Dead Speedballed Crack after few months of use [solved]

[ilgello]

Hello Guys, My crack just died, I was listening to some music and puff it went off and never got back on again. Tubes are not glowing, all leds in the back are off too. Crack has been speedballed since the beginning and haven't be used much to be honest, all readings were perfect until a few months ago.

Where should I start for troubleshooting it ? Fuse is still intact.

Thanks!
Gia

 

[Grainger49]

If the fuse is Ok, then you need to check the voltages on the transformer with it turned on and the tubes in.  Be very careful, these voltages can really hurt you.

Edited to correct terminals.

Measure Voltage, AC, from transformer terminal 1 to transformer terminal 2.  It should be 120V +/- 15%.


Measure Voltage, AC, from transformer terminal 4 to transformer terminal 5.  It should be 6.3V AC +/- 15%.

Measure Voltage, AC, from transformer terminal 6 to transformer terminal 7.  It should be 150V +/- 15%.


Measure Voltage, AC, from transformer terminal 9 to transformer terminal 10.  It should be 150V +/- 15%.

Post back any that are out of spec.

 

[ilgello]

Hello Garinger and thanks for your help, below my reading, bear in mind I am in the EU so on 220v:

1-2: 230V

4-2: 0 edit: 1.8v

1-4: 0 edit: 2.4v

6-7: 166V

9-10: 166V

Edit to tune down the multimeter to check 2/4 and 1/4

Thanks
Gia

 

[Grainger49]

Well, I made a mistake.  I will edit the first response to make it correct.  Looks like I made several typos.  I will stop using the laptop.  It is part of the cause.

I should have said that you read from transformer terminal 4 to transformer terminal 5.  It still should be about 6.3V AC.

If you have that voltage there, the heater voltage is not getting to the tubes, they don't glow.  There are 6 connections in the heater circuit.  The first are the two at the transformer.  Check those, touch up the solder.

Then the twisted wires go to the large tube socket on pins B7 and B8.  There are 4 wires on these two pins, all need a good connection.  Touch these solder joints up.

Finally the heater wires go to the small tube socket, pins A4/5 and A9.  Touch up these solder joints.

This just might cure the problem.

 

[fullheadofnothing]

It appears your transformer is working, whether or not the measurement techniques were correct (or necessary). Your problem is going to be downstream from the transformer. Resistance and voltage checks from the manuals will illuminate the problem area.

 

[Grainger49]

Joshua,

That is why I directed him to the heater circuit.  He said in the OP that the tubes were not glowing. 

 

[Paul Birkeland]

Tubes are not glowing [...] Fuse is still intact.

The twisted pair leaving power transformer T4/T5.  This makes the tubes glow (or not in your case).  A funky solder joint or broken wire leaving this pair will leave the tubes unlit.

(If the tubes don't glow, a myriad of other symptoms will pop up that should be ignored until the tubes are glowing again)

You can measure the AC voltage between 4 and 5 on the power transformer to be sure you have something close to 6V present there.

-PB

 

[Grainger49]

Kind of what I said.

 

[Doc B]

Grainger we appreciate that you are putting in a lot of time offering suggestions, and that you now have more free time to do so. There have just been a couple of instances where we have felt the typographical errors that accompany some of them may create some confusion for the person asking for assistance. If my guys are offering clarification in these situations it is simply because it is their job to know the products and to support them in an expedient manner.

 

[ilgello]

Thank you guys. So I pretty much reflowed what you indicated (with exception of some Ax I couldn't reach well)... Tubes are glowing again!

Do you reccomend me to do a full voltage check before doing anything else ? Would I get the one from the speedball manual I Assume ?

 

[Paul Birkeland]

Yeah, for the voltages, just measure the metal tab of the MJE-350 (should be 60-90V or thereabouts) and the "O" pads on the bigger PC board (should be around 100V). 

-PB

 

[ilgello]

Yeah, for the voltages, just measure the metal tab of the MJE-350 (should be 60-90V or thereabouts) and the "O" pads on the bigger PC board (should be around 100V). 

-PB

Let's say I am within 15% 

You made all this troubleshooting easy, I would have been lost without your advice, thanks for the support!