Tom mentions that he replaced all the electrolytic's. He details replacement of C-4 and C-5 with 22 uf @ 450v caps (factory spec = 20 uf @ 250V). What is the recommended replacement value for C-1 (spec = 250 uf @ 6v) and would you replace C-101 (spec = 10 uf @ 35v)? Thank you for your insight.
Regarding the M-5 and M-6 T-55 bulbs... Does it matter what "brand" of bulb you use here? My assumption is that the bulbs we buy today are darn close to what was made back in the day. If they are not, then the bulbs should have specs on them like internal resistance, power dissipation over a voltage range, etc.
Would a bad 83 tube cause the transformer to smoke? I unplugged it right away, but I'm worrying maybe the transformer is now shot. It's on the 700 model that I acquired recently. I plugged it in tested a bulb, started to smell something and then saw smoke. Obviously I unplugged it right away. Any advice is appreciated.
Does this tester really do what it says and adjust for variations in line voltage, since the 120+AC we have now might otherwise throw off the test results, since household voltages used to be 117?
I bought this tester couple years ago. It was fully working and calibrated couple years earlier according to the seller. Well It's been the next couple of years so calibration would be good idea. Also hundreds of hoarded tubes would like to be finally tested 😄 So everything went well but I have a little problem with calibrating signal voltage. R20 pot turned all the way but meter stops at ~ 2.5 V ac. Won't go any lower. What could be wrong? Thanks!
Very useful information as I start down the restoration road of my Dad's 700. At this point, I have no electrical questions. I will be doing a wholesale replacement of all the capacitors and resistors. The grey pebbled covering of the case is very damaged and I'd like to recover the case. Any idea where I can get a similar material to re-do the case? Thanks
John.... I too went looking for material to recover my B&K. Its nearly impossible to find. Instead, I used wallpaper remover and then primed and painted the box.
Hello I just bought a B&K 707 off ebay with a frozen heater switch. Any advice on getting the spring clip off the shaft to get some cleaner inside the shaft?
Is or does the replacement of the #83 tube make a difference as far as voltage regulation? The Rectifier Tube has mercury in it so it helps to regulate the voltage. Also there is a 15 volt drop with the tube. Do the silicon diode resistors do the same thing? or just do a current limit to the diodes?
The ss83 works well but better when you add 2 5.6v zener diodes with the 2 1n4007 when those are added all DC voltages are more proper without needing to recalibrate. Transformer will also not work as hard since less current being drawn.
I have one last question on my B&K 707. I can connect a 56 ohm 1/2 watt resistor on the negative side of the meter just before or at the connection of the push button board, correct? Someone stacked 2 diodes on top of the electrolytic capacitor, but I rather install the correct resistor. Thanks again!
It depends on which meter you have. B&K changed meters in mid-production of the 700 and the new meter needed a 56 ohm resistor to make up the difference. They never changed the design and so the 707 has the same resistor. However, they later made some 707's with the old meter which did not need the 56 ohm resistor. I do not know a way to tell one meter from the other by looking at it. My best advice is, if it works, to leave it the way it is unless you can determine which meter was used. Of course, the 56 ohm resistor will not damage anything but it may throw the calibration off if your unit uses the old meter.
I have an opportunity to procure a B&K 700 or Hickok 533a (also B&K 650 and 606 available). I have seen your videos for the 650, 700, and 707, and thought that one of those might suit my needs well. I mostly work on hi-fi audio, tube amps, and radios. Which would you say would be best suited to these needs?
If you will be working with any old tube types (pre-octal like 4, 5, or 6 pin tubes) then the 533 is your best choice. I would avoid the 606 but all the rest would be fine for octal and later tubes with a slight preference for the 650 if it has the 610 test panel. I will be publishing a two-part series on tube testers that you might want to watch before buying. I should have the first part up by tomorrow.
Thank you for your reply. The 650 does have the 610 test panel. Would you say that it's a better candidate for restoration than the 533a, all things being equal? I was under the impression that people like the Hickok more, but your videos make the B&K 650 look pretty enticing. I was originally leaning toward the 700, but I don't really need speed as much as accuracy and flexibility. In addition to hi-fi, radio, and instrument amplification, I frequently work on Hammond organs, my first passion.
Restoration is more a question of condition, so if the 533 is in better condition and about the same price I would go with it. A 650 with 610 test panel is, in my opinion about the equal of the Hickok 600A which is similar to the 533. However, I would pay a little more for a 600A (or 533) than I would for a 650 with 610 panel because of the extra sockets (4, 5,6 pin etc.). In part 2 of the two videos I intend to start posting tomorrow, I offer the opinion that of the B&K testers I prefer the 650 with 610 panel but if I had to own just one tube tester it would be the Hickok 600A. As it happens I have both but the 600A suits all my needs while the 650 cannot test early radio tubes like the 80, 83, etc. The circuits are essentially the same in the 650 and the 600A (which is also the circuit used in the 533), but you will find that, due to the reputation of Hickok, those testers will usually command a higher price than B&K on e-bay, other things being equal. I should be able to post Part 2 of the tube tester videos (which covers mutual conductance testers like the 650 and 600A) by Sunday or so. I hope you will watch those and let me know what you think.
+John Cunningham I did use the PR57 to set the AC voltage for calibration. I don't remember the details of this particular tester but generally I use 120 volts instead of the 115 Volts recommended because my local line voltage is 125 Volts instead of the 115 that prevailed in the 1950-60's. By using this higher line voltage I have been able to get consistency between the Gm reading across several B&K testers on the same tube. I think I talked about this in the Model 700 and 770 restorations where I tested several tubes in both testers and found the two testers to be remarkably consistent with each other. I chose 120 Volts as my standard because it is midway between the 115 of the 1950-60's and the 125 I see today. It has worked for me but I do not have any other justification except that it seems "about right."
I found the same thing and used 120 volts as the standard, our line voltage is usually around 125, exactly the same as yours. After calibrating the B&K 747B I then compared it to my older 747 and found a very slight difference in readings, "usually between 2&3 points which I consider excellent " the readings by and large were consistent with the many tests I performed. The configuration between the two meters are different, that might have a slight bearing on the readouts, but what ever the reason accuracy is the key. I have watched a good portion of your video's on the restoration process and enjoyed them all, please keep them coming.
Well, I replaced several resistors on my B&K 707 what were out of tolerance. I am not having any success calibrating the Signal Voltage Adjustment on socket 1, pins 1 & 2 as mentioned on the manual. I'm only seeing random numbers on my multi-meter. Instead, I'm pushing down on test button 1 and doing the adjustment on the potentiometer on socket no. 25. I'm using a modern multi meter. Do I need to install a vacuum tube for this calibration?
No, you make the adjustment with no tube in socket 1. You must have good contact on all the bulbs in the bridge for this to work correctly. Make sure the bulbs are making good contact in each socket. If this does not solve the problem then there is probably a component or wiring error in the bridge circuit. It is unlikely that the transformer voltage is wrong, probably a resistor out of tolerance (assuming the bulbs are good and making good contact.)
I have a B&K 707. Where can I find a schematic? On pin 8 of vacuum tube 6BN8 has a 22mf 250 volt electrolytic capacitor. The negative lead of the capacitor is attached to pin 8 of the vacuum tube and the positive side is attached to a terminal. Is this correct?
On the Signal Voltage Adjustment, I'm using a multimeter instead of a VTVM. Is this okay? I'm using sock #1, pin 1 & 2, according to the manual. Before pressing down on the test button 1, I have a reading of 6.5 volts, but when I press down on the button 1, I have fluctuating volts from 80 volts to 230 volts. The voltmeter is set on AC.
If it a modern digital multimeter, it should work. Look at the manual for the meter and determine the input impedance - most modern meters are around 10 Megohm - VTVM's were usually 11 Megohm. The meter to avoid is one that says 20,000 ohms/V or worse, 1000 ohms/V. These were usually called Volt-Ohm-Meters or VOM's. VOM's will load the circuit more and cause the reading to be lower than it actually is.
question? I have b&k 700 tester on sockets 1 29 and 30. when doing TEST 1 the meter goes to the left very hard. Does that mean the tubes is super bad or do I have a problem in the tester.
@@themichigander4924 Mine hit left very hard. Can you check the lamps behind tube 6BN8 both light up and evenly? If not, check them, clean the sockets etc. It is an absolute must these work correctly.
I just burned the transformer of my b&k 667 tube tester. I live in Belgium, so I was using power converter with max power of 200 watts, all the tubes i tested, had bad results. I thought it had something to do with the lack of power. So i bought a travel electrical outlet converter, i plugged in the american outlet into the converter and turned on my tester. It started to make loud humming sound and next was smoke from my transformer. I have no idea what to do now. The transformer is burned...and it's an old type of transformer.
At that ss83 joint where the diodes meet resistors add a fuse cause if those diodes short it will short transformer.
Thank you. Helpful video.
Great video. I have one of these B&K 700s. Would you happen to know anyone that could restore it?
I wish I would have found this video earlier. I hurt my 700, when I push test the needle goes negative. I don’t know what to do.
Tom mentions that he replaced all the electrolytic's. He details replacement of C-4 and C-5 with 22 uf @ 450v caps (factory spec = 20 uf @ 250V). What is the recommended replacement value for C-1 (spec = 250 uf @ 6v) and would you replace C-101 (spec = 10 uf @ 35v)? Thank you for your insight.
Regarding the M-5 and M-6 T-55 bulbs... Does it matter what "brand" of bulb you use here? My assumption is that the bulbs we buy today are darn close to what was made back in the day. If they are not, then the bulbs should have specs on them like internal resistance, power dissipation over a voltage range, etc.
Would a bad 83 tube cause the transformer to smoke? I unplugged it right away, but I'm worrying maybe the transformer is now shot. It's on the 700 model that I acquired recently. I plugged it in tested a bulb, started to smell something and then saw smoke. Obviously I unplugged it right away. Any advice is appreciated.
Does this tester really do what it says and adjust for variations in line voltage, since the 120+AC we have now might otherwise throw off the test results, since household voltages used to be 117?
a common problem with the B&k is the poor contact of two lamps. many recommend hard wiring the lamps directly to their respective holder.
I bought this tester couple years ago. It was fully working and calibrated couple years earlier according to the seller. Well It's been the next couple of years so calibration would be good idea. Also hundreds of hoarded tubes would like to be finally tested 😄 So everything went well but I have a little problem with calibrating signal voltage. R20 pot turned all the way but meter stops at ~ 2.5 V ac. Won't go any lower. What could be wrong? Thanks!
what tube his required for the B&K 625 model tester would you know what type and tube number it requires ? thanks Dan
Very useful information as I start down the restoration road of my Dad's 700. At this point, I have no electrical questions. I will be doing a wholesale replacement of all the capacitors and resistors. The grey pebbled covering of the case is very damaged and I'd like to recover the case. Any idea where I can get a similar material to re-do the case? Thanks
John.... I too went looking for material to recover my B&K. Its nearly impossible to find. Instead, I used wallpaper remover and then primed and painted the box.
Hello I just bought a B&K 707 off ebay with a frozen heater switch. Any advice on getting the spring clip off the shaft to get some cleaner inside the shaft?
Is or does the replacement of the #83 tube make a difference as far as voltage regulation? The Rectifier Tube has mercury in it so it helps to regulate the voltage. Also there is a 15 volt drop with the tube. Do the silicon diode resistors do the same thing? or just do a current limit to the diodes?
The ss83 works well but better when you add 2 5.6v zener diodes with the 2 1n4007 when those are added all DC voltages are more proper without needing to recalibrate. Transformer will also not work as hard since less current being drawn.
I have one last question on my B&K 707. I can connect a 56 ohm 1/2 watt resistor on the negative side of the meter just before or at the connection of the push button board, correct? Someone stacked 2 diodes on top of the electrolytic capacitor, but I rather install the correct resistor. Thanks again!
It depends on which meter you have. B&K changed meters in mid-production of the 700 and the new meter needed a 56 ohm resistor to make up the difference. They never changed the design and so the 707 has the same resistor. However, they later made some 707's with the old meter which did not need the 56 ohm resistor. I do not know a way to tell one meter from the other by looking at it. My best advice is, if it works, to leave it the way it is unless you can determine which meter was used. Of course, the 56 ohm resistor will not damage anything but it may throw the calibration off if your unit uses the old meter.
I have an opportunity to procure a B&K 700 or Hickok 533a (also B&K 650 and 606 available). I have seen your videos for the 650, 700, and 707, and thought that one of those might suit my needs well. I mostly work on hi-fi audio, tube amps, and radios. Which would you say would be best suited to these needs?
If you will be working with any old tube types (pre-octal like 4, 5, or 6 pin tubes) then the 533 is your best choice. I would avoid the 606 but all the rest would be fine for octal and later tubes with a slight preference for the 650 if it has the 610 test panel. I will be publishing a two-part series on tube testers that you might want to watch before buying. I should have the first part up by tomorrow.
Thank you for your reply. The 650 does have the 610 test panel. Would you say that it's a better candidate for restoration than the 533a, all things being equal? I was under the impression that people like the Hickok more, but your videos make the B&K 650 look pretty enticing. I was originally leaning toward the 700, but I don't really need speed as much as accuracy and flexibility. In addition to hi-fi, radio, and instrument amplification, I frequently work on Hammond organs, my first passion.
Restoration is more a question of condition, so if the 533 is in better condition and about the same price I would go with it. A 650 with 610 test panel is, in my opinion about the equal of the Hickok 600A which is similar to the 533. However, I would pay a little more for a 600A (or 533) than I would for a 650 with 610 panel because of the extra sockets (4, 5,6 pin etc.). In part 2 of the two videos I intend to start posting tomorrow, I offer the opinion that of the B&K testers I prefer the 650 with 610 panel but if I had to own just one tube tester it would be the Hickok 600A. As it happens I have both but the 600A suits all my needs while the 650 cannot test early radio tubes like the 80, 83, etc. The circuits are essentially the same in the 650 and the 600A (which is also the circuit used in the 533), but you will find that, due to the reputation of Hickok, those testers will usually command a higher price than B&K on e-bay, other things being equal. I should be able to post Part 2 of the tube tester videos (which covers mutual conductance testers like the 650 and 600A) by Sunday or so. I hope you will watch those and let me know what you think.
Question; did you use the PR 57 to calibrate the B&K 700? if that is the case, was the voltage set at 115 volts or higher?
+John Cunningham I did use the PR57 to set the AC voltage for calibration. I don't remember the details of this particular tester but generally I use 120 volts instead of the 115 Volts recommended because my local line voltage is 125 Volts instead of the 115 that prevailed in the 1950-60's. By using this higher line voltage I have been able to get consistency between the Gm reading across several B&K testers on the same tube. I think I talked about this in the Model 700 and 770 restorations where I tested several tubes in both testers and found the two testers to be remarkably consistent with each other. I chose 120 Volts as my standard because it is midway between the 115 of the 1950-60's and the 125 I see today. It has worked for me but I do not have any other justification except that it seems "about right."
I found the same thing and used 120 volts as the standard, our line voltage is usually around 125, exactly the same as yours. After calibrating the B&K 747B I then compared it to my older 747 and found a very slight difference in readings, "usually between 2&3 points which I consider excellent " the readings by and large were consistent with the many tests I performed. The configuration between the two meters are different, that might have a slight bearing on the readouts, but what ever the reason accuracy is the key. I have watched a good portion of your video's on the restoration process and enjoyed them all, please keep them coming.
Well, I replaced several resistors on my B&K 707 what were out of tolerance. I am not having any success calibrating the Signal Voltage Adjustment on socket 1, pins 1 & 2 as mentioned on the manual. I'm only seeing random numbers on my multi-meter. Instead, I'm pushing down on test button 1 and doing the adjustment on the potentiometer on socket no. 25. I'm using a modern multi meter. Do I need to install a vacuum tube for this calibration?
No, you make the adjustment with no tube in socket 1. You must have good contact on all the bulbs in the bridge for this to work correctly. Make sure the bulbs are making good contact in each socket. If this does not solve the problem then there is probably a component or wiring error in the bridge circuit. It is unlikely that the transformer voltage is wrong, probably a resistor out of tolerance (assuming the bulbs are good and making good contact.)
Duh, stupid me! I had the the connections on pins 6 & 7. Thank you so much for your help. I finally calibrated at 1.5 volts
I have a B&K 707. Where can I find a schematic? On pin 8 of vacuum tube 6BN8 has a 22mf 250 volt electrolytic capacitor. The negative lead of the capacitor is attached to pin 8 of the vacuum tube and the positive side is attached to a terminal. Is this correct?
Pin 8 of the 6BN8 should have a .01 mfd paper capacitor, not an electrolytic. I got my manual from Boat Anchor Manual Archive (BAMA).
On the Signal Voltage Adjustment, I'm using a multimeter instead of a VTVM. Is this okay? I'm using sock #1, pin 1 & 2, according to the manual. Before pressing down on the test button 1, I have a reading of 6.5 volts, but when I press down on the button 1, I have fluctuating volts from 80 volts to 230 volts. The voltmeter is set on AC.
If it a modern digital multimeter, it should work. Look at the manual for the meter and determine the input impedance - most modern meters are around 10 Megohm - VTVM's were usually 11 Megohm. The meter to avoid is one that says 20,000 ohms/V or worse, 1000 ohms/V. These were usually called Volt-Ohm-Meters or VOM's. VOM's will load the circuit more and cause the reading to be lower than it actually is.
question? I have b&k 700 tester on sockets 1 29 and 30. when doing TEST 1 the meter goes to the left very hard. Does that mean the tubes is super bad or do I have a problem in the tester.
I have a similar problem with the meter going to the right hard
@@themichigander4924 Is this still an issue for you?
Problem with tester. Still an issue?
@@emmanuelvakakis1374 yeah I haven't messed with it for a long time
@@themichigander4924 Mine hit left very hard. Can you check the lamps behind tube 6BN8 both light up and evenly? If not, check them, clean the sockets etc. It is an absolute must these work correctly.
I just burned the transformer of my b&k 667 tube tester. I live in Belgium, so I was using power converter with max power of 200 watts, all the tubes i tested, had bad results. I thought it had something to do with the lack of power. So i bought a travel electrical outlet converter, i plugged in the american outlet into the converter and turned on my tester. It started to make loud humming sound and next was smoke from my transformer. I have no idea what to do now. The transformer is burned...and it's an old type of transformer.
Wasn't a power issue probably a bad 83 tube or out of spec components usually drifted resistors
I wish I could find one that been refurbed by someone that knows what they are doing....you do not know what you are getting on ebay.