Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Bruciedoesntknow on March 24, 2025, 02:00:43 pm

Title: Spider valve no output but guitar noises playing through the amp itself
Post by: Bruciedoesntknow on March 24, 2025, 02:00:43 pm: Hey, first off, thanks for taking the time. Minor backstory, I'm an amateur that grew up poor and I don't really have the money to send out amps to have them fixed, so I've been learning on my own.

I'm having issues with an amp, it's the line 6 hd100. It came to me with a volume issue where it would pop in and out, but when it made sound, it was basically full volume. I tried to start troubleshooting, but then that issue went away completely and now there's no output at all, but the amp itself is making the input noise. Has me confused to be honest.

Things I've tried so far:
Power amp in from a known good amp
Preamp out to a known good amp
Pulled tubes 1 at a time
Switched tubes from a known good amp

Note: the only time the input noise is present in the amp itself is when I'm plugged into the input and trying to get noise out of the speaker jack. That problem is not present during the preamp/power amp tests I performed above.

I have not removed the body yet, will be taking it apart shortly to begin voltage and resistance testing, but I do not have a schematic and from what I'm reading in other forum searches, those may be hard to come by for this particular amp.

If anyone could either point me in the direction of a helpful thread, and/or send me a schematic or has knowledge of an issue like this, I would really appreciate it. Thanks!
Title: Re: Spider valve no output but guitar noises playing through the amp itself
Post by: tubeswell on March 24, 2025, 07:08:21 pm: Suggest you contact Line 6 and obtain the schematic from them

That amp is probably full of transistor circuitry blended with tube circuitry. Without at least some knowledge of the circuitry, everyone here is flying blind and you're asking people to volunteer their time.
Title: Re: Spider valve no output but guitar noises playing through the amp itself
Post by: bmccowan on March 25, 2025, 11:25:04 am: https://thecodemachine.co.uk/Schematics/Search.php?manuf=Line%206#google_vignette (https://thecodemachine.co.uk/Schematics/Search.php?manuf=Line%206#google_vignette)
I think they have the schematic.
This is a hybrid modelling amp. Not so good for learning troubleshooting, so hopefully it is something simple like a loose wire or a bad pot.
Title: Re: Spider valve no output but guitar noises playing through the amp itself
Post by: Latole on March 26, 2025, 03:25:52 am: Service manual here :

http://bee.mif.pg.gda.pl/ciasteczkowypotwor/%23pro_audio/Line6/Line_6_Spider_Valve_HD100_sm.pdf
Title: Re: Spider valve no output but guitar noises playing through the amp itself
Post by: Latole on March 26, 2025, 03:29:06 am: You wrote ;

"I'm having issues with an amp, it's the line 6 hd100. It came to me with a volume issue where it would pop in and out, but when it made sound, it was basically full volume."

IMO full volume = broken ground solder at volume pot circuit
Title: Re: Spider valve no output but guitar noises playing through the amp itself
Post by: Bruciedoesntknow on March 26, 2025, 07:53:21 pm: Huge thanks to everyone who's commented so far. I now have a schematic and should be able to start testing.

Just for documentation sake, in case anyone is looking through this in the future trying to work on their amp, my first step is going to be visual inspection. I'm gonna look into that volume pot guest, and now that I have values in the schematic it should be much simpler.

I suspect the modelling side of this amp is functioning properly as I can hear the changes in tone through the sound that's coming from the amp.

If I can I'll try and get a video of the nose coming from the amp before I dig in. This is a new symptom to me, and one that I can't really find well documented online.