MartyMart
Well-known member
Hi all, this is my first post and a request for some assistance I'm afraid !.
I've found you, after spending some time at arons "DIY stompbox" forum
and have many good builds/designs under my belt, including a couple of
valve projects.
I have not touched much over 18 volts though !
I have a "Mindprint Envoice MK I" valve mic-pre, which at the moment is half dead.
Pre amp/48v phantom and all controls are "working" ( LED's etc ) but
the eq/compression/saturation block is not.
( I dont have a schematic for it )
Inside the unit there's evidence of a few burnt up components :
1 - 15 ohm 2 watt power resistor ( measures 15 ohms removed )
2 - 2x 22ohm half watt reistors and 1N4007 coming from the transformer
toward the valve section.
These also measure correctly, once removed.
I'm wondering what to look at next.
Would you advice replacing these components anyway ?
There is a pair of 2,200uf 16v caps between the 22 ohm/1N4007 and the
valve section, perhaps these have also been damaged ...?
Could a "section" of the transformer have blown ( powering the eq/comp)
seems odd that all else including the 48v line is working !
The 12AX7 also lights up.
Many thanks for any pointers/advice, this seems like a great place
Cheers,
Marty.
I've found you, after spending some time at arons "DIY stompbox" forum
and have many good builds/designs under my belt, including a couple of
valve projects.
I have not touched much over 18 volts though !
I have a "Mindprint Envoice MK I" valve mic-pre, which at the moment is half dead.
Pre amp/48v phantom and all controls are "working" ( LED's etc ) but
the eq/compression/saturation block is not.
( I dont have a schematic for it )
Inside the unit there's evidence of a few burnt up components :
1 - 15 ohm 2 watt power resistor ( measures 15 ohms removed )
2 - 2x 22ohm half watt reistors and 1N4007 coming from the transformer
toward the valve section.
These also measure correctly, once removed.
I'm wondering what to look at next.
Would you advice replacing these components anyway ?
There is a pair of 2,200uf 16v caps between the 22 ohm/1N4007 and the
valve section, perhaps these have also been damaged ...?
Could a "section" of the transformer have blown ( powering the eq/comp)
seems odd that all else including the 48v line is working !
The 12AX7 also lights up.
Many thanks for any pointers/advice, this seems like a great place
Cheers,
Marty.