Is heater voltage also low?
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Is heater voltage also low?
What does your meter say on diode check across those zeners?
There's not a lot running off those low voltage rails. 3 IC's and a couple other items. Easy enough to de-solder the IC supply pins (4...
Did you check if it is working? Just wondering if there could have been a mix-up and you got shipped something that was actually a defective return or something like that? (although I'd be surprised...
You set bias for total current through standby switch?
That is what they specify.
If you set for 75mA idle current at power tube, it would certainly pull down all the voltages.
Sounds like this unit matches the Hot Rod, not the Blues.
Here is Rev.B which shows the items you mentioned:
Don't rewire it to match a different schematic.
Can you post some pictures of the board, including the bias circuit area and any board number markings?
If yours has a coupling cap into the tank, like C43, check that signal is getting through it.
Do either of these schematics match up?
:thumbsup: on the melted in staples. Great way to add strength when bonding plastic.
All I can say without a schematic is that if you can't get a real loud response from the springs with the reverb and volume turned up, then I think the problem is on the recovery side of the reverb...
I've had problems with the shield wire in the wiring harness to the preamp with these, or the connectors.
Every time you have described the sound it sounds like the amp is picking up some kind of external interference.
Have you tried it at other locations? How have you determined the noise is not being...
Have you verified with your meter that 0 on the pot is 0 ohms?
Aside from that, the pulsing could be coupled through the power supply, C22 would be a suspect.
So if it measures the same as other diodes, and a new one also measures same, it should be ok.
Meantime, what is the unit you are trying to fix and what is the fault? :)
If you bought another new bridge and it reads the same, then the bridge is probably ok.
So just a question about your meter, or whether it is some odd type of bridge.
I'd also expect the epoxy to work well.
However, because this is a bias probe, it is going to be stressed much more than a normal tube would.
If the glue won't hold up, try to find one of these...
Also some very good but expensive industrial products out there, for example scotch-weld DP8010 or 4693.
You can't free it up because it is forming "diodes" with the plates and cathodes cross-connected like that.
Haven't read through all of this, but it's discussed here:...
DVL type was specifically called for in that position due to safety concerns (due to failure mode of non DVL caps in line to ground and line to neutral applications).
Now they use type Y for line...
It's a bit hard to tell, but it looks like that (-) lug arced over to the chassis. I assume it's one of the caps that needs it's shell insulated from ground.
In this case, often the solder joint at the IEC cracks and becomes resistive. The heat buildup causes the trace to burn.
That's if the burn is right beside or on the solder joint.
If you can still...
The switch is shown as 2 halves, SA6-A, and SA6-B. 3 pins on each half.
If it has a can cap that is soldered to the chassis, you need a very good joint there for proper grounding. There are lots of tips & tricks available from folks here if that is required.
I'd guess it's OEM and the 'comm' on the label is for Commando.
Without pictures I have no idea what is or is not on the main board, and I doubt you will be allowed to post pictures yet, but you can try.
Some high end mixers have all modular construction, so...
Have you opened the unit?
Does it have connectors on the individual channels?
If not, for a novice, it will be no easier for you to disable it than to fix it.
(P.S. for those following,...
You mean the cap he has added, .1uF 63V ?
It is not electrolytic. Any .1uF of 63V or higher voltage rating will do.
Here is the post I was referring to: https://music-electronics-forum.com/showthread.php?t=49628&p=537786&viewfull=1#post537786