And iv been playin this dsl40c since this vid just a whole lot . I have a 4x12 w/ grnbks & v30s . Retired a while back , i got time to work em good . Its been 100% until now its not . Just plain died earlier . Power lite comes on but no sound . No blown fuses . Tubes all light up expect v1 . All tubes are good until it goes in v1. No juice , not enuf to light up a 12ax7 . Any clue where to go from here ? Meter says pin 1 and 6 are 2.65mv dc in v1 Thx for any help .
Been wanting to do this for while , and so i did . All good xcept 1 tube the bias , the numbers on the multimeter wont stay still it keeps creeping up , the numbers get bigger up to 15 over . Any ideas ?
Do you have the same model amp? I have read that some of the early DSL100H amps has PCBs that turned conductive and caused the bias to runaway like that.
Its a dsl40c , after putting in the new tubes turns out they were picking up lots of vibration . Like tap on top the cabinet it comes thru the spkr . So put in diff set and the meter stays real close varies 3 to 4 ma each way . Cld the other tubes cause tht since they seemed to b not quite rt , mayb ? Thts100% guess on my part . Seem fine now . Thks for ur time . Hav a good day .
@@tomfoolery2082 mine was caused by the unsoldered grid bias resistor. Could be a bad tube but could also be a bad component in the bias circuit. If you don't feel comfortable poking around in there, don't feel bad about taking it in for service. Were the microphonic tubes the power tubes or the preamp tubes? When the amp is on tap on them with a chopstick or a pencil. Maybe you can see which one is causing the issue.
I changed n biased the newest power tubes earlier this morning . If they preamp tubes causing the same problem id say they were microphonic . All systems go for now . Thks alot .
Con 4/6 are plugged in good . There is a con 4a / 6a ,, if tht might tell somthing . Pin 20 on the microcontroller idk lol ,, not seeing anything that looks like tht . Not seein tht on my schematic tho j thk it for a dsl 100 . Where would this controller be . Thx
If you're changing preamp tubes you don't really have to be concerned with biasing. However, if you replace one and it dies quickly you need to find the reason before replacing it again.
