Laney TT50H No Outout

[The Dude]

No lights lit up now. Don't know if there was ever 5v@ pin#8?What do you make of pin#8 to ground @ 4.1 ohms? Does that mean a short-U2?

Do you mean pin 14? It means a near short somewhere on the 5V line. It could be anything attached to that supply. See my post above.

[ca7922303]

Do you mean pin 14? It means a near short somewhere on the 5V line. It could be anything attached to that supply. See my post above.

Correction: pin#14(6.0 ohms)

[ca7922303]

Do you mean pin 14? It means a near short somewhere on the 5V line. It could be anything attached to that supply. See my post above.

In the process of getting ready to remove U6, I'm seeing burn marks on R11,13 ,15, 17.

[Enzo]

R13 looks burnt, the ones around it look like they got soot on them from R13.

Dear lord. Did we ever post a schematic for this thing? I'm not going back to read through 200 posts to find out.

[ca7922303]

Do you mean pin 14? It means a near short somewhere on the 5V line. It could be anything attached to that supply. See my post above.

Before I pull U6, I checked resistance on all three(3) legs. From left to right(76k,

[ca7922303]

Before I pull U6, I checked resistance on all three(3) legs. From left to right(76k,

U6 l to r(76k, 0.0, 33k)

[ca7922303]

There is obviously a short (or near short) somewhere on the 5V line. You'll have to track it down. Since the supply side of the regulator is also quite low, my first suspect would be the regulator itself. I'd remove the regulator and see if the resistance reading on the rail is still low resistance.

Removed U6, U2 pin #14 to ground now reads(49.6 ohms)

[nosaj]

schematic

[g1]

Correction: pin#14(6.0 ohms)

U6 l to r(76k, 0.0, 33k)

U6 pin3 is supposed to connect to U2 pin14. So I'm not sure why one would be 6 ohms and the other 33K, unless there is now a burnt trace in there as well.

[Enzo]

R13 burnt. R13 is a pullup for pin 4 of U2. Pin 4 of U2 also connects to a pin on the 15 pin "switches" connector. SK3 pin 14. I suspect something bad happened in the switches and burnt up that resistor and likely damaged U2.

SInce R13 pulls up to +5 and U2 is powered by +5, that might explain the dead 5v regulator U6. WIth U6 removed, does +12v appear on the input pin connection?

[ca7922303]

R13 burnt. R13 is a pullup for pin 4 of U2. Pin 4 of U2 also connects to a pin on the 15 pin "switches" connector. SK3 pin 14. I suspect something bad happened in the switches and burnt up that resistor and likely damaged U2.

SInce R13 pulls up to +5 and U2 is powered by +5, that might explain the dead 5v regulator U6. WIth U6 removed, does +12v appear on the input pin connection?

I'm guessing pin #14 on SK3 is on bottom row 2nd from the right. Is that correct?

[ca7922303]

U6 pin3 is supposed to connect to U2 pin14. So I'm not sure why one would be 6 ohms and the other 33K, unless there is now a burnt trace in there as well.

U6 pin#3 to U2 pin#14 is 0.0 ohms. (U6 removed).

[ca7922303]

U6 pin#3 to U2 pin#14 is 0.0 ohms. (U6 removed).

Also, R43 now is (0.9mvdc/0.9mvdc) V1-V6 #9-#5(6.6vac) hum balance pot(5.2mvdc/5.2mvdc), R52(0.0vdc/0.0vdc)R43(4.7k ohms resistance)

[ca7922303]

Also, R43 now is (0.9mvdc/0.9mvdc) V1-V6 #9-#5(6.6vac) hum balance pot(5.2mvdc/5.2mvdc), R52(0.0vdc/0.0vdc)R43(4.7k ohms resistance)

Also, see burn marks at HT which reads (-236vdc), left fuse pin reads(-452vdc)right fuse pin(0.0vdc) all three(3) grid pins read(-39vdc)

[g1]

Also, see burn marks at HT which reads (-236vdc), left fuse pin reads(-452vdc)right fuse pin(0.0vdc) all three(3) grid pins read(-39vdc)

No idea what you are referring to here. Tell us what the schematic reference is, or post pictures. You have the unit, we only have the schematic.