Well, what should I do with the T1RVT

zulu

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I'ts been discussed here in the past, the amp would run for a while then shut down.

Well, after a while it wouldn't power up any more at all, and I put it in the 'fix it someday' amp stack.

What do you guys think? I've got a multi meter and a soldering iron, but no real skill, knowledge, or experience besides changing guitar pickups and fixing cables. ( I can tell the diffference between a capacitor and a resistor, as long as a resistor is the little tiny one with colored stripes, and I know the theory of electrons, protons, and crutons).

I thnk it's time to fix it or forget about it. possibly put it off longer.

Is this something I could look into myself, or should I save some money up and find an amp tech? should I pump it up or part it out or give it away or trade it for an Artist Award?....anyone?
should I just start sending beer to the cap'n now?

:D thanks

Z
 

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You could shoot coastie a pm. He has the trannies for that amp up for grabs.
 

capnjuan

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Hi Z: hold the beer for now (burp ...). Of course it could be this ... or ... it could be that ... or ... it could be this and that ... or ... it could be something else. :wink: If the come-and-go is accompanied by staticy snap, crackles, and pops, it's likely dirty tube pins and sockets. If not and it's just a guess but it sounds like one or more sections of the primary multi-section can capacitor [the reverb section has its own can cap] are weak or one of the cathode resistor bypass caps is giving it up.

The sections of the power supply can cap filter or smooth the DC by charging and discharging. The cathode resistor bypass capacitors are also electrolytic ... filled with an acidic paste ... and, like filter capacitors, wear out or dry out from years of use, abuse, or extended lack of use. If a cathode bypass cap fails, it can provide the signal a path to ground around the cathode resistor effectively grounding out the signal. The rest of the amp ... including the power supply caps can be fine but the signal has been grounded. The power supply and cathode bypass caps share some of the properties of failing batteries; they work but then have to recharge and then function for a while longer.

The exact replacement power supply can cap is out of production but this one is pretty close: 2 40uf sections and 2 20uf sections / 525vdc; the original is 4 sections at 40uf. The difference between 40uf and 20uf is immaterial; those sections filter power for the two preamp supplies - any tone distinction would be immaterial and at no reduction in safety. That model also uses a single 40uf/450V cap that sits in the space between the rectifier socket and the transformer ... like this one ... Some creativity needed to figure out how mount/stabilize it. If you post pics of the underside of the chassis, I can spot the two (or three?) cathode bypass caps.

Route 66: If you go this route, the original can cap has 3 or 4 resistors tied to its hot posts; they have to come off and be remounted or you have to buy fresh ones. Since any one of these could either be intermittent or drifted out of tolerance and since they are cheap and since you are re-building the power supply anyway, re-using the old ones is a waste of time. The cathode bypass caps are pretty easy. The mechanics aren't that tough; you are just putting back what was already there; you can help yourself by taking lots of pics and making sketches.

Hunt and Peck: if re-building the power supply strikes you as tedious, they you can always turn the amp on and do hot resistance checks on every resistor or turn it off, disconnect one end of every signal cap, and check it. As you can imagine, this is time consuming and carries some risk of error ... not to mention the fact that there's at least an even chance that it isn't a resistor or capacitor and you are stuck rebuilding the supply anyway. You're right; you might get lucky and find that it's an inexpensive defective part ... well .... do you feel lucky?

Dodge Ball: It might cost you $150-$175 or so for a tech to provide new power supply and reverb caps; whether you did it or somebody else, doing so would put 20 years of life on the amp. If you have a tech do the work and the problem isn't in the caps, then it'll take them no time to find the defective resistor / capacitor and the amp will sound as good as new.

Power supply caps are a cost of ownership of any tube amp. The biggest reason people put 2nd-tier '60s tubers on eBay is wanting to avoid paying as much in maintenance as the amp is worth. No matter who does it, with a refreshed power supply, the amp will sound dramatically better; cleaner, tighter bass and tinklier highs ... it really makes a big difference ... good luck with it. John
 

zulu

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AAAH!

Just typed an hour long reply and it vanished. damn.

basically it was thanks John.

%%$$$#^
 

capnjuan

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You're welcome Z; good luck. :) John
 

zulu

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So here's what I'm thinking:

If the come-and-go is accompanied by staticy snap, crackles, and pops, it's likely dirty tube pins and sockets.
-nope, no noise (when it used to fade out, now it wont power on at all). Just a fade of volume to zero within about 5 seconds. Also, the power indicator light fades out as well.

maybe I'll order some parts, take a day, and rebuild the power supply, which may or may not cure the current issue, but will certainly narrow it down and seems like it should be done anyway if I plan to keep and use the amp.

If I'm reading correctly this will entail
1. replace the power supply can cap with the one you linked. this will also require adding an additional capacitor. I should also replace the three or four resistors on the can cap, or does the replacement not require them?
2. replace the two or three cathode bypass caps, these should be available to R&R? Should I do these first and see if it works?

So maybe this will fix the amp, maybe the next step would be to hunt and peck. as far as feeling lucky, well I firmly believe it's bad luck to be superstitious. :? But Clint sure looks young in that movie!
 

capnjuan

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zulu said:
If I'm reading correctly this will entail
1. replace the power supply can cap with the one you linked. this will also require adding an additional capacitor. I should also replace the three or four resistors on the can cap, or does the replacement not require them?

The resistors are cheap but it's your choice; it's a PITA to get them off, get the solder off, straighten the leads, and re-use them. If they test w/i tolerance, they can stay.

2. replace the two or three cathode bypass caps, these should be available to R&R? Should I do these first and see if it works?

The schematic is Here. 3 30uf/25v cathode caps; 2 in the primary amp and one in the reverb amp. Reverb amp 6BM8 also uses a 50uf/25v cap ... you can use 25uf/25V but stick with the 50uf/25v. Yes, you could replace just these and if one of them is a problem, the amp should kick back to life. In other than 50s/60sFender collector stuff, the cathode caps are done whenever the ps caps are done.

So maybe this will fix the amp, maybe the next step would be to hunt and peck. as far as feeling lucky, well I firmly believe it's bad luck to be superstitious. :? But Clint sure looks young in that movie!

Yes; time flies when you're having fun or, like Clint, making some real money.
The amp can always use fresh caps; if it doesn't fix the problem, the amp is healthier and you've ruled out what would be the most likely source of trouble. Good luck. J
 

zulu

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Now I'm actually looking at the amp, maybe these can caps have been changed. the one mounted next to the big transformer is a CE Electronics C-EC 40x3- 525

the one on the other side by the reverb speaker, etc. is a C-EC 50x4- 350


I can see two big blue capacitors that look newer on the inside of the amp chassis they are Sprague Atom TVA1908 and are 40uf/500vdc

somebody might have changed things around a bit, what do you think?
 

capnjuan

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zulu said:
Now I'm actually looking at the amp, maybe these can caps have been changed. the one mounted next to the big transformer is a CE Electronics C-EC 40x3- 525 the one on the other side by the reverb speaker, etc. is a C-EC 50x4- 350 I can see two big blue capacitors that look newer on the inside of the amp chassis they are Sprague Atom TVA1908 and are 40uf/500vdc somebody might have changed things around a bit, what do you think?
Hi Z; yes, those are replacement can caps. Can you post some pics of the component side of the chassis?
 

zulu

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What's the trick to getting the chassis out? do I have to take the handle off? if so, how?

Thanks so much, capn
 

capnjuan

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zulu said:
What's the trick to getting the chassis out? do I have to take the handle off? if so, how? Thanks so much, capn
Getting it out depends on which model you have ... some had a squarish luggage handle, others have a strap handle ... and metal chassis straps across the top.

For both versions:
Disconnect the speakers from the chassis; carefully wiggle the little bulgin connectors out of their female jacks on the underside of the chassis. Disconnect the reverb in/out cables from the reverb can. The footswitch cable is hard-wired to the chassis ... it goes where the chassis goes ... use your third hand to handle the footswitch.

Luggage handle/no chassis straps:
Remove the two left and right rear anchor screws ... as you are facing the chassis from the rear, they are in the rear corners and pass up through a block of wood and bite into the chassis. Finally, there's piece of shiny metal that spans between the legs of the handle ... pop it loose and there's a small bolt that passes through the cabinet and threads into a support bracket ... back the bolt out ... get some help and drag the chassis out the back.

Strap handle/chassis straps:
Undo all the cables as ID'd above. I think with these it's just remove the screws/bolts whatever that hold the chassis straps to the top ... they pass down into holes in the chassis. There might be bolts in the rear corners too ... I don't know this model.

Good luck! John
 

zulu

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you da man. I was afrraid to pop the metal piece from the luggage handle.

DSCF2185.jpg
 

capnjuan

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capnjuan said:
zulu said:
... maybe these can caps have been changed. the one mounted next to the big transformer is a CE Electronics C-EC 40x3- 525 the one on the other side by the reverb speaker, etc. is a C-EC 50x4- 350...
Hi Z; yes, those are replacement can caps. Can you post some pics of the component side of the chassis?
Hi Juan ... you ought to wait until you see the pics ... Hi Z; not so sure those are replacements ... the big blue ones are new but look like partial patches ... see below.
 

capnjuan

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Hi Z; a voltage checking / troubleshooting post this evening. John
 

capnjuan

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Hi Z; I'd like to see a pic of the tube deck with closeup of labels on can caps; despite earlier remark, I think they are original ... just about positive the reverb can cap is original. The two new Spragues; the one nearest the rectifier tube is for the B+ to the output transformer/6GW8 plates and the other is for the 6GW8 screens. They do nothing for the preamp or for the supply to the reverb amp. Before going any further, make sure you have at least one known good 12AX7 to sub in.

Voltage checks at primary can cap; pull the output tubes [note to matsickma below*], turn the amp on and check the DC voltages at all 4 hot posts of the can cap; set meter to VDC, black to chassis, and red to each posts (pins may be marked triangle, square, circle symbols); 335VDC, 300VDC, 250VDC, and 290VDC respectively; don't worry so much about specific voltage, we're looking for a section with 0 or near 0 voltage.

T1Z.jpg



Voltage checks at preamp: with output tubes out, amp on, meter to VDC, black to chassis; red to V1 pins 1 and 6 and V2 pins 1 and 6; squint to see small numbers on tube socket or count clockwise from the gap where there's no pins. V1 pins 1 and 6 should be 125-175 VDC; maybe higher on V2 because one of those sections is the trem oscillator. (See pic for ID #s). Again, don't worry about precision, we're looking for 0 / near 0 voltage.

I tried to ID the cathode bypass caps; they always have a + and - at either end; when being replaced, you must observe polarity ... the + end goes toward the tube, the - end to ground. Also, I marked something that looks like a cathode bypass cap with an asterisk (being picky ... next time take the pic straight down). At least from the pic, that cap looks discolored on one end. If it has + and - marks and it looks bad compared to the others, there's a possibility that that's the problem.

Also the reverb preamp tube also has a cathode bypass cap .. if you're doing one ...


Anyway, sorry this is late but should get you going. John



*Hi Mike: we talked about this last year and I sort of fished out on the subject of amp on without speakers connected to OTs. Anyway if the output tubes are pulled, then the DC circuit is open and although there's a DC potential on the plate, no current is flowing through the OT. If that's the case, then no load on the OT secondary can't mean anything. J
 

capnjuan

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zulu said:
I was afrraid to pop the metal piece from the luggage handle.
You caught a break; whoever did the cap work last time took the bolt out. Note the threaded hole in the support bar; that's where the bolt would have threaded into. If the bolt had been in place, the amp wouldn't have come out but I think you will want to replace that bolt. The cross-piece is there to provide some stability but it also keeps the chassis from sagging; it's so thin, it's barely able to support it's own weight.
 
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