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Valve testing

Discussion in 'classic' started by nmtjb, Sep 22, 2021.

  1. nmtjb

    nmtjb pfm Member

    Are there any recommended dealers or hobbyists capable of testing a range of valves near post codes SE24 or TQ9 please? I'm currently having my valve pre repaired and apparently the fault has likely been caused by a rogue PCC88 so I'd like to get my spares checked before using them.
  2. Vinny

    Vinny pfm Member

    Checked for what? Given that valve testers are about as accurate/useful as seaweed is for forecasting the weather, you are asking a lot, in effect asking for a prediction of failure.
    A "failed" valve taking out an amp' that it was designed to be used in (I am assuming that that is/was the case), sounds rather unlikely anyway. @Arkless in particular would be the one to comment on that aspect, or possibly @GTAudio.
  3. nmtjb

    nmtjb pfm Member

    I'm also a bit surprised that a valve failure would do that but apparently it has:
    (from the German designer)
    "A transistor was burned. In the phono first stage - R channel. Probably caused by a catastrophic failure in the PCC88 double triode valve.
    So it would be good to get the original valves for check-up."

    Unfortunately the valves didn't get delivered with the pre (long story....) so I have had him replace all with new.
    I'm assuming the old valves and a box of spares will need checking so it doesn't happen again, and I thought an Avo or similar could do that, or perhaps just continuity needs checking? Can that be achieved with a multimeter? Are the u-tracers also next to useless in assessing valve health?

    I've used this pre and power set up for many years without issue and the repair/service and upgrade is FOC so I can't complain. The main, post-Brexit hassle has been getting it back to him and wondering how to get it returned to me.
  4. Vinny

    Vinny pfm Member

    I very much doubt that anything could be checked in a worthwhile way - heater open circuit isn't going to cause a problem with the amp (apart from not working at all) for instance.

    You need a statement with the amp' when it is returned stating that it was sent UK to Germany, it was repaired and is being returned, and the total cost of the repair and return carriage was £X (or Euro). The main thing is that customs should not take insured value as what you have spent. There is probably a particualr customs form to be able to do this.
    If it is picked-up by customs you will pay roughly, around, 30% of the declared costs in charges - VAT, duty plus handling charge. Getting caught by customs is not a certainty - I find about a third get missed, completely unlinked to parcel size, sender's country and value.
  5. bencat

    bencat pfm Member

    When the unit was sent using a courier or parcel company then the invoice details you are required to send should have stated very clearly Used Equipment returned for repair. The tracking number of the parcel going out should be stated on any return and then again that shipment has to be clearly declared as Repair unit . They will also need to include a full copy of the repair invoice with full details of cost and what has been charged. They should not have charged any VAT on the work they have completed but the UK Customs will charge you VAT on the work done so you should be charged twice for VAT .
  6. nmtjb

    nmtjb pfm Member

    Thanks Vinny,

    I've looked long and hard at the methods by which I can send and return items to the EU for repair and return and have concluded there's no failsafe way of doing it as an individual and I don't think its fair to expect the supplier to ensure the paperwork is absolutely correct should it be picked up.

    Several specialists I've contacted for repairs to cartridge's and other non-hifi items simply won't deal with the UK anymore due to the hassle.

    Your final statement sums it up, getting anything passed through HMRC appears to be a lottery and totally reliant on the whim/mood/IQ of whomsoever gets to chuck the box around the warehouse.
  7. nmtjb

    nmtjb pfm Member

  8. Vinny

    Vinny pfm Member

    Because any foreign seller, AT ALL, shipping to the UK MUST be registered for VAT with UK HMRC. That enables them to charge UK VAT when charging you, that VAT is then sent to UK HMRC. The only real exception are sales from person to person, private individuals.

    If your repairer isn't UK-VAT-registered, I can see that you may have problems when it comes back - best option would probably be to somehow portray them as an individual, not a company.
  9. nmtjb

    nmtjb pfm Member

    That might well be a way to tweak the process in my favour but it involves a minor subterfuge both on my part and then by the repairer, which if investigated could lead to a negative response from HMRC going either way.
    I'm quite happy to pay all of the required C&E on this transaction, which given the repairs are FOC should only be levied on the cost of return postage but even if I go the full OP route, get certified with EORI # etc. would still rely on HMRC accepting a £££££ item coming into the UK is "returned after repair" with a £10.00 VAT receipt payable. It might well do, in the same way that "presents" can be exchanged without attracting import costs but its not worth the risk, and I've been there before with items from the states.

    Anyway, the unit has been repaired FOC having been dropped off by friends travelling in the locality. After a few days of testing it will be sent to Switzerland via Munich and then I'll smuggle it back in to the UK next time I drive across Europe. Simple really.

    I could still do with knowing how the valves can be checked over though...
  10. Barrymagrec

    Barrymagrec pfm Member

    It`s not impossible that a valve fault in what appears to be a hybrid design could damage semiconductors in the circuit, however there is no guarantee that a quick check in a valve tester would show the fault, though it might.

    There are virtually no useful tests that can be carried out with an AVO or DVM - heater continuity is obvious and as above, will not blow anything up and heater cathode insulation is unlikely to show cold or at the low test voltage of a testmeter.
  11. ghostbusters

    ghostbusters pfm Member

    I just wanted to follow up on the original question as I am interested in this subject as well.
    I have a number of old valves for my Quad II to sell and wanted some advice as to the best place and how to present the valves.

    I would normally look to sell on the forum or eBay , but any other suggestions would be appreciated.

    Also any advice as to how to list, how to reassure buyer, caveats etc.

    I have access to a basic B&K 606 tester which will give some data Grid Emission + Emission Test ( Good/?/Replace) + Short + I could also demo tubes in a Quad II .
    Testing I feel does give a certain reassurance, but I also appreciate, that with the age of these , that is no guarantee it will work next day.

    Are there any valve testing businesses any one could recommend?

    Many thanks in advance for your comments.
  12. toprepairman

    toprepairman pfm Member

    Crikey, TQ9 and SE24 are a long way apart.

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