OP
Ok, so no burned areas, and no visibly loose solder joints. De-dusted it and used De-Oxit 5 to clean the tube sockets, a Q-tip with D-5 into all the jacks and i also cleaned up a ton of rosin spatter.
Germino Lead 55 Trouble - We Summon The Amp Gods:
- Thread starter Inspector #20
- Start date
OP
Got a missing washer around one of the (4) front high/low jacks. Gonna head to Home Depot and source a visually acceptable replacement, rather than order up and wait...
syscokid
Ambassador of War & Peace
The input jacks are suppose to be isolated from the chassis holes at where they are installed. But eventually all the input jacks are grounded to the chassis one way or another.
Ditto!!!!!
OP
Busy week doing sountracks for commercials and spending all my free time on the bike...
The owner has one of my loaner Marshall's, so he's not hurting...
OP
Ok,
After cleaning, no more static/scratchy sound. Currently, looking into the back of the amp from left to right, i am running the following preamp tubes:
1. JJ-ECC83S
2. JJ-ECC83S
3. JJ-ECC82
Power tubes are Sovtek El-34's.
Very good tone. I have rolled over a dozen tubez tonight. With ALL tubes i noticed tbat i could generate a light 'pop' in the speaker - similar to a breath pop on a microphone - by poking the items shown in the attached images.
This noise anomaly occurs only on the first two preamp tubes - and it remains the same with over 8 tube changes.
Bumping the wires shown at each tube socket creates a 'pop' as if you are tapping a microphone. Not at all like the way a microphonic tube sounds.
Also, bumping the two resistors shown also creates this pop effect.
Tapping the tube or shaking the socket also does it.
Thoughts????
After cleaning, no more static/scratchy sound. Currently, looking into the back of the amp from left to right, i am running the following preamp tubes:
1. JJ-ECC83S
2. JJ-ECC83S
3. JJ-ECC82
Power tubes are Sovtek El-34's.
Very good tone. I have rolled over a dozen tubez tonight. With ALL tubes i noticed tbat i could generate a light 'pop' in the speaker - similar to a breath pop on a microphone - by poking the items shown in the attached images.
This noise anomaly occurs only on the first two preamp tubes - and it remains the same with over 8 tube changes.
Bumping the wires shown at each tube socket creates a 'pop' as if you are tapping a microphone. Not at all like the way a microphonic tube sounds.
Also, bumping the two resistors shown also creates this pop effect.
Tapping the tube or shaking the socket also does it.
Thoughts????
Cadorman
Ambassador of the Catocaster
First, I did not stay at a Holiday Inn Express last night, so don't take what I say as gospel. I think you fixed your problem. Run away. Don't poke the bear. If you move stuff on a live tube amp it will make noise. If you want to have fun move the wires from the ohm switch. That can be noisy.
Get it hot and run it until it should make noise. If it doesn't, ship it.
Get it hot and run it until it should make noise. If it doesn't, ship it.
OP
After 1 hour of 'idling,' I'm reading 470 VDC plate voltage at pin #3 on the power tubes.
OP
Just for kicks, i swapped in the old tubes and recorded 464VDC plate voltages...
OP
Which????
Cadorman
Ambassador of the Catocaster
Yeah, I wouldn't use the EL34B tubes in that amp. They don't generally agree with old school circuitry. Totally mess up the voltages.
Cadorman
Ambassador of the Catocaster
The one at the end of the board by the presence pot.
OP
Cadorman
Ambassador of the Catocaster
Yes! Those are 8.2k each on the 1968 schematic. 10k on the 1970 version.