New HT1 owner-non runner!
Posted: Fri Jun 21, 2019 6:43 am
Hi,I was given a non working ht1 combo by a friend.
He had been using it and it died and he says to me keep it because it was resigned to the bin!
Myself,never one to shy from a challenge,I brought it home and plugged it in.
so,the power led came on but no sound.no sound in speaker,phones or the mp3 jack.
A few tests reveal the pcb fuse gone so,i fix it with some light fuse wire.
Now...we have sound.
Plays fine for 2 minutes on clean then it distorts and the sound diminishes until nothing so I turn it off.
5 mins later...It goes again and I keep an eye on the valves and notice the 12au7 valve red plating and arcing and the 12ax7 is microphonic with the tap test.
I suspect,he kept using it with bad valves until the pcb fuse cried enough and blew.
I have 2 new valves coming for this and hopefully these cure it.
Any thoughts?
I was also instructed,there is supposedly a flaw in the pcb design where the resistors in d87 and d93 on the pcb are wrong and was advised swap these out for a 4k7 resistor and a 680 resistor which i have already done.
Hopefully..these new valves come and no more issues and i can use this ht1.
If it works out,next plan is to install a port so I can use a footswitch to change channel
Does it sound like a bad valve issue that killed the amp with the previous owner being unaware and using it until his fuse went?
Thanks in advance
He had been using it and it died and he says to me keep it because it was resigned to the bin!
Myself,never one to shy from a challenge,I brought it home and plugged it in.
so,the power led came on but no sound.no sound in speaker,phones or the mp3 jack.
A few tests reveal the pcb fuse gone so,i fix it with some light fuse wire.
Now...we have sound.
Plays fine for 2 minutes on clean then it distorts and the sound diminishes until nothing so I turn it off.
5 mins later...It goes again and I keep an eye on the valves and notice the 12au7 valve red plating and arcing and the 12ax7 is microphonic with the tap test.
I suspect,he kept using it with bad valves until the pcb fuse cried enough and blew.
I have 2 new valves coming for this and hopefully these cure it.
Any thoughts?
I was also instructed,there is supposedly a flaw in the pcb design where the resistors in d87 and d93 on the pcb are wrong and was advised swap these out for a 4k7 resistor and a 680 resistor which i have already done.
Hopefully..these new valves come and no more issues and i can use this ht1.
If it works out,next plan is to install a port so I can use a footswitch to change channel
Does it sound like a bad valve issue that killed the amp with the previous owner being unaware and using it until his fuse went?
Thanks in advance