I was hoping that someone might know the specs of the PS transformers that came in the Parasound Zamp series. I have several v.1 and v.2 that are beyond repair, but the trans seems to be alright in most of them. I was thinking of salvaging a two of them for a dual mono high impedance headphone amp, that might double for a regular amp for some VERY efficient speakers. I know that these are solid state trans, but was hoping to do some experimenting with some SE tube boards(the ones on china from fleabay).
Any advice of info would be greatly appreciated.
Any advice of info would be greatly appreciated.
remove the transformer.
Lay it on an insulated table/surface.
Connect each lead to separate terminals of an insulated terminal strip.
Set your measuring instrument to read low ohms.
Measure the resistance of every terminal to every other terminal and write down each result.
The open circuit results confirm which windings are isolated from all the other windings.
Labels the windings.
Continuity confirms a single winding. Some may have multiple tappings. Use the resistances to determine which terminals are in the middle of the end tappings. Label them.
Identify the highest resistance winding. If this also has double insulated wire leadouts, then this is probably the Mains input winding, the Primary. Some Primaries are dual. You MUST identify the correct phasing SAFELY.
Use a Mains Bulb Tester.
ONLY power ON via the Bulb Tester !!!!!!!!!!
If the bulb lights you have the wrong phasing for the dual primaries. Reverse ONE primary pair of lead outs.
The transformer should power ON without the bulb showing any glow not even a dim glow.
Measure the voltage on every secondary pair. and any intermediate tappings.
Carefully measure the primary voltage.
Estimate the thickness of every winding, including the primary/ies.
Present your findings here.
A transformer with a single Primary is easy, just plug it into your bulb tester. Bulb OFF = no shorted windings.
A dual primary can initially be powered through the bulb tester with ONLY one Primary pair connected.
BUT !!!!!! the other primary pair now has Mains Voltage at thew terminal strip. Take care.
This allows safe Power up when you don't know the phasing and lets you check for Bulb OFF condition. You can then check power through the Bulb Tester with the other Primary. Then finally connect both Primaries as earlier.
Lay it on an insulated table/surface.
Connect each lead to separate terminals of an insulated terminal strip.
Set your measuring instrument to read low ohms.
Measure the resistance of every terminal to every other terminal and write down each result.
The open circuit results confirm which windings are isolated from all the other windings.
Labels the windings.
Continuity confirms a single winding. Some may have multiple tappings. Use the resistances to determine which terminals are in the middle of the end tappings. Label them.
Identify the highest resistance winding. If this also has double insulated wire leadouts, then this is probably the Mains input winding, the Primary. Some Primaries are dual. You MUST identify the correct phasing SAFELY.
Use a Mains Bulb Tester.
ONLY power ON via the Bulb Tester !!!!!!!!!!
If the bulb lights you have the wrong phasing for the dual primaries. Reverse ONE primary pair of lead outs.
The transformer should power ON without the bulb showing any glow not even a dim glow.
Measure the voltage on every secondary pair. and any intermediate tappings.
Carefully measure the primary voltage.
Estimate the thickness of every winding, including the primary/ies.
Present your findings here.
A transformer with a single Primary is easy, just plug it into your bulb tester. Bulb OFF = no shorted windings.
A dual primary can initially be powered through the bulb tester with ONLY one Primary pair connected.
BUT !!!!!! the other primary pair now has Mains Voltage at thew terminal strip. Take care.
This allows safe Power up when you don't know the phasing and lets you check for Bulb OFF condition. You can then check power through the Bulb Tester with the other Primary. Then finally connect both Primaries as earlier.
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Do'H! Homework assignment??? 
I suppose I can clear off a spot on my bench. Since the xfmr is still hooked up in the amp(dead turn on relay), I can tell the 110V input(s), and "output" windings to the amp board(three wires...I'm guessing for a voltage swing). There is a secondary winding on the input(mains) side. I am assuming that is how the correct input voltage (110 or 220) can be achieved. I will get it apart and report back as soon as I can. My workbench is in the middle of being moved, but I should be able to find what I need. Thanks....
I suppose I can clear off a spot on my bench. Since the xfmr is still hooked up in the amp(dead turn on relay), I can tell the 110V input(s), and "output" windings to the amp board(three wires...I'm guessing for a voltage swing). There is a secondary winding on the input(mains) side. I am assuming that is how the correct input voltage (110 or 220) can be achieved. I will get it apart and report back as soon as I can. My workbench is in the middle of being moved, but I should be able to find what I need. Thanks....Well I cheated a little bit. I did dig out my Fluke 77 and confirm that the "mains" inputs are....
Red Paralleled with White
Blue Paralleled with Brown
...to the power cord.
When I separated the two pairs to get individual readings;
Red/White - 0 Ohms no continuity
Red/Blue - 11.6 Ohms continuity
Red/Brown - 0 Ohms no continuity
White/Blue - 0 no continuity
White/Brown - 11 ohms continuity
Brown/Blue - 0 no continuity
I am going to assume that I should leave that side paralleled like it is as I believe that is how the amp is “switched” to 220V mains, and I need to keep it at 110v as wired. I believe that will also solve the phasing issue you mentioned.
The other three wires go to the driver board, two Yellow and one Green....
Yellow1/Yellow2 - 1 Ohm continuity 50Vac
Yellow1/Green - .7 Ohm continuity 25Vac
Yellow2/Green - .7 Ohm continuity 25Vac
Sooo.... I did all that with a test bulb. My variac is buried and needs a new “front end”, as I said, my bench is down...sadly did this on the kitchen counter... (and the couch...no live testing!!!)
From what I can tell the transformer is just fine, no shorts...bulb didnt even light up with turn on(and I did make sure it works). With the mains wired as they were it gave me a +/-25 Vac swing(right?). I can see what I think is a bridge rectifier (four diodes) to bring that to a DC voltage. I didnt do any testing of the driver boards after the relay failed to turn on. I have known good boards that I can check functionality of the transformer, just to be sure. But this was a fun little exercise, plus Ive been jonesn' for some wire stripping...lol.
Should be fine for SS , but that isnt nearly enough voltage to get me into tube territory...even for headphones right? I have no problem building a solid state dual mono amp for my headphones(currently 80 Ohm but will be up to 600 Ohm with future sets). Would like to keep it as simple as possible, but kind of want to stay away from chip amps...I dunno. It has been a while since I looked at building anything solid state.
Thanks for the list AndrewT, I by no means claim to know much more than theory on how transformers and electromagnetism works, hopefully what I provided was meaningful and what you wanted me to measure. Please let me know your thoughts, both positive and negative.......
Red Paralleled with White
Blue Paralleled with Brown
...to the power cord.
When I separated the two pairs to get individual readings;
Red/White - 0 Ohms no continuity
Red/Blue - 11.6 Ohms continuity
Red/Brown - 0 Ohms no continuity
White/Blue - 0 no continuity
White/Brown - 11 ohms continuity
Brown/Blue - 0 no continuity
I am going to assume that I should leave that side paralleled like it is as I believe that is how the amp is “switched” to 220V mains, and I need to keep it at 110v as wired. I believe that will also solve the phasing issue you mentioned.
The other three wires go to the driver board, two Yellow and one Green....
Yellow1/Yellow2 - 1 Ohm continuity 50Vac
Yellow1/Green - .7 Ohm continuity 25Vac
Yellow2/Green - .7 Ohm continuity 25Vac
Sooo.... I did all that with a test bulb. My variac is buried and needs a new “front end”, as I said, my bench is down...sadly did this on the kitchen counter... (and the couch...no live testing!!!)
From what I can tell the transformer is just fine, no shorts...bulb didnt even light up with turn on(and I did make sure it works). With the mains wired as they were it gave me a +/-25 Vac swing(right?). I can see what I think is a bridge rectifier (four diodes) to bring that to a DC voltage. I didnt do any testing of the driver boards after the relay failed to turn on. I have known good boards that I can check functionality of the transformer, just to be sure. But this was a fun little exercise, plus Ive been jonesn' for some wire stripping...lol.
Should be fine for SS , but that isnt nearly enough voltage to get me into tube territory...even for headphones right? I have no problem building a solid state dual mono amp for my headphones(currently 80 Ohm but will be up to 600 Ohm with future sets). Would like to keep it as simple as possible, but kind of want to stay away from chip amps...I dunno. It has been a while since I looked at building anything solid state.
Thanks for the list AndrewT, I by no means claim to know much more than theory on how transformers and electromagnetism works, hopefully what I provided was meaningful and what you wanted me to measure. Please let me know your thoughts, both positive and negative.......
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keeping the Primaries paralleled as supplied for your 110/120Vac mains is OK.
The bulb tester has proved that.
The three resistance readings confirm that the y1, y2, Grn are on the same winding and that grn is roughly a centre tap.
The voltages 25Vac & 25Vac confirm it is a centre tap.
You have a 115:25-0-25Vac transformer.
Now all we need is a weight and wire thicknesses to estimate the VA.
BTW,
it looks like you have a 0r4 offset when low ohms measuring.
0r7 - 0r4 = 0r3 for both windings separately.
1r0 - 0r4 = 0r6 for the two windings in series.
Check by comparing the sum of the separate windings to the series winding.
0r3+0r3 = 0r6. checked.
Now check what reading you get using probe to probe and on metal surface with the contact points just 0.5mm apart. That too should read 0r4. That is the offset your need to subtract from every measurement you make with the low resistance scale. It is also a check you should make before and after measuring with this scale.
The bulb tester has proved that.
The three resistance readings confirm that the y1, y2, Grn are on the same winding and that grn is roughly a centre tap.
The voltages 25Vac & 25Vac confirm it is a centre tap.
You have a 115:25-0-25Vac transformer.
Now all we need is a weight and wire thicknesses to estimate the VA.
BTW,
it looks like you have a 0r4 offset when low ohms measuring.
0r7 - 0r4 = 0r3 for both windings separately.
1r0 - 0r4 = 0r6 for the two windings in series.
Check by comparing the sum of the separate windings to the series winding.
0r3+0r3 = 0r6. checked.
Now check what reading you get using probe to probe and on metal surface with the contact points just 0.5mm apart. That too should read 0r4. That is the offset your need to subtract from every measurement you make with the low resistance scale. It is also a check you should make before and after measuring with this scale.
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THANKS!!! AndrewT
Looks like it is about 1Kg even and the outer winding(Yl/Gr/Yl) appears to be about 20 gauge and the inner appears to be about half that.
Will look into the other readings and what not, once I have my "kitchen bench" back...lol. Thanks again for all the help and information! Looks like I have some studying to do....
Looks like it is about 1Kg even and the outer winding(Yl/Gr/Yl) appears to be about 20 gauge and the inner appears to be about half that.
Will look into the other readings and what not, once I have my "kitchen bench" back...lol. Thanks again for all the help and information! Looks like I have some studying to do....
1kg is light.
20awg is light.
Expect less than 3Aac.
20awg = 0.5mm² and that has a current capacity of the order of 1.6Aac.
Some modern toroids with much less copper than used in the past might rate this around 2Aac to 2.5Aac.
for 1.6Aac and 25+25Vac secondaries you have ~80VA
My 80VA toroid weighs 900g, 120VA = 1270g
An EI would be much heavier.
20awg is light.
Expect less than 3Aac.
20awg = 0.5mm² and that has a current capacity of the order of 1.6Aac.
Some modern toroids with much less copper than used in the past might rate this around 2Aac to 2.5Aac.
for 1.6Aac and 25+25Vac secondaries you have ~80VA
My 80VA toroid weighs 900g, 120VA = 1270g
An EI would be much heavier.
You can make a few very nice sounding LM3886 50W/8 ohms amps.
They match perfectly the +/- 35V rails you'll get.
1 transformer per amplifier.
Or a few plate amps for powered speakers.
Or a 50W Guitar/Bass/Keyboards amp for own use or a friend if you don't play any instrument.
Just googled a little.
If you have this:
you may junk the PCB if unrepairable, but keep the nice cabinet, toroid and heatsink and mount a simple but excellent LM3886 amp there if you wish.
Usually the problem for the homebuilder is the "mechanicals" , specially the cabinet or chassis.
The "electronics" ... not that much
I bet you can reuse those nice filter caps too, a bonus saving
They match perfectly the +/- 35V rails you'll get.
1 transformer per amplifier.
Or a few plate amps for powered speakers.
Or a 50W Guitar/Bass/Keyboards amp for own use or a friend if you don't play any instrument.
Just googled a little.
If you have this:
An externally hosted image should be here but it was not working when we last tested it.
you may junk the PCB if unrepairable, but keep the nice cabinet, toroid and heatsink and mount a simple but excellent LM3886 amp there if you wish.
Usually the problem for the homebuilder is the "mechanicals" , specially the cabinet or chassis.
The "electronics" ... not that much
I bet you can reuse those nice filter caps too, a bonus saving
Yep they were nice amps when new. I still have several that are in very good condition, and have been in use for nearly 20 years, daily. None in silver though, mostly the v.1 and v.2. I used to sell Parasound many many years ago. I have the opposite problem, I'm good with the mechanicals, not so much with the electronics. I also did speaker repair/restoration, and a few design, build, tune "one-off" speaker builds for "special" customers. But have somewhat limited design knowledge for anything but passive crossovers. I know how to use a soldering iron and can stick parts into place, but ideally would like to get further into design. I believe I messed around with "The Williamson Amplifier", again many many years ago....lol....nothing ever came of it. I do know how to read most schematics though. I dabble in car audio repair, but really that is just replacing parts too....in most cases.
I did manage to repair my tube preamp for my listening room without disaster, but really should know more than what I do. I actually already have the LM3886 chips, I had looked into building them a few years ago. Finding them is another thing...lol. Lots of stuff in boxes....ugh...
Zamp v2 wiring
guys, I have a Parasound Zamp v2 that was wired wrong at the 115v/230v switch and blowing fuses. I've tried it with 115 straight to one of the primaries and it seems to work. Can someone draw up the switch to transformer primaries wiring for me please? I just want to be sure about this.
Thanks in advance.
Bob
guys, I have a Parasound Zamp v2 that was wired wrong at the 115v/230v switch and blowing fuses. I've tried it with 115 straight to one of the primaries and it seems to work. Can someone draw up the switch to transformer primaries wiring for me please? I just want to be sure about this.
Thanks in advance.
Bob
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