I have a recapped Pilot SA-260 which biases and sound fine. I have a Pilot SP-210 preamp (it is powered by the 260) which I sometimes want to use with other Amps. I have taken all the tubes except the rectifiers from the 260 and ran just the SP-210 feeding another amp and then put the tubes back in the SA-260 using them in the intended fashion and everything seems normal. Acting as just a pwr supply the 260 pwr trf is just warm(usually hot) the rectifiers look fine. Am I doing any long term harm or taking a risk with the 260 as just a pwr supply? Thanks for any advice. ron
Pilot SA-260/SP-210 Pwr Supply
- Thread starter ronton3
- Start date
The voltages across all the filter caps will be much higher with the output tubes removed. You should check that the voltages presents with no output tubes installed do not exceed the rated voltage of the filter caps as well as the coupling caps in the unit. The voltages to the preamp will be notably higher as well in this scenario, so you might check their ratings as well compared to the actual voltages present. If all is good, then you should be fine -- although it would likely be more practical to build a small little power supply to power the preamp if you plan to use it often without its power amp mate. If you search, I think another AKer did just that and posted his project on this forum.
Dave
Dave
bean_counter
Active Member
here's an example supply; schematic on page 3. I've got a 210 I need to build a supply for.
http://audiokarma.org/forums/index.php?threads/pilot-sp-210-power-supply-build-photos.193694/
http://audiokarma.org/forums/index.php?threads/pilot-sp-210-power-supply-build-photos.193694/
I will try the 5Y3 I had not thought of using just one rectifier. With a 120 line voltage I have 530V on one cap and 480V on the other, they are both 500v LCR's installed about 20 years ago, they get warm but not hot. The 260 is sending 218V to the 210, one cap is 218V and the other 184V, I am concerned that V1 which is supposed to have 120 and 90 on the plates has 183 and 96, V4 should be 150 and 115 and is 175 and 130. I will look into the separate pwr supply idea. Thanks for all the help.
As an interesting aside the 210 in regular use had an annoying, hum I think 120 hz, I was going to add another filter stage and ordered some resistors, they have not arrived yet. There were 6 remaining fixed caps including 4 pyramids, around the selector switch and V1/V3, I replaced those yesterday and it is now silent. I small miracle.
As an interesting aside the 210 in regular use had an annoying, hum I think 120 hz, I was going to add another filter stage and ordered some resistors, they have not arrived yet. There were 6 remaining fixed caps including 4 pyramids, around the selector switch and V1/V3, I replaced those yesterday and it is now silent. I small miracle.
The stock 210 in proper working condition should not hum. It doesn't need extra caps, though with little load on the SA-260 supply it may not be running as clean as it should.
I repaired one for someone, the paper caps were all in bad shape and it caused a lot of trouble. There was also no ground connection between the input panel and the case without going through the cabinet. I added a wire to the bundle to fix that. If yours has the case, make sure the input jack panel is clean and tightly mounted or you might get some hum from that. I think the console models had the input jacks built into the chassis at one end so those shouldn't have issues.
I repaired one for someone, the paper caps were all in bad shape and it caused a lot of trouble. There was also no ground connection between the input panel and the case without going through the cabinet. I added a wire to the bundle to fix that. If yours has the case, make sure the input jack panel is clean and tightly mounted or you might get some hum from that. I think the console models had the input jacks built into the chassis at one end so those shouldn't have issues.
Working B+ high voltage DC at the Pilot 210 11 pin power socket, pin # 7, should measure close to 150VDC. After the 15K B+ dropping resistor inside the 210, 120V DC is expected. V1 and V3, the phono stage tubes, should have plate voltage of 90V and 75V respectively. The V2 and V4 Line Level tubes read 90V and 115V Plate Voltage.
This is according to the Sam's Folder 16, Set 454 Photofact from 9-1959 for Pilot models SA-232 and SP-210, as well as FA-540 tuner within the C-1076, C-1071, and C-1075 Consoles. I have fixed a few of these amps and preamps over the years. The most difficult aspect of building a preamp power supply will probably be finding a 23V CT fil transformer. If you find a 24V CT tranny, adding small value resistors in the fil supply, before or after the diodes in the 210, will suffice.
The 210 is a fantastic sounding, early vintage stereo preamp. The calibrated tone controls are a great idea and become very versatile with pre-RIAA mono discs. However, while you can choose channel A or B for mono, there is no A+B mono switch ! When you get involved with mono discs, simply wire the cartridge in the tt headshell for mono....
I still have a console model 210 with beefy, custom supply and am actually reluctant to sell it. I am about to endeavor converting the Tape Head input/EQ into another Phono input, but the cue line of repairs and retro resto causes delays....
The 210 is very worthy of a custom pwr supply and some parts upgrades...ENJOY !
This is according to the Sam's Folder 16, Set 454 Photofact from 9-1959 for Pilot models SA-232 and SP-210, as well as FA-540 tuner within the C-1076, C-1071, and C-1075 Consoles. I have fixed a few of these amps and preamps over the years. The most difficult aspect of building a preamp power supply will probably be finding a 23V CT fil transformer. If you find a 24V CT tranny, adding small value resistors in the fil supply, before or after the diodes in the 210, will suffice.
The 210 is a fantastic sounding, early vintage stereo preamp. The calibrated tone controls are a great idea and become very versatile with pre-RIAA mono discs. However, while you can choose channel A or B for mono, there is no A+B mono switch ! When you get involved with mono discs, simply wire the cartridge in the tt headshell for mono....
I still have a console model 210 with beefy, custom supply and am actually reluctant to sell it. I am about to endeavor converting the Tape Head input/EQ into another Phono input, but the cue line of repairs and retro resto causes delays....
The 210 is very worthy of a custom pwr supply and some parts upgrades...ENJOY !
Dave was right about the increased voltage, when I put the tubes back in V1 is now 93/77, and V4 is 95/117, V2 and 3 are also on the money. The caps are supposed to be 150/120 and are 150/123. These values are right on the money.
I have an Altec pwr supply. I have never plugged it in and would not until I ran it up on a Variac, it has a 6X4 rectifier,The model number is 5812. Do you think it would work.
I have an Altec pwr supply. I have never plugged it in and would not until I ran it up on a Variac, it has a 6X4 rectifier,The model number is 5812. Do you think it would work.
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If you simply hope to "plug-in" the Pilot's 11 pin plug into a ready made device with an 11 pin socket, I think you will have to make it happen. You probably only "need to" simply tweak that supply and add a 23 to 24VCT@ 1A, AC filament trans, then tweak the voltage dropping resistors as needed. That will "work" and could sound fantastic. Please beef up the capacitance in the power supply though. The 210 has so much sonic potential ! ENJOY !
s-petersen
Scott
There may be another possibility, The Dynaco power supply for the Pam1 may be easily adapted for this application. Many mono octal power supplies were designed to work between different brands back in the day.
Well, besides that Dyna pwr supply now being a rarity, it's high voltage is way higher than needed. Adding resistance in the power supply, "along the line" or installing "bleeder resistors" across the line may "work okay" but are not always great sounding. There were plenty of power trannies made with 120 to 150 VAC secondaries plus low filament voltage, made during the vintage era. Finding a power tranny which supplies less than 250 VDC will be easy. It's that 23 to 24 VCT @1 Amp secondary which is tough to find, other than a stand-alone filament tranny.
So, the pwr supply build could use some good "prior planning" to "provide proper performance" and look nice. I used a rather large, wrinkle black pwr sup chassis, which supplied higher than needed DC Volts. I converted that supply to a choke input filter type with a robust choke to lower B+ and beefed up the capacitance in the DC supply. I run a 5V/2A rectifier of choice, 5Y3 or 5R4 or 5V4 with the original tranny, then mounted an additional, beefier than needed 24VCT filament tranny to supply the AC to the DC filament supply residing inside all of the Pilot 210 versions. My next 210 pwr supply build will be smaller and use ss diodes. Then, I will eventually compare which supply I prefer and then, of course, trade it away...
So, the pwr supply build could use some good "prior planning" to "provide proper performance" and look nice. I used a rather large, wrinkle black pwr sup chassis, which supplied higher than needed DC Volts. I converted that supply to a choke input filter type with a robust choke to lower B+ and beefed up the capacitance in the DC supply. I run a 5V/2A rectifier of choice, 5Y3 or 5R4 or 5V4 with the original tranny, then mounted an additional, beefier than needed 24VCT filament tranny to supply the AC to the DC filament supply residing inside all of the Pilot 210 versions. My next 210 pwr supply build will be smaller and use ss diodes. Then, I will eventually compare which supply I prefer and then, of course, trade it away...
That room heater would still need a "dummy load" resistor in place of the speakers. Plus, the electrical supply companies like our obsession....
There have been so many good suggestions, that I think I need to determine first what the voltages on the Altec are. There are 5 pins, ground, B1, B2, and then 2 pins for 6.3 vac, it says 300 vdc nominal for loads shown. I am wondering if B1 and B2 are 150v each. which I think would work. I would like to power up the Altec using a Variac, it has the original can caps, should I use a dim bulb limiter, or would that effect the reforming of the caps. I usually start by moving the dial slowly to 30v leaving it there for 20 minutes and then moving up 20 volts at a time to 120. Would that be a good way to proceed.
I believe that using the 260 with tubes in to power the 210 is the best for occasions when I want put the signal through another amp.
I believe that using the 260 with tubes in to power the 210 is the best for occasions when I want put the signal through another amp.
Maybe, but, that 260 is drawing about 3A of 120VAC current from the wall. You can rebuild, resto-mod or build a supply or augment a supply, like that Altec, with a 24VCT@1A filament tranny, then only draw about 1/2-1 A of 120VAC from the wall.
Also, consider that the power amp starts off with well over 400VDC and we only need 150 VDC. That is a lot of resistance "along the line" needed to drop the voltage. I know the 260 is a great sounder. I have had two. Maybe, keeping the 260 on is best done while listening to its' precious tubes and trannies....
There are many threads and posts in the archives about Variac "ramping-up" for warming-up old, rested devices. Search thru if you have some time. Try and increase the AC Volts leaving the Variac slower and with less incremental voltage increases as you wrote. When bringing units back to life, the capacitors inherently "leak" a bit of AC, then settle down to minimal, when another few AC Volts can be added. Measuring the AC Volts leaking at the power supply caps needs to be checked/monitored regularly. It is not a matter of time, but a matter of stabilizing the old cap while it "vibrates" warming-up inside.
When I attempt reforming caps in power amps, I pull the opt tubes and driver tubes before turn-on and ramp-up. The less current drain is more likely to stabilize the old electro sections quicker. I verify lowest AC leakage at HV test points. Let's say I begin with 50 VAC leaving the Variac. The still inserted amp's rectifier and a few signal tubes will take a few minutes to begin conducting. Measure the DC Volts at the HV points. Turn the meter to AC Volts and measure at the same points. Initially, the AC leakage at the input cap filter may read .8 VAC. In a few minutes, it might go down to .3A. At the filter cap section nearest the voltage take-off for the preamp might read .1 VAC initially, if we are lucky. But, as it re-forms and settles down, that same test point could read .003 VAC or at least less than ..07 VAC. Then, we can raise the Variac 5 to 10 volts and re-measure. A few You Tube videos later, re-measure again. Settled down to less than .05 at the preamp sup[ply point ? Good, raise the Variac another 5-10 VAC and repeat.
Eventually, if the electros stay cool and AC V leakage dies off quickly, we will be getting close to the maximum working voltage of the electros. Turn it all off. Insert the driver tubes and redo the slow ramping-up procedure/testing, starting at 50VAC in again. All good and leakage getting low quickly ? Get to the cap working voltage and...Great, Turn it all down. Now, insert the real current drawing culprits, the opt tubes. Assure speaker taps are loaded with speakers or beefy "dummy load" resistors.
Now, the real testing and reforming begins, as the large current can quickly create heat in the electros. Be careful increasing the ACVolts. Slow and steady wins the race...Test those voltages constantly. You will note the initial filter stage cap could now indicate a perpetual amount of residual ACV leakage, around 1V to a few. Check the further along, voltage take-off points, especially the preamp supply point. If that test point still shows super low leakage, Hallelujah ! Repeat the ramp-up as the leakage dies down. Slow and steady...rushing here will undoubtedly heat up a weak cap section and ruin the night.
I often back-off ACVolts if any cap gets even warm. If any get hot, definitely back down and wait to hope it cools down. Measure the take-off points and make sure AC Volts are receding, not increasing. Presuming all went well after many hours of the ramping-up, it's listening time. However, be aware the amp electro caps may still be "shaking loose" the layer they are trying to reform. Don't be surprised if a cap gets hot...just get disappointed and replace it. Then, it's ramp-up time again....
Also, consider that the power amp starts off with well over 400VDC and we only need 150 VDC. That is a lot of resistance "along the line" needed to drop the voltage. I know the 260 is a great sounder. I have had two. Maybe, keeping the 260 on is best done while listening to its' precious tubes and trannies....
There are many threads and posts in the archives about Variac "ramping-up" for warming-up old, rested devices. Search thru if you have some time. Try and increase the AC Volts leaving the Variac slower and with less incremental voltage increases as you wrote. When bringing units back to life, the capacitors inherently "leak" a bit of AC, then settle down to minimal, when another few AC Volts can be added. Measuring the AC Volts leaking at the power supply caps needs to be checked/monitored regularly. It is not a matter of time, but a matter of stabilizing the old cap while it "vibrates" warming-up inside.
When I attempt reforming caps in power amps, I pull the opt tubes and driver tubes before turn-on and ramp-up. The less current drain is more likely to stabilize the old electro sections quicker. I verify lowest AC leakage at HV test points. Let's say I begin with 50 VAC leaving the Variac. The still inserted amp's rectifier and a few signal tubes will take a few minutes to begin conducting. Measure the DC Volts at the HV points. Turn the meter to AC Volts and measure at the same points. Initially, the AC leakage at the input cap filter may read .8 VAC. In a few minutes, it might go down to .3A. At the filter cap section nearest the voltage take-off for the preamp might read .1 VAC initially, if we are lucky. But, as it re-forms and settles down, that same test point could read .003 VAC or at least less than ..07 VAC. Then, we can raise the Variac 5 to 10 volts and re-measure. A few You Tube videos later, re-measure again. Settled down to less than .05 at the preamp sup[ply point ? Good, raise the Variac another 5-10 VAC and repeat.
Eventually, if the electros stay cool and AC V leakage dies off quickly, we will be getting close to the maximum working voltage of the electros. Turn it all off. Insert the driver tubes and redo the slow ramping-up procedure/testing, starting at 50VAC in again. All good and leakage getting low quickly ? Get to the cap working voltage and...Great, Turn it all down. Now, insert the real current drawing culprits, the opt tubes. Assure speaker taps are loaded with speakers or beefy "dummy load" resistors.
Now, the real testing and reforming begins, as the large current can quickly create heat in the electros. Be careful increasing the ACVolts. Slow and steady wins the race...Test those voltages constantly. You will note the initial filter stage cap could now indicate a perpetual amount of residual ACV leakage, around 1V to a few. Check the further along, voltage take-off points, especially the preamp supply point. If that test point still shows super low leakage, Hallelujah ! Repeat the ramp-up as the leakage dies down. Slow and steady...rushing here will undoubtedly heat up a weak cap section and ruin the night.
I often back-off ACVolts if any cap gets even warm. If any get hot, definitely back down and wait to hope it cools down. Measure the take-off points and make sure AC Volts are receding, not increasing. Presuming all went well after many hours of the ramping-up, it's listening time. However, be aware the amp electro caps may still be "shaking loose" the layer they are trying to reform. Don't be surprised if a cap gets hot...just get disappointed and replace it. Then, it's ramp-up time again....
