Question about cap value on 6G7 Bandmaster

BoomTexan

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I'm going slowly through the schematic for the 6G7 Bandmaster, and I'm wondering what the capacitor value is for the one between the two plate voltages on the 7025 in the power section. It looks like 47, but I can't make out the last part. Looks like uu to me, and I can't for the life of me find any schematics that have that more clearly written. I don't think it's uF or pF, and since the schematic on the 6G9B Tremolux is .0001uf, it's gotta be a very similarly low value. Does this even matter at all, can I just drop a super low value cap in there and it'll work out fine? I'm presuming that the function is just to filter out DC voltage runoff between the two plates.

Also, while you're here, would it be possible at all to drop a 5E9 Tremolux tremolo circuit in there? I'm pretty sure it could happen, just seeing if there's something that I'm not considering here that could prove detrimental to the design. I'm toying with the idea because I want a more basic tremolo circuit in this amp. The 6G7 one is nice, but I'm really not looking for hamonic tremolo in this amp, just good old fashioned swampy choppy stuff.
 

corliss1

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Certainly looks like "mm" to me:

Screenshot 2022-04-06 at 15-35-00 bandmaster_6g7.pdf.png
 

BoomTexan

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Exactly what I was thinking, but that's not a cap value, haha, so I just assumed mu-mu, because it has those tails on the back.
 

corliss1

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Sure it is - it's the old way of writing "micro micro" before they used "pico"
 
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BoomTexan

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Wait, actually, this does raise an interesting issue. The rest of the values are in uf. Why is that one in mm format? Even the 59 Tremolux schematic I was looking at earlier used uf, not mm. 5f1 Champs use uf, not mm. Any idea why that was used in this one case?

Edit: oh, you meant pico, not nano.
 

Paul G.

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Cap is 47pf. mm was acceptable terminology, and commonly used at the time, so somebody did. No specific reason needed. To write it in uf it is 0.000047uf. Pretty unwieldy.
 




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