[BUILD] 1176LN Rev D DIY

[Chryst]

COuld be a bad pot.  What's the date of manufacture on it?

It's the last line engraved on it.  4 numbers followed by a letter.

Mike

I think you mean 1311M. Right? Thanks!

Was it a bad batch Mike? Or do I need to look somewhere else? Thanks for your help!

 

[Echo North]

No more than 10%.  But honestly even 33VDC seems a little high.

Are you using the Hairball power transformer (Avel) 2X25V?

Are your R87 R89 values correct?

Yes to the Avel. Just double checked the resistor values at 87 & 89 and they are correct. 1.1k and 220r.

That's weird.  You're caps and diodes are all the right value and positioned correctly?  What is your -10VDC reading?

You're measuring your DC V between the CT pad and +30 point correct?

 

[Echo North]

COuld be a bad pot.  What's the date of manufacture on it?

It's the last line engraved on it.  4 numbers followed by a letter.

Mike

I think you mean 1311M. Right? Thanks!

Was it a bad batch Mike? Or do I need to look somewhere else? Thanks for your help!

Not that I'm aware of.

Send me an email.  "info (at) hairballaudio.com"

 

[tronnyjenkins]

No more than 10%.  But honestly even 33VDC seems a little high.

Are you using the Hairball power transformer (Avel) 2X25V?

Are your R87 R89 values correct?

Yes to the Avel. Just double checked the resistor values at 87 & 89 and they are correct. 1.1k and 220r.

That's weird.  You're caps and diodes are all the right value and positioned correctly?  What is your -10VDC reading?

You're measuring your DC V between the CT pad and +30 point correct?

I'll double check the diode and cap values, but I'm 98% sure they're correct and in the right positions.
I'm getting a -9.76VDC, so that's close enough, right?

And yes to the test points.

 

[Echo North]

No more than 10%.  But honestly even 33VDC seems a little high.

Are you using the Hairball power transformer (Avel) 2X25V?

Are your R87 R89 values correct?

Yes to the Avel. Just double checked the resistor values at 87 & 89 and they are correct. 1.1k and 220r.

That's weird.  You're caps and diodes are all the right value and positioned correctly?  What is your -10VDC reading?

You're measuring your DC V between the CT pad and +30 point correct?

I'll double check the diode and cap values, but I'm 98% sure they're correct and in the right positions.
I'm getting a -9.76VDC, so that's close enough, right?

And yes to the test points.

Do you only have the power supply stuffed.  Is the regulator oriented correctly?

 

[tronnyjenkins]

No more than 10%.  But honestly even 33VDC seems a little high.

Are you using the Hairball power transformer (Avel) 2X25V?

Are your R87 R89 values correct?

Yes to the Avel. Just double checked the resistor values at 87 & 89 and they are correct. 1.1k and 220r.

That's weird.  You're caps and diodes are all the right value and positioned correctly?  What is your -10VDC reading?

You're measuring your DC V between the CT pad and +30 point correct?

I'll double check the diode and cap values, but I'm 98% sure they're correct and in the right positions.
I'm getting a -9.76VDC, so that's close enough, right?

And yes to the test points.

Do you only have the power supply stuffed.  Is the regulator oriented correctly?

Yep, just PSU.
Do you have a clarification on the regulator orientation? That was the only part I was not confident about orienting- I'm pretty sure I ended up doing it correctly, though I'd like to confirm.

 

[Echo North]

There is a thin line on the silkscreen layer on the side where the AC-CT-AC pads are.  This is where the "tab" should be.

If your -10VDC looks good, which it does, there has to be a component issue in the 30V rail smoothing and regulation.

Mike

 

[tronnyjenkins]

There is a thin line on the silkscreen layer on the side where the AC-CT-AC pads are.  This is where the "tab" should be.

If your -10VDC looks good, which it does, there has to be a component issue in the 30V rail smoothing and regulation.

Mike

Problem solved! This is why you always check your PSU first before moving on! I'm glad I did.

Thanks Mike.

 

[Echo North]

There is a thin line on the silkscreen layer on the side where the AC-CT-AC pads are.  This is where the "tab" should be.

If your -10VDC looks good, which it does, there has to be a component issue in the 30V rail smoothing and regulation.

Mike

Problem solved! This is why you always check your PSU first before moving on! I'm glad I did.

Thanks Mike.

Exactly.

Glad you got it sorted.

 

[Bellico]

I'm a newbee so bare with me if I sound dumb.  I have a good amount of experience fixing, moding, soldering and wiring but this is only my second full build. 

I Have just finished the build on my REV D kit from Hairball.  My friend and I built 2 side by side.  We have followed all the instructions to the letter. 

Our builds are identical apart from 2 aspects.
1. Mine is hardwired to the board and he used terminals
2. Mine has a silver case and his is black ( I don't think this is the issue)

We went for the smoke test and the black face turned on, VU lit up and pinged... Blue stripe case unit did nothing. 

I began testing everything starting at the plug.  Everything seems fine through the secondaries on the power transformer.  Fuse is fine, switch is fine, connections are fine, ground is fine.

I'm getting 24v on my red and yellow secondaries as expected and 0 on black and orange. 

once the power is connected to my board everything goes out of wack. 

I'm getting nothing at my test points and no light at the VU.  I even tried only hooking up the VU light to the power to see if that works and got nothing.  I am sure the wiring is proper as it is exactly the same as the black case version that works.

I tried passing audio thinking it could just be the light in the VU and it did not pass audio. 

I replaced all the wires and re made all the connections between the power tranny and the PCB.  I hardwired instead of terminals and my connections test solid. 

took the vu light out of the connection and still nothing at the test points. 

continuity is fine through the tranny, VU, VU lamp, Power supply section.  I have signal continuity as well through the board without the power tranny connected from both AC's to the CT.

All components are placed identically to our working black case version and I have reflowed every solder on the board.  We tested every component and they are all well within the tolerance limits.  We were super anal about that.  We matched the tolerances on every component between the two units as we populated so that they could be used in stereo if needed. 

Output tranny is wired correctly.  All of my solders look clean and no visible traces or damage to the PCB. 

My friend swears he did not sabotage my comp either. 

any thoughts?

My next move will be to remove all the components leaving the PSU to isolate the PSU and re test it. 

 

[jplebre]

did you follow the recommendation of powering up the board with the PSU part only?
if so, was it working then?

once the power is connected to my board everything goes out of wack. 

Did you check o/p transformer wiring? there were quite a bit of problems with that reported.

you can also disconnect everything out of the VR section as that will take quite a lot of stuff that is connected to the -10 rail.

What do the DC points measure out of curiosity>

 

[Bellico]

did you follow the recommendation of powering up the board with the PSU part only?
if so, was it working then?

Honestly.  I'm a jerk and I didn't.  I Decided to learn my lesson this time and now I am going to pay for it by desolder all the components leading out of the PSU and test again. 

[/quote]

once the power is connected to my board everything goes out of wack. 

Did you check o/p transformer wiring? there were quite a bit of problems with that reported.

you can also disconnect everything out of the VR section as that will take quite a lot of stuff that is connected to the -10 rail.[/quote]

Maybe i'll try that first.
[/quote]

What do the DC points measure out of curiosity>

[/quote]

DC reads 0 on both rails 

checking resistance between AC and the test points shows continuity

1.229 K at the +30 tp  to the AC point near the out tran

222r on +30tp from the other ac point

1.226k from +30tp to CT

1.58k  at -10tp from both AC's, CT and ground

I dont know if that info helps

My output tran is wired correctly and I have reflowed the solders.

My wiring parts and components are identical to the black face we built.  Everything was ordered together and built together step by step on the same assembly table.  That is what is confusing me here.  A bad component seems more likely than a wiring error. 

My version of the PCB also has the ground wired to the - on C25 as instructed.

 

[Bellico]

OK

I isolated the PSU and still nothing on the rails. 

disconnected the power tranfo.

My secondaries are reading 18v straight of the power tranfo.  So My power tranfo is no good right?

That was my first instinct 3 days ago. 

 

[Bellico]

... I still don't understand why I'm getting nothing at the rails even if it is only pushing 18v out of the power transfo.

All my component values and placements are correct.  solders are fine.  continuity is fine.   

 

[Echo North]

... I still don't understand why I'm getting nothing at the rails even if it is only pushing 18v out of the power transfo.

All my component values and placements are correct.  solders are fine.  continuity is fine. 

are you measuring the rails against the CT?  DC setting?  Are you connecting the transformer to a wire header in the PCB?  Is it broken/bad solder joint?

Mike

 

[Echo North]

What is your DC voltage at the cathode (side with the line) of CR7 and CR8?

What is your DC voltage at the anode (side without the line) of CR9 and CR10?

 

[U87610]

Hey DIY'ers!!

I appreciate the input I received a few weeks ago about my power section. I am about to stuff the rest of the board, since my power rails are accurate, but still had a question about fuses - I blew another one. 

This got me thinking, so I created a setup using a couple of alligator cables, attached one end to each lead in the fuse housing and connected the other ends to the leads of my multimeter to test AC current through the PSU circuit.

When I push +4, +8 or GR the meter will sometimes spike (highest I've seen is just over 500 mA) for a fraction of a second and then display a constant 12mA continuously - i.e. does not waver.  The spike is almost instantaneous, and is normally under 100mA if at all - most times it just moves from 0 mA to 12 mA. 

Is that normal?  I am assuming it must be, otherwise, why are we using slo blo fuses, but wanted to make sure that this is normal before continuing.  I am still confused why I've blown a few, but normally the fuse is fine and I always observe 29.63 to 29.65 Vdc at the + 30 Vdc rail and - 9.76 to - 9.77 Vdc at the - 10 Vdc rail.  AC voltage before the PSU section is consistently 29.99 to 30.08 Vac.

Is a current spike normal? Could my first batch of fuses been fast-acting? The +30 Vdc large capacitors is grounded so it disharges quickly, but the two negative large capacitors do not (I observe -9.66 Vdc after unit is unplugged).  Could this discrepancy in stored charge contribute to the observed current spike? Am I over thinking things?

I just want to verify with more experienced builders before I populate the rest of the board.

Thanks!!

 

[jplebre]

If at all, there's a problem with the switch. You can populate the board as normal.
(I'm assuming you didn't connect the meter to their respective points on the PCB. Even then, shouln't matter as it's unpopulated IIRC)

Maybe Mike can pitch in on the switch.

 

[Harpo]

.., but still had a question about fuses - I blew another one. 
.. AC voltage before the PSU section is consistently 29.99 to 30.08 Vac.
.. Is a current spike normal?

Inrush current spike is normal and has nothing to do with a switch. AC mains voltage isn't constant, but might vary by +/-10%, depending on location or time of day.
Fuse rating required is depending on local mains voltage (only one of the reasons you better update your profile with your location data for an intercontinental forum) and VA rating of your mains transformer. Assuming yours is a toroidal transformer (EI-core will be different) with maybe 80% efficiency (your transformers datasheet will know better if yours come with maybe 85% efficiency, so you would replace the typ. 0.80 with 0.85 in the formula below),
30VA / 230VAC * (1 / (1 - 2*(1 - 0.80))) = 0.217A.
(rough approximation will be transformer VA / AC mains voltage * 1.6)
Next avail.standard parts value is 250mA.
For a toroidal transformer you want a '/ t' (for time lag or slow blow) fusing characteristic, so if you are located in maybe europe, your order probably will be a '250mA / t' rated fuse with fuses outer dimensions that matches your fuseholder.

 

[U87610]

Thank you for the input!!

Thanks Jplebre! I have not connected the meter wires to the PCB yet.  Only the PSU section of my board is populated at the moment.

Thank you for the info Harpo! I updated my profile (I'm in the states).  What is the name of the equation you posted?
I couldn't readily find the datasheet for my avel linberg toroidal transformer from Hairball, but for argument sake, let's assume it's efficiency is 80%.

After substituting .8 in the formula you posted I get

30Vac/115Vac * (1/(1-2*(1-.8 ))) = 0.435A; with 85% efficiency the current falls to 0.373 mA

Looks like I'd be okay with 500 mA slo blo fuse, assuming once I populate my board and fire it up again I get a constant current well under 250 mA, correct?