HMV 2046 Volume stuck on Full

[Edward Huggins]

Noting what a "corner shop" TV Repairman might charge if you are unable to fix it, there are at least two of this model, working, now online for £25.00.

[SiriusHardware]

Originally Posted by ldadipscm

Yes, happy to confirm that I do myself possess a multimeter and it is in good condition.

From everything you've reported so far it seems likely that this fault is going to be a visually detectable fault if you don't mind taking the unit apart far enough to get to the area which needs to be looked at, namely, the PCB upon which the slider controls are mounted. As the balance control does work normally, you're now looking at a problem somewhere very close to the volume control.

The meter will be useful for verifying the health of the volume control slider itself, if it comes to that point. We'll cross that bridge when you come to it.

[steve1010uk]

I could be ( and often are) wrong but from long back in my dark and distant past i seem to remember something mechanical going wrong with these slider controls, something like the metal slider piece coming detached from the plastic slider shaft or similar.


Steve

[Nuvistor]

I always had to change the slider controls in domestic equipment, still spares were easy to obtain.
Hopefully it is just a bad connection that’s causing the trouble in this record player.

[julie_m]

Originally Posted by ldadipscm

Alan (owner of the HMV 2046) confirmed last evening that, using the balance slider, the sound does come out of both speakers and furthermore, when the balance fader is pushed fully to the left, the sound disappears from the right speaker (and vice versa).

Interesting. This means that the earth connection between the amplifier and control PCBs is good. My prime suspect has just shown me a cast-iron alibi.

I've heard horror stories where people have tried to clean potentiometers using over-aggressive solvents that have wound up eating right through the carbon track But the symptom then is that you don't get any signal coming through at all. To get your symptom of full volume all the time, the very bottom ends of both tracks would have to have come disconnected from Earth. It's still possible that the fault could lie outside the potentiometer, but it could be within. At any rate, the broken connection is definitely somewhere on the controls PCB.

Unfortunately, while I have seen the insides of the family stereo on a few occasions (only a very few occasions; it was very reliable), I can't for the life of me remember how the controls PCB comes off. Does anyone else know? It would be a shame to break anything in the course of disassembly.

Then we're going to need some pictures of both sides. With it being so long and narrow, you might be best off taking four or five shots along its length. This will ensure the best resolution, as the Forum software will automatically reduce pictures to no more than 800 pixels on the long edge. Also note anything printed or stamped on the potentiometers. Then, one of us will be able to suggest where to probe with your multimeter.

There is one more test you might be able to try before you open her up. You will need a record with noticeably different material on the left and right hand channels. There are some music records that are like that anyway, especially some early stereo pressings; there were also special test discs for setting up record players, with bursts of different frequencies, solo passages of certain instruments, and left-right test tracks. There is a famous recording of a steam train that starts coming from the left and goes across to the right. The owner of the player may well already have something suitable. Or maybe you could use something connected to the tape inputs. Anyway. The test is to set the treble, bass and balance to centre, volume to minimum, both speakers connected and make sure the "mono" button is out; turn on the power, and play something that should be different in each channel. Are you still getting proper stereo separation, or is some of the left-hand signal leaking into the right-hand channel and vice versa? If in doubt, try pressing and unpressing the "mono" button (which directly connects the left and right signals together, so killing any separation). If this makes an audible difference, then you have stereo separation.

If the two bottom ends of the carbon tracks were still connected to each other even although they were not then connected to earth, that would mean the fault could not be inside the pot. In this case, with the volume control set to minimum, the amplifier inputs would be connected together; so whichever track a signal was arriving along, it would end up being fed to both speakers -- no stereo separation. The link between the two pins of the potentiometer is doing the exact same job as the "mono" switch. As the control was slid towards maximum, the resistance between the two channels would increase, thus giving less of the "wrong" signal in each channel, i.e. better separation. Pressing the "mono" button should then make a difference.

If you are getting proper separation between the stereo channels, and pressing the "mono" button makes a difference, this means that the two bottom ends are not connected to each other. This still doesn't necessarily mean the pot is to blame, though.

Anyway, pictures will be a real help. Someone here will be able to devise a sequence telling you exactly where to put your meter probes, to determine exactly where the fault lies.

[Nuvistor]

The link in post 14 gives dismantling instructions.

[Tim]

If you have another control of suitable value, could you wire it across the existing one, and see if you then get some sort of controllability?

[ajgriff]

I think Steve (see post #23) may well have a point. I recently had exactly the same issue with a Grundig Elte Boy 600 radio. The solution involved gently removing the rectangular control knob and re-fitting it so that its 'prong' engaged correctly with the lug in the slider mechanism. Easier to do than explain but hope this gives you an idea.

The Grundig radio is mono of course so the exact arrangement may be different on the HMV but I think the principle should be the same.

Alan

[Nuvistor]

The control knob not being mated with the control is a good thought and probably easy to see without dismantling.

[Edward Huggins]

There are some very well intentioned and highly detailed Posts within this thread, but if you re-read posts #2 and #6, it's obvious that the OP does not have the skills to do the work somehow expected of him. That is why third party expert help is recommended or go buy another working HMV2046. These are available at very low prices.

[ajgriff]

I agree with Edward that Lawrence may not be able or confident enough to tackle some of the work suggested, especially as the HMV belongs to someone else. However, re-engaging a displaced control knob doesn't require any dismantlig or real expertise, just a bit of care. Of course this may not be the problem but it is surely worth checking.

Alan

[SiriusHardware]

Edward, I agree with your general observation but I do not think we should discourage the O/P from at least a preliminary visual investigation.

It probably is too early to be giving detailed explanations of how things work, but once posted, the information remains online and may yet prove invaluable to some other party who surfs into this thread in search of similar information, so the time and trouble taken (mainly by Julie in this case) is never wasted.

Everyone on this forum started with no knowledge at all and was either guided initially by someone more experienced or self-taught, or more likely a mixture of both.

It's been said that both this unit and one other unit that the OP noticed for sale were originally suffering from volume control problems - that suggests to me the possibility of a weakness / stock fault on these volume controls which may be present or about to happen on any similar unit found for sale.

So why not at least try to fix this one?

[ldadipscm]

Hi All (Edward, Nuvistor, Sirius Hardware and Julie m)

I conveyed the advice you all very kindly offered in respect of Alan's 'full volume' issue with his beloved HMV 2046, particularly your suggestions as to what he could do to identify the nature and location of the problem.

I spoke to Alan late yesterday afternoon and he told me that whilst diligently following the 'tests' you suggested on Monday, during the list of tests suggested by Julie he suddenly realised that his player was working quite normally again with absolutely no crackle on moving the volume slider and, most importantly, the volume slider was then raising and lowering the volume level on both channels exactly as it is supposed to do. In other words, problem solved.

Alan tells me that he was 'astounded' when it suddenly started to work normally but confessses he has no idea what caused it to do so. Perhaps it was a loose clip or wire that is now just about connecting again, due to the player being moved around, so the problem could re-appear in the future I suppose but, if it does, it would probably indicate that it is a simple connection problem rather than something more serious.

Alan has asked me to thank each and every one of you for taking such a swift and keen interest in his problem. So do I thank you. Your help was very much appreciated!

[Now, as a novice forum user, all I have to do, is to work out how to 'close' this thread?]

Best regards
Lawrence

[Hartley118]

Originally Posted by ldadipscm

[Now, as a novice forum user, all I have to do, is to work out how to 'close' this thread?]

Best regards
Lawrence

We have excellent and dedicated staff who look after that!

Martin

[AC/HL]

We don't normally close this type of thread, in case of late additions. It will close automatically in the fullness of time.

[julie_m]

On the one hand I'm pleased for Alan that his HMV is working as it should and he is able to enjoy his music collection again. On the other hand, I can't deny feeling just a tiny bit disappointed not to have found out what the original fault was, beyond "something not making proper contact somewhere". It's a bit like a book where a minor character did something that looked as though it was going to have a bearing on the plot, but was never mentioned again subsequently.

Anyway, if the HMV starts misbehaving again -- or if a different fault manifests -- you know where to come for the answers .....

[Michael Maurice]

Originally Posted by ldadipscm

He took advice from a friend of his to spray the slider with DP60, which he did.

I’ve never heard of DP60 but looking it up it looks similar to WD40 and would not be suitable to use on electronic components.

[Boater Sam]

There are miriad products similar and just as bad for electronic assemblies.
I have had sets in where the tuning gangs are gummed up totally because of its use. They fail to tune until removed, stripped and washed clean.