How do fix a Amp when you Do Not Know Whats Wrong

[dumbassbob]

I have a 1964 Fender Bandmaster..I sent it too Kendricks amps and he did some things too it new caps bias cap resoildered some spots and new diodes and tubes $464.00..The amp sounded great for a few hrs.(I play for 1 1/2 hrs every day) poof it starts sounding weak power loss distortion ,I sent it back 6 months later get my amp and it sounds great for a total of 6-7 hrs over 4-5 days...poof same thing sound weak power loss distortion..So noew I sent it to him for 8 months I get it back it sounds gray poof..but this time it sounds like the preamp or EQ or grounging problem,,Now I go to a nice guy in Orange County Ca He has it 2 months tells me its all good $235.I take it home and it is unchanged Now it is thin sounding and the bright switchs are poping real harsh distortion on the high end and WAY too much bass also he took out a few mods Kendricks did to the power..He took it back and worked on it for 4 hrs but it still sounds like crap.Can a good tech who has worked on Fenders fix the problem.If I would of let this one guy keep working on it at $75.00 per hr I might as well through it in the junk and buy a boteek amp How do you Troubleshoot a Fender amp

[rf7]

Where are you in OC? Have you tried Paul Morte Technical Services in Orange?

[dumbassbob]

Where are you in OC? Have you tried Paul Morte Technical Services in Orange?

Paul doesn't do much tech work now He has the Yamaha service contract and is too busy most of the time ..He gave me this new guy in OC and he is trying to find the problem..It just a great amp but has sometjing thats not right maybe every time something is fixed another part pops and dies

[Sweetfinger]

The day that Gerald Weber failed to fix my silverface Bassman for the second time but fixed the problem of having several hundred dollars in my wallet was the day I vowed to learn how to fix my own amps. For what you've paid on that Bandmaster, a good tech would have been able to replace every part, INCLUDING the transformers!
1. Is the problem tube related? Switch all the tubes with known good backups.
2. If it isn't tubes, start at the output section and work your way back to the preamp.
with a problem like this it is more like checking off what you know is good until all you're left with is the problem.

[johnk_10]

those old blackface fenders are extremely simple amps to repair/service (i've repaired restored 100's and 100's of them), and once they're running at stock specs, they should go another 30 years (not hours!) without any issues. i visit orange county once a week (i'm in thousand oaks), so if you like to meet me somewhere and drop it off, i could bring it back to you fixed for good the following week.

[Gtr_tech]

Someone's laughing all the way to the bank....

[big_teee]

Someone's laughing all the way to the bank....

Yes, but Like the OP, it Ain't Real Funny if it's Your Wallet!
T

[km6xz]

6 months...8 months...what is going on. That is absurd, and time for a small claims suit to reclaim money from a rip off.
The real problem is so many tube-amp-only guys put out a shingle and specialize in the simplest systems in consumer electronics by using habit and seat of the pants repair techniques and not proper diagnostics and logic. When I see how little in test gear, or precision anything is used in those sort of shops it is easy to see how they can't diagnose a non-routine problem. When you see a whole lot of parts swapped out and charged for it is the first clue that it was shotgunned and not ever properly diagnosed as to the real problem or the mechanism of fault. Why something went wrong is as or more important than what went wrong.
Did any of the failed repair attempts come with complete written descriptions of what was done and why? Are the problems related to each other? Did you get an explanation why your repairs took 5.8 and 7.8 months too long for any serious professional repair facility?
You are being too patient, you should be raising hell over high prices and incompetent work, bordering on scams. Try demanding your money back and compensation for time lost. They probably won't care but it would help in a small claims case that you tried to solve the problem. Rip off shops and incompetency really get me angry and I have volunteered a number of times to testify against shoddy outfits that give the industry a bad name. Charging much higher than legitimate shops with competent staffs and efficient operations is the first clue to be wary of. Good techs are cheaper, they diagnose well and conclude caused of problems faster and don't get hung up for days in a simple problem, anything in your amp is a simple problem if skill and understanding of the principles involved is applied to the task.
Sorry about your situation. Next time you should probably refuse it if it does not sound like you expect Before you take it home. Play it for the tech, show him exact what you expect to be resolved and let him prove it to you in sound that it is when you pick it up.

[johnk_10]

6 months...8 months...what is going on. That is absurd, and time for a small claims suit to reclaim money from a rip off.
The real problem is so many tube-amp-only guys put out a shingle and specialize in the simplest systems in consumer electronics by using habit and seat of the pants repair techniques and not proper diagnostics and logic. When I see how little in test gear, or precision anything used in those sort of shops it is easy to see how they can't diagnose a non-routine problem. When you see a whole lot of parts swapped out and charged for it is the first clue that it was shotgunned and not every diagnosed as to the real problem or the mechanism of fault. Why something went wrong is as or more important than what wrong.
Did any of the failed repair attempts come with complete written descriptions of what was done and why? Are the problems related to each other? Did you get an explanation why your repairs took 5.8 and 7.8 months too long for any serious professional repair facility?
You are being too patient, you should be raising hell over high prices and incompetent work, bordering on scams. Try demanding your money back and compensation for time lost. They probably won't care but it would help in a small claims case that you tried to solve the problem. Rip off shops and incompetency really get me angry and I have volunteered a number of times to testify against shoddy outfits that give the industry a bad name. Charging much higher than legitimate shops with competent staffs and efficient operations is the first clue to be wary of. Good techs are cheaper, they diagnose well and conclude caused of problems faster and don't get hung up for days in a simple problem, anything in your amp is a simple problem if skill and understanding of the principles involved is applied to the task.
Sorry about your situation. Next time you should probably refuse it if it does not sound like you expect Before you take it home. Play it for the tech, show him exact what you expect to be resolved and let him prove it to you in sound that it is when you pick it up.

+1!

[dumbassbob]

What Wrong with Bandmaster

The day that Gerald Weber failed to fix my silverface Bassman for the second time but fixed the problem of having several hundred dollars in my wallet was the day I vowed to learn how to fix my own amps. For what you've paid on that Bandmaster, a good tech would have been able to replace every part, INCLUDING the transformers!
1. Is the problem tube related? Switch all the tubes with known good backups.
2. If it isn't tubes, start at the output section and work your way back to the preamp.
with a problem like this it is more like checking off what you know is good until all you're left with is the problem.

The OC tech went back and checked the Bias Cap that he had put in.It was BAD..now the amp sounds ok but still has the popping bright switch's.Iam going to resolder all the tube sockets and anything else I see, clean the jacks ect... I am broke...But this amp has some really cool history and deserves some love...I made the mistake of bragging who played this thing and got it stolen for all that time I was lucky I had my name SS#and Ca DL# and mom's phone # inside. and a honest pawn shop back in NYC

[dumbassbob]

JohnK

those old blackface fenders are extremely simple amps to repair/service (i've repaired restored 100's and 100's of them), and once they're running at stock specs, they should go another 30 years (not hours!) without any issues. i visit orange county once a week (i'm in thousand oaks), so if you like to meet me somewhere and drop it off, i could bring it back to you fixed for good the following week.

Thanks,I am out of money right now but if it goes down I will take you up on offer,Is there a phone # or email address on your web site contact page? You make some nice Bass's

[johnk_10]

my email address is on my website's contact page. IMO, it should cost next to nothing to get it right.

[dumbassbob]

6 months...8 months...what is going on. That is absurd, and time for a small claims suit to reclaim money from a rip off.
The real problem is so many tube-amp-only guys put out a shingle and specialize in the simplest systems in consumer electronics by using habit and seat of the pants repair techniques and not proper diagnostics and logic. When I see how little in test gear, or precision anything is used in those sort of shops it is easy to see how they can't diagnose a non-routine problem. When you see a whole lot of parts swapped out and charged for it is the first clue that it was shotgunned and not ever properly diagnosed as to the real problem or the mechanism of fault. Why something went wrong is as or more important than what went wrong.
Did any of the failed repair attempts come with complete written descriptions of what was done and why? Are the problems related to each other? Did you get an explanation why your repairs took 5.8 and 7.8 months too long for any serious professional repair facility?
You are being too patient, you should be raising hell over high prices and incompetent work, bordering on scams. Try demanding your money back and compensation for time lost. They probably won't care but it would help in a small claims case that you tried to solve the problem. Rip off shops and incompetency really get me angry and I have volunteered a number of times to testify against shoddy outfits that give the industry a bad name. Charging much higher than legitimate shops with competent staffs and efficient operations is the first clue to be wary of. Good techs are cheaper, they diagnose well and conclude caused of problems faster and don't get hung up for days in a simple problem, anything in your amp is a simple problem if skill and understanding of the principles involved is applied to the task.
Sorry about your situation. Next time you should probably refuse it if it does not sound like you expect Before you take it home. Play it for the tech, show him exact what you expect to be resolved and let him prove it to you in sound that it is when you pick it up.

I didn't even get a repair bill..Just asked for my credit card # It sure wasn't how I thought it should be,but I am in Ca and he was in Texas

[dumbassbob]

my email address is on my website's contact page. IMO, it should cost next to nothing to get it right.

Thanks John

[km6xz]

With no invoice or records, there is a problem for you but a bigger one for the rip off shop...he can't prove that the transaction took place to your satisfaction. That means he has no credit card authorization. File a charge back request from your credit card issuer and just report that the work requested was never done. It will take a month or so but you will get your money back. He needs your signature on a card authorization to prove the work was done as requested.

The second post, relating to the OC tech finding a bad cap that he put in, probably has resulting in your power tubes being overstressed from lack of bias. A cap if open will put pulsing DC on your grid and at the swings closer to ground potential means full saturation anode current was being pulled. Make sure he checks the power tubes properly and replaces them for free if there is any deviation from spec.

The popping switch will be pretty easy to find, did he know about that when it was on his bench? One way a customer can protect himself from less than complete repairs is being a proactive owner. Make sure the tech has enough information to be able to clearing know what you are requesting and what conditions are needed to reproduce the problem. It is best to use a local tech and demonstrate the problem so you are both speaking the same language. If a tech can reproduce the problem on the bench, it can be repaired without much drama. For example does the popping mostly show up with some specific control settings or note being played? If so tell him or better, show him.
When I had my large shop, with 15 full time techs and 28 fully equipped work benches, the girls at the counter had it their resposibility tyo witness and be able to reproduce the problem. They had a little test bench in the lobby that allowed them to safely test out the reported symptoms while the owner was present. If reproducible, any repair is much easier, and much more likely to not come back as a do-over. That one step of verifying the problem often took care of the problem without accepting the unit, by finding a switch out of place or power supply module problem. Some devices such as a mixing console has so many possible combinations of settings that can occur only when a specific set of conditions and control settings are present that step reduced returns and labor charges greatly for every unit worked on. A customer was not considered serious if they just said "check everything" meaning they know why they brought it in but will not share that with us. A larger console or keyboard is very difficult to test every possible combination of conditions, levels, temperatures, mechanical stress etc that might be required to make the defect appear. When commissioning a large format console in a studio it might take 2 techs 7-10 days to fully test it before signing it off as functioning.
Good luck with keeping your amp going, you have both been through a lot.
One bit of advice, do not follow the common internet "wisdom" of replacing commonly suspect parts in an attempt to repair something. That is pure amateur and likely to confuse the problem and the repair. Repair and diagnosis is very different than restoring an amp. Repair to stock and full function before starting any restoration. Replace only what you can prove to yourself it in need of replacing. If in doubt, get on here and ask. Be wary of any tech or shop who replaces a laundry list of parts in a repair, they did not diagnose the problem and the real problem might exist. The just added cost and confusion by changing parts until the symptom changed or disappeared. When hiring techs, even ones claiming years of experience, I put them through thorough vetting by having them diagnose various units and explain to me what they found, and how that evidence relates to the symptoms. Those thought experiments showed whether they could think through a problem logically or were just throwing parts at something. Most techs work by habit, not by knowing how something really works and what would be expected in any test result. Putting a test probe on any point, should tell a tech what would be expected to be observed. Another exercise that turned into a game was competitive diagnosis where a tech would "bid" on the number of separate test points or conditions that would need to pinpoint the problem and why. One might claim a problem could be diagnosed with 10 measurements and another might think they can do it with 9 and the winner gets some prize, usually one of the promo gifts reps brought or an hour off work early(they were all on salary not hourly so that mean something). That exercise showed the newer techs a new way to think through a problem, to be actively ferreting out the most significant information the most effectively instead of blindly probing around until something did not appear to be right. What failure could account for all the symptoms? Some things, most possible things, are easily ruled out before opening the unit because those possible defects would not fit all the symptoms, just some of them. As a general rule, if a mode of failure and mechanism of fault was not known in 30 minutes of bench time, the tech did not understand the circuit or the symptoms were not reproducible with the information provided by the customer. That is why I am convinced many of the tube gurus are poor techs despite(or because of) the high prices and long repair times.