• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Fisher X-100 B - restoring story

Yes, those are the leads. The schematic shows that the two AC switch sections are paralleled together which if true, is odd for Fisher, but then theoretically means that if the switch is bad, then neither the auxiliary AC plugs nor the amplifier would operate -- but we know that the switch section powering the auxiliary plugs is good. Still, it's worth checking between the black and white leads in case the sections on your unit are not paralleled together.

Let us know!

Dave
 
IMG_20160723_232051.jpg
dcgillespie said:
Yes, those are the leads. The schematic shows that the two AC switch sections are paralleled together which if true, is odd for Fisher, but then theoretically means that if the switch is bad, then neither the auxiliary AC plugs nor the amplifier would operate -- but we know that the switch section powering the auxiliary plugs is good. Still, it's worth checking between the black and white leads in case the sections on your unit are not paralleled together.

Let us know!

Dave
Click to expand...

Dave, thank you for help!
Black and white coupled have 0 Ω so (thanks God) it's not transformator failure (may not).
AC switch is well sealed with solder. Is there a service checklist to maintain it?
 
Last edited:
As I wrote I have volume a little bit more high in a right channel so I guess this issue linked with volume control/on-off switch
 
Last edited:
That's good news! -- or the least of any possible bad news anyway. The power switch is a completely separate piece of the volume control, and has nothing to do with any channel balance issues you might have.

As a point of accuracy, when your Ohmmeter is connected to a circuit that does not conduct any current at all (as in the case of the defective switch), the indication is NOT one of zero Ohms, but OL (meaning Open Lead) -- which is indicating an infinite amount of resistance present. In this case, it is the same indication that would be had if your probes were not connected to the switch terminals at all. Resistance works to reduce current flow, so with an infinite amount of resistance present, no current can flow at all. On the other hand, a true zero Ohms indication means no resistance whatsoever, meaning that there is no opposition to current flow, so that maximum possible current flow is allowed. This is (basically) the same indication produced as when shorting the probes of your Ohmmeter together, with any small reading produced under that condition being the resistance of your meter leads. In your pic then, the meter is indicating Open Lead, indicating that the circuit (or switch in this case) is "open", and not allowing any current to flow at all. And in fact it doesn't -- because the amplifier won't turn on.

I mention this only to help anyone following along who might be confused by the comment versus the picture. It is very common for folks to think that no reading on the Ohmmeter means no resistance, when in fact, it is just the opposite!

Dave
 
If you ever use an analog meter, generally the analog meter pin is to the left (infinity or open circuit.) The 1st thing you do after setting the rotary switch to a range is to ZERO the meter out by shorting the probes and adjusting the meter for ZERO OHMS. Then you can measure your circuit. An open switch or non continuity event will show as the needle sitting on the left pin (infinity), If there is continuity the meter pin will deflect to the value in ohms. If there is a dead short or no resistance the meter will deflect to ZERO Ohms just as it did when you did the meter adjustment by touching the probes together.

About the only real difference is on most digital meters( unless you have a Very High End Fluke or equivalent meter that does almost everything) there is not a ZERO ADJUSTMENT available to the owner. So what you do then is to touch the probes together,wait about 10-15 seconds for it to settle down and note the value in ohms. This value (usually between .5 and 2.0 ohms depending on the meter and the probes) is your baseline or ZERO. Once you take a measurement on the gear, sutract that initial test reading from the value from the gear.

For Example; I test my meter for zero by holding the probes together 15 seconds and it stabilizes out at 0.7ohm. That is my ZERO. Now I test a resistor that is supposed to be 220K and get 239.2k ohms. Subtract 0.7 from 239.2K to get 238,999.5ohms.

Recapping; Functionally OL or O/L on a digital is equivalent to an Analog meter sitting on infinity (open circuit). Depending on the meter you may have 1 or 2 decimal places and a ZERO OHMS reading will always take those into account. (0.00 ohms) plus the zero measurement. This is equivalent to the Analog meter deflecting across the meter face to ZERO OHMS.
 
dcgillespie said:
That's good news! -- or the least of any possible bad news anyway. The power switch is a completely separate piece of the volume control, and has nothing to do with any channel balance issues you might have.

As a point of accuracy, when your Ohmmeter is connected to a circuit that does not conduct any current at all (as in the case of the defective switch), the indication is NOT one of zero Ohms, but OL (meaning Open Lead) -- which is indicating an infinite amount of resistance present. In this case, it is the same indication that would be had if your probes were not connected to the switch terminals at all. Resistance works to reduce current flow, so with an infinite amount of resistance present, no current can flow at all. On the other hand, a true zero Ohms indication means no resistance whatsoever, meaning that there is no opposition to current flow, so that maximum possible current flow is allowed. This is (basically) the same indication produced as when shorting the probes of your Ohmmeter together, with any small reading produced under that condition being the resistance of your meter leads. In your pic then, the meter is indicating Open Lead, indicating that the circuit (or switch in this case) is "open", and not allowing any current to flow at all. And in fact it doesn't -- because the amplifier won't turn on.

I mention this only to help anyone following along who might be confused by the comment versus the picture. It is very common for folks to think that no reading on the Ohmmeter means no resistance, when in fact, it is just the opposite!

Dave
Click to expand...

Hello guys!
Volume/switch on-off pot was removed and disassembled. Volume blocks were cleaned and restored but on/off block burned-out.
I read several threads and here are ways to get rid of this issue:
1. Solder contacts to make amp be powered on every time
2. Put new not original switch (drilling the chassis will need)
3. Get lucky and find original NOS or used pot

So I choose 1 but is searching for 3.
Where can I find original pot?
 
Last edited:
Hello guys.
A kind gentleman from AK community offer me 2 different switches but I don't know which to choose (left one or right one?).

Please help!

a49f0112-99cc-489f-85c2-b57d305e819f.jpg
 
They are probably functionally the same. Pull yours off and match up the mounting flange side. There are 2 different types used by FISHER. Both are Dual POLE Single throw (DPST) switches, but the mounting flange is different as is the case. Match the case and mounting flange up and you should be good.

Take a couple of pictures of your switch (top, bottom. side) and post here.

As for the two shown, I'd think the RIGHT HAND one is closer but no way to tell on the mating flange/case. This is where multiple angle pictures come in handy.
 
The pictures of those switches help, somewhat. What would narrow things down are pictures of YOUR original switch. Remember, what you've pictured is actually a volume pot AND a switch. The rear section where the power terminals are is the switch section; the knob, obviously, is the pot. Both of the samples you have are not familiar to me as switches used by Fisher. Either would work IF the internal mechanism is the same as your original switch and IF you could mount the switch case to the pot. If you can't mount the switch securely to the forward section, it just ain't going to work.

The one with the white insulator might help you nonetheless. Other than the case, it looks very similar to the switch Fisher used. If so, and if you're up to it, you can take that switch apart to see if the guts are the same as your bad switch. If so, you can swap for parts. If you're not comfortable rebuilding it, then your only option is to wait until one pops up for sale.

This post will give you an idea of what to expect;

http://audiokarma.org/forums/index.php?threads/fisher-fm-200-b-muting-switch.635478/

In post #48 you mentioned that you took the switch apart, If you took pictures, post them. They'll help determine what you need..
 
Last edited:
notdigital said:
The pictures of those switches help, somewhat. What would narrow things down are pictures of YOUR original switch. Remember, what you've pictured is actually a volume pot AND a switch. The rear section where the power terminals are is the switch section; the knob, obviously, is the pot. Both of the samples you have are not familiar to me as switches used by Fisher. Either would work IF the internal mechanism is the same as your original switch and IF you could mount the switch case to the pot. If you can't mount the switch securely to the forward section, it just ain't going to work.

The one with the white insulator might help you nonetheless. Other than the case, it looks very similar to the switch Fisher used. If so, and if you're up to it, you can take that switch apart to see if the guts are the same as your bad switch. If so, you can swap for parts. If you're not comfortable rebuilding it, then your only option is to wait until one pops up for sale.

This post will give you an idea of what to expect;

http://audiokarma.org/forums/index.php?threads/fisher-fm-200-b-muting-switch.635478/

In post #48 you mentioned that you took the switch apart, If you took pictures, post them. They'll help determine what you need..
Click to expand...

Hello notdigital!
Thank you for your help!
Problem is I haven't got switch anymore because service guy removed it and solder 2 signal cables so my amp is always power on.
Ebay can't helps me ((
 
OR -- just post a good pic of the back of your volume control and that should be able to indicate which type of switch your unit uses.

Dave
 
Not to scare you but that switch has 3 tabs that you can clearly see in the second picture from the left. When you lift those 3 tabs, the actual switch is disengaged from the other section. Unless you have a volume pot case that accepts those tabs, you cannot mount it.

I believe the "protection hack" you're speaking of is the addition of a thermistor to slowly ramp up voltage to the unit.

As has been mentioned, the best thing to do is post a picture of the back of your volume pot so we can see what you have.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom