Speedball install trouble shoot

[JamieMcC]

Please can I have some assistance with trouble shooting a Speedball install.

After five fault free Crack builds number six has me scratching my head 

Crack built stock first last week except for a Neutrik locking headphone socket. All resistance and voltage testing completed OK and it has been working fine.

Speedball fitted today.

Post Speedball install Voltage readings

Terminal & Readings, I left out the ones that where ok

1    89
2    217
4    217
5    85
7    148
9    122
13  218
15  229
19  94
20  0
A1  86
A6 0
B1 85
B2 214
B3 150
B4 86
B5 214
B6 123

Tip test looked ok

I ohmed out the resistors on install and have tried reflowing my connections several times but do need glasses now 

Observations

On the large Speedball pcb and on one side only the outboard most led does not look lit (check with magnifier and also tried replacing with a spare led with no change) all others glowing well.

As the tip measurement looked ok I tried running some tunes with my test cans and was only getting sound through the black rca channel input only. Went over red channel again reflowing but still no change.

Suggestions on what to try next welcome.

Thanks

Jamie

[Paul Birkeland]

Your voltages at 1 and 5 are in range, so no issues there.

I would be resoldering all the joints on the large PC board, as well as checking the jumpers that connect that board into the circuit.

[JamieMcC]

Ok thanks

I demounted the large board and have gone over all the connections with a magnifier and reflowed all connections again with no change to voltages. Audio still only in the one channel.

Its a bit darker now and one LED on the large board is definitely out.

Any thoughts on what to try next?

(https://www.head-fi.org/image/id/7670589/width/900/height/900/flags/LL)

(https://www.head-fi.org/image/id/7670586/width/900/height/900/flags/LL)

[JamieMcC]

A little progress perhaps?

After a bit of prodding poking and more reflowing if I listen during powering on I can for the briefest instance hear music output from both channels then its gone and the channel is dead again.

Will try again in the morning with fresh eyes.

Edit Time to fire up the Mainline for some RnR 

Cheers

Jamie

[Doc B.]

You might test the resistance across the legs of the 2n2222a.

[JamieMcC]

You might test the resistance across the legs of the 2n2222a.

I struggled to get any readings at all so pulled it out and replaced it with a spare 2n2222a and the led again (just in case) but the result is the same brief audio a fraction of a second in the non working channel when turned on then it drops out as the other channel kicks in.

Further observations

On initial power up the led before the non lighting led (see pic) lights up brightly and instantly the power switch is thrown brief sound is heard on the non working channel, then as all the other leds start to glow (except non working one) the second channel comes in and the first channel goes silent.

 

[Doc B.]

So the LED bias string is conducting for an instant, and then when things start to warm up and flow current something shorts and effectively bypasses the LED that goes out. That's why I suggested measuring the 2n2222a, as it is in parallel with one LED.

You might also check the insulator of the TIP 50 heat sink.

[JamieMcC]

Hi Doc yes that just about sums it up I replaced both the insulator and TIP50 with new parts no success, still have the one led out. 

Over to you again.

Cheers

Jamie
 

[JamieMcC]

I know its probably unlikely but my problem seemed to be with the large pcb board a fracture in the trace perhaps?

Any how I swapped the components to a similar board I acquired a while back off of headfi and am up and running now.
I will have a play with the used board and see if I can find the problem perhaps it can still be salvaged for use in another build.

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fcdn.head-fi.org%2Fe%2Fe1%2F900x900px-LL-e1def119_001.jpeg&hash=f9c75040fdc181e53d06515655afd081514ad3b8)

 

[Doc B.]

You could certainly test the traces. I would guess it's more likely that you had a short, maybe thru some flux, that was in the circuit such that it came into play as the tubes warmed up.

[JamieMcC]

I will give the board a good scrub and clean up and try it out again on the next one. Did I read somewhere it was ok to put the pcb boards in the dishwasher?