Phase Linear Dual 500 Diagnosis Assistance Requested
- Thread starter zeppelinofled69
- Start date
- Tags dual 500 phase linear
- Joined
- Feb 9, 2019
- Messages
- 37
Why would I shotgun an amp with a whole bunch of new parts without testing and fixing the problems first? I don't have a bunch of money to throw at this thing and it's already going to be better than anything I own and/or can afford to get into, so I'll take my time with it and replace what needs to be replaced. I don't see replacing every output as a necessity at this point.
Tick tick tick tick....
Replacing all the outputs is not shotgunning. Considering they are older than shit and probably would blow up unexpectedly because of that. Stressed out transistors can go at any time and will they current share happily without taking your speakers for a road trip next week? Replacing them one at a time is what the repair center does and is a friggin bandaid at best (and a CHEAP temporary fix) . Recapping 40 year old caps is not shotgunning. They will fail and make a mess of your mess. You consider putting in White Oak back planes shotgunning? Replacing old technology with new, shotgunning? No, shotgunning is replacing parts because of bad troubleshooting practices NOT upgrading your amp. Can't afford it? Cool. Replacing outputs all at once is common practice especially if there is modern outputs available which do a better job and are a better choice. Why would you throw new parts at an amp? You tell me..... can't afford it? Cool. I can't afford New speakers so I shotgunned my amp into the 21st century with a gut job and a White Oak treatment. Want to WOPL up on a payment plan? I've heard it can be done, want to risk life and limb with an old dangerous time bomb of an amp? You can do that too. The tech's and info are here for you either way.
Replacing all the outputs is not shotgunning. Considering they are older than shit and probably would blow up unexpectedly because of that. Stressed out transistors can go at any time and will they current share happily without taking your speakers for a road trip next week? Replacing them one at a time is what the repair center does and is a friggin bandaid at best (and a CHEAP temporary fix) . Recapping 40 year old caps is not shotgunning. They will fail and make a mess of your mess. You consider putting in White Oak back planes shotgunning? Replacing old technology with new, shotgunning? No, shotgunning is replacing parts because of bad troubleshooting practices NOT upgrading your amp. Can't afford it? Cool. Replacing outputs all at once is common practice especially if there is modern outputs available which do a better job and are a better choice. Why would you throw new parts at an amp? You tell me..... can't afford it? Cool. I can't afford New speakers so I shotgunned my amp into the 21st century with a gut job and a White Oak treatment. Want to WOPL up on a payment plan? I've heard it can be done, want to risk life and limb with an old dangerous time bomb of an amp? You can do that too. The tech's and info are here for you either way.
- Joined
- Feb 9, 2019
- Messages
- 37
You seem to have made some assumptions about what is going on here...
I never said I was just going to get it going and then run it hard day in and day out as if it were brand new. I simply said I wanted to diagnose and repair the amp before I put new output devices in. Yes they are old, and yeah, they may be worn, but if they work, then It lets me get the amp to a point that when I can afford to replace all of them, I don't have to worry about something in the amp taking those expensive new devices out.
Did you read the whole thread? I already stated I was replacing all of the caps that are testing out of spec... which is virtually every cap in the amp.
I also never responded to the WOPL comment, so I am not sure why you brought that up.
I understand the dangers of running old equipment, but I appreciate your concern and comments on the matter.
I never said I was just going to get it going and then run it hard day in and day out as if it were brand new. I simply said I wanted to diagnose and repair the amp before I put new output devices in. Yes they are old, and yeah, they may be worn, but if they work, then It lets me get the amp to a point that when I can afford to replace all of them, I don't have to worry about something in the amp taking those expensive new devices out.
Did you read the whole thread? I already stated I was replacing all of the caps that are testing out of spec... which is virtually every cap in the amp.
I also never responded to the WOPL comment, so I am not sure why you brought that up.
I understand the dangers of running old equipment, but I appreciate your concern and comments on the matter.
- Joined
- Feb 9, 2019
- Messages
- 37
I got my mouser order and replaced all of the electrolytic caps on the front meter board. The intermittent output issue is now gone, but one of the meters has stopped moving with the input. I swapped the 4558s to the opposite channels and the problem moved with the op-amp, so I have ordered some replacements for those.
Still waiting on a few more parts, but as it sits, the amp is almost there. Then it will be on to building an appropriately sized load box so I can start doing some testing and make sure everything is up to snuff.
Still waiting on a few more parts, but as it sits, the amp is almost there. Then it will be on to building an appropriately sized load box so I can start doing some testing and make sure everything is up to snuff.
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- Joined
- Feb 9, 2019
- Messages
- 37
I have finally received the new output devices. After putting them in and making sure they were isolated properly from the heat sink, I started it up and all appears to be well with the amp.
Only thing that concerns me is the Bias sits just under the max threshold of .6V with the bias pot turned all the way down.
I have ordered new bias transistors, but I am wondering if this will actually fix the problem? Or is the wall voltage too high causing the circuit to be higher voltage than it should be?
Only thing that concerns me is the Bias sits just under the max threshold of .6V with the bias pot turned all the way down.
I have ordered new bias transistors, but I am wondering if this will actually fix the problem? Or is the wall voltage too high causing the circuit to be higher voltage than it should be?
- Joined
- Feb 9, 2019
- Messages
- 37
Thanks Gepetto.
Do you think replacing the transistors in the Bias circuit will bring the level down to a more reasonable range? or should I look at any particular resistors for drift? I have ordered new Q106/206, z101/z201, and q102/q202 for the driver boards, so I have all three if they need to be changed. I just wanted to know if this was even something that would affect the adjustment window, or if I should look elsewhere.
Both channels sit in exactly the same spot at about .56 to .58mV across R133.
Do you think replacing the transistors in the Bias circuit will bring the level down to a more reasonable range? or should I look at any particular resistors for drift? I have ordered new Q106/206, z101/z201, and q102/q202 for the driver boards, so I have all three if they need to be changed. I just wanted to know if this was even something that would affect the adjustment window, or if I should look elsewhere.
Both channels sit in exactly the same spot at about .56 to .58mV across R133.
