After speedball some problems

[spitzer]

Hello all,

Firstly sorry for my english. I assembled my crack without any problems and it worked flawlessly. But with speedball ı have some problems. right channel has lower out with all volume levels and sometimes it has staticy randomly. all pcm leds are litting, 9 pin leds are litting but one of them is very dim.

t1: 13v
t2: 177v
t3: 0v
t4: 178v
t5: 23v

t1 and t5 have problem, As i'm reading here I am using 2 of 470 ohm resistor instead of 2 dead leds on the little pcm boards. so this can be problem?

[Paul Birkeland]

You 100% cannot substitute a resistor on the PC boards for an LED, that will not work.

[spitzer]

thanks for quick reply.

i m from turkey, and shipping to here takes 5 weeks. really too long time for me. so resistors works instead of 9 pin socket leds not pc boards? or any red led will work instead of 9 pin led?

 what can i do?

[Paul Birkeland]

You can look for a 1.5V red LED.  It should be moderately easy to find locally.  There is also the possibility that a transistor has been damaged from this modification, but that will be easier to determine once you have new red LED's.

Just out of curiosity, you did this to both of the smaller green PC boards?

[spitzer]

yes, both of small pc green boards have a 470 ohm resistor instead of leds. okey i will try to find some red leds, i hope i will. so, using 2 of 470 ohm resistors instead of 9 pin leds will work?

[Paul Birkeland]

It's very likely that you'll damage the LED's when removing them from the sockets, then you'll need 4 1.5V red LED's...

[spitzer]

Well, I replaced 4 leds with new ones. T1 is now 75v, but T5 is now 160v and unfortunately 2 leds on b board is not litting now.

[Paul Birkeland]

160V on T5 means the small green PC board on the right side of the chassis (when it's flipped over) is not functioning.

Are both the LED's on the 9 pin socket glowing?

-PB

[spitzer]

yes both led s on the 9 pin socket is glowing. meanwhile i checked now 237 ohm resistor on b board and is showing only 33 ohm. it is corrupt i hope only reason is this resistor. i ll replace it tomorrow.

[Doc B.]

Make sure the LEDs are installed the proper way. A very low resistor value would cause the current to increase and the plate voltage to be low, not high. The 2N2907 may be bad, and it could give you a false reading on the resistor if it is being measured in the circuit.
 

[spitzer]

i checked led's many times and they are okey. no it is not being measured in the circuit, so it is bad? maybe the transistor is bad too.

[Paul Birkeland]

I would replace both the transistors on that board.  A damaged 2N2907 may also stress the MJE350.

You can replace the 2N2907 with a PN2907 if that's easier to source.

-PB

[spitzer]

okey, i replaced my bad resistor with new one and now t5 is 83v. i think it is in limits. and this amp is really nice with my hd800. it really sings, especially treble is great:) only problem now is right channel a bit lower output than left channel.

[Paul Birkeland]

How is the T1 voltage? (83V is a good spot to be)

Sometimes if you have sensitive headphones and a strong source, you won't use much of the rotation of the volume control.  If this is your situation, it's easily fixed by padding the inputs with a pair of resistors.

-PB

[spitzer]

t1 is exactly 75v. okey i got it. another question, when i tap the 6080 tube, its sound is heard from only right channel. it is a problem or?