The B and K manual has the variac before the isolation transformer, which to me is a little strange unless it aids in reducing inrush (magnetization) current. A common modification is installing a switch to enable floating of the output outlet grounds, which may require a custom output box (use an isolated ground orange duplex receptacle) depending on how the output jacks are wire and if they are strapped (connected) to the chassis through the mounting ears, which is generally not the case with the square single panel push mount types. Usually on older 1655s the front square jacks are sprung (low or no plug tension), so a separate AC output box is added. I have the little brother to the 1655 which is the 1653 which also does not float the output AC safety ground. So it too has to be modified to float the output ground. If you do a lot of bench AC powered appliance (device) repair, and have used different AC power supplies over the years, most experienced electronic technicians design there own to include additional features like: Higher current output 10A (which means a large transformer and variac with surge circuit), current limit dead short option (bulbs or resistor), magnetic/hydraulic AC circuit breaker protection (circuit breaker protection to protect firstly the variac which is usually after the isolation transformer) instead of fuses, two analog AC current meters (with a switch MBB to select different ranges), one analog output AC voltage meter, two types of isolated output receptacle both orange floating ground GFCI duplex and regular duplex with a selector switch and with each having a separate power on switch. The isolation transformer is usually a toroidal hospital grade transformer with internal shield and over-temp self resetting thermal switch. The GFCI is a basic AC current leakage detector for the DUT. It will trip at about 6mA or above. So if it does not trip this means that if there is leakage it is below the GFCI threshold. Before each use the GFCI should be tested with its test button.
I think your drawing of the autotransformer is wrong since you are shorting windings. The slider shouldn’t be connected to the bottom line. Besides of this small problem I like your videos. You are doing a great job. 👍
I've got one just like this, minus the defect labeling. I made a fancy dim bulb tester with a built in ammeter so that I can get both readings simultaneously.
@@artifactelectronics True. I'm just bring up a line voltage device slowly though and the dim bulb limiter will warn me of shorts and the variac has a somewhat reasonable voltmeter built in. The KaW is there to help me hit the proper line voltage and check the power draw as the dut warms up. It's a multi-part, cobbled together solution but it works :)
Made a similar one years ago, having a spare 12VAC 50VA transformer, and a surplus unusable variac, as it is hard to use a 115VAC 5A 400Hz variac normally, but running it at 12VAC keeps the core from saturating, and made it a 0-12VAC power supply that I could use.
What is the leakage probe testing? the leakage of the AC hot side leakage current referenced to ground and the leakage current of the neutral side referenced to ground? I'm just confused what the leakage probe would be used for or have more examples of using the leakage probe to test transistors, fets, capacitors, inductors?
Leakage is the what the GFCI outlets are based on. The general rule is that if >50mA is lost in the circuit then there's a problem. A GFCI will trip in this situation.
Germanium diodes or Schottky diodes, which will work there perfectly. But being point contact likely OA91 germanium diodes, perfectly capable of being replaced by Schottky diodes here, as the diodes are barely being operated in reverse. Likely the one that failed just had the point contact come loose inside, or the actual tiny die cracked.
It’s actually not a temperature control, but rather a wattage control. It’s better than nothing, but nowhere near as nice as a modern digital temperature controlled iron that actually has a temperature sensor in the tip and a feedback loop.
The best I could determine during my research (see my comment, above,) the unit was never sold with a soldering iron. And, IIRC, the soldering iron output wattage was really low.
Here's my story... I am working from (poor) memory, here, so the exact details may vary... Around March of 2021, I realized my need (personal safety) for a proper AC power supply. I purchased a brand new 1655A (which is v-e-r-y similar to the non-A model; I forget the minor difference.) It arrived defective, due to a manufacturing/build defect. The seller replaced it, but the second unit was also defective. In both incidences, I was given authorization to see if I could make repairs, without voiding the warranty. What I found inside was an extremely old design that was 1) poorly engineered, even for the days in which it was designed and 2) that it was extremely poorly built (likely all by hand.) As the (new) price tag was hundreds of dollars and I having no confidence in the design, or build, I returned the unit for a refund. I know that the unit is rebranded, because Global also sells it. But, it is not of the quality of these two well know companies. I don't know who really builds it. I was able to find the 1655 schematic and service manual. I wanted to stock the consumable parts, for future need. The variable autotransformer brush is not available as a separate part (it is only available with the complete brush arm assembly, for hundreds of dollars.) I was able, through much research, to determine what the proper individual brush was ($40.) The fuse in the probe handle is not listed anywhere, but I did find out what it is. I knew that my (deep) research was likely the only source of this information, so I documented everything on the EEVBlog Forum. RUclips will not allow me to post the links. But, you can find the details of my adventures, documents, parts numbers and sources and work-arounds by doing an advanced search on the EEVBlog Forum for “BK,” for my user name “t1d.” The exact titles on the topic are: 1) BK Precision 1655A AC Power Suppy- Replacement Brush and Leakage Probe Fuse Info 2) Help configuring ACS724 to monitor/limit current of Iso Variable AC Power Supply 3) Do you know this "YS" or "SY" Taiwan Manufacturer Logo? 4) I need an education on electric brushes for a variac - AKA electric motor brush? 5) variac carbon brush material? I do not have any more information than what is contained in these threads. I deleted everything from my computer, as I did not keep the unit. I hope this helps. PS: As I recall, the solder output wattage was really low, too. However, if I had absolutely no AC power supply equipment and I found one of these, fully working and for super-cheap, I might buy it.
The difference between the 1655 and 1655A is that the former was built in the US and the latter overseas which may account for the poor quality you observed. The designs are identical. It's a nice unit, and the analog meter is large enough to get good a good reading, but only after proper calibration. Thanks for the info.
@@artifactelectronics Poor quality> Overseas makes sense, because I was recalling that my board was white, no solder mask, hand soldered and flooded traces with solder. Not the nice BK board that you have. Glad the information was helpful. Hmm... I think I recall something about the difference between the two having to do with the probe... Maybe the switch, maybe the safety rating. Been too long to remember...
I guess the soldering iron would be isolated too - if you were dumb enough to attempt to solder a live chassis might save a few sparks? It is nearly 3an as I write this so it could be garbage.
Interesting video. Love the humor in your content.
That's a handy little device. It's nice to have a simple AC source on the bench. Thanks for the video. I enjoyed it and appreciate it....
The isolation transformer really helps too.
Nice instrument- and repair!
The B and K manual has the variac before the isolation transformer, which to me is a little strange unless it aids in reducing inrush (magnetization) current. A common modification is installing a switch to enable floating of the output outlet grounds, which may require a custom output box (use an isolated ground orange duplex receptacle) depending on how the output jacks are wire and if they are strapped (connected) to the chassis through the mounting ears, which is generally not the case with the square single panel push mount types. Usually on older 1655s the front square jacks are sprung (low or no plug tension), so a separate AC output box is added.
I have the little brother to the 1655 which is the 1653 which also does not float the output AC safety ground. So it too has to be modified to float the output ground.
If you do a lot of bench AC powered appliance (device) repair, and have used different AC power supplies over the years, most experienced electronic technicians design there own to include additional features like: Higher current output 10A (which means a large transformer and variac with surge circuit), current limit dead short option (bulbs or resistor), magnetic/hydraulic AC circuit breaker protection (circuit breaker protection to protect firstly the variac which is usually after the isolation transformer) instead of fuses, two analog AC current meters (with a switch MBB to select different ranges), one analog output AC voltage meter, two types of isolated output receptacle both orange floating ground GFCI duplex and regular duplex with a selector switch and with each having a separate power on switch. The isolation transformer is usually a toroidal hospital grade transformer with internal shield and over-temp self resetting thermal switch. The GFCI is a basic AC current leakage detector for the DUT. It will trip at about 6mA or above. So if it does not trip this means that if there is leakage it is below the GFCI threshold. Before each use the GFCI should be tested with its test button.
I just got one of these last week and your video has really helped me. I have the schematic if you want a copy. Let me know.
I might take you up on that offer if it starts misbehaving, but it has been running like a champ so far.
That is a lovely thing. I want one.
I think your drawing of the autotransformer is wrong since you are shorting windings. The slider shouldn’t be connected to the bottom line.
Besides of this small problem I like your videos. You are doing a great job. 👍
Thanks for the correction.
Nice work
I've got one just like this, minus the defect labeling. I made a fancy dim bulb tester with a built in ammeter so that I can get both readings simultaneously.
Nice kit. I have an old medical isolation transformer and a chinese variac. Takes up more space :)
Plus a kill-a-watt to get more accurate voltage and amps, etc.
The problem with Kii-A-Watt is that it needs about 65 VAC to start up, so nothing below that can be measured.
@@artifactelectronics True. I'm just bring up a line voltage device slowly though and the dim bulb limiter will warn me of shorts and the variac has a somewhat reasonable voltmeter built in. The KaW is there to help me hit the proper line voltage and check the power draw as the dut warms up. It's a multi-part, cobbled together solution but it works :)
Made a similar one years ago, having a spare 12VAC 50VA transformer, and a surplus unusable variac, as it is hard to use a 115VAC 5A 400Hz variac normally, but running it at 12VAC keeps the core from saturating, and made it a 0-12VAC power supply that I could use.
BK Precision still makes that as an "A" model. I looked at the manual and wasn't any better than what you had...
The 'A' is the same unit but built in a land far away with questionable materials.
What is the leakage probe testing? the leakage of the AC hot side leakage current referenced to ground and the leakage current of the neutral side referenced to ground? I'm just confused what the leakage probe would be used for or have more examples of using the leakage probe to test transistors, fets, capacitors, inductors?
Could you use the Leakage probe to check AC leakage on the DC power supply. Like checking the filters for AC?
That's how I think it works.
Leakage is the what the GFCI outlets are based on. The general rule is that if >50mA is lost in the circuit then there's a problem. A GFCI will trip in this situation.
PS. Subscribed.
Germanium diodes or Schottky diodes, which will work there perfectly. But being point contact likely OA91 germanium diodes, perfectly capable of being replaced by Schottky diodes here, as the diodes are barely being operated in reverse. Likely the one that failed just had the point contact come loose inside, or the actual tiny die cracked.
I did poke the leads before cutting them, and they were solid. The ohmic contact(s) may have failed.
Did i miss it? what is the solder temp control all about? does it have a temp controlled soldering iron with it?
Old irons were not adjustable. Plugged into 110v you'd always get the same temp. With this you could get some relative control.
It’s actually not a temperature control, but rather a wattage control. It’s better than nothing, but nowhere near as nice as a modern digital temperature controlled iron that actually has a temperature sensor in the tip and a feedback loop.
The best I could determine during my research (see my comment, above,) the unit was never sold with a soldering iron. And, IIRC, the soldering iron output wattage was really low.
I found a sentence in the manual that states the output is adjustable from 70 - 120 VAC using a Triac with turn on delayed directly by the pot.
Here's my story... I am working from (poor) memory, here, so the exact details may vary... Around March of 2021, I realized my need (personal safety) for a proper AC power supply. I purchased a brand new 1655A (which is v-e-r-y similar to the non-A model; I forget the minor difference.) It arrived defective, due to a manufacturing/build defect. The seller replaced it, but the second unit was also defective. In both incidences, I was given authorization to see if I could make repairs, without voiding the warranty. What I found inside was an extremely old design that was 1) poorly engineered, even for the days in which it was designed and 2) that it was extremely poorly built (likely all by hand.) As the (new) price tag was hundreds of dollars and I having no confidence in the design, or build, I returned the unit for a refund. I know that the unit is rebranded, because Global also sells it. But, it is not of the quality of these two well know companies. I don't know who really builds it. I was able to find the 1655 schematic and service manual. I wanted to stock the consumable parts, for future need. The variable autotransformer brush is not available as a separate part (it is only available with the complete brush arm assembly, for hundreds of dollars.) I was able, through much research, to determine what the proper individual brush was ($40.) The fuse in the probe handle is not listed anywhere, but I did find out what it is. I knew that my (deep) research was likely the only source of this information, so I documented everything on the EEVBlog Forum. RUclips will not allow me to post the links. But, you can find the details of my adventures, documents, parts numbers and sources and work-arounds by doing an advanced search on the EEVBlog Forum for “BK,” for my user name “t1d.” The exact titles on the topic are:
1) BK Precision 1655A AC Power Suppy- Replacement Brush and Leakage Probe Fuse Info
2) Help configuring ACS724 to monitor/limit current of Iso Variable AC Power Supply
3) Do you know this "YS" or "SY" Taiwan Manufacturer Logo?
4) I need an education on electric brushes for a variac - AKA electric motor brush?
5) variac carbon brush material?
I do not have any more information than what is contained in these threads. I deleted everything from my computer, as I did not keep the unit. I hope this helps. PS: As I recall, the solder output wattage was really low, too. However, if I had absolutely no AC power supply equipment and I found one of these, fully working and for super-cheap, I might buy it.
The difference between the 1655 and 1655A is that the former was built in the US and the latter overseas which may account for the poor quality you observed. The designs are identical. It's a nice unit, and the analog meter is large enough to get good a good reading, but only after proper calibration. Thanks for the info.
@@artifactelectronics Poor quality> Overseas makes sense, because I was recalling that my board was white, no solder mask, hand soldered and flooded traces with solder. Not the nice BK board that you have. Glad the information was helpful. Hmm... I think I recall something about the difference between the two having to do with the probe... Maybe the switch, maybe the safety rating. Been too long to remember...
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I guess the soldering iron would be isolated too - if you were dumb enough to attempt to solder a live chassis might save a few sparks? It is nearly 3an as I write this so it could be garbage.
The solder output is tapped from the secondary of the isolation transformer.