Page 2 of 2 FirstFirst 12
Results 36 to 63 of 63

Thread: Secondary Fuse Value

  1. #36
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    3,202
    Thumbs Up/Down
    Received: 2,341/1
    Given: 1,332/2
    Rep Power
    8
    How did you measure total cathode current?
    I was asking this as cathode current consists of DC and (a lot of) signal AC. Your meter might not be able to correctly read averaged DC.

    0 Not allowed! Not allowed!
    - Own Opinions Only -

  2. #37
    Senior Member
    Join Date
    Feb 2009
    Posts
    581
    Thumbs Up/Down
    Received: 32/0
    Given: 33/0
    Rep Power
    12
    Sorry, across a 1 Ohm resistor from power tubes cathodes to ground.

    0 Not allowed! Not allowed!

  3. #38
    Senior Member
    Join Date
    Feb 2009
    Posts
    581
    Thumbs Up/Down
    Received: 32/0
    Given: 33/0
    Rep Power
    12
    Quote Originally Posted by trobbins View Post
    A 700mA B+ loading and 395V aligns well with the measured transformer parameters. For my PSUD2 sim I tweaked the load resistor R1 to 570 ohm, and the results table gave I(R1) = 703mA and V(R1) = 401V.
    Yes, I can see now how the sim aligns with my measured values! In response to Hemholtz I also gave my values at full clean power as well (instead of of maximum output with lots of clipping), and plugging those into PSUD2 lined up as well.

    Quote Originally Posted by trobbins View Post
    Note that PSUD2 also provides an estimate of filter capacitor ripple current, so best to check your filter capacitor datasheet to make sure it is rated for something approaching 1A. You may find the ripple rating is down below 0.5A at 120Hz for some caps, although the 1A is a 'metal' level.
    This is interesting and something I never considered. Right now my caps are rated at 720mA, but I have two 400V caps in series. Does the rating double like voltage does in series?

    Quote Originally Posted by trobbins View Post
    Based on IEC fuses, the table below indicates the minimum limit fuse capability for 0.5A, 0.63A and 0.75A fuses. A bogey fuse sits in between min and max compliance levels, so even the 0.5A fuse would be quite unlikely to blow on an in-rush, and given the compliance level is at least 1.5hr at 150% rating, then the 0.5A fuse would seem reasonable unless the metal gig went on for a lot longer.
    Attachment 57527
    I looked at all my fuses and they are UL. You say in your article: "the circuit operating current must be no more than 75% of the fuse current rating" for UL fuses. Since my absolute maximum current through the T1 is about 1.3A, does that mean my fuse should be rated at 1.5A (which is the nearest standard value)?

    0 Not allowed! Not allowed!

  4. #39
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    3,202
    Thumbs Up/Down
    Received: 2,341/1
    Given: 1,332/2
    Rep Power
    8
    Quote Originally Posted by Gaz View Post
    Sorry, across a 1 Ohm resistor from power tubes cathodes to ground.
    You may try to bypass the cathode resistor with a 220ĶF or higher value cap for smoothing/averaging. Does this change the DC reading?

    But I recommend to take the total DC current reading directly after the reservoir cap (where some amps have the standby switch), as this would be the real "I(R1)" value. Beware of high voltage!

    When I mention "full power" I always mean output power just before or at the onset of clipping as results with clipped output are not predictable.

    0 Not allowed! Not allowed!
    - Own Opinions Only -

  5. #40
    Senior Member
    Join Date
    Feb 2009
    Posts
    581
    Thumbs Up/Down
    Received: 32/0
    Given: 33/0
    Rep Power
    12
    Quote Originally Posted by Helmholtz View Post
    You may try to bypass the cathode resistor with a 220ĶF or higher value cap for smoothing/averaging. Does this change the DC reading?

    But I recommend to take the total DC current reading directly after the reservoir cap (where some amps have the standby switch), as this would be the real "I(R1)" value. Beware of high voltage!

    When I mention "full power" I always mean output power just before or at the onset of clipping as results with clipped output are not predictable.
    I tried the smoothing cap, but results were the same.

    I also tried taking a measurement after the first reservoir cap (before the choke and screen filter cap), and got 90mA at clippping, which seems odd. I tried across 1 Ohm resistor as well. Same - 90mV. In any case, the PSUD sim lines up with the measurements I have taken so far at both full output and with maximum clipped output. That seems like a good thing, ya?

    0 Not allowed! Not allowed!

  6. #41
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    3,202
    Thumbs Up/Down
    Received: 2,341/1
    Given: 1,332/2
    Rep Power
    8
    Since my absolute maximum current through the T1 is about 1.3A, does that mean my fuse should be rated at 1.5A (which is the nearest standard value)?
    Don't forget that the main purpose of the secondary fuse is to protect the HT winding. So it's the PT's rated current and not the amp's max current demand that matters.
    I am not familiar with UL type fuses, but I think you should not go above 1A.

    0 Not allowed! Not allowed!
    - Own Opinions Only -

  7. #42
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    3,202
    Thumbs Up/Down
    Received: 2,341/1
    Given: 1,332/2
    Rep Power
    8
    I also tried taking a measurement after the first reservoir cap (before the choke and screen filter cap), and got 90mA at clippping, which seems odd. I tried across 1 Ohm resistor as well. Same - 90mV.
    90mA at that point is not possible. Sure you measured DC not AC?
    Could you post a drawing of the power supply showing where you measured current?

    I tried the smoothing cap, but results were the same.
    That seems to confirm the original measurement.

    0 Not allowed! Not allowed!
    - Own Opinions Only -

  8. #43
    Senior Member
    Join Date
    Feb 2009
    Posts
    581
    Thumbs Up/Down
    Received: 32/0
    Given: 33/0
    Rep Power
    12
    Quote Originally Posted by Helmholtz View Post
    90mA at that point is not possible. Sure you measured DC not AC?
    Could you post a drawing of the power supply showing where you measured current?



    That seems to confirm the original measurement.
    Yes, I screwed up and was just measuring screens + preamp.

    Full DC current draw at clipping is 520mA.

    1 Not allowed! Not allowed!

  9. #44
    Senior Member
    Join Date
    Feb 2009
    Posts
    581
    Thumbs Up/Down
    Received: 32/0
    Given: 33/0
    Rep Power
    12
    Both of these sims are now accurate with my measurements for T1 and R1 both just before the onset of clipping and with the maximum power the amp can draw. This has been a great learning experience using PSUD and measurements from the amp.

    Click image for larger version. 

Name:	Full power before clipping Sim.jpg 
Views:	13 
Size:	80.1 KB 
ID:	57568
    Click image for larger version. 

Name:	Maximum power with clipping Sim.jpg 
Views:	11 
Size:	82.7 KB 
ID:	57569

    I'm still a bit confused with what fuse value to choose based on all the technical and anecdotal info in this thread lol

    0 Not allowed! Not allowed!
    Last edited by Gaz; 03-29-2020 at 02:10 AM.

  10. #45
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    3,202
    Thumbs Up/Down
    Received: 2,341/1
    Given: 1,332/2
    Rep Power
    8
    Both of these sims are now accurate with my measurements for T1 and R1 both just before the onset of clipping and with the maximum power the amp can draw.
    Different R1 values, same results - not possible.

    0 Not allowed! Not allowed!
    - Own Opinions Only -

  11. #46
    Senior Member trobbins's Avatar
    Join Date
    Jun 2010
    Location
    Australia
    Posts
    752
    Thumbs Up/Down
    Received: 120/0
    Given: 1/0
    Rep Power
    10
    I can suggest you first identify a part supplier that provides datasheets for the fuses sold, unless you are lucky enough to have previously purchased fuses and know specifically the manufacturer and fuse model. If you need to buy in a fuse, and can purchase an IEC specified fuse, then I would recommend that type of fuse be purchased, rather than a UL (unless the fuse manufacturer provides sufficiently detailed datasheet).

    That doesn't mean a generic no-name fuse won't be just as good - one would never achieve that guarantee because there are so many variables as to what faults can occur, and what tolerance/time a particular fuse will perform with, but like buying new valves - confidence of knowing what you are using can have benefit.

    0 Not allowed! Not allowed!

  12. #47
    Senior Member
    Join Date
    Feb 2009
    Posts
    581
    Thumbs Up/Down
    Received: 32/0
    Given: 33/0
    Rep Power
    12
    Quote Originally Posted by Helmholtz View Post
    Different R1 values, same results - not possible.
    Sorry, forgot to hit "simulate" again after changing R1. I reuploaded the files.

    0 Not allowed! Not allowed!

  13. #48
    Senior Member
    Join Date
    Feb 2009
    Posts
    581
    Thumbs Up/Down
    Received: 32/0
    Given: 33/0
    Rep Power
    12
    Quote Originally Posted by trobbins View Post
    I can suggest you first identify a part supplier that provides datasheets for the fuses sold, unless you are lucky enough to have previously purchased fuses and know specifically the manufacturer and fuse model. If you need to buy in a fuse, and can purchase an IEC specified fuse, then I would recommend that type of fuse be purchased, rather than a UL (unless the fuse manufacturer provides sufficiently detailed datasheet).

    That doesn't mean a generic no-name fuse won't be just as good - one would never achieve that guarantee because there are so many variables as to what faults can occur, and what tolerance/time a particular fuse will perform with, but like buying new valves - confidence of knowing what you are using can have benefit.
    Tim, didn't think they were listed, but easily found the datasheet on the suppliers' site:

    https://www.cedist.com/sites/default...files/f-zs.pdf

    It seems like every fuse I have is UL, so probably smart for me to design around those. I guess I should be clear that my main objective is to prevent the HV winding from getting damaged under fault conditions and not blowing even with totally clipped output based on my measurements and the simulations.

    Nickb's story about the doom band frying Hammonds is interesting, but I know a lot of bands that play like that and don't fry PT's... unless they are Jet City's or other cheap imports that can't take the heat. My understanding of the HV winding's rating was what it was the amount of current it voltage could supply while staying within it's 5-10% regulation, not the maximum amount of current before failure. Maybe I'm wrong about that, but I just think the story shows that Hammond transformers are not designed as well as they used to be, not that most transformers will fail when pushed past their current rating.

    1 Not allowed! Not allowed!
    Last edited by Gaz; 03-29-2020 at 07:14 AM.

  14. #49
    "Thermionic Apocalypse" -JT nickb's Avatar
    Join Date
    Dec 2009
    Location
    Devon, UK
    Posts
    3,807
    Thumbs Up/Down
    Received: 938/1
    Given: 691/1
    Rep Power
    14
    You'll notice at full tilt that the transformer RMS current is 1.3A for an output average current of 0.718A. Pretty much the in the same ballpark is I reported earlier, this is why you should not use a secondary fuse rating that is higher than the secondary rating, unless you are prepared to accept the consequences.

    Manufacturers have a different rules as they are required to prove that the equipment is protected from causing a fire by the primary fuse, but the transformer will be damaged. They can afford that as it allows them to safely use a smaller transformer.


    PS: Gaz, whose transformer and part number are you using?

    0 Not allowed! Not allowed!
    Experience is something you get, just after you really needed it.

  15. #50
    Senior Member
    Join Date
    Feb 2009
    Posts
    581
    Thumbs Up/Down
    Received: 32/0
    Given: 33/0
    Rep Power
    12
    Quote Originally Posted by nickb View Post
    You'll notice at full tilt that the transformer RMS current is 1.3A for an output average current of 0.718A. Pretty much the in the same ballpark is I reported earlier, this is why you should not use a secondary fuse rating that is higher than the secondary rating, unless you are prepared to accept the consequences.

    Manufacturers have a different rules as they are required to prove that the equipment is protected from causing a fire by the primary fuse, but the transformer will be damaged. They can afford that as it allows them to safely use a smaller transformer.


    PS: Gaz, whose transformer and part number are you using?
    I appreciate the thoughts and totally understand the logic there, but I have never seen a large or boutique manufacturer use a fuse rating that matches the secondary rating closely. It's always at least 2x the rating. Does it means that every manufacturer of guitar amps big and boutique alike are using the wrong size HV fuses for their amps (serious question)? I really do think that maybe Hammond's insulation is not up to snuff. Because lots of people completely dime small amps all the time and the PT's don't fry. I think the rating is not the maximum limit before meltdown, but I will ask Heyboer how they rate them (if they are still open!).

    By the way, I am using a Heyboer unit a bought second hand that is supposed to be a clone of a Hiwatt DR103 PT. They said it had a 550mA secondary so I do know that for sure.

    0 Not allowed! Not allowed!

  16. #51
    "Thermionic Apocalypse" -JT nickb's Avatar
    Join Date
    Dec 2009
    Location
    Devon, UK
    Posts
    3,807
    Thumbs Up/Down
    Received: 938/1
    Given: 691/1
    Rep Power
    14
    If you play "normally" through a dimed amp the secondary current will have high peaks but, due to the usual crest factor of the guitar input (10 to 20dB), the average is less than the transformer rating so there is no problem. Given the average is low there is no justification for using a bigger fuse. As I mentioned above a slow blow fuse with 1.5x it's rating will take around 60 mins to open so most of the time there's no issue. The problem comes if you drive it really hard, in your case the current will 2.35 (1300mA/550mA) times the fuse rating and it will blow after just s few seconds and that is why people use bigger fuses.

    It seems maybe we're looking at it the wrong way. If your max current is 1.3A and you want to be able to handle that without ever damaging the PT and without fuses blowing, I suggest you need at least a half that i.e. a 650mA transformer with a 630mA fuse. The fuse would blow in 10 secs at 1.3A which, without trying it, seems reasonable. Just because everyone is doing it a certain way doesn't make it right.

    Yes, a bunch of boutique manufacturers use a 2 x fuse but I suspect they are using the rule of thumb without really thinking it through. It also matters what primary fuse rating is so we'd need to look at it in more detail. I suspect they'll have the usual 2 x expected max current there too in which case I guarantee I can blow up the PT in about a hour or two. I have learned that very few people realize how the power supply causes massive transformer current. If you look at the Hammond site you will find they claim for a bridge rectifier that the average DC current is 0.65 the transformer current (i.e. secondary is 1.6 x DC current), This could mislead a lot of people. You yourself have demonstrated a factor of 1.8 and I'd say use x2 if you want a rule of thumb.

    The amp I mentioned actually burned out a total of three PT''s, the original and two replacements so I don't think you can blame Hammond. They have to demonstrate compliance to regs in any case. I would say that the 420mA JCM 800 transformer seems very inadequate in light of the above, but they have been in use for donkeys years and are fine for "normal" use. I didn't mention it, but they did they same to another amp. This had 6 x EL34's and a 900mA PT.

    2 Not allowed! Not allowed!
    Last edited by nickb; 03-30-2020 at 09:58 PM.
    Experience is something you get, just after you really needed it.

  17. #52
    Supporting Member SoulFetish's Avatar
    Join Date
    Jan 2016
    Location
    Massachusetts
    Posts
    1,410
    Thumbs Up/Down
    Received: 539/1
    Given: 451/0
    Rep Power
    7
    Quote Originally Posted by Gaz View Post
    I appreciate the thoughts and totally understand the logic there, but I have never seen a large or boutique manufacturer use a fuse rating that matches the secondary rating closely. It's always at least 2x the rating. Does it means that every manufacturer of guitar amps big and boutique alike are using the wrong size HV fuses for their amps (serious question)?
    I'm not exactly sure how you would know. I mean, you would have to know the OEM design specs for the transformer model to make that assesment.
    This is not information that is readily available, and in my experience, can be quite difficult to get a hold of; and This is for OEM data on any individual model.


    I really do think that maybe Hammond's insulation is not up to snuff. Because lots of people completely dime small amps all the time and the PT's don't fry.
    Hammod has been supplying transformers for the industry for decades. They're one of the most well know manufacturers in the buisiness. I find it hard to believe that this would be the case.

    0 Not allowed! Not allowed!
    If I have a 50% chance of guessing the right answer, I guess wrong 80% of the time.

  18. #53
    Don't forget the joker g1's Avatar
    Join Date
    Feb 2010
    Location
    Canada, somewhere north of Fargo
    Posts
    12,612
    Thumbs Up/Down
    Received: 2,172/24
    Given: 5,478/11
    Rep Power
    24
    Just to throw some numbers out, although it's coming out of the rectifier rather than going in, standard Marshall value is 1AT for 100W and 500mAT for 50W. Rough specs for their PT's should be easy to find.

    0 Not allowed! Not allowed!
    "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

  19. #54
    Senior Member
    Join Date
    Feb 2009
    Posts
    581
    Thumbs Up/Down
    Received: 32/0
    Given: 33/0
    Rep Power
    12
    I'm not exactly sure how you would know. I mean, you would have to know the OEM design specs for the transformer model to make that assesment.
    This is not information that is readily available, and in my experience, can be quite difficult to get a hold of; and This is for OEM data on any individual model.
    Tons of replacement transformers out there with specs. Definitely enough to make that statement. Also find one 100W with an HT less than 1A. I can’t, and I guarantee no one is using transformers rated for 1A secondary current.

    Quote Originally Posted by SoulFetish View Post
    Hammond has been supplying transformers for the industry for decades. They're one of the most well know manufacturers in the buisiness. I find it hard to believe that this would be the case.
    Ok, I’m not so confident in huge brands. The only other PTs I’ve seen shit the bed are cheap imports. I just thought perhaps the insulation may not have been up to real world demands. Nick pointed out in his last post that the original blew too, so probably not the Hammond specifically, but I don’t just don’t let companies rest on their laurels.

    0 Not allowed! Not allowed!
    Last edited by Gaz; 03-31-2020 at 10:02 AM. Reason: Misspelling

  20. #55
    Senior Member
    Join Date
    Feb 2009
    Posts
    581
    Thumbs Up/Down
    Received: 32/0
    Given: 33/0
    Rep Power
    12
    Quote Originally Posted by nickb View Post
    If you play "normally" through a dimed amp the secondary current will have high peaks but, due to the usual crest factor of...
    Nick, thanks a lot for your thoughts on this. Food for thought. I think youíre right that a lot donít think it through and just use the rule of thumb approach. It does protect against most common failures. I just canít believe I havenít seen more PTís overheat learning what I have from this thread. Sure big amps donít get played full bore all the time, but little amps do, and many donít even have HT Fuses. Why arenít they all overheating?

    1 Not allowed! Not allowed!

  21. #56
    "Thermionic Apocalypse" -JT nickb's Avatar
    Join Date
    Dec 2009
    Location
    Devon, UK
    Posts
    3,807
    Thumbs Up/Down
    Received: 938/1
    Given: 691/1
    Rep Power
    14
    Quote Originally Posted by Gaz View Post
    Nick, thanks a lot for your thoughts on this. Food for thought. I think you’re right that a lot don’t think it through and just use the rule of thumb approach. It does protect against most common failures. I just can’t believe I haven’t seen more PT’s overheat learning what I have from this thread. Sure big amps don’t get played full bore all the time, but little amps do, and many don’t even have HT Fuses. Why aren’t they all overheating?
    They aren't all overheating because 99.9% of people don't push them that hard.

    OTOH, a leaky cap in the bias supply could cause a high DC current that could easily overload the transformer.

    0 Not allowed! Not allowed!
    Experience is something you get, just after you really needed it.

  22. #57
    Senior Member
    Join Date
    Feb 2009
    Posts
    581
    Thumbs Up/Down
    Received: 32/0
    Given: 33/0
    Rep Power
    12
    Hey just wanted to follow up in this thread because I emailed Heyboer about the 550ma rated PT. Thoughts?

    ďNow as to current rated hv winding. We usual just go by what the wire is rated to carry full duty. In this case is 24 ga. we sort of round it off. It can really handle about 600mA all day long. This also depends on length of, and total turns comes into play with size of core for total VA . that winding is 200 VA or can say it like 100 volts at 2 amp or 200 volts at 1amp. the wire itself is rated to 130c. for a fuse on the font end of this transformer , id think you need total ampers the primary will see. yea? the total is 285 VA ( give or take a few ,is sort of rounded) so divided by primary volts 120 . primary will see 2.375 Amp if all windings are put to max current draw at their voltage. If any one of those windings shorts or cooks, the primary current will spike way up and pop the fuse, provided you dont overkill on the fuse. the old farmers trick , well ill just shove a coin in here because the fuse keeps popping. Its got to be a bad batch of fuses, not bad or shorted wire or something else running off the chain. am joking here a bit, but you get my drift. Id think go by total VA at full duty for fuse. But im not an amp builder.Ē

    0 Not allowed! Not allowed!

  23. #58
    Supporting Member
    Join Date
    May 2006
    Location
    Staffordshire UK
    Posts
    3,874
    Thumbs Up/Down
    Received: 599/1
    Given: 549/2
    Rep Power
    19
    130C insulation?!
    That sounds like even Hammond are now using cheap wire
    See J M Fahey's run down on the topic https://music-electronics-forum.com/...l=1#post306712
    Explains how I managed to frazzle a 1650G OT last year; I'd been using it on the basis that the 16XX range could be used a little above their rated hifi power in a guitar amp, so I was pushing it to nearly 40W clean, 55W heavily overdriven.

    Quote Originally Posted by Gaz View Post
    ...Sure big amps don’t get played full bore all the time, but little amps do, and many don’t even have HT Fuses. Why aren’t they all overheating?
    These Marshalls are somewhat unusual (for vintage type amps at least) in that they used FWB, rather than biphase rectification; hence the winding current can be much higher.
    Does the lowish reservoir cap value mean that at high demand, the conduction angle is very wide?

    0 Not allowed! Not allowed!

  24. #59
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    3,202
    Thumbs Up/Down
    Received: 2,341/1
    Given: 1,332/2
    Rep Power
    8
    130C insulation?!
    That sounds like even Hammond are now using cheap wire
    This is Heyboer.
    What is known about the temperature class used by Hammond?

    0 Not allowed! Not allowed!
    - Own Opinions Only -

  25. #60
    Supporting Member
    Join Date
    May 2006
    Location
    Staffordshire UK
    Posts
    3,874
    Thumbs Up/Down
    Received: 599/1
    Given: 549/2
    Rep Power
    19
    Oops, Iíll try and blame the small character size on my phone, I saw the ĎHí, seemed to remember it being a Hammond PT previously, and read it as ĎHammondí

    0 Not allowed! Not allowed!

  26. #61
    Supporting Member SoulFetish's Avatar
    Join Date
    Jan 2016
    Location
    Massachusetts
    Posts
    1,410
    Thumbs Up/Down
    Received: 539/1
    Given: 451/0
    Rep Power
    7
    Quote Originally Posted by Helmholtz View Post
    This is Heyboer.
    What is known about the temperature class used by Hammond?
    I wanted to correct some information here. I emailed Heyboer to confirm what temperature class magnet wire they use and he responded that the temperature class 155C is Typically used. This is fairly common in transformers. Motors, relays, and other coils. Obviously, 180C is “better”, in that I would want my transformer to have it. But it comes down to a cost/benefit analysis.

    0 Not allowed! Not allowed!

  27. #62
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    3,202
    Thumbs Up/Down
    Received: 2,341/1
    Given: 1,332/2
    Rep Power
    8
    Quote Originally Posted by SoulFetish View Post
    I wanted to correct some information here. I emailed Heyboer to confirm what temperature class magnet wire they use and he responded that the temperature class 155C is Typically used. This is fairly common in transformers. Motors, relays, and other coils. Obviously, 180C is “better”, in that I would want my transformer to have it. But it comes down to a cost/benefit analysis.
    Looks like contradictory statements on the part of Heyboer.

    0 Not allowed! Not allowed!
    - Own Opinions Only -

  28. #63
    Senior Member
    Join Date
    Feb 2009
    Posts
    581
    Thumbs Up/Down
    Received: 32/0
    Given: 33/0
    Rep Power
    12
    Quote Originally Posted by Helmholtz View Post
    Looks like contradictory statements on the part of Heyboer.
    Ok, so it looks like the mixup with the temp was the rating of the lead wire, which is PVC "appliance wire". It's rated at 130c, but the gauge of that is 22AWG. Strange mixup

    2 Not allowed! Not allowed!

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. GK 2001RB Buss Fuse F4 open. This ALWAYS bothers me when just one 15A fuse blows!
    By nevetslab in forum Maintenance, Troubleshooting & Repair
    Replies: 3
    Last Post: 06-12-2019, 11:31 PM
  2. Yamaha G-100 secondary fuse
    By KM1 in forum Vintage Amps
    Replies: 18
    Last Post: 03-07-2016, 01:15 PM
  3. Vintage Yamaha EM 150 II fuse holder & fuse.
    By Shmitty312 in forum Music Electronics
    Replies: 5
    Last Post: 08-05-2013, 03:14 AM
  4. Fuse on both windings of a center-tapped secondary
    By greekie in forum Theory & Design
    Replies: 44
    Last Post: 11-23-2011, 08:39 PM
  5. O.T. secondary confusion
    By mbailey in forum Theory & Design
    Replies: 2
    Last Post: 03-21-2009, 04:16 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •