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Recapping Fisher X19 amp and FM19 tuner

rcflybob

rcflybob

Member
Hi and happy holidays to all, I'm getting ready to do my first recap and I have a few questions as I'm am a complete newb to this. I found the following values on the existing (coupling?) brown gumdrop looking capacitors and I'm am wondering if these values will work.
Model X19 Amp
existing___________________replacement with Orange drop
RT3 .047K 250v_______________716PS .05mfd @600v
RT3 .022K 250v_______________716PS .03mfd @600v
.022 400v 10%_______________716PS .03mfd @600v

I also have this one small electrolytic:
8mfd @50v and the closest I can find is a Sprague 10mfd @150v, I've researched on here and understand that the voltage can be higher, just not lower. But what about the mfd value? Should I keep that as close as possible to the orig. value as long as its within 10%?
I also have two black plastic cased capacitors they say .01MFD 600vdc +-20% IMP . I'm looking to replace these with .01mfd@630v mallory 150's.
whats wierd is that both are connected to the same spot on only one end, I attached a photo and circled them in red to help clarify what I'm saying. Any ideas as to why they would be that way? I guess I would hook up the new ones the same way. I wondered if they were connected to the power plug which is wrapped in black tape in the photo, I've fixed the plug to the way it should be back in its holder.
FM19 Multiplex Tuner
existing_____________________replacement
RT3 0047K 400v_________________716PS .005 mfd @600v
RT3 .047K 250v_________________716PS .05 mfd @600v
.1 10% 250v________________716PS .1mfd @600v

The questions about the tuner are the same,the values are just different, with the exception that there is a 1mfd @350 electrolytic in the multiplexer and the closest I can find for that one is 2.2MFD @450volts, I'm wondering if that might be to far out of the tolerence. The large orange electrolytic is a 40mfd @350vdc and looking to replace that with a 40mfd @500vdc.
My biggest problem so far has been in trying to locate a service manual for this unit. If anybody has a suggestion as to where I can find one it would really help.
 

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You're talking about....

These units, right?....

FisherAllegroX19.JPG


Fisher_Allegro_007.jpg


If so, they came out of an Allegro or Allegro II console. I have the instruction manuals in pdf, and may have a schematic somewhere, as mine is waiting it's turn in the restore and repair queue. PM me with an e-mail for the manuals, and if you put "allegro" in the e-mail title, I'll send along the other documents when I find them.

I'll warn you, I am not organized or fast in this regard.....:no:

Also, you should be able to find exact values for the caps you are looking for. I can't really see the caps in question in your pix, but perhaps they share a common ground? Try wjoe.com for the caps. Joe should have all of them, including a 1uF/450VDC. And yes higher voltage rating is just fine for any cap substitute, limited by size and space....

EDIT: I didn't see the 1uF cap there. I know I've bought some, maybe from Digikey or Mouser. If you can't find one, let me know. I could prolly spare one....
 
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Finally starting to do the recapp

Hi everyone,

Well its been awhile but I finally started doing the recap on my Allegro X-19 amp and the FM-19 tuner will follow. Since my soldering skills were a little rusty I started with the coupling caps and replaced those with the 716PS orange drops. I also replaced the small 8microfarad @50v lytic with a 10microfarad 50v. My next ones will be the film cap and the carbon comp. resisters under the tranny, with an orange drop and new carbon comp resisters of the same value.

What kinda of has me stumped is the two .01 600v caps and the resistor going to ground near the plug. On my schematic it shows one of the caps and the 820K resistor going to the unswitched (black wire) side of the plug, but nothing about the other .01 cap. Would I be safe in assuming that it would attach to the switched (white wire) side of the plug?:scratch2: Why would the be there anyway? to clean up power? Just a newb trying to find things out.

I'm also planning on restuffing the two lytic cans that sit on top of the chassis. I have a parts order coming in from Mouser with the same sizes and new carbon comp resistors that are attached. I will take pictures of the restuffing process and post those when I start that.:yes: If anybody has comments and or suggestions about replacing anything else that I've missed I'm very open as this is my first project, and a learning process for me.:yes:
 

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What kinda of has me stumped is the two .01 600v caps and the resistor going to ground near the plug.

Fisher used those often and just as often didn't include them in the schematics. You can use orange drops there. I use .1uf 600Vs. Yeh, they clean up the power. I've never seen that implementation before, but typically, there's one from the halfway point in the voltage doubler, or somewhere about a 215v tap to ground, and the other from the top point of the voltage doubler, or asomewhere about 430v tap to the mid-way point. Just my $0.02. Are those leads clipped on one end or does one to to ground? Where's the other one go?
 
Hi Audiodon,

Both of the capacitors and the 820k resistor share the same ground point right now. The other end of all three have been clipped off, my schematic shows one of the caps and the resistor connected in parallel to the unswitched( black) wire were the power cord connects. I didn't see the other cap on the schematic but kinda thought that it probably goes to the switched(white) wire connection of the power cord. I originally was going to put mallory 150's in there but thinking that orange drops would be better, look better also.:yes:
Thanks for the two cents, it all adds up and helps me understand.:yes:
 
rcflybob,
I've never worked on that amp. But I've worked on other Fisher integrateds as well as receivers and these particular caps are always sketchy. In some, they have ceramic bodies and the bodies will remain intact and the guts will blow out one end.
 
DON'T increase those .01s! A .1 will pass abut 5 mA to the chassis, and if you touch it, that's 5 mA though YOU. 1 mA is not considered a shock hazard, but it's considered the "startle" threshold, where it might cause you to jump or drop something... more is definitely hazardous. Modern equipment must use UL approved capacitors on the power line - called 'Y' caps or "safety" caps. I use them myself in this position of the circuit (sometimes I'll eliminate them entirely...).
 
analog addict said:
I take it the service manual showed up? Keep the pix coming!...:thmbsp:
Click to expand...

Hi Alan, yep the manual came in the mail, thanks so much.:yes: Even though its for the later FM-190 model, and mine is the early FM-19 model, it really helped me to decipher the layout of the amp. In studying the schematic against my model amp I found that both the FM-19 and FM-190 are nearly identical with the exception of a few resistors being a different value. Most likely performance tweaks from the fisher engineers. Not a problem as I'm using the values of the ones on my FM-19 unit, which worked before undergoing the restoration.

Hi Tom, Thanks for the info.:yes: I plan on keeping the same .01 600v value of those capacitors. At first I planned on using mallory 150's there of the same value, but started to lean towards orange drops as I'm not crazy about the look of the 150's. Just getting picky now I guess. lol:D

My plan is to use the same values or stay as close as possible to the stock values. I'm even replacing the carbon comp. resisters with new carbon comp of the same value, my thinking being that the engineer who designed the system knew much more than I ever will :yes:
 
Did I say .1? Oops, my mistake. I meant .01.Coulda been worse than being off a column when balancing the checkbook.

The Y cap analogy works for me though Tom, thanks. I've never gotten a clear explanation before.
 
Tom Bavis said:
Modern equipment must use UL approved capacitors on the power line - called 'Y' caps or "safety" caps. I use them myself in this position of the circuit (sometimes I'll eliminate them entirely...).
Click to expand...

Tom, you got me really thinking about this now from a safety standpoint:scratch2:. Since there is no fuse on this unit would it be wise to use two safety caps in that spot instead of the orange drops?:scratch2: If so where do I get those from? and I would keep the same values, .01microfarad@600v correct? Or should I just eliminate them completely. In my first post you can see in the first pic that someone had fiddled with the power cord and clipped the caps and resistor out of the circuit anyway. So now I'm wondering if I should even bother putting them back into the circuit?
 
If there's no fuse you should add one. I use an under-chassis clip to avoid drilling big holes. The "safety" caps are available from the usual cap sources - look for "EMI suppression" or "Y" caps. They will withstand the line surges that can blow ordinary caps apart. They are usually disc or plastic box style. They're there to provide a ground for the chassis, to prevent hum pickup and provide a ground for the antenna. Also for safety when an outside antenna is used - the 820K will bleed off any static charge. With a 3-wire cord, they're unnecessary.
 
Hi Tom,

Ok, so your suggesting that I should install a fuse, say 3amp 250v and two safety caps of .01@250v along with an 820k resistor for both safety caps? Had thought about installing an inline fuse anyway but hadn't thought about the safety caps. Would the safety cap and resistor connect to the plug first and then the fuse or vice versa?:scratch2:
 
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Ok, thought fuse would come first, that makes sense after I started to think about it. Would I use two 820k resistors, one for each safety cap? Or just one 820k on the hot (unswitched) side? :scratch2: Time to go to bed, brain isn't thinking clearly.lol
 
Well, I'd fuse and switch the hot side. connect the resistor to the neutral side. You can only be SURE of this if change the cord to a polarized one (wide blade is neutral). If you keep the original cord, plug it in whichever way gives less hum or less voltage (to ground) on the chassis.
 
Here's a picture of a comparable circuit (again not completely on the schematic) of an early issue Fisher 400.

One cap goes across the diode from mid-point (~200Vdc) to ground, the other goes from the mid-point to the top point (~400Vdc). One's in parallel with CR3, which is a diode with the - tied to ground and the + to a secondary output transformer tap from midpoint to ground and is called C63, the other goes from the high voltage rail at the output of CR2 back to the + leg of CR3. The second cap isn't on the schematic though. The resistor parallels C63, but isn't on the schematic either.

Does that correspond to what you're talking about Tom? I just want to learn.
audiodon
 

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Restuffing the big lytics

Well, after getting away from the project for a couple of days and letting the brain fart clear I realized that I was reading the wires coming off the plug backwards, ie: the black was the hot and the white was the neutral. This didn't make sense though because then the white was connected to the switch. Like I said after getting away from it for awhile, the source of my confusion was very clear.:yes: I fell into a common problem of assuming that if a wire is black then its hot and if its white then its neutral.:no:I should know better than this, being a Journeyman electrician.:yes: My instructors at the academy would never let me live it down if they new.:D So, reading it like it should be read, the black coming off the plug is the neutral, and the white wire off the plug going to the power switch is the hot and when the fuse holder and safety caps come in I plan on wiring them in with a safety cap to the hot and one to the neutral and the resistor to the neutral also.:yes:Thanks Tom for helping me realize my mistake:yes: By the way, I have some 3amp 250v fast blo fuses, would those be sufficient?

The parts came in today to start the restuffing of the big lytic cans on top,:banana: I've never tried this before but figured it would be worth a shot to try and keep the original look.:yes: One other question I have though is about the two diodes connected to the large electrolytics in the attached pic. I'm assuming :D that they should be replaced, but with what type? All that's printed on them is CER70 and a google search brings up nothing. Any suggestions from the people here that know more about this than I do. Thanks
 

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Well, since this Allegro has been in the family since it was new and is two years older than me, born in '66. I can be sure that the system has not been in for any repairs or mods for the last 35 years. Anything before that and I would have been too young to remember. I do know that it was used everyday up until about a year or two ago, and it did work well before the restoration. true workmanship and quality:music:
 
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