X-101-C in need of help

[MadPik]

Greetings All and Hello! I've been reading through this forum like crazy and hope I can get some guidance from all the knowledge here. My apologies if this turns into a bit of a long post.

My father purchased this amp new and at some point upgraded to new equipment, put the x-101-c on a shelf in the basement, and there it sat for at least 30+ years (I'm 32 and never seen it in action). He states it was working when he put on the shelf and to the best I can tell everything is original except for one of the 7591 tubes is a different brand. Fast forward to a couple of weeks ago, family was over which resulted in the amp getting pulled out, admired, and eventually hooked up and plugged in (not the right way to go about it I know ). Before I get to the issues, here are some pics:

Fisher x-101-c

• MadPik
• Mar 2, 2019

Fisher x-101-c

• MadPik
• Mar 2, 2019

Fisher x-101-c

• MadPik
• Mar 2, 2019

When plugged in all of the tubes glowed like normal, however, there were the following issues:

1. There was no sound output.
2. The resistor indicated in the following picture became very hot (220+ degrees F) within about 10 seconds and began to smoke. Once this occurred the amp was unplugged.
   

   Fisher X-101-c resistor

   • MadPik
   • Mar 2, 2019
3. As I've learned is a common problem, the volume pot/switch does not click to off. The amp remains on unless unplugged. Additionally, the case and rear of the volume pot appear to have experienced some heat as seen here:
   

   Fisher x-101-c Volume Pot

   • MadPik
   • Mar 2, 2019

Since it's brief moment being plugged in, the only thing I have done is test the "hot" resistor which showed as normal on the multimeter.

This is where I turn to all of your amazing knowledge. Where do I start with all of this to make sure I don't cause any more issues?

(For background I am mechanically inclined although knowledge of the inner workings of electronics is at the bottom of my knowledge bank. I have experience building RC cars and the like so I'm comfortable soldering etc. but aside from that this is pretty far out of my element. With that being said the more you can "explain it like I'm five" the better and greatly appreciate the extra time that takes).

 

[notdigital]

Welcome aboard Mad. You've certainly hit the right place to get that heirloom up and running!

At this point, a good start is to get your pics up so we can see. Your links aren't working. Perhaps you can post to AK's servers by using the button on the bottom right: "Upload a File." That way we can all see what you're talking about and guide you from there.

As a preliminary matter, as you've probably read, one shouldn't apply full voltage to a piece that hasn't had any juice run through it for 30+ years. Kinda like a bucket of ice on a slumbering drunk. Still drunk but now pissed. I don't think you killed it but a variac would come in very handy during the early stages of restoration. A dim bulb tester as well. With those two diagnostic tools at hand you can confidently move forward in getting your family's X-101-C up and running! Remember, patience is a virtue with this kinda project. Also, download and print the Service Manual found here:

http://akdatabase.com/AKview/albums/userpics/10004/Fisher X-101-C Service Manual.pdf

 

[notdigital]

I think he's already here Tim. At least that's where I found the post.

Anyway, you've got original Fisher branded Westies there dude! Really nice tubes One quick question: what was your connected source when you first fired it up? Also, the heat damage at the volume pot is indicative of a toasted switch. Not fatal to operation though. In my view, it's an important but still a punch list repair.

 

[MadPik]

Thanks notdigital! I uploaded the photos to an album here before adding them to post. I noticed the permissions were set to private for the album, I've adjusted it so others can view, hopefully, that fixed the links. Thanks for the link to the service manual. A variac is on my list of gadgets to acquire, what size is would be appropriate?

Tim D - Am I not in the Fisher subforum? If not the admins can feel free to move this to the most appropriate place.

 

[MadPik]

Anyway, you've got original Fisher branded Westies there dude! Really nice tubes One quick question: what was your connected source when you first fired it up? Also, the heat damage at the volume pot is indicative of a toasted switch. Not fatal to operation though. In my view, it's an important but still a punch list repair.

Thanks! It was hooked up to an iPad via the AUX inputs and to a pair of speakers. 3 of the tubes are speakers. One is another brand. I don't recall what though and am not home at the moment.

 

[notdigital]

...... A variac is on my list of gadgets to acquire, what size is would be appropriate?

Unless you're planning to work on a good number of pieces, get something small. I'm sure anything from 5A to 10A 130vac is more than enuf.

Before moving down the road, casually read though a few restoration threads. Doesn't really matter what is being restored. What you're looking for are the basic first steps which, most importantly, includes cleaning. That is all the electrical contacts involving the rotary switches, slide switches, copper contacts, tube pins and sockets. All of it. The metal oxidizes and forms a barrier preventing, believe it or not, proper signal transfer. In the most hopeful case, if your "no sound" condition is simply due to oxidized contacts, you're 80% done! Cleaning is a painstaking process but absolutely necessary.

Just so you know, that green resistor that you said got hot gets hot under normal operating conditions. Whether it is excessively hot depends on the condition of the capacitor it is servicing. For me, that is always the first port of call: the multi section can capacitors. I address them ALWAYS. Some folk just replace the section that is leaky or shorted but I just rather replace the entire assembly. But that's just me. Once you get everything clean and the amp is run through a variac, you can begin your analysis and formulate a restoration plan that will make your instrument run safely and with confidence.

Good luck and again, welcome aboard. The folk here are extremely helpful and knowledgeable so you certainly are in the right place!

 

[bhamham]

I have an X-101-C on the bench right now. If you can do RC cars then these guys should be a walk in the park. Do they have capacitors in those cars?

My first order of business is to replace all the electrolytic capacitors in the unit including the cans on top of the chassis. Lots of different ways to do this - you can search the forums to see how everyone does theirs. Then it's a bit of fine tuning... replacing out-of-spec resistors and film capacitors; doing a couple of modifications for safety and longevity and verifying whether your tubes are good or bad. Oh, and replacing that volume control switch.

That's a lovely X-101-C; it would be really nice to preserve a family heirloom.

Welcome to the Fisher group!

 

[MadPik]

Before moving down the road, casually read though a few restoration threads. Doesn't really matter what is being restored. What you're looking for are the basic first steps which, most importantly, includes cleaning. That is all the electrical contacts involving the rotary switches, slide switches, copper contacts, tube pins and sockets. All of it.

I've read through a few restoration threads already and think I have a good understanding of the basic premise. Cleaning is certainly a task I can handle and will begin working on that while waiting for the variac to arrive. After that will be the bigger challenge as I don't feel I have the knowledge yet to fully understand how everything works together and what and where to test.

My first order of business is to replace all the electrolytic capacitors in the unit including the cans on top of the chassis. Lots of different ways to do this - you can search the forums to see how everyone does theirs. Then it's a bit of fine tuning... replacing out-of-spec resistors and film capacitors; doing a couple of modifications for safety and longevity and verifying whether your tubes are good or bad. Oh, and replacing that volume control switch.

Any recommendations on a reliable source for the capacitors and other components I will likely need? I've seen Hayseed Hamfest sells a re-cap kit. I also stumbled across this kit on ebay. The seller also sells a modern production volume pot. Are any of these worth it/a good route? I like the idea/convenience of a kit that is already put together but I also don't want to foolishly spend money (although this is all foolish if you ask the wife ) or sacrifice the quality of the parts for the sake of convenience. Finally, what modifications/upgrades for safety and longevity are recommended?

That's a lovely X-101-C; it would be really nice to preserve a family heirloom.

Thanks! My dad engraved his driver's license number in the case back in the day so it certainly is a family heirloom haha.

 

[bhamham]

I have bought one of those volume pots/switches you referenced for a Fisher 500-B and was very pleased.

I buy discreet caps and resistors from Mouser. I stuff my own cans and leave the bottoms intact as not to desolder all the lugs to remove the entire can: http://www.audiokarma.org/forums/index.php?threads/fisher-x-100-3-refresh.841240/#post-12053138
Many here like the Hayseed Hamfest cans and I've not heard a bad word about them.

That was the thing back then using those engraving tools to inscribe DL's numbers and other identifying info.

 

[notdigital]

The place I start is cleaning. A low cost but labor intensive exercise. Completing that task will eliminate oxidation/corrosion from the equation. Sometimes you have to go at it again but you'll know it because the unit will have some life assuming nothing else major is wrong.

Assuming it was working when shelved years ago, then the capacitors need to be woken up, or reformed. The fact that any individual cap can still function currently is no guarantee that tomorrow will be the same. As part of your restoration, a decision has to be made as to which components you want to swap out. Some replace every electrolytic and film capacitor in the unit. Some are more selective. For me the notion is always to see if the unit can make a sound. If it does, then you'll be way ahead and you can then begin replacing individual components. Of course, that's where the variac comes in.

Personally, I shy away from kits. That is because I'm frugal and I rather pick the component I need/want and go to one of the big vendors with a list of what I want. I rather spend the money on the highest quality component instead of giving a chunk to a vendor for his assemblage. Just me. That said, however, Jim McShane puts together excellent packages almost in a custom way. But again, you're paying a premium for his expertise. If you're going to put together your own list, Mouser, DigiKey, for example, are trusted sources. Not so much at the auction house because of so much bogus merchandise in the stream of commerce. In the end how you move forward with this aspect will depend entirely on you.

As far as "where to test, well, you're going to have to consult the schematic for that. As I mentioned, I always start with the can capacitors. Virtually everything downstream is connected to them. If any one section is unhealthy, then the unit will never perform as designed unless you make the correction. As Bruce mentioned above, there are lots of ways to do this and you're going to have to make a decision in that regard.

That said, here are the cap connections:



You'll notice that there are voltages specific to certain points. Those are ideal, or design measurements in an otherwise perfect world. You'll never hit those numbers but getting close is possible. At the outset the trick is learning how to read the schematic and then safely test for voltage. Not trying to scare you but being careless messing with high voltages will curl both the short and long hairs. So, as your restoration progresses, I and certainly others will come along and advise you on how to proceed with caution.

Most of the time I mount a blown up copy of the schematic on a piece of cardboard so I don't have to consult the computer or further ruin my eyes by referencing a hard copy. If you're not skilled at reading a schematic, now is a good time to familiarize yourself with how the real life components are logically laid out in a conventional schematic. The can cap group is a good place to start.

I do not have a 101-c but I always loved the look of the line of instruments that have that drop down door feature. The contrast of the face plate is just too cool. Once you get this thing singing I think even the wife will be sold!

 

[RUmad]

The x101c is a breeze to bring back to life, and a great first project. It’s not over complicated and there are no bypass caps to dig out and replace. Just keep in mind the can cap with the cardboard sleeve over it is part of a voltage doubler and the entire body of it is positive. That threw me off for a minute, I was happy I didn’t blow anything up before I realized. I love the hidey-hole control panel too, and it sounds spectacular about three years after I last had it apart. Good luck which her.

 

[MadPik]

Wow. I'm truly overwhelmed by all the support with this. My plan is to get started with cleaning while I wait for the variac and other tools to arrive. I'll update if I encounter anything interesting and when I'm ready to start actually testing/repairing.

For those following along, my goal with this project is to restore this amp to a functional state that is going to be fairly safe and reliable. I'm interested in any modifications that meet this goal or improve sound quality so long as the modifications are fairly simple provide a good benefit for the cost.

 

[RS Steve]

It's very possible that someone sprayed contact cleaner into the power switch at one time causing it to cause a brief fire or blowout. I had one of my Fisher units that had similar damage, if not worse. I was able to find a replacement, although common for these switches to fail, not common for them to show such a burn out. Most should know anything liquid and possibly flammable should not be sprayed into these switches, only the control pots. Your amp should really be nice when finished!

 

[MadPik]

Howdy everyone. So I've been slowly working on cleaning all the contact points on the Fisher but haven't had much uninterrupted time to work on it. I also got slightly distracted cleaning up my old JVC R-S77 while I had everything out.



Also, a guy near me is selling an old B&K 1472c 15Mhz oscilloscope for $20. He claims everything works. I'm inclined to get it 1. because it's cheap and 2. because it's old and interesting, but I also don't need any more unused old junk sitting around my house haha. Would this be worth picking up? Would it be useful to have? I can see myself getting more into basic electronic repair as I continue to learn more.



Have a great weekend everyone!

 

[thornev]

It's worth picking up if you plan to learn how to use it and have a plan that involves using it on a regular basis. I have one, I'm a novice, but it was useful when debugging a volume imbalance between my 2 channels. I could see both waves at the same time (using a frequency generator to input a 1kHz sine wave to each channel) while probing around my amp.

 

[MadPik]

It's alive! So I went through and carefully cleaned all of the switches, contacts, etc. and then powered it up slowly over a couple of days on the variac before reaching full power and giving it a test. The hot/smoking resistor problem is gone and I have sound output! I didn't have time to give it an in-depth listen or test anything other than the main speaker output but so far I haven't heard any obvious buzzing, popping, or other unfriendly noises.

I think my next steps are going to be:
1. Check/adjust the bias.
2. Replace electrolytic capacitors.
3. Replace the faulty power switch.
4. Test and replace any other out of spec capacitors and resistors.

For the bias is it as simple as taking a voltage reading at pin 5 of an output tube and using the bias trim pot to adjust to about 40v? Multimeter red lead to pin 5 connection and black lead to a ground point?
Are there adjustments to the phase pots as well?

 

[larryderouin]

2 of the best of the X-101-C threads on The fisher Forum

By the late Audiodon (RIP BUDDY!) https://audiokarma.org/forums/index...s-x-101-c-integrated-amp-restorations.491521/

And improving the X-101-C to the nth degree, by our own Dave Gilliespie. https://audiokarma.org/forums/index.php?threads/improving-the-fisher-x-101c.582379/

Read, READ, READ! Study these until you know it inside out, backwards and upside down. Best way to get intimately familiar with the X-101-C.

 

[audmod01]

MadPik;

Your X-101-C is a very handsome amp in its factory cabinet! You will find plenty of help here. Like another member, I prefer to either rebuild the existing can capacitors or replace them completely. I found rebuilding the existing ones a labor intensive task and I finally relented and bought new can capacitor set from Hayseed for my current 800-C restoration. They go in with less work that rebuilding existing capacitors.

I also have an X-101-C that I restored some time ago and it has developed some drop-out issues on the right channel which come back sometimes if the power switch is toggled off and on. That is usually an indication of a capacitor that is intermittently open circuit. This amplifier serves me when I am working in the barn. I have a set of customized speakers that are connected to the Fisher. Each speaker has a 15" woofer, two 5" mid-range speakers and 2" tweeters. I custom tuned each woofer (a replacement from Parts Express) using a set of 4" PVC pipes with some port flares on each end. The low end goes down to around 22Hz with authority now. I am hoping to find the bad capacitor in my X-101-C and get it back into service. The amplifier had been much hacked and modified before I acquired it. It was a long path bringing this one back from the brink.

Mine is in a metal cabinet which came with it. The rear screen is missing and I need to find a replacement.

I know you will be well pleased with the performance of your amplifier when it is finished. Your wife will like the simple push-button function choices and two main controls present on the outside. Having the other controls behind the door makes for a very clean and uncluttered front panel appearance.

Have fun!

Joe

 

[MadPik]

2 of the best of the X-101-C threads on The fisher Forum

I originally read through both of those. What an incredible amount of info! I understand more each time I go back to them now that I've spent some time poking around the Fisher and reading up on electronics in general.

I found rebuilding the existing ones a labor intensive task and I finally relented and bought new can capacitor set from Hayseed for my current 800-C restoration. They go in with less work that rebuilding existing capacitors.

I've been leaning towards the Hayseed cans for that very reason. The process seems simple enough, just a lot of tedious labor and greater chance for me to mess something up.

The rear screen is missing and I need to find a replacement.

There seller on everyone's favorite auction site that sells reproduction screens for ~$30. They're listed for the Fisher 30U cabinet but claim in the ad that they'll make it any size you need.

Now for an update on my progress:

1. I ended up ordering a new volume pot/switch to replace my faulty one. It should arrive this weekend so hopefully, I'll have time to install it soon.
2. I've put together a list of what capacitors, diodes, etc. I think I'll need to replace the current ones. I'd really appreciate a second set of eyes from all of you knowledgeable folks here if anyone is willing. I saved my mouser cart as a PDF so I could share it here or through PM (I'm not sure if I'd violate any forum rules by posting it directly here.)

Thanks again, everyone!

 

[audmod01]

MadPik;

I believe you are on the right track. The most likely to fail capacitors that can cause you considerable expense are the coupling capacitors between the Phase Inverters and the signal grids of the output tubes. If one shorts it will take out an output tube and those are costly these days.

I just repaired my X-101-C today. It had developed an intermittent short that was grounding out the left channel at the LM82 Op Amp that I had added previously. It was being held in place by double-sticky foam tape. Two layers of the tape stopped the problem. It is singing sweetly again.

Joe