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SRE330 build
MUFF WIGGLER Forum Index -> Oakley Sound Systems Goto page 1, 2  Next [all]
Author SRE330 build
Pav
Hi Tony,

some additional thoughts on the buildguide as i am building.

the build guide talks to the (dc) power led on the SRE330 main board but does not mention the AC led in the RPSU issue2.

It is not in the parts list so we are not expected to use it.

Instructions do say omit R5 ,D11, and C13 of which R5 and D11 would be needed to complete the led circuit, maybe all three. So if the reader does not have the schematic they might be helped by mentioning these are for the LED which is not used / optional.

Can it be used in SRE330 as a standby led ?

Also .. if using external PSU should there be a mention of RPSU "CASE" pad not being necessary as well as the AC LED when used with SRE?

currently it is only discussed in the transformer option section.

finally ..it might be worth bringing forward to the parts section the sentence about their being no harm in fitting Fuse1 and diodes even if using 1/2 wave rectification to the parts list section.

I am still not sure which way i will go ..I have a 1A AC switchable wall wart sitting on the shelf..with a 15V option saying "use me use me".
Synthbuilder
Pav wrote:
the build guide talks to the (dc) power led on the SRE330 main board but does not mention the AC led in the RPSU issue2.

The suggested build doesn't use the RPSU's standby LED as it tries to keep things simple as much as possible. However, you could populate the parts shown on the RPSU schematic and use it for a standby LED. Having a standby LED is quite a good idea since it does tell you the linelump/wallwart is live.

Quote:
Also .. if using external PSU should there be a mention of RPSU "CASE" pad not being necessary as well as the AC LED when used with SRE?


I could certainly add this information to future revision of the guide.

Quote:
it might be worth bringing forward to the parts section the sentence about their being no harm in fitting Fuse1 and diodes even if using 1/2 wave rectification to the parts list section.


Noted.

Tony
Pav
Hi, I just need some reassurance before soldering the switchcraft io sockets recommended that there is only one way to fit the pins. Looking at the top side PCb, I have the shamfered corner bottom left. This does seem consistent with other sock boards. Maybe worth a mention in the build guide. I suppose I should compare specs with schematics and form a conclusion.
All the best for 2018.
Synthbuilder
Pav wrote:
I just need some reassurance before soldering the switchcraft io sockets recommended that there is only one way to fit the pins.


They should fit in one way only. At least that's what I thought. help

Can they put in more than one way? I've not got any stereo ones here at the moment to try out.

Remember to fit them to the underside of the board though.

Tony
Pav
I tested again..You are right, it does appear there is only one way to fit these stereo sockets. Thanks
Pav
Tried again..you are correct ...only one way .ta
Synthbuilder
Good to know. Thanks for trying it. thumbs up
Pav
just spent a couple of hours fitting the SRE330 pcb to its front panel. This is the Bryant 1U 250mm deep 19” rack enclosure.

I thought i had done a reasonable drilling job for the pots using the fpd example, but I appear to have made a couple of tiny (some would say slapdash ) errors.

a) horizontal alignment of template to panel:

The template does not extend to the rack lugs so looking at the picture in build guide , I now suspect that i had to line up the template to the "flange" edge of the front panel ..ie where you screw it to the top or bottom panels. I might have done that or I might have just centered the template.

Which would be the better way?

The issue i have is the proximity of the screw hole fittings...I have barely 1mm gap between the plastic thread insert and an input socket pin, and the opposite side this insert is directly aligned to where the "ON" led is to be fitted.

As long as I check the screws do not penetrate onto the case and short anything ..I think i have just got away with it.

b) pcb fitted switches

with the pots successfully soldered..i came to fit the switches. Here my drilling let me down with one hole needing filing as it was too tight.
However im surprised the metal sleeves of the switches are barely reaching the holes. I would expect them to protrude at least a couple of mm so that the full length of the toggle can be got at.

What might i have done wrong here?
..the nuts on the pots are all tightened, the switches were soldered as per the buildguide.

In hindsight, I might recommend the less expereienced DIYer like me to avoid the pcb mounted switches and use the switches used on the Oakley modules - Just to allow some wiggle room if the holes are not 100% perfect.

I just have the LEDs and interconnects to wire up, and the ICs to fit and i will be ready to test this week.
nanners
Synthbuilder
Pav wrote:
.... horizontal alignment of template to panel.

It fits in the middle of the panel both horizontally and vertically. You need to ensure that the distance between the ends of the template and the vertical edges of the rack panel is the same for both left and right. I just did it by eye.

Quote:
The issue i have is the proximity of the screw hole fittings...I have barely 1mm gap between the plastic thread insert and an input socket pin, and the opposite side this insert is directly aligned to where the "ON" led is to be fitted.

You've lost me there. Is this on the back panel?

Quote:
pcb fitted switches

If you are using a Scheaffer overlay like on the first prototype you can be quite sloppy with your drilling. The overlay will cover up the naughties. Just make the switch holes bigger than you need and the Schaeffer panel will hide the excessive panel holes. I also make the pot holes in the case around 8mm. This gives the board some wiggle room.

If you are not using the Schaeffer overlay like my second one:



Accurate drilling is required.

Quote:
im surprised the metal sleeves of the switches are barely reaching the holes. I would expect them to protrude at least a couple of mm so that the full length of the toggle can be got at.

If you're not using the Schaeffer overlay they are perfect - see picture above. With the overlay they only just touch the inner surface of the overlay and the toggles are partially buried. You should still be able to adjust them easily enough though.

Tony
Synthbuilder
A builder has reported a fault in the Builder's Guide Versions 2.5 and earlier.

The correct values are:

R102 is 56K
R104 is 330K

Version 2.5 and earlier have these the wrong way around.

Sorry for any confusion this may have caused.

Tony
Pav
Hi,

I cannot find any documentation picture or fpd that tells me which are the I/O ins and outs sockets. It is not printed on the SEIO pcb. either.

I wasnt sure of the consequences of trial and error stuffing an in direct into the output ..and my next post will explain why i didnt have time for trial and error!

I went to the schematic and the a clue is that inputs are normalized for mono and outputs are not suggests
-------------------------------------------
- L-out R-Out L-in R-in -
- O O O O -
-------------------------------------------

but my mind sorta says this is more english style.
-------------------------------------------
- L-In R-In L-Out R-Out -
- O O O O
-------------------------------------------

looking at a keyboard ..to get the printing on the top panel reading L R
that translates into R-L when looking at the back panel left to right very frustrating

any confirmation would be extremely helpful.
Pav
I followed the instructions in the build guide ... 15.1v on positive rail , 15.5v on negative... I assume thats within tolerance .

No overheating after 5 minutes or more
Plug in SEIO ... yes the relay clicks and +15v measured on interconnect.

Plug in main board...and power on (Without anything plugged in I/O sockets)
and switched on ..Leds sequence as stated, On Led is On .. No smoke or heating of ICs on main board ...BUT..

..U1 (+) on RPSU is overheating after 90 seconds.

I checked my heatsink on U1 and my DMM shows no coductivity between screw and tab or base and tab . Using the little pink tabs not mica.

Suggests to me maybe its not the heatsink but i will reseat it anyway as I need to add the LED circuit components ... need that extra reassurance i have unplugged.

I cannot check if audio passes in and out yet.. (see previous note) but is the next likely cause a short on the main board ?
Synthbuilder
U1 is the +15V regulator so I expect the +15V rail is drawing too much current. In correctly working behaviour the current draw on both rails is about the same with both regulators having to dissipate similar amounts of heat.

The problem is probably on the SRE330 main board. A electrolytic capacitor could be the wrong way around. Check them all before switching it back on again.

If all the caps are OK then remove all the 3207 and 3102 driver chips. Power up again and see what happens. If it doesn't overheat, switch off and reseat the 3102 chips only. Power up and check U1 on the RPSU. If U1 is getting hot it's probably one of the 3102s. The bad one will be getting warm, or the little 78L09 driving will be.

If they're all OK then do the same with the 3207s. Again a bad one will almost certainly be getting warm. Be careful about warm chips. I burnt my finger on a overheating V2164 last week and I still have the blister to prove it.

If U1 overheats without the BBD and BBD driver ICs in place then the fault is clearly elsewhere. Check the 9V supplies in each BBD section - pin 5 on the 3207 in each of the four sections. If that's reading anything less than 8.5V that's the section with the problem.

Tony
Synthbuilder
Pav wrote:
I cannot find any documentation picture or fpd that tells me which are the I/O ins and outs sockets.


Looking from the rear it's output right, output left, input right and input left.

While this may seem like reading backwards, when the unit is viewed from the front (which it would be when in operation) you have the standard flow from left to right.
Pav
Thanks for the speedy response.

I have reseated the voltage regulator and whilst warmer than i am used too, it is not continuing to overheat... I have run it for 20 mins.

I have not found a warm chip on the main board.

with the dry setting 100% i can hear my 220Hz triangle wave
from the outs.

But the wet signal is not producing any artifacts prior to calibration ...it just attenuates to nothing the in signal.

Another point of note . with dry 100%. Increasing the input is only lighting the green at around 10 oclock knob position..and none of the others lighting as i go further clockwise.

Nothing else wiggled does anything...

[Edit] All elec caps and diodes oriented correctly.
The BBD chip and driver chip do have 8.9 or 9V vdd and are cool.

I still have to remove them to see if they are causing U1 heating.
[/end edit at 1am GMT !]
Pav
Hi Tony

The BBD chip and driver chips do have 8.9 or 9V vdd and are not warm..
The TL072s above them have +15 and -15V

>>remove all the 3207 and 3102 driver chips

The temp of U1 is not affected ..it remains warmer than i would expect but some say they do run warm. Still suspect but less of a priority.

I have an attenuated triangle from the Oakley VCO for 5-6v p-p as input
Both inputs work, Both outputs work on the dry signal.

Contrary to my previous edit..the LED is working to spec with the input connected.

I do not have any Wet component. The Oscilloscope just shows the voltage attenuating to zero as i introduce the wet signal.

U34 appears to be gateway to the BBD circuit..outs labelled L-BBD_IN and R-BBD-In pins 1 & 7 have 2v pp triangle... with a 5.6v pp input and sorta fits with the user guide mentioning compression before it gets to BBD circuit.

AM i right in thinking the BBD -BBD-OUt circiots are the next stage to look at ?
Synthbuilder
Yes, you need to have a look at the signal at the outputs of each BBD stage. They're found at pin 7 of the top op-amp in each BBD channel. You should get your triangle wave there, and if you have modulation going it'll be changing in frequency with the modulation.

If you have nothing there then there is a problem with the BBDs or BBD drivers I think. This is unlikely since to have all four down would be unlucky. That said you may have a common problem with the high frequency VCO circuit for each channel. Each of the pin 4s on the 3102s should be oscillating with a nice square wave between 50Khz and 100Khz.

You should also have the same, but now expanded, audio signal at the outputs of the expanders. That's pins 6 and pins 10 on both U35 and U40. If not then the companders are bust somehow.

If all is well so far then the signal is getting lost in the quad to stereo circuitry which is on the penultimate page of the schematic. Pins 1 and 7 of U45 and U47 should have the signal present. But if U55 is bust then it won't reach U54 and not get to the wet/dry pot.

Tony
Pav
Now looks like we are closer to the problem..or problems

>>pin 7 of the top op-amp in each BBD channel. You should get your triangle wave there

I do. these are the inputs to U35 and U40


>>> Each of the pin 4s on the 3102s should be oscillating with a nice square wave between 50Khz and 100Khz.

All 4 have a square wave but my dmm and oscilloscope disagree
the dmm says all but U63 are 50Khz - U63 being 667Khz seriously, i just don't get it
the oscilloscope has a measurement display says all 4 have 5Khz .
However i compared the voltages on all pins of U63 with its neighbour U44
and all are similar values so..im thinking U63 is not dead.

>>>pins 6 and pins 10 on both U35 and U40 should also have the same, but now expanded, audio signal
Aha! No AC signals on these pins for both
they all have +14.36 volts dc ? woah // need to check soldering i think

>>Pins 1 and 7 of U45 and U47

Have zero signal present.

Looks like U35 and U 40 circuitry soldering needs examining.
Synthbuilder
Pav wrote:
U63 being 667Khz...


If you mean U33 then see my post above where I wrote:

The correct values are:

R102 is 56K
R104 is 330K

Which is not what was in Builder's Guides prior to version 2.5

Tony
Pav
Not sure why i typed U63 .. I actually meant U52 ..
I had implemented those resistor changes prior to testing.
Synthbuilder
For U52 misbehaving take a look at the voltage of pin 7 U22. This should be around +3.5V. If it's stuck at +13V then suspect the resistor values to the right of U22.

Regarding the expanders, having all four not behaving sounds not like a soldering problem but a wrong component value. Check that the 8K2 resistor (R182 and others) is actually 8K2 on all four expanders.

Tony
Pav
>>>Check that the 8K2 resistor (R182 and others) is actually 8K2

Btw build guide has R182 as 10K .? Never mind..that gave me to the answer.

So before I rant .. Thanks. applause

.. I checked pcb at and in fact I had put in a 100R not a 10K very frustrating

On checking further .. All 30 10K resistors i had put in the pcb ..are in fact 100R Dead Banana cry cry cry cry cry

On checking the Farnell bag of 10K resistors QTY 100 freshly ordered for the project .. . I have 70 100R resistors on a single strip left angry angry angry angry angry

THis explains the mass failure. 50 quids worth of ICs potentially
Dead Banana Dead Banana Dead Banana


I got complacent. In my defense the 5 ring coding is very similar and Farnell have only screwed up a couple of times...and i caught those before soldering.

I havent slept all night - really angry with myself ..and i need to call Farnell to get my 10K resistors. I really struggle with clean holes after desoldering..so joy oh joy.
Synthbuilder
Pav wrote:
>>>Check that the 8K2 resistor (R182 and others) is actually 8K2

Btw build guide has R182 as 10K .?


Yes, sorry, the SRE330 uses 10K in that position. The forthcoming ADR30, of which I have been working on all this week, and the datasheet for the NE570, uses 8K2 hence my confusion.

Quote:
All 30 10K resistors i had put in the pcb ..are in fact 100R.


It might help you to know that I think we've all done that from time to time. It's also the main reason stuff gets sent back to me.

Quote:
I really struggle with clean holes after desoldering..so joy oh joy.


Just cut the resistor's body off the board from the top. Then from the underside pull the stumps out of the board (with a pair of tweezers) while heating the pad with your iron. I use a 2mm chisel bit. Put a little fresh solder into the hole - ersin flux is best if a little messy - and then suck it out using a solder pump. Clean the hole with IPA on a cotton wool bud. It'll be good as new.

With the 10Ks in place you'll probably find your +15V current consumption will drop and U1 on the RPSU will run cool.
Pav


Reference me adding the LED to the RPSU-2

I didnt think i put it in the wrong way Dead Banana seriously, i just don't get it applause
Not much left to check either way.
power Diode destroyed too - removing the solder pad.
Also broke my swivel chair...falling off it.

Decided to go back to running without the LED and all is fine again.

Have refitted 30 10 resistors to main SRE330 pcb and powered up.
Progress has been made .. I now have modulation controls working when type switch is Multi ... sounds like a washing machine in spin mode ...but i havent calibrated yet but im suspicious the BBD section isnt kicking in

With type switch set to 3-phase ... the wet signal is identical to dry and no modulation changes that.

As i say ..I need to read the user guide again to know what to rxpect og 3-phase ..and then repeat the voltage checks of the BBD section , then calibrating.

Both voltage regs are running hotter than i would like... but thats progress.

Keep u posted.
Synthbuilder
Pav wrote:


Ouch.

I think either the diode had already failed or the capacitor was inserted the wrong way. The capacitor does need to be at least 35V rated.

The issue 1 SRE330 board had one electrolytic labelled the wrong way. It did pretty much the same as yours. Made a right mess.

Just to sure I've rechecked the RPSU2's layout and all the parts' legends are correctly orientated.

Tony
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