Speedball Final LED / Voltage - Troubleshooting Help, Please

[ItsAllInMyHead]

I seem to have made an error somewhere in my upgrade.  It's not test point position this time... LOL!  I had finished the build (or so I thought) earlier this evening.  I stepped away, but I wanted to give it a listen before turning in.

Sequence -

Per process, I did the voltage check on the small board.  All LEDs lit, and the voltages were within tolerance.  Proceeded with the big board and finished up.  I checked all voltages below. Resistances prior to the voltage check were are in the megaohm range at OB and OA.

Voltages

OA -- 101.7
OB -- 98.2
G -- 0
B+ -- 179.3

I went to flip the chassis and tidy up prior to getting it going and thought I'd do a last once over.  No nada nowhere are any LEDs lit.  Nowhere in the entire build.  Not at the 0 pin socket, not on the little board, and not on the big board.  I'm glad I noticed and read the last page.

So, needless to say... I did not hook it up to listen.  I re-went over every joint.  I can't find anything.  The crack was perfectly functional before the attempted upgrade.

Attached are photos.  If I need to get tighter to any section, please let me know.

I did a quick listen and full final voltage check / LED check prior to shutting it down before the upgrade.  Everything was measuring the same as the initial build and was working great.

Any help is greatly appreciated.  I thought I had an error free build...

 

[Paul Birkeland]

OA -- 101.7
OB -- 98.2
G -- 0
B+ -- 179.3

Those are OK for big board voltages.  If you don't have glowing LEDs, you will have voltages that won't be anywhere near perfect, and you'll want to start by posting those.

-PB

 

[ItsAllInMyHead]

Hi Paul -

Thank you for the reply.

tl;dr version - I now have all LEDs, proper voltages, and sweet sweet music.  The saga below is for reference.  No need to review if you're busy, but I'd still love a thought or two.

Last night, I did the voltage check on the big board, but had to leave the project before listening to go to supper.  I admit I didn't read the last page re: the LEDs until later when doing the second check.  As you can tell, I'm a bit new to DIY and very cautious about my skills.  I try to follow the directions to the letter.  As an example, I can't see in the manual where it tells you to put in the 2nd 2N2222A on the A side, but it seemed obvious.  Those were the voltages measured last night at the 1st and 2nd checks on the big board.

This morning, after reading your reply - I rechecked wiring once more with freshly caffeinated eyes.  I looked it over under magnification, and I took new pics to zoom in and compare / review.  I am also trying to learn more about circuits, so I tried to figure out how I could not have ANY LEDs lit when the small board and the 2 at the 9 pin were just fine previously.  It just seems unlikely (impossible??), but I am a complete novice.

I went to measure the voltages again.  Powered up.  Still no LEDs.  I did it out of sequence.  Just as I was reaching to hook the clip to U12, I knew I goofed.  I had powered the unit before attaching the alligator clip...  POP! I thought I had blown the 220uF across U12/U13.  No magic smoke or smells though.  Just an arc between the lead and one of the terminals.  After cursing for a bit.  I disconnected the power and physically inspected everything.  I checked capacitance for all 3 220uF - I got 550+-uF at each cap.  My meter only has a range of 600uF.  +- 5%  None of the caps look discolored or are bulging.  In the past, when I've "popped" caps - they physically pop and there is a wisp of smoke.  There is no apparent damage to any parts nearby or in the PSU section of the schematic.  I just got very, very lucky and the lead arced as I was reaching in without damaging anything.  I put this here to possibly help others and for transparency in troubleshooting in case I'm wrong about being lucky.

I did a another physical re-inspection, but I am not sure what additional test points would be most valid after the Speedball installation.

Feeling confident, I powered back up, and using the proper sequence took new measurements.  Still No LEDs.  Nowhere.  I turned off all lights just to be sure.  Both tubes glow properly.

Measurements.

OA - 100.1 (Started higher and settled / locked here)
OB - 98.2 (Started higher and settled / locked here)
G - 0
B+ - 173 +- (it bounces around a bit and never locked)

Thanks as always. 
----------

I wrote everything above the dotted line, paused - and waited.  I plugged back in for one last and final look, and we have properly lit LEDs.  Gorgeous LEDs.  We have tunes... The sound is clean, and the amp is functioning.  Now I need to go over everything again.  Given my mishap with the 3rd voltage check, are there any other components or test points you recommend taking a look at just for taking extra care?

Is there anything logical (other than me imagining things over 4 checks or needing a very serious vision check  :) that can cause the test points to measure properly, but have no lit LEDs?  I simply can't imagine a cold joint can do it.  I could go happily along, and act like I never made a mistake... but I don't mind looking like a dunce if it helps me and possibly others learn.

 

[Doc B]

It does take a few seconds for the tubes to conduct and allow current to flow through the LEDs so they will glow. It sounds like maybe you didn't wait long enough. If it works don't worry about any damage to caps.

 

[ItsAllInMyHead]

Thanks so much!

Perhaps I was too quick on the draw, but all's well that ends well.  I'll quit being paranoid and enjoy the music.

 

[Paul Birkeland]

Also if you attempt to measure the capacitance of the 220uF/250V caps, your meter will likely pick up on the other 220uF/250V caps since they are only separated by low value resistors.

 

[ItsAllInMyHead]

Hi Paul -

Thanks so much to you as well.  I am just learning, so I was not sure what exact value to expect.  I saw in the schematic (and building) the filter caps were in parallel along with having the resistors.  I fully admit that I wasn't sure exactly what value I'd get.  I figured somewhere shy of 660.  Anything below 440, and I'd have written for advice before powering back up to recheck the voltages.

The more mistakes I make, the more I learn.  Unfortunately, even with all the sage advice... I learn the hard way.

I suppose the good news is that some of my friends figure that if I can do it.... so can they.  We did a group build day with another project, a few weeks ago, and everyone really enjoyed it.  Next may be Cracks.  I have my other Crack kit ready to go.  How is it that I am always the guinea pig...?  ;D

-Cheers