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Ill advised Champ 600 project

Discussion in 'Glowing Bottle Tube Amp Forum' started by Prophetsnake, Jul 15, 2017.

  1. Bendyha

    Bendyha Tele-Holic Ad Free Member

    889
    Mar 26, 2014
    Northern Germany
    Nothing at 15, to ground ? What about across J 9 & 10 ? and from each of them to ground? Before you said you had a reading across the filament supply. I hope you have checked Fuse 2

    So what are you readings AC and DC at TP12 & 9 to ground?
     
    Last edited: Jul 17, 2017 at 4:18 AM

  2. Prophetsnake

    Prophetsnake TDPRI Member

    Age:
    63
    15
    Aug 2, 2016
    ireland
    Doesn't appear to be anything at all from 15 to ground. I did check across J9 and 10 and they have 5.9V
    TP 12 has 390 DC and 859 Ac. TP 9 has 0, but I still haven't put the tubes back, and surely it needs that to complete the circuit? I'm not sure why I was supposed to take them out in the first place, so I'm not sure if it's time to put them back for further testing
     

  3. Bendyha

    Bendyha Tele-Holic Ad Free Member

    889
    Mar 26, 2014
    Northern Germany
    First get the supply sorted out, continuity checked, then put the tubes in for the next stage of testing.... a then b then c.... don't jump from the plane till you have checked the parachute is in the backpack and the strings are attached.

    If you have J 9 & 10 showing voltage, but not TP 15 then find out wher the connection is broken...fuse F2....a disconected wire....look, search and find.

    If you have voltage at TP 12 but not J9 then test for continuity between J9 and J4. If there is none....then there is a problem with your output transformer.
     

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  5. Prophetsnake

    Prophetsnake TDPRI Member

    Age:
    63
    15
    Aug 2, 2016
    ireland
    Strange an unexplainable readings all around, and now, my multimeter is acting up, so I will have to abandon the chase until I can get a new one.
    Your comment on the output transformer made me check. No continuity on the power winding! And the tubes are not heating now, they were yesterday. So a lot of strange things going on.
    Thanks so much. I'll post again in a few days, hopefully with a bit of positive news.
     

  6. robrob

    robrob Poster Extraordinaire Ad Free Member

    Dec 29, 2012
    United States
    Did you replace the battery in your multimeter? That might be the only problem with it.
     

  7. Prophetsnake

    Prophetsnake TDPRI Member

    Age:
    63
    15
    Aug 2, 2016
    ireland
    Robrob,

    I did, thanks. It behaves differently when the battery is low. Might be worth a try replacing it again, though.
     

  8. Prophetsnake

    Prophetsnake TDPRI Member

    Age:
    63
    15
    Aug 2, 2016
    ireland
    Okay.
    Bought a new multi meter and its improved the picture considerably.
    For starters, it's showing 6.4V on the filament winding. And 279V on the other secondary, so that all looks good.
    A lot of the spurious looking AC voltages (300-800) I reported have settled down to zero.
    TP15 still appears to be dead. The fuse is okay, but the tubes are not heating, so I'll have to locate the problem there, obviously.
    There is no continuity on the primary winding of the output transformer, so I'm thinking that that is shot as well.
    With the tubes in, I'm still getting nothing at the TP, which should be indicating tiny voltages, so I figure that that simply means the tubes aren't doing their thing because of the heater circuit.

    One odd thing I have noticed with the new multi meter is that it often gives readings that dissipate to zero or near zero after twent or thirty seconds, or they jump around for no apparent reason. These are usually places where I'd expect to see nothing at all, for example at TP9, where the numbers seemed to jump from say, 181 to 390 and then to zero and finally settled at .4 (AC). Is this sort of thing normal?
    On others it might start off at say 30V and bleed off to nothing. Cap relieving itself?
     

  9. Bendyha

    Bendyha Tele-Holic Ad Free Member

    889
    Mar 26, 2014
    Northern Germany
    None of those small AC voltages will be there if the tubes are cold.
    Putting large DC voltages across cold tubes is not a thing one should do!
    Yes, caps can and will cause voltages to change as they blled of through the multimeter.
    Jumping around....does happen....could be various causes...sometimes bad contact of probes, sometimes meter set to wrong range or AC/DC setting, sometimes trying to read across a resistance that is very high......Usually trying to read the right things in the right way in the right places will solve this problem, but when there is a still unknown defect in the circuit, then we don't know if this might be causing the problem.

    Solve those continuity problems with the heater circuit and the out-put transformer, then we might discover more.
     

  10. Prophetsnake

    Prophetsnake TDPRI Member

    Age:
    63
    15
    Aug 2, 2016
    ireland
    Thank you. I'm slowly beginning to come to grips with this process.
    Having said that, I'm no closer to solving the power supply issue. Nothing appears obviously wrong in the filament supply circuit, though a couple of things seem odd to me.

    All of this is with tubes out, by the way.

    I snipped the diode out and jumped R24, hoping that something magical might happen and all would be good. It would have had to be done anyhow. No luck, obviously.
    The fuse (F2) seems to be ok, but could something else in the circuit make it appear so?
    I've powered the pilot light with a dying 9V battery that is showing around 6V. It glows for a second, then dies out. If I leave it for a minute or two it will do the same again. Could be that the secondary is soaking it up?
    At this stage I am considering bypassing the PC board altogether and wiring the circuit directly.
    Add a fuse holder, the appropriate resistors, either in the control panel or somewhere inside, and connect the power supply somewhere - I'm not sure where, but I'm thinking the socket pins. Any thoughts on this?
     

  11. Prophetsnake

    Prophetsnake TDPRI Member

    Age:
    63
    15
    Aug 2, 2016
    ireland
    One other thing. The solder joint at WJ2, which is where the light is connected, is a little large and splattery. When I test it connected to either the adjacent end of the fuse or R24, I show no resistance. Now, on the schematic, those points seem to be directly connected. But on the printed backside of the PC they are attached to different strips. I'm not sure what to make of that.
     

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