Repairing a Quad 200HD Kustom guitar amplifier

I have a Kustom 200 watt guitar amplifier head, it's several years old. When I plugged it in to test a new set of speakers I had built, it seemed to power on, but I couldn't get any sound out of it. (lights came on, all the channels seemed to be selecting properly, etc..) I opened it up, and found that one of the capacitors on the power board had completely fallen off the board. The positive pole wire was broken off to about 1/32 of an inch long, and the negative wire had apparently come unsoldered from the board. These are Aluminum Electrolytic Capacitors, 6800uf, 63V. The question I have is: What could make the capacitor fall off the board like this? I've included a picture of the capacitor with the broken pole wire. It isn't swollen, and it's not leaking...actually looks like it is in good shape, but I know looks can be deceiving in components like this! I did not test it, as I decided to just replace both of them with new ones regardless. (there are two identical ones on the board).

I already have the new capacitors, they were relatively easy to find at Digi-Key.

I'm a little concerned that there might be some other component on the board that caused the problem. I have really looked the board over closely, and it doesn't appear to have any obvious damage, but I know sometimes there can be damage without anything showing signs. The capacitors aren't really very expensive, but I would hate to replace them just to have the new one get damaged right away.

Thanks for any help anyone can give me with this!

There's nothing to go wrong to remove the capacitor from the board - it's purely physical - and probably the result of the amplifier been dropped (probably many times over the years), and it's simply mechanical damage.

There's no signs of any glue on the capacitor, they are usually glued in place to prevent this.

Basically it's a question of replacing the capacitors, and seeing if it works - it 'may' have caused further damage.

Assuming it then works?, then run some hot melt glue round the bottom to secure them to the board.

Ok! Thanks so much for your reply. I'll post after I replace them and let everyone know if it worked or not!

Exactly what Nigel said.
Nowadays you will see that all large electro caps are firmly attached to the PWBA, usually with hot melt glue or a bracket.

Unless they are secured, their usual tall profile will put a lot of stress on the leads, leading to metal fatigue and failure.

Also, Kustom amps were guitar amps, correct? If so they will have received more than its fair share of abuse during its life on the road.

Thanks schmitt trigger! Yes, this Kustom amp is for Lead Guitar, and apparently it did indeed have it's fair share of abuse!!, The amp is now working perfectly now though! I did add some hot glue to the bottom of the caps this time, so hopefully they won't just fall off anytime soon!
On another note though, after I got them soldered on, I did notice that the new caps were rated for max 85 degrees, while the originals were at 105. Since this is 4x more lifetime than the 85 degree ones, I have already ordered the correct temperature ones and will be replacing them in the next few days.
The amplifier does work and sounds awesome though, and my new speaker cabinet I built for it (4x12, 2400 watt RMS) sounds better than any I have heard in the music stores!! Not going to be using the amp too much before switching the caps again though....wouldn't want to fry something else.

Thanks for all your help here, this has been a great experience getting so many pertinent/knowledgeable answers in such a short amount of time!

Kustom were one of the first ruggedized, all silicon transistor amps, suitable for the hard life on the road of a budding rock and roll band.

They have a very distinct sound, of late 60s to early 70s. If I recall correctly the famous hit “In a Gadda da Vidda” from Iron Butterfly was recorded using Kustom amps thorougout.

schmitt trigger said:

Kustom were one of the first ruggedized, all silicon transistor amps, suitable for the hard life on the road of a budding rock and roll band.

They have a very distinct sound, of late 60s to early 70s. If I recall correctly the famous hit “In a Gadda da Vidda” from Iron Butterfly was recorded using Kustom amps thorougout.

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They are pretty well unknown in the UK - I only know of them because when I bought my daughter a bass guitar 'kit' it came with a small Kustom practice amp. I don't think I've ever seen another?.

Indeed Nigel.
In the UK, most likely bands would have used locally produced amps, most of them excellent designs (Marshall immediately comes to mind) which were part of the unique sound of British Invasion rock bands.
If I recall correctly, they held to valve designs longer than American designs.

I know the following statement is highly subjective and personal, but I have always considered British rock of the era to be the world’s most progressive and refined.

schmitt trigger said:

Indeed Nigel.
In the UK, most likely bands would have used locally produced amps, most of them excellent designs (Marshall immediately comes to mind) which were part of the unique sound of British Invasion rock bands.
If I recall correctly, they held to valve designs longer than American designs.

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They still do, simply for those who prefer the distorted valve sound - did Marshall ever make any amps that weren't valve I've never looked, but I don't recall ever seeing one, and I've seen a LOT of Marshall amps over the years.

The first popular transistor amps were from HH Electronics over here, and were famous for their small slim size and light weight.

I know the following statement is highly subjective and personal, but I have always considered British rock of the era to be the world’s most progressive and refined.

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There's been some serious world leading bands from the UK, it's always had an amazing music scene over here and tends to lead the world - one of the best 'local' bands was Nirvana (the original one, not the Kurt Cobain copy ). They used to play sometimes at a rock club I used to help run, they were run by a guy called Tony who was lead guitarist, and completely blind - and usually stoned!. You just had to help him on stage at the beginning of the night, he'd feel the edge of the stage with his foot, and then he could jump on and off stage all night, all while playing amazing guitar solos. We had some great nights, and saw some amazing bands.

The UK club scene in the 60s and 70s must have been beyond fantastic. If you were lucky, you could have glimpsed some artists which later became rock- gods.

As a fact an acquaintance of mine, significantly wealthier than me, spent s couple of years studying in the UK.
He mentioned that he had seen this little band in a club, and had liked the band so much and the singer in particular, that he sought their record later.
He showed it to me. I don’t recall much about the album’s artwork, is was fairly plain, but the name stood out: Queen.

He had seen Freddy Mercury perform from a few feet away!

The rest is, as they say, Rock and Roll history.

Sorry for the thread drift!

schmitt trigger said:

The UK club scene in the 60s and 70s must have been beyond fantastic. If you were lucky, you could have glimpsed some artists which later became rock- gods.

As a fact an acquaintance of mine, significantly wealthier than me, spent s couple of years studying in the UK.
He mentioned that he had seen this little band in a club, and had liked the band so much and the singer in particular, that he sought their record later.
He showed it to me. I don’t recall much about the album’s artwork, is was fairly plain, but the name stood out: Queen.

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Did you ever see the TV series "The Old Grey Whistle Test"?, I first say Queen on that.

In fact the series was so good I used to come home early from the pub just to watch it - where were VCR's when you needed them

They had some amazing bands on, many you'd never heard of, and many American bands coming over here and trying to break the British market.

I've always liked the Marshall amps, except for the price tag. This is the first of the 'newer' Kustom amps that I've ever had the opportunity to play through, and I must say it has tons of sound! 8 on-board effects that are actually pretty decent, a 'Balls' knob on the lead channel that acts like a pre-amp so you can get the distortion you want, and several other tone-altering options.

I saw Iron Butterfly along with the Byrds at an auditorium at Iowa State University back in the early 70's. I think it was just as Iron Butteryfly had released Ina-Gadda-Davida, and the Byrds were more or less at the tail end of their most popular era....only cost $5 to see them, no seating, everyone just wandered around the stage....it was awesome! Byrds blew Iron Butterfly off the stage though...they were definitely the better band!

I’ve only seen The Old Grey Whistle Test on YouTube. Great, great stuff.

At the time, because of the different TV standards, it would have been difficult to see in the Americas any European content TV.

I would guess that your situation was similar, unless the broadcast had been originally recorded on film, which could then be transcoded in a TeleCine equipment.

schmitt trigger said:

I’ve only seen The Old Grey Whistle Test on YouTube. Great, great stuff.

At the time, because of the different TV standards, it would have been difficult to see in the Americas any European content TV.

I would guess that your situation was similar, unless the broadcast had been originally recorded on film, which could then be transcoded in a TeleCine equipment.

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Not at all, conversion both ways was commonplace - particularly here, as we had two different systems for years, the old 405 and the later 625 - so both required conversion from the other.

In fact, when the USA moved from mostly film to mostly video tape, it was blindingly obvious over here - as quality plummeted. To some extent it was similar the other way, but the higher standard of the 625 system meant conversion to 525 wasn't too bad - but even so, cine film was used for decades, and may still be used sometimes. A lot of the old series, like The Prisoner (which I know has been shown over there) and The Avengers were made on film, which is why they are still stunning quality today.

Nigel Goodwin said:

In fact, when the USA moved from mostly film to mostly video tape, it was blindingly obvious over here - as quality plummeted. To some extent it was similar the other way, but the higher standard of the 625 system meant conversion to 525 wasn't too bad - but even so, cine film was used for decades, and may still be used sometimes. A lot of the old series, like The Prisoner (which I know has been shown over there) and The Avengers were made on film, which is why they are still stunning quality today.

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In the Friends reunion, there were various shots that showed the making of the original series, from 1994 - 2004. That was shot on 35 mm film.

I would guess that the producers would want a format that would convert for all the countries it was shown in, and would not want to change process mid-series. After the first series, cost would be no object.