Hacker Cavalier Loud Noise

[Herald1360]

All of the electrolytic capacitors in that circuit have their negative ends direct to chassis except C3 which has its negative end connected via R5 100 ohms to chassis.

[Station X]

Looking at the OP's pictures, I'd say that the blue electrolytic third from the left is the wrong way round. What do other member's think?

[Herald1360]

I'd agree that the third blue electrolytic from the left is backwards.

It's the blue electrolytic fourth from the left though since there's a black one first from left.

Quite a few of the new soldered joints also look decidedly dry.

[martinpinner]

Thanks for everyone's comments. As i now know which is the correct way to fit the caps I will swap the offending caps around and also look at the joints. I will invest in some new solder as what I have been using is some years old.

[Michael Maurice]

Old solder wont be the problem you just haven't soldered it correctly. There seems to be a number of missing components on those tag strips.

This is a picture of one I rebuilt some time ago.

[Audio1950]

Originally Posted by Michael Maurice

By the way you can use thiscartridge

Good choice, except that it doesn't appear to have the mounting bracket, which is essential.

[Herald1360]

Originally Posted by martinpinner

I will invest in some new solder as what I have been using is some years old.

Is the solder you are using actually flux cored tin/lead electrical solder "60/40" or "63/37" or "Savbit". The joints look to be suffering from either lack of flux or lack of heat from too small an iron, or perhaps from being done with lead free solder which requires more heat anyway and is trickier to use too.

Plain solder wire won't work well on its own and the sort of flux it's used with for plumbing and the like is too corrosive for electrical work.

As far as age is concerned, some of the solder I use is probably over thirty years old- it looks a bit dull but works just fine.

[Boater Sam]

Oddly I have a reel of fine cored solder that must be 20 years old and it too is grey and quite useless. It just melts into blobs as though all the flux has disappeared. Can't be lead free that old.
It was not the common Savbit or Ersine M/core, I suspect it came from Maplins.

[Station X]

Originally Posted by Michael Maurice

There seems to be a number of missing components on those tag strips.

This is a picture of one I rebuilt some time ago.

Well spotted Michael.

It's missing at least one smoothing cap and possibly the 1.5K smoothing resistor to start with. No wonder it's noisy and new valves ain't going to cure it!

I suspect we've only been given half the story here. Perhaps there's been a previous repair or modification attempt?

When giving advice in these threads it's way too easy to assume things and only pictures tell the true story.

With the growing popularity of "vinyl" things can only get worse.

[Nickthedentist]

Further to Michael's excellent pic, here's one I have on file of an all-original, unmessed-with GP15. Hope that helps.

[Station X]

Very good. Is there another electrolytic capacitor somewhere? I reckon there should be seven in all.

[Edward Huggins]

Well, it's taken 3 pages of threads to get this far and I just hope that in the meantime no money has yet been spent on valves which are unlikley to be at fault. Edward.

[Lucien Nunes]

To clarify (in the light of the slightly confusing exchange above) it is never correct or acceptable to install a conventional electrolytic capacitor with reversed polarity. All such capacitors will either have their polarity marked explicitly, or it can be determined from visible constructional features. Only special non-polarised types, used mainly in loudspeaker crossovers, may be installed either way round.

Depending on the capacitor's purpose in the circuit, consequences of reversed installation could include:
* Not working quite as well as it should.
* Working OK initially but failing prematurely.
* Capacitor exploding.
* Valve or transformer overheating and burnout.

Very rarely, a reversed electrolytic might give satisfactory service if the voltages involved are extemely low. I recently overhauled a chassis where the cathode bypass capacitor for a small signal triode had been installed reversed from new. The unit had worked acceptably well although the capacitor had deteriorated badly compared to the others of the same type. Had the main reservoir capacitor been reversed instead, the rectifier would probably have been destroyed at first test or the capacitor might have exploded.

Returning to the Hacker, I agree about the soldering. Many of those joints look suspect to me, because the solder has not properly flowed around both the tag and the component lead. I would recommend to the OP to get some tagstrip, lengths of wire and good quality 60/40 cored solder and practice making joints until a smooth, even, shiny result can be quickly and consistently achieved. It is a known problem when changing large numbers of components that new faults can be introduced due to bad or wrong connections, even by professionals. This is a good argument in favour of not changing parts that are in working order.

[martinpinner]

Thanks once again for everyone's comments. I have been using Resin Cored Solder but will obtain the recommended solder and practice as suggested. I purchased the player at an auction. It was in a filthy condition but it cleaned up OK. When I tested it and found it was not operating correctly I found the Forum and decided to have a go at repairing. From the photo's posted I will try and identify the capacitors/resistors that it is missing. With regard to Nick's photo my player does not have three of the yellow capacitors but only two which I have replaced. Is it possible to post a photo showing all three for their fitment.Thanks

[Lucien Nunes]

What you might have run into is an incomplete repair, modification or general tinkering by the previous owner. This can be extremely confusing if you are new to the world of electronic repair, as incorrrect wiring and component choices won't stand out in the way they do to an old hand. Rather than visually copying another chassis, might I recommend tracing out all the wiring relative to the schematic, both to discover what is amiss with your player and as an orientation exercise in working around valve circuits?

[martinpinner]

Thanks for the advice. I have studied the photo's posted in respect of the components and layout. In comparing these to the GP15/GP42 component layouts that I have downloaded it would appear to me that these relate more to the GP42 than the GP15.

[Station X]

Originally Posted by martinpinner

With regard to Nick's photo my player does not have three of the yellow capacitors but only two which I have replaced. Is it possible to post a photo showing all three for their fitment. Thanks

The yellow capacitors are C7, C13 and C15. I see there's a note on the diagram about C15 not being fitted on some models, but this may refer to the external amp used for stereo.

[Station X]

There's something strange about this player. Looking at the OP's pictures, it's quite obvious that some of the tags on the tag strips have never had anything soldered to them, unlike the tag strips in Michael's and Nick's pictures.

Surely the tag strips haven't been replaced?

[Nickthedentist]

Graham,

Originally Posted by martinpinner

Thanks for the advice. I have studied the photo's posted in respect of the components and layout. In comparing these to the GP15/GP42 component layouts that I have downloaded it would appear to me that these relate more to the GP42 than the GP15.

It may be that my pic was indeed from a GP42 as Martin suspects, as I have both models, but it the folder on the computer was labelled "Cavalier". Sorry for the confusion if that's the case.

Here's the layout diagrams for the Cavalier from the manufacturer's manual, taken from the superb Yahoo Hacker Audio Group, and originally scanned by forum member and Hacker expert Mark Hennessey.

[martinpinner]

Thanks. Could you identify the type of C14 capacitor. Is it a silver mica and what voltage.