tube change - circuit schematic gro 100

[seidel]

hi everybody,

i need your help!

i bought an old orange gro 100 head in a second hand hifi(!) store.

i brought it to an amp doctor who checked all funktions and replaced all tubes ...(three of them were still o.k)

after a short while of playing one of these new tubes "failed with a crack in the glas".

i replaced it with another el 34 but now the clean sound is gone.
someone told me that i had to replace all 4 tubes and that it must be matched tubes ...( i have no idea of it...)

the original (hifi)seller told me that he maybe could match the tube when i got a circuit schematic ...
he also asked me why the amp-doctor didn't gave me back the other old tubes ... and if i never saw that even old tubes were sold on the market ...

my questions:
1.where can i get the circuit schematic of an gro 100?
2.can i change the tubes by myself when putting in a couple of 4 matched tubes?
3. when one of four tubes is broken what can i do with the other almost brandnew three?
4. did the amp doctor really cheat me with the original old tubes?

thanks in advance

dirk

[Edbig]

you should have asked for the old tubes back. They may have been of some value.
One of the new tubes could have been faulty if it cracked.
You should take it back to the tech and get a matched replacement.
You can change your own tubes as long as they are EL34's that fall within the same range as the ones that were in it.
A schematic is not necessery to match tubes. You need a tube tester.

[seidel]

hi edbig,

thanks for your response.

how can i find out if a new tube has the same range the the others?
Are new tubes labeled?

dirk