.88VR1 = 270, R2 = 10005.91VR1 = 220, R2 = 8205.92VR1 = 150, R2 = 5605.97VR1 = 180, R2 = 6806.04VR1 = 470, R2 = 18006.06VR1 = 390, R2 = 15006.32VR1 = 370, R2 = 15006.46VR1 = 240, R2 = 10006.81VR1 = 270, R2 = 12006.92VR1 = 150, R2 = 6806.93VR1 = 330, R2 = 15006.94VR1 = 180, R2 = 8207.02VR1 = 390, R2 = 18007.10VR1 = 470, R2 = 22007.33VR1 = 370, R2 = 18007.50VR1 = 240, R2 = 12008.07VR1 = 330, R2 = 18008.08VR1 = 150, R2 = 8208.19VR1 = 270, R2 = 15008.30VR1 = 390, R2 = 22008.43VR1 = 470, R2 = 27008.68VR1 = 370, R2 = 22009.06VR1 = 240, R2 = 15009.58VR1 = 330, R2 = 22009.77VR1 = 220, R2 = 15009.90VR1 = 390, R2 = 270010.03VR1 = 470, R2 = 330010.37VR1 = 370, R2 = 270010.63VR1 = 240, R2 = 180011.25VR1 = 150, R2 = 120011.44VR1 = 270, R2 = 220011.48VR1 = 330, R2 = 270011.67VR1 = 180, R2 = 150011.83VR1 = 390, R2 = 330012.40VR1 = 370, R2 = 330012.71VR1 = 240, R2 = 220013.75VR1 = 330, R2 = 330015.31VR1 = 240, R2 = 270016.25VR1 = 150, R2 = 180016.53VR1 = 270, R2 = 330016.59VR1 = 220, R2 = 270018.44VR1 = 240, R2 = 330019.58VR1 = 150, R2 = 220020.00VR1 = 220, R2 = 330023.75VR1 = 150, R2 = 270024.17VR1 = 180, R2 = 330028.75VR1 = 150, R2 = 3300In a way this is a good learning experience because it forces me to learn about the circuit rather than just soldering by numbers.

The result will be all the more satisfying when I sit down and listen to music through it

I've noticed that on a couple of builds that folks have taken the speaker connections from the amp board and not the connections on the p/s board. Does this make a difference?

How do I choose and use an Avatar? Showing my computer illiteracy here.