T1RVT - FEELING PRETTY DUMB NOW

john_kidder

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Just received the T1RVT today, beautifully packed, looks fine.

Except: where the tube layout diagram tells me I should have one 12AX7A and the 6BM8 in sockets on the chassis, I have a piggyback circuit board instead

tubelayout.jpg


Am I right that the 12AX7A should go in the rear socket on this board and 6BM8 in the front as you can almost see in the photo?

Colour me uncertain,
John
 

john_kidder

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Re: T1RVT Tube Layout - Query Before I Power It Up

BUMP
Hey there Cap'n, Default, I see you're online. I'm eager to power up this amp.

If I have these tubes in the wrong places (hard for a klutz like me when the sockets accept both tube), and turn the power on anyway, will I blow anything up, or will it just fail to work?
 

capnjuan

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Re: T1RVT Tube Layout - Query Before I Power It Up

Hi John; yes, the 6BM8 goes at the back of the chassis as shown in your pic


tubedeck.jpg



J
 

capnjuan

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Re: T1RVT Tube Layout - Query Before I Power It Up

john_kidder said:
If I have these tubes in the wrong places ... and turn the power on anyway, will I blow anything up, or will it just fail to work?
eh ..... both; I think it would blow up first and then fail to work ......
 

capnjuan

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Re: T1RVT Tube Layout - Query Before I Power It Up

.... either one or both tubes would go ... the only question would be whether they failed short or open .... open = good (can always get new), short = jeopardy .... and not talking about the game show :wink:
 

john_kidder

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Re: T1RVT Tube Layout - Query Before I Power It Up

Well, I'm confused now. Power up, warm up, all good, no reverb.

Panels off, and this is what I see:

Both leads to reverb speaker go to one side of connecting lug, other side is (feebly) grounded(?) to frame of main speaker.

IMG00148.jpg


left lug of main speaker connector runs to Reverb can:

eakertorev.jpg


Other lead to reverb can is from piggyback board (thin wire on left):

IMG00146.jpg



All this on an amp that is "just been serviced by area's top tech", etc.

Can anyone decode what's going on here, or have I just been had (again)?
 

capnjuan

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Re: T1RVT - STARTING TO GET P****D OFF NOW!

will reply in a few minutes...
 

capnjuan

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Re: T1RVT - STARTING TO GET P****D OFF NOW!

Hi John:

Pic 1: the solid ground wire going off to pic right is fine. One of the two wires to the 8" has been disconnected and reconnected on the other speaker lug; the speaker is disconnected ?????? From the pic, I can't tell + from -. Usually the white would go on either of the terminals marked + or with red dot to distinguish them from - or in AC parlance, common. You might look at the back of the 12" speaker to determine which is + and -.

Pic 2: the green wire is the tap off the + 12" speaker terminal that feeds the reverb can. The reverb supply passes through a resistor and capacitor before going in the can. The little blue cap can be seen peeking out in pic 2; all of this looks normal.

Will post again in a few more minutes.
 

capnjuan

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Re: T1RVT - STARTING TO GET P****D OFF NOW!

Pic 3: the gray line at pic left is the reverb return bringing the signal from the can. The 8" speaker supply white/black is connected to the Bulgin pin in the foreground. Confirm that it is snugly seated. Is the thick white cable the footswitch cable?
 

capnjuan

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Re: T1RVT - STARTING TO GET P****D OFF NOW!

8" speaker connection. After looking to see if the + terminal is marked and you don't know for sure, then take the less-well connected line off - snip or de-solder - and put it on the other lug.

The only penalty here is that you might hook it up out of phase. Once connected listen to see how it sounds. It will still produce sound but if out of phase will be less volume, a little hollow and odd-sounding.

Disconnect and reverse them, play and listen. Whichever of two conditions produces a better sound is the in-phase condition. As annoying as it is, must be one or the other.
 

capnjuan

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Re: T1RVT - STARTING TO GET P****D OFF NOW!

Seller may have disconnected the speaker some time ago and forgot about it ... could be anyway.

It also might rub, crackle, or spit which is why he disconnected it. Finally, there might be something wrong with the can or board or can cap or oar ore o'er

You there .... ???
 

john_kidder

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Re: T1RVT - STARTING TO GET P****D OFF NOW!

Yup, I' here.

3) Thick white cable is footswitch
2) Bulgin pin is firmly seated
1) no colour or other ID on 12" speaker lugs. Black wire goes to left side, as seen in Pic 2. If white went to right side on 8", that would connect it to frame on 12" as well through grounding wire?

I note that the seller included an old Bulgin pin (along with original Guild tubes and the old 2-wire power cord), and that the 12" is now connected with a standard 1/4" jack.

What harm might be done by reconnecting the 8" speaker?
 

john_kidder

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Re: T1RVT - STARTING TO GET P****D OFF NOW!

Whoops - asked that last question before seeing your earlier suggestion to go for it. That's what I'll do.

Back soon, he says hopefully.
 

capnjuan

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Re: T1RVT - STARTING TO GET P****D OFF NOW!

Unless it is shorted, none.

If you have a meter, put it on resistance and measure ohms across speaker terminals. If it read 0 or thereabouts, it is shorted. Posta read 5.5 to 8 ohms. If your meter just flaps around like a fish out of water, the voice coil is open / broken / no good

Unless you read 0 ohms, no harm in hooking it up.
 

john_kidder

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Re: T1RVT - STARTING TO GET P****D OFF NOW!

No resistance, zero.

I want to try replacing the speaker with the 8" from my partly working TBird. Should find out what's up that way, no?

If it has been shorted in the past, would that have been likely to damage the reverb output circuitry, and should I then expect to find a clean signal with a new speaker?
 

capnjuan

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Re: T1RVT - STARTING TO GET P****D OFF NOW!

john_kidder said:
No resistance, zero. I want to try replacing the speaker with the 8" from my partly working TBird. Should find out what's up that way, no? Don't do it ! :evil: If it has been shorted in the past, would that have been likely to damage the reverb output circuitry ... it is somewhat more likely that a crappy part of the reverb circuitry toasted the speaker ... , and should I then expect to find a clean signal with a new speaker? No

If the secondary side of the reverb amp output transformer is shorted, you could ruin anything else you connect to it.

The way the speaker was formerly wired is a dead short ... no load / resistance / impedance between the hot and common ...

The same as taking your lamp apart, disconnecting the wiring to the socket, turning the wall switch on, and touching the two wires together. In a house that's properly wired, your dead short will cause the circuit breaker to open.

Not good ... Ugh.
 

capnjuan

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Re: T1RVT - STARTING TO GET P****D OFF NOW!

Hi John, sent you an email ... suggest we take it off the BB. John
 

JazzWest

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Re: T1RVT - STARTING TO GET P****D OFF NOW!

The wiring on the 8" Reverb Amp speaker is not original, both wires (+, -) should go to there respective terminals. Unsolder the ground (-) and attach it back to the other terminal that's grounded to the speaker frame. Also it's be a good idea first to disconnect all the wires and check the polarity of the speaker with a 9V battery across the terminals. The speaker cone will move forward with the correct polarity.

Nice score John, and these have an all wood cabinet, as opposed to the earlier ones that were entirely particle board. Difference in tone having owned both.
 
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