Einstein Problem - Filter Cap?

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bhuether

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Peter,

I just came across this post:

viewtopic.php?f=14&t=12322

My Einstein has similar problem. I am replacing tubes tomorrow, but am starting to think that maybe it is filter cap. If it is, what is the part number and where on the board are the 2 caps? Are they C67 and C69? If I do replace it, I want to make sure it is same exact part. A link to a site where I can get the part would be great. Or I suppose the amp is under warranty in which case could I send it to someone for service?

thanks,

brian
 
If V1 is not working or not in the socket You have the
same squealing noise.

Are You sure You have a problem with a filter cap ?
 
Hi Peter,

I just tried replacing V1 (tried a 12AX7EH as well as a Tung Sol 12AX7). I am still having same problems I had with stock preamp tubes.

Chan 1: In general, just sounds very odd. Doesn't seem to have much gain even in Mode 3. And at loud volume it has this strange fuzzy, muffled tone. Sometimes, when the volume knob is in a low position, makes high pitched squeal.

Chan2: Even with volumes cranked high, this channel is not loud at all. And when the gain knob goes past 3:00, makes high pitched squeal.

The power tubes are stock. I didn't try replacing those yet. Should I, or do these problems seem much more serious?

thanks,

brian
 
Brian,

here's the tube layout of Einstein:

Einstein:
V1 Used by both channels
V2 Used by channel 2
V3 Used by both channels
V4 Mixer & Loop Driver
V5 Return Driver
V6 Phase Inverter

Unplug everything from the loop and swap those tubes which are affecting both channels (V1 (you did that already), V3, V6). Pretty sure its a faulty preamp tube.
 
Hi,

I replaced V1-V6 with brand new tubes from dougstubes.com and the problem still persists. V1 is Tung Sol 12AX7. V2-V6 are Chinese 12AX7Cs and V7 is the 12AT7 for reverb. The power tubes are stock but they tested ok. The fact that Chan 2 has relatively low volume (even with master and volumes cranked) seems odd, huh?

thanks,

brian
 
A test:

Plug your guitar into the serial return please. See if the volume is "normal".
 
Meant to also say that V6 is a Sovtek 12AX7LPS that Doug provided with my order free of charge...

Doing test now...

Both Master channels are behaving the same. I think my initial test was flawed (I think I may have not had Master Chan 2 engaged...). As far as loudness goes, not sure if it is normal or not. I expected it to be louder than it was.

Another thing to note is that the V1 tube never seems to light up that much. Very faint compared to others. Regardless of what tube I have in for V1. V6 doesn't light up much either.

I made an audio recording of these weird noises, etc. Maybe this will shed some light:

 
Try now... Maybe try to right click and choose Save As.

brian
 
Gotcha. Thats IMO NOT a tube caused problem, Brian. Peter needs to chime in me thinks.
 
Does it sound like it could be filter cap? My dad is pretty good with amps (albeit ham radio amps). He can look at it for me but needs a schematic. I didn't find one on the diezel site. If I can have a schematic that would be quite helpful. I am desperately trying to get the amp in working condition. I suppose I could sent to Uwe, but he is out til 4 Jan...

thanks,

brian
 
Peter did say I should replace the 3 black 22uF 500V caps. Now I am just trying to determine the exact part I should use. Many options out there from $3 caps to $25 NOS stuff. Can't imagine I really need NOS...

Here is an example of a part

http://www.partsexpress.com/pe/showdetl ... er=020-668

In any case, I am waiting to hear from Peter or his repair guy in the US to recommend the exact part.

thanks,

brian
 
Peter,

Should I just focus on these 3 filter caps? Are there any other caps that could cause my problem?

danke,

brian
 
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