ADA Depot - A Forum To Support Users of ADA Amplification Gear
Non ADA Gear => Rack Gear => Topic started by: rabidgerry on November 14, 2019, 01:11:55 PM
-
Anyone ever had any experience with a Furman PC breaking?
Basically the power switch lights up but the volt meter and current meter do not come on and no power gets though to any outlets.
I have made a few tests, but not a lot according to my limited knowledge.
Basically power is getting in, getting past the switch, through the fuse and gets to the main board at the back (top of the pictures). Then this is where I can't go any further.
(https://i.ibb.co/ZWSt3Js/furman-1.jpg) (https://ibb.co/ZWSt3Js)
(https://i.ibb.co/ThzmJV1/furman-2.jpg) (https://ibb.co/ThzmJV1)
In searching the web I came across this website
https://jestineyong.com/power-conditioner-repair/ (https://jestineyong.com/power-conditioner-repair/)
I wonder might I be having the same issue? In which case it's the big red cap at the back.
Any advice is welcome. Thanks.
-
Hiya Gerry,
Did you check the circuit breaker ain't tripped ?
A lot of the time a poor capacitor with a high ESR reading on the over voltage shut down protection circuit can be the cause.
In many cases and also with some high power amplifiers there is a crowbar circuit = shut down = bad cap = triac has triggered and zero functionality,
Try finding a schem for this unit, and maybe I can talk you through it.
Just saying, I am not familiar with this particular piece of kit, but I'm sure it's very do-able.
-
If you turn it on do you hear the relay click? If not it could be that cap. My guess is that the cap is part of a transformerless power supply to feed the relay. Also I don't think it has a crowbar circuit in it. It might just have a simple overvoltage protection circuit in that shuts down the relay. Anyway that's what I think I see on the pics.
RG, could you send me a high res pic of the back pcb so I can have a better look? I see some brown stuff on the pcb.
-
Yeah I hear no relay myself.
Also this unit used to turn on, but there was always a delay in actual powering up. It was like that when I got it. It was second hand of course.
Leave the hi res picture to me. I will us my girlfriends hi res camera on her phone.
-
Hi Gerry,
Looking at your pics, MJMP is correct, plus, I can’t see a triac either. There is a more basic protection circuit in place. There is no crowbar circuit in there. A crowbar is usually utilized in circuits to kick in if there is any DC component lifting up the AC voltage above a zero V center or a neutral reference and it’s not needed here in this case by design topology I would guess, so lets rule that one out as it could be mis-leading.
I cannot see enough provision for a soft-start providing the load, if there is, then it’s severely under-speced in my opinion to supply so many outlets. Then again that’s where the fault may reside. I don’t mean that this is a piece of junk by design, it is what it has been designed for, and certainly not to provide a very large switch on current capacity, but nevertheless, a good piece of equipment for what it’s supposed to be for.
I can see a zener diode in there to hold/clamp the voltage for the main big relay coil. Normally zeners are quite stable unless they get over-cooked and blow short which would lead backwards to a burned out resistor or a defunct plastic cap immediately beforehand in the design.
I cannot see brown burn stuff as per; MJMP can identify in those pics, my eyes ain’t so good these days, so please do excuse me on that one if I’m wrong.
As MJMP has said, If you could pull that circuit board up and out and take some high res pics then we could get much further and be on standby with your DVM.
Even better !!! Find a schem, or one very close model wise to this Furman series and we have the road map.
This can be nailed Gerry.
-
Well I think I see some brown, could be wrong. Anyway could also be th erelay itself but that's easy to check. Do any of the front leds go on?
As for limiting inrush current sometimes they use an NTC for this.
-
No leds come on, just the power switch lights up. Sometimes after a delay and sometimes right away. What used to happen was the delay would occur, and then as soon as the power light came on I would hear the clicking of the relay inside as the meters on the front display started to measure volts and current.
Also since I have had this issue, the unit did power on properly one more time. So I don't know why that was.
new photos
(https://i.ibb.co/vhgmqfz/IMG-20191124-WA0002.jpg) (https://ibb.co/vhgmqfz)
(https://i.ibb.co/GnNCshL/IMG-20191124-WA0001.jpg) (https://ibb.co/GnNCshL)
-
Ok Have a look at the pic I attached. White, I see something there but not sure what it is? Green, looks like a crack in the cap?
-
Good man MJMP, and thanks for better pics RG,
Now I can see brown/black stuff on the board, and the crack on that orange capacitor which is the AC voltage droping cap for the transformerless supply. R1 looks like a 125K fuseable resistor for that circuit from here on my screen I think, measure it's resistance too, it might have bought the farm aswell. :-\
Brown/black stuff too is also under that cap that I marked in white.
Also I think there is some burn up by that RF inductor on the board which I marked in light blue, I think. :-\
-
Holy :poop:!!!!
You boys are good!!
I will examine in further detail.
Now that big cap, would you try replacing it first? That is kind like that link I posted where that same big cap had died on the guy.
ok in the mean time I bought the exact same model of furman so I am up and running again but I need to fix the old one and either sell on or keep as a spare.
-
Good Rusty, forgot about the black stuff under the black 0.47uf cap. Also good that you saw the burn up. It also seems to me that the core got hot (see pic red line on the inductor). Talking about R1 ,I would also check R5 and the other big grey resistor these because it seems (as far as I can see) it also has a small crack (see red line). They look like flame proof resistors (so also fusible).
What I would do, is check those 3 resistors, R1,R5 and the other one I mentioned. Replace the brown cap near the relay, replace the black 0.47µF cap and have a look at the solder joint that Rusty mentioned. BTW I would check all the high power solderjoints. Also check the other caps for this brown/black stuff.
-
Hey RG,
I'd would like to only suggest;
Take that board out and send it up to me, I'm only 70 miles up the road, or else send the whole complete unit up to me.
There is more than just a few components in there that have suffered, and soon they will become catastrophist candidates for definite future failure, they are going to do so very soon.
They will need a thorough check out, as that whole board essentially, necessarily does need some in-depth attention. Now, I can also identify a melt on the side of that inductor, and given that there is some timing delay to fire up, lets go time, then I would be confident that that individual integrated circuit and the rest needs repaired and re-calibrated.
This unit is getting much older and has taken a piece of electrical abuse. Very quite possibly by someone who didn’t understand it’s limitations and never considered or realized it’s true purpose or intentions.
If you have the hands, patience, time, knowledge, desire and above all, the vigour to go out and source which can be difficult and buy the best quality components from reputable, not ebay garb dealers, plus add a few up-grade mods in the circuits because they need it it in this day and age with the amount of garbage/hash on the AC line, then go for it.
But I can warn you, and I hate sounding like your grand mother, a piece of equipment like this that supply's the rest of your cherished equipment must be truly bullet proof, or else.
Unless MJMP would like to talk you through this or take it on, he is the best around, I dunno, I cant speak for him, but he knows his stuff for sure.
I originally said that this is nail-able, and that’s true, but we could be here all year.
I’m finished posting investigation, obvious and possible causes on this one. I think it needs to go in to a tech.
PM me if you want to do so.
Cheers RG.
Rusty.
-
Thank you MJMP.
See, my eyes are not so good these days. As MJMP has identified even more problematic areas for investigation and repair.
I would need the unit here under daylight. Apart from our natural day light, I don't use alien sources of light anymore to work on circuit boards as they cause me migrane and destroy my judgment. Therefore I work only on circuits from light from the Sun. :)
-
Well Gerry is my friend so I don't mind helping him out, but he decides what has to be done. If he wants to ship it to you, fine ,does he want to fix it himself and he needs my help, also fine.
-
++++1 ^^^ MJMP.
-
Guy's you both are a great help. Really I am in debt to you for always helping me out. I mean that sincerely and others on here who are a constant font of knowledge. I actually wish I was properly electrically engineer minded (I might take a course time if I ever get time).
MJMP totally much appreciated my man! :thumb-up: I look forward to getting back to Belgium with the band, or even as a tourist. I loved that tour, it was an amazing experience. To get to meet you then in the process of that was a mega bonus. And to think my tone was nowhere near as good as it is now (shorter cable runs my friend ;) like you always said) so I'd be keen for you to hear how it all sounds now I'm fully fledged rack user. Then again, I've developed a flight rig with only one rack unit in it :facepalm: but has a high voltage preamp pedal at the heart :whoohoo!:
As for the Furman. I'd replace that one cap, may be a few other bits here and there and no doubt it will take me a while to get the time to do it. But it sounds/seems possible that there are other parts in there that have A) taken some beating or B) could possibly be screwed already. So Rusty I may take you up on your offer. I will perhaps get to checking the components out to see where we are first of all though so we will take it from there. It's nice to have a challenge but can be really time consuming what with all the other shit I got going on (and plus I'm lazy too :lol:) .
Ok guy's so here is the next question, what do you think caused this? I thought these furman PC's were meant to indestructible?? I can definitely tell you I was not the one messing about inside with the unit. It's stayed in my rack since I bought it of ebay a few years back and powered everything nicely. Until a few weeks ago.
Again thanks to both you guys.
-
Resurrecting this thread despite the unit seemingly working now I replaced the brown cap. I'm going to replace those black Panasonic caps.
How can I clean off the black tar like substance that is on the PCB's? I will re-cap this unit and sell it I think.
-
Hey RG, you can buy PCB cleaning stuff (spray?). Not sure what a good brand is for that.
-
Hey RG, you can buy PCB cleaning stuff (spray?). Not sure what a good brand is for that.
I dunno, I thought most people used alcohol the isopropyl stuff. I dunno if that is going to shift the black tar like substance. I could try it.
-
CRC makes a ton of electrical sprays , cleaners etc. It's all over the states but try amazon I have gotten it from amazon before.
-
I will have a look. Also see them on amazon too :thumb-up: Thanks for that.
-
CRC also sells under the "kontakt chemie" brand name in Europe.
-
I've been reading through this thread, and looking at the pictures, I noticed something, and I wonder if it offers any explanation to the cause...
Am I the only one who thinks the screw heads that hold the PCB's to the chassis, have rust on them?
Has this Furman been stored, or used in an excessively damp environment? Furman's ARE bullet proof, but they are not waterproof. No electronics likes moisture in it's circuits.
Just an observation.
Harley 8)
-
My old house was quite cold but I wouldn't have said that room it was in was damp or anything, nothing else was affected in the slightest so I'm ruling that out. However the previous owner might have stored it somewhere.
I think the outcome of this was when I finally got caps for it it worked fine. However I have other caps that I bought that I still need to replace. Panasonic ones which can be seen in some of the pics.
-
Hey Gerry,
Have you looked at Mouser Electronics? I believe they ship world wide.
Harley 8)