Thomas Vox Viscount issues

[Jot]

Picked up a Thomas Vox Viscount combo (plus an original four-button footswitch, which clinched the deal) recently as a backup for a beloved Vox Buckingham head plus cab (also have a Royal Guardsman head without a cab). The Viscount has an extensive list of issues, and I'm looking for general suggestions rather than asking for detailed replies concerning repairs.

The issues include the following:

Normal channel: low volume---maximum Viscount volume on this channel is equivalent to a volume control setting of about 8 o'clock (i.e., barely on) on the Buckingham's normal channel; no tremolo (without or without the use of the footswitch button); hitting the distortion button on the footswitch boosts the volume a little and adds a tiny bit of distortion, but maximum volume is still low; treble control seems to roll off the treble as the knob is turned clockwise. Top boost switch works.

Brilliant channel: effectively no volume (guitar volume through speakers at maximum amp volume setting is not much more than the unplugged guitar level, if at all).

Bass channel: the most volume of the three, but still below the equivalent on the Royal Guardsman (the bass channel is weak on the Buckingham).

The midrange boost switch makes a pop when switched (can't tell whether the boost is working, since the Brilliant channel is effectively useless); the various volume and tone knobs on all channels exhibit various levels of scratchiness, nonlinearities, etc.

The reverb makes ghostly background noises as I insert and remove the guitar cable plug at the amp's input jacks but otherwise has no effect.

The power switch illuminates in the Standby and On settings, but the amp is on as soon as the switch is turned from Off to Standby and remains on when turned to On.

All of which is disappointing, of course.

As it happens, Baltimore has a locally owned music store (Bill's Music, Catonsville, MD) with a repairman who has worked there since the late '60s, so he's probably seen the innards of a Thomas Vox amp before, but not for a few decades.

I was going to take the amp to him and lend him my copy of the Royal Guardsman schematics (bought on line a few years ago), but I've read here that some parts of the schematics might be inaccurate.

So, to my general questions.

Would asking the repairman to do the replacement of all of the preamp's polarized and nonpolarized electrolytic capacitors (as recommended in R.G. Keen's GeoFex pages) plus cleaning or replacing the switches and pots (plus giving him my list of amp issues, of course) be my best course of action?

Or should I wait until Mr. Keen's soon-to-be-proofread comprehensive repair manual set is ready for purchase so that I can hand that over to the repairman?

Sorry about the length of this. Final question: given how many problems the amp has, would it make more sense to wait and buy one of Mr. Keen's Thomas Vox problem-solver PCBs, when they're available for purchase, for use as the basis for the amp repair?

[loudthud]

Fixing these things fits into the "Labor of Love" camp. Even with RG's board, it's not easy or cheap. If you are unwilling or unable to do much of the work yourself, the cost of a re-build can exceed what you paid to acquire the amp.

Does RG's board support the big filter caps in the power supply that will need to be replaced? They are on the power amp chassis, not in the preamp. On the Berkeley/Cambridge board there is only one such cap and it is on the board since everything is on one chassis.

RG's repair guide is said to make things simple enough for the amateur, so if that's what you need, you'll have to wait.

[52 Bill]

Fixing these things fits into the "Labor of Love" camp.

Amen to that!

Some of the things that you describe as symptoms are pretty typical of the problems created by dying coupling caps. Replacing them are not that big of a deal for a trained tech, but can be a nightmare for the typical amateur/hobbyist.

As for Thomas Organ solid state Vox amps, I own three Viscounts and one Buckingham that have had some of if not all of their caps replaced. Understand that replacing all of the caps will not necessarily fix all of your problems.

If you are seriously looking to have this amp repaired, I would suggest that you talk to the repairman that you plan to have do the work and get his input as to how to get where you want to be in a cost effective way. Fixing the amp by replacing only the parts that are bad is probably cheaper in parts costs, but will not save much money in labor time. And as the amp ages the older parts will continue to fail, creating additional labor costs in the future.

Complete board replacement is a rather drastic approach that in my mind is best saved for total wrecks and abuse cases that can no longer be repaired by normal means.

Depending upon the model numbers involved, having the Guardsman schematic would be helpful to the repairman as the preamp sections are nearly identical. If you know the model number of the Viscount, I will check to see if I have a copy of the one that you need.

[Jot]

Fixing these things fits into the "Labor of Love" camp. Even with RG's board, it's not easy or cheap. If you are unwilling or unable to do much of the work yourself, the cost of a re-build can exceed what you paid to acquire the amp.

Does RG's board support the big filter caps in the power supply that will need to be replaced? They are on the power amp chassis, not in the preamp. On the Berkeley/Cambridge board there is only one such cap and it is on the board since everything is on one chassis.

RG's repair guide is said to make things simple enough for the amateur, so if that's what you need, you'll have to wait.

Thanks, LG. "Labor of Love" is exactly right; unrequited love, in this case. I definitely overpaid for it after a hurried look at it. On the other hand, the guy who sold it to me donated a Hammond B3 and two Leslies to a church, so I guess our transaction is part of his karma or darma or whatever it is.

The power caps should be on the power amp chassis. I believe RG Keen is making two different boards to accommodate the different layouts.

[Jot]

Amen to that!

Some of the things that you describe as symptoms are pretty typical of the problems created by dying coupling caps. Replacing them are not that big of a deal for a trained tech, but can be a nightmare for the typical amateur/hobbyist.

As for Thomas Organ solid state Vox amps, I own three Viscounts and one Buckingham that have had some of if not all of their caps replaced. Understand that replacing all of the caps will not necessarily fix all of your problems.

If you are seriously looking to have this amp repaired, I would suggest that you talk to the repairman that you plan to have do the work and get his input as to how to get where you want to be in a cost effective way. Fixing the amp by replacing only the parts that are bad is probably cheaper in parts costs, but will not save much money in labor time. And as the amp ages the older parts will continue to fail, creating additional labor costs in the future.

Complete board replacement is a rather drastic approach that in my mind is best saved for total wrecks and abuse cases that can no longer be repaired by normal means.

Depending upon the model numbers involved, having the Guardsman schematic would be helpful to the repairman as the preamp sections are nearly identical. If you know the model number of the Viscount, I will check to see if I have a copy of the one that you need.

I appreciate the simple and clear explanation of what to expect and how to evaluate the options. That's exactly what I was hoping for.

The Viscount is model V1154.

[R.G.]

Ah. We're discussing my mania.

The Viscount V1154 is the later JFET-input preamp. It has the same preamp and power amp as the V1123 Buckingham, and is 30Wrms. It has, unfortunately, germanium power output devices.

Like all Thomas Organ Vox amps of this age, the first step toward having a working amp is replacing every single electrolytic cap. If it's not already dead or faulty in some way, it will be next week or next month. Fixes that do not include this step for a 50 year old amp are asking for a second and perhaps third, forth, ... trip to the tech. As noted, simply replacing all the caps is not a guaranteed way to fix it all, but you're wasting your time if you don't do it first.

As noted, most if not all of your symptoms might be from dying electros, although there are other possibilities too. Never assume that there's only one problem to fix. Ask me how I learned that.

The big trade off in fixing Thomas Vox amps is fixing problems faster than you create them by stressing the rats' nest of wires. Every single time you bend the wire nest to get at the solder side of the PCB, you take a chance on breaking a wire. If you don't figure this into your repair strategy, it's entirely possible to have a never ending repair job. That is the fundamental reason I did the repair boards - they are a step sideways around the breaking-wires problem, and at the same time force replacement of every single electro cap.

Yes, there is a JFET-series board that works in all the later amps, including the V1154.

My comments on the comments:

Does RG's board support the big filter caps in the power supply that will need to be replaced? They are on the power amp chassis, not in the preamp. On the Berkeley/Cambridge board there is only one such cap and it is on the board since everything is on one chassis.

No, it does not on the Viscount. The power filters on the Viscount power supply should be replaced with 1 3/8" capacitors in round capacitor clamps. Diagram of this in the repair book I'm furiously writing. In the Berkeley/Cambridge board, the main power filter cap IS on the replacement PCB, so the old cap shell can be left on the chassis and just disconnected. And on the Viscount, there are a few other caps on the power amp to replace, but these are very easy to get at and fix.

As for Thomas Organ solid state Vox amps, I own three Viscounts and one Buckingham that have had some of if not all of their caps replaced. Understand that replacing all of the caps will not necessarily fix all of your problems.

Kewl! We share a mania!

If you are seriously looking to have this amp repaired, I would suggest that you talk to the repairman that you plan to have do the work and get his input as to how to get where you want to be in a cost effective way. Fixing the amp by replacing only the parts that are bad is probably cheaper in parts costs, but will not save much money in labor time. And as the amp ages the older parts will continue to fail, creating additional labor costs in the future.

Amen to that. Take the repairman to lunch and talk it over with him in detail. Show him some of the pictures on my web site, including "The Nature Of The Beast".

Complete board replacement is a rather drastic approach that in my mind is best saved for total wrecks and abuse cases that can no longer be repaired by normal means.

I have a slightly different viewpoint on this. I would otherwise agree, but Thomas Organ Vox is a special case. The difference is that it is remarkably difficult or impossible to find a tech that will even try.

Most techs flatly refuse to work on them at all, being professionally wise to some of the issues. This forces repairs into amateur hands that can't quite cope with the somewhat delicate surgery required. That can easily make a bad situation worse. The end result of not having a tech to work on the amp, or having it be too expensive to afford the repairs, or having an amateur with low skills trying to save a buck is that the amp eventually is junked or sold for parts, not fixed. In these circumstances, even small issues can lead to junking the amp.

Complete board replacement *is* drastic, but it's a more certain repair process, and simpler. It has the *possibility* to make more techs take the job on, and the *possibility* that the tech may be able to do it less expensively. It does offer the possibility of a repair in 2-4 hours instead of perhaps never-ending. And it's a backstop, in case early repairing doesn't work. I veiw the repair boards as a means of convincing a tech to take on the job, instead of refusing to touch it.

The field results are coming in on the boards. I'm up to about half a dozen now that have done the wholesale replacement, and they all worked. Every one of them required my handholding, not on the preamp boards but on fixing the rest of the amp.

Depending upon the model numbers involved, having the Guardsman schematic would be helpful to the repairman as the preamp sections are nearly identical. If you know the model number of the Viscount, I will check to see if I have a copy of the one that you need.

Yep. The schematics you want are for the V1154, but the corresponding Guardsman is the V1133. I have the V1154 schematics, but more importantly, I have the draft of the V1154 repair supplement.

On the repair issues:

Normal channel: low volume---maximum Viscount volume on this channel is equivalent to a volume control setting of about 8 o'clock (i.e., barely on) on the Buckingham's normal channel; no tremolo (without or without the use of the footswitch button); hitting the distortion button on the footswitch boosts the volume a little and adds a tiny bit of distortion, but maximum volume is still low; treble control seems to roll off the treble as the knob is turned clockwise. Top boost switch works.

Brilliant channel: effectively no volume (guitar volume through speakers at maximum amp volume setting is not much more than the unplugged guitar level, if at all).

Bass channel: the most volume of the three, but still below the equivalent on the Royal Guardsman (the bass channel is weak on the Buckingham).

The midrange boost switch makes a pop when switched (can't tell whether the boost is working, since the Brilliant channel is effectively useless); the various volume and tone knobs on all channels exhibit various levels of scratchiness, nonlinearities, etc.

The reverb makes ghostly background noises as I insert and remove the guitar cable plug at the amp's input jacks but otherwise has no effect.

My first guess is that these disappear with new caps. Maybe not, but most of them could be electro cap issues. IMHO, it's silly to fix individual issues without replacing all the known-decaying parts, the electros.

The power switch illuminates in the Standby and On settings, but the amp is on as soon as the switch is turned from Off to Standby and remains on when turned to On.

The power switch assembly is fragile and a special purpose switch. There is an article on geofex on fixing or replacing them.

As it happens, Baltimore has a locally owned music store (Bill's Music, Catonsville, MD) with a repairman who has worked there since the late '60s, so he's probably seen the innards of a Thomas Vox amp before, but not for a few decades.

I was going to take the amp to him and lend him my copy of the Royal Guardsman schematics (bought on line a few years ago), but I've read here that some parts of the schematics might be inaccurate.
...
Would asking the repairman to do the replacement of all of the preamp's polarized and nonpolarized electrolytic capacitors (as recommended in R.G. Keen's GeoFex pages) plus cleaning or replacing the switches and pots (plus giving him my list of amp issues, of course) be my best course of action?

Or should I wait until Mr. Keen's soon-to-be-proofread comprehensive repair manual set is ready for purchase so that I can hand that over to the repairman?

Sorry about the length of this. Final question: given how many problems the amp has, would it make more sense to wait and buy one of Mr. Keen's Thomas Vox problem-solver PCBs, when they're available for purchase, for use as the basis for the amp repair?

I might suggest a different solution. First talk to the repairman personally, and see if he's willing to take it on. If he is, I'd be happy to help him (if he needs it - he may be good enough that he doesn't even bat an eye at it) via phone and email. If he wants to take it on, I'll be happy to provide him a draft of the V1154 repair supplement as it sits, as well as any bits and pieces of info he needs.

If he won't take it on, use the replacement board as an enticement. The boards work, they're proven now, but getting field acceptance will take a while.

If he's willing, tell him you want all the electros replaced, then any remaining problems fixed. Expect him to tell you that it's going to be expensive. It's unrealistic to expect it to come in under $300, and it may be much more, depending on how much labor time is involved.

I would not advise waiting for me to finish any particular documentation. The end date on that is uncertain. I have entirely too many items on my plate that have deadlines.

[Jot]

In the interest of conserving space, I'm replying the R.G. without quoting his lengthy, meticulously worded reply to the earlier replies and to my original message.

First, thanks. I feel much more energized about implementing a repair plan for the amplifier. I'll visit the repairman this weekend and talk the job over with him.

By the way, R.G., you said that you have plenty of volunteers for the proofreading job, all of whom doubtless know the electronics details, but I'd be happy to help in any way I can with your massive Thomas Vox project.

As it happens, I edit microbiology journal articles for a living, and after 14 years, I still have only a rudimentary grasp of the science involved. But what I know how to do is to change sentences whose meaning is ambiguous into unambiguous sentences. That way, when an article's writer corrects the proofs, the fixes needed are unmistakable.

[Enzo]

As a professional repair tech, I have to say, if you think the guy is competent, and if he is willing to work on this amp, he probably doesn't need suggestions like change these particular caps and make sure to clean the switches and pots. That is like asking the band to play a song and reminding them to tune their instruments and play at a certain tempo. he needs to know your complaints about the amp and what you want from the amp when it is done. Don't tell the cab driver how to drive, just tell him where you want to go.

[R.G.]

As a professional repair tech, I have to say, if you think the guy is competent, and if he is willing to work on this amp, he probably doesn't need suggestions like change these particular caps and make sure to clean the switches and pots. That is like asking the band to play a song and reminding them to tune their instruments and play at a certain tempo. he needs to know your complaints about the amp and what you want from the amp when it is done. Don't tell the cab driver how to drive, just tell him where you want to go.

I would completely agree with any other amp family. I would not hesitate to send any of the Thomas Vox family to you, Enzo, if you were still practicing. There are three other techs I know of in the continental USA that fit that category as well. But these guys will not accept new Thomas Vox repairs because of the amount of work and cussed nit-picky-ness of the repairs. Most average techs can do the repairs simply by having the symptoms described and getting the schemos and parts lists, just as you suspect.

My coaching to Jot was focused on how to get the tech convinced to take the job in spite of what he may have heard from other techs or seen in the past. It's the "willing" part I was working on.

[Enzo]

Oh I am tickled you would offer your assistance. My main concern is to stop the oft repeated query for things to tell a technician to check when someone is about to take something somewhere for repair. "Make sure to clean the controls, now..."



On the other hand, my wife and I often go to restaurants and joke, "Now we want the GOLDEN French fries, not the regular ones."

[J M Fahey]

As a professional repair tech, I have to say, if you think the guy is competent, and if he is willing to work on this amp, he probably doesn't need suggestions like change these particular caps and make sure to clean the switches and pots. That is like asking the band to play a song and reminding them to tune their instruments and play at a certain tempo. he needs to know your complaints about the amp and what you want from the amp when it is done. Don't tell the cab driver how to drive, just tell him where you want to go.

Don't make me start on customers who sit by me and explain how to do my job, from suggesting I use lead free solder (because that's the norm today) to discharging static so I don't damage their precious tubes to parts brands and colours to biasing tubes to 70% .... to .... to .... to .....

Last week I accepted a visit (just to end the issue for good) from an old customer who had been bugging me for months about some mystery Tech information he couldn't comment on the phone, only in person , which would be very convenient for me.

He came the other Sunday (he swore he was busy 24/6 otherwise) carrying a backpack ... and a couple Pizzas, my typical self suggested bribe/admission ticket in such cases, and proceeded to show me a cheesy chassis from a cheesy no name generic Japan made 30W practice amplifier from the 80's , think Squier or similar.

"This one sounds real good and if you copy it, you'll make Million$$$$$$ !!!!!
He wanted no share of thar treasure, his prize was just seeing me happy.
A generic 80's style power amp, discrete and with TO220 output transistors? ...... yea, sure.
Oh well.

That said, I treated him well, he has some other funky ideas about .... well ..... *everything* (you wouldn't think he was kooky only in the area of Electronics ) so chatting with im is funny, unless you try to show him his errors, and at the end he ordered a 100W guitar head, so "all is well that ends well" .
Of course, with *only* a speaker out jack because if I put my customary 2 jacks in parallel he can't be absolutely certain that 100% of the power will go to the one he's using, and an extra preamp out, power amp in pair of jacks, so he can send preamp out to a mixer (those cheesy U$99 ones, with 2 XLR connectors and 2 "stereo" channels) and then back into the power amp.
Why?
Because Guitar Gods (EVH, Yngwie, etc.) have their sound sent to a mixer (obviously either recording or playing for an audience) , so that MUST be their secret, so why not him?

Impeccable logic if you ask.
The fact that the mixer will be set flat and to unity gain does not change the point.

So: customers telling me how to do stuff?
I guess by now my skin grew as thick as that of:



EDIT: now that I look at it, I guess I have the exact same expression in my face when somebody explains me about sound differences because of cap colour, tube brand or wire insulation.

[52 Bill]

Don't tell the cab driver how to drive, just tell him where you want to go.

Unless you're in New York City.

[eschertron]

...Of course, with *only* a speaker out jack because if I put my customary 2 jacks in parallel he can't be absolutely certain that 100% of the power will go to the one he's using.

I know a guy like that! Bright, funny, and sincere; but when it comes to technical matters he acts as if every day he wakes up, he's a blank slate.

[52 Bill]

As luck would have it, a V112 Buckingham came in for repair. I had never fixed one of these models before, so I took this opportunity to time the entire repair from start to finish. Total bench time was 3.5 hours. At least a half hour of the total was for removal and re-installation of the chassis (and I have the right tools to get to the nuts and screws).

The best thing about this repair was that I don't think that it had ever been worked on before or at least if it had been it was done very well. A few things that I found that helped make it easier to work on was to stand the preamp chassis on end allowing the pc board to hang, supported by the hinged support. This allows for access to both sides of the board without constantly lifting the board and thereby flexing the all too fragile wires.

Another thing that I thought of but didn't try was to bolt down the bundle of wires that connect the preamp to the power amp/speaker/ac cord. This bundle of wires is normally held down by a cable clamp that keeps the tension off of the wires that connect the speaker wires to the back of the power/standby switch. In order to remove the cover of the preamp chassis, you need to remove the screw that holds the wires in position. Once the wires are loose, they can easily pull directly on the wafer of the power switch. I would guess that this is one of the many reasons why so many of the power switches are broken. The next one I do, I'll rebolt the cable clamp down to the chassis to keep the wires from hanging loose until the cover goes back on.

And I found and scanned the V1154 schematic.