philtno Posted July 9, 2021 Share Posted July 9, 2021 Hi there, I'm struggling to find info about where the bias probe ports are on the DT50HD and which valve is V1, which one is V2 etc when looking from the back of the DT50HD after having removed the back panel. I found plenty of info on DT25 or on the Combo but nothing on the DT50HD....There are videos and photos of all sort for the DT25 but nothing for the DT50HD. Is there any schematic availabe that shows where to set up the bias after having changed the valves?? I don't have any Line6 service center where i live Any help would be welcome. Thank you very much in advance Philtno Quote Link to comment Share on other sites More sharing options...
psarkissian Posted July 9, 2021 Share Posted July 9, 2021 There aren't any on the DT50 that are easily accessible to to the user. Due to the high voltage shock hazard, it is something that should be left to an authorized service tech who knows the insides of these amps. Due to certain proprietary considerations, there is no published service information on our products. Service centers,... there are two in Auckland, on the north island. The only options, darn. Maybe arrange to take the amp chassis in and they can run tests using a dummy load. They would have access to service info and me, through our normal service channels. I deal with and assist,... Music Link New Zealand Servicing: Electronics,Guitars Warehouse 5-174 Marua Road Ellerslie 5, Aukland, 0064 9 5792220 rogerajeffery@lycos.com ... from time to time when they want to consult me about something. Quote Link to comment Share on other sites More sharing options...
philtno Posted July 9, 2021 Author Share Posted July 9, 2021 Thanks for replying to me. This is not good news indeed. I had to send my DT50 to them through the so-called dealer of my region (South Island) a few year ago and they........lost the amp!!! No joke, they lost it!! At least they were kind enough to replace it after a few months of supposedly searching for it but the one they sent me had flaws......for instance, the Line 6 edit and the HD500X were recognising the amp as being a combo, not a head......and sounding completely different.....anyway I made due with that. Those guys have really bad references/reputation amongst the musician community here in NZ....to the point that I made the decision to buy a spare DT50 head, just in case...in order to make sure I would still be gigging in case of problem with the first one..... Why is it looking so simple for the DT25 (based on the info i found on the forum) and impossible to do with the DT50??? Quote Link to comment Share on other sites More sharing options...
psarkissian Posted July 9, 2021 Share Posted July 9, 2021 Lost it,... wow. Never heard of that happening with them. How odd. Howick Electronics 175 Cook St Howick Auckland, 64 9 537 2592 roger@allegromusicstudio.co.nz What about Howick? "... recognising the amp as being a combo, not a head......and sounding completely different " --- there's a switch on the program board for that. Must have been switched incorrectly. Yes, it would sound different. " Why is it looking so simple for the DT25 (based on the info i found on the forum) and impossible to do with the DT50??? "--- The thing with the differences is the size and the overall lay out,... and especially the voltage shock hazard. Those 200V capacitors really hurt when you get zapped by them, even with the power off. One slip,.... BTW, say hello to the Kea down there. Cool birds. Quote Link to comment Share on other sites More sharing options...
philtno Posted July 10, 2021 Author Share Posted July 10, 2021 4 hours ago, psarkissian said: Lost it,... wow. Never heard of that happening with them. How odd. I bet they wouldn't be proud of that so they keep that in the closet.....amp left Rockshop in Christchurch, arrived at the warehouse, then piouffff ...vanished!! What about Howick? If my memory is good, it's not the client who decides where the amp goes to.....Rockshop are the offical dealers for Line6 products so guess they send them to the first who replies to them??? I don't know.....I don't have any experience with them (Howick). "... recognising the amp as being a combo, not a head......and sounding completely different " --- there's a switch on the program board for that. Must have been switched incorrectly. Yes, it would sound different. I switch it manually on the HD500.....but it's still not normal that I have to do that. BTW, say hello to the Kea down there. Cool birds. Will do. Cheers Quote Link to comment Share on other sites More sharing options...
psarkissian Posted July 12, 2021 Share Posted July 12, 2021 The switch on the DT main board would be done at the shop. Quote Link to comment Share on other sites More sharing options...
orbitus Posted September 6, 2021 Share Posted September 6, 2021 Anyone who is clever, attentive (like me), finds the bias setting (on white plastic 3 spikes next to each other on the motherboard - Bias 1, com, bias 2). Not far from a bluish rotating potentiometer. You can set it up with simple multimeter and phase-pencil . But it is necessary to take care of the risk of electric shock !!! Quote Link to comment Share on other sites More sharing options...
psarkissian Posted September 7, 2021 Share Posted September 7, 2021 1) Keep your fingers out of the insides of that due to shock hazard. Large capacitors give quite a jolt, and it hurts. 2) There is more to it than just setting bias, as there are four topologies, and a produce for testing all that. 3) Use the specified tubes, as these are not all analog tube amps. 4) Have a Line 6 authorized service center change and bias tubes when needed, and run the post bias test procedure. Quote Link to comment Share on other sites More sharing options...
orbitus Posted September 7, 2021 Share Posted September 7, 2021 Yes of course I'm very careful! I use Electro Harmonyx tubes. They sound very well! Quote Link to comment Share on other sites More sharing options...
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