3 Attachment(s)
Re: Zapco DC Reference 500.1
Might as well order more caps and tag it onto my fan order.
The caps that are in here are some cheaply made Korean brand I have never heard of. On top of the normal specs of capacity and operating voltage you need to also pay attention to operating temp range, life time rating, ripple current rating, and of course case size. With all of this info at hand I can order replacements from suppliers I know and have experience with like Nichicon and Kemet.
Attachment 10743
Attachment 10744
Attachment 10745
I have replacements on order. I'll update this post once they arrive.
Ge0
Re: Zapco DC Reference 500.1
What a great catch - good move swapping those out. Should both be a pretty fun project to swap those out and fix the fan.
So much more fun to fix an awesome amp than to pick something new up, in my opinion.
I actually need to find an amp technician - I've been watching Barevids channel (Sam in the UK) and getting into the deep dives. My first degree in college was electrical engineering, but I only got to year two before I found myself in a data warehouse implementation working with some prestigious business intelligence consultants, so I seized the opportunity to switch my major and now at 46 wouldn't know where to start troubleshooting, sad to say...
But I have an old (but still post-DEI) Orion XTR amp, a nice Xetec amp - and the one that I really want to fix, a Better Audio 1600M1, which was a nice powerhouse for a brand that I did some sub engineering for. All currently dead for unknown reasons.
Know anyone who does amp repair like Sam from Barevids? Man, I wish he was stateside. It's awesome watching him breeze through that stuff like he knows the schematics by heart. Mastery.
Re: Zapco DC Reference 500.1
Quote:
Originally Posted by
geolemon
What a great catch - good move swapping those out. Should both be a pretty fun project to swap those out and fix the fan.
So much more fun to fix an awesome amp than to pick something new up, in my opinion.
I actually need to find an amp technician - I've been watching Barevids channel (Sam in the UK) and getting into the deep dives. My first degree in college was electrical engineering, but I only got to year two before I found myself in a data warehouse implementation working with some prestigious business intelligence consultants, so I seized the opportunity to switch my major and now at 46 wouldn't know where to start troubleshooting, sad to say...
But I have an old (but still post-DEI) Orion XTR amp, a nice Xetec amp - and the one that I really want to fix, a Better Audio 1600M1, which was a nice powerhouse for a brand that I did some sub engineering for. All currently dead for unknown reasons.
Know anyone who does amp repair like Sam from Barevids? Man, I wish he was stateside. It's awesome watching him breeze through that stuff like he knows the schematics by heart. Mastery.
I used to do amp design and repair back in the day. But, found I don't have a lot of time to mess with it anymore. I may be coerced, but, there are always guys looking to buy dead amps to repair and resell them in the Classifieds forum. Keep an eye out there.
As a matter of fact their is a whole sub forum on DIYMA to discuss this topic. You may want to check it out.
Ge0
10 Attachment(s)
Re: Zapco DC Reference 500.1
I have the parts in and time on my hands to fix it. Here is where we left off:
Attachment 11165
I absolutely HATED these heat sink clamps. I tried A bunch of things to break them loose. I could not due it. Then, I watched a random youtube video from some SPL amp repair dude. He made it look so simple.
Attachment 11166
Take a tool, wedge it in the hole, then push down on the fulcrum as the inserted tip pushes up. With enough pressure the clip breaks free:
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Now finish the rest like this. If you don't have clearance or have one that won't budge change tools.
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Next, get out your 1/4" hex drive and remove 3 screws holding the PCB down:
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At picture limit. More to come...
Ge0
11 Attachment(s)
Re: Zapco DC Reference 500.1
One you have released all the heat sink clamps and have removed all three 7/34" retraining screws + washers the main board will work itself out with a little manipulation:
Attachment 11175
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Again. here are the sick and bloated caps we need to remove
Attachment 11178
And here is some heatsink crap that needs to be cleared off:
Attachment 11180
Fire up that old and crusty soldering iron. We are going to need a broad tip to do this job.
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Picture limit again dammit...
Ge0
10 Attachment(s)
Re: Zapco DC Reference 500.1
My secret underground lair. Or, extremely messy utility room doubling as electronics lab:)
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Prepping for surgery:
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A lot of this procedure I had to do without pictures because it took both hands to work. To extract a capacitor heat both leads until the solder is obviously flowing. Then pull it out gently while continuing to apply heat. If your soldering iron only has a narrow tip then you can heat one lead at a time & pull up on it. With this method you essentially walk or wiggle the capacitor out. Remember, the caps are secured down with silicon too. You may need to cut the silicon before you can pull the cap out.
Attachment 11204
Look how bloated the bottom of this cap got. The fluid inside must have boiled:
Attachment 11205
The top of this cap blew and spewed electrolytic fluid onto the amps cover. The tabs were lifted up. I pushed them back down with my finger by accident when measuring them earlier.
Attachment 11206
Extract both caps and clean the remaining solder out of the hole with solder wick. next, clean excess flux from the area with rubbing alcohol or flux removal spray. Finally scrape away any silicon left on the solder pads :
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Ge0
10 Attachment(s)
Re: Zapco DC Reference 500.1
Now you can install the new capacitors. Be careful here. I lifted a solder pad on the bottom side of the board while extracting my first cap. You'll need to solder these from the top side since the bottom solder land is gone. Simply load your soldering iron tip with solder, push the capacitors lead in the hole (watch and make sure the polarity is correct) and then heat the joint between the top side solder land and capacitor lead. Once the solder is hot and flowing you can push the capacitor in all the way. The solder will cool under the capacitor. The next lead you can solder from the bottom side like normal. The other lead will poke through the circuit board but there is no solder land to solder to. Put fresh solder on your irons tip and warm that lead up again. This will help reflow solder on the top side to make sure you do not have a cold solder joint. Unfortunately this is a cheap circuit board with light weight copper. You may end up lifting more than one solder land no matter how careful you are. Make sure to clean left over flux once done. Trim the leads right above the solder joint:
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Much of this now is just rinse and repeat. All of the secondary caps either blew of were about to explode:
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This one in particular really shit the bed. It spewed electrolytic fluid all over the board:
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Gotta clean that mess up. Don't want to leave contamination behind on your circuit board. It could eventually attract nasties that create short circuits.
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Now suck out the remaining solder out of the holes with solder wick, clean the area thoroughly, then install your new caps:
Attachment 11260
Don't forget to clear away left over solder flux when done. Deactivated solder flux is a corrosive that will attack the metals on your board:
Attachment 11261
The two electrolytic capacitors on the power supply primary didn't look too bad. However, since I was in here I decided to replace them as well to give the amp a fresh start. I didn't document this because it was identical to the others I've just shown.
Ge0
Re: Zapco DC Reference 500.1
Error. Fighting software to make sure my pictures upload properly...
10 Attachment(s)
Re: Zapco DC Reference 500.1
Before re-assembling the amp we need to clean off all the old heat sink compound and put fresh stuff on. Iso-propyl alcohol is perfect for this. You may want to scrape away larger chunks of dry stuff first before cleaning. Be patient and have plenty of paper towels handy. This is going to take a while. Be gentle, you don't want to bend transistor leads while cleaning.
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I thought at first I would use the fancy heat sink compound I use on my computer CPU and GPU. However, I forgot this stuff only spreads well when heat activated. I could not spread it at room temperature with a q-tip. So, I went the more conventional route with normal heat sink compound. Remember, you just need a light coat over the transistors. Don't goop it on:
Attachment 11267
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Now, insert the board back into the heat sink and re-place the heat sink clips. The smaller ones can be pressed back in by hand for the most part. If you can't do this with your thumb then a Phillips head screw driver will help. Just give the end a gentle tap with a hammer and the heat sink clips will pop right back in:
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Ge0
10 Attachment(s)
Re: Zapco DC Reference 500.1
Now, finish assembling the PCB and make sure everything is secured. It may be a good idea to do a quick power-up before putting everything back together. Yep, amp comes out of protection mode. Green light means go and fans are spinning:
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This is the noisy / howling fan:
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Now, clip the leads on the old fans and solder them to the new ones:
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Fans re-installed and ready to go
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One of the toughest parts is to make sure all the indicator L.E.D's are aligned properly when putting the cover back on. They are easy to bend when handling the board:
Attachment 11281
Ge0
8 Attachment(s)
Re: Zapco DC Reference 500.1
OK. Got the lid on tight. Let's power this sucker up and put the juice to it :)
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Need to use my old test mule. Can't seem to find my box of 500W load resistors. Trust me, these things are large. How could I misplace them? Each one is about the size of a shoe :(. Well, we won't be testing the amp to full load today. But, we can give it a good burn in within the 300W limit of the sub.
Attachment 11285
Signal generator maxed out at 20V and only applying about 130W to the sub.
Attachment 11286
The jumper settings are too high on my high level input converter. I don't feel like digging out the manual to make the proper jumper connections. It's easier to just switch over to the line level converter:
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There we go. 30Hz at 9.8V input is giving 300W output. I purposely set my current limit at 30A to protect the sub. Its only rated for 300W. So, ran the amp at 10V and 30A for an hour to burn it in and test it. Fans ramp up and down properly under heavy load. But, most of all they are whisper quiet. If you remember, this was the entire reason I started this exercise in the first place. A noisy / dying fan. Well, mission accomplished...
Ge0
Re: Zapco DC Reference 500.1
Hmm, can't see the pictures for the last posts, that's a shame...
So all the crap you clean off the transistors - is that essentially the same stuff you use to assemble computers, CPU to heatsinks - thermal paste?
What do you use when you reassemble it - is Arctic Silver the stuff, like it is for computers?
Re: Zapco DC Reference 500.1
Quote:
Originally Posted by
geolemon
Hmm, can't see the pictures for the last posts, that's a shame...
So all the crap you clean off the transistors - is that essentially the same stuff you use to assemble computers, CPU to heatsinks - thermal paste?
What do you use when you reassemble it - is Arctic Silver the stuff, like it is for computers?
The photo hosting on this site is hit or miss. Need to re-upload photos again for the 4th time. Makes wanting to post anything here a hassle. But, to answer your question yes. Thermal paste is thermal paste. However, you can buy grades with better thermal conductivity. The stuff I tried is highly rated. But, not easy to apply to weak and floppy transistors. I ended up using an industrial grade like I use at work.
Ge0
Re: Zapco DC Reference 500.1
Quote:
Originally Posted by
geolemon
Hmm, can't see the pictures for the last posts, that's a shame...
So all the crap you clean off the transistors - is that essentially the same stuff you use to assemble computers, CPU to heatsinks - thermal paste?
What do you use when you reassemble it - is Arctic Silver the stuff, like it is for computers?
After my 4th attempt it appears the photos are sticking now. I'm going to go ape shit if I need to redo another post.
Ge0
Re: Zapco DC Reference 500.1
Awesome results. What a can of worms, when you just expected to replace some fans! But you have to be glad you cracked it open, finding all that stuff.
Basically a complete amp restoration, for an amp that's totally worth restoring and keeping going.
Such good work. :thumbup:
Re: Zapco DC Reference 500.1
Quote:
Originally Posted by
geolemon
Awesome results. What a can of worms, when you just expected to replace some fans! But you have to be glad you cracked it open, finding all that stuff.
Basically a complete amp restoration, for an amp that's totally worth restoring and keeping going.
Such good work. :thumbup:
Thanks. I paid nearly $1000 for this sucker new 10 years ago. It was the best of its time. Even though Zapco name brand has been reduced to eBay lately I still like the design of this amp and will support.
Ge0
Re: Zapco DC Reference 500.1
On a related note - do you ever watch Barevids videos?
I'm NOT an amp tech, and I find them super interesting. He's great at taking them up a level so it's not all tech talk, but yet deep dives enough to point out individual components in amps, potential failures, things to inspect and look for, points out which amps are truly manufacturer engineered vs. salad bar contract manufacturer house specialty jobs...
Highly recommended.
I haven't really been paying attention much, and suddenly here we are in a world with... Skar? Taramps? Orion and Soundstream reduced to cookie cutter contract manufacturer brands? Pretty interesting seeing him (and Williston too, for the test side) pick them apart. Wish these guys were around in the 90's. :cool:
Re: Zapco DC Reference 500.1
Quote:
Originally Posted by
geolemon
On a related note - do you ever watch Barevids videos?
I'm NOT an amp tech, and I find them super interesting. He's great at taking them up a level so it's not all tech talk, but yet deep dives enough to point out individual components in amps, potential failures, things to inspect and look for, points out which amps are truly manufacturer engineered vs. salad bar contract manufacturer house specialty jobs...
Highly recommended.
I haven't really been paying attention much, and suddenly here we are in a world with... Skar? Taramps? Orion and Soundstream reduced to cookie cutter contract manufacturer brands? Pretty interesting seeing him (and Williston too, for the test side) pick them apart. Wish these guys were around in the 90's. :cool:
I've seen a glimpse at one of his vidoes but have not followed him. I'm still looking for more documentary videos debating the murder mysteries in Tiger King... :)
Ge0
Re: Zapco DC Reference 500.1
All this work on this amp making sure it would last another ten years. Well, I was testing subs tonight and I think it shit the bed. It heated up rapidly and blew a 40A fuse. Diagnosis does not look good. More on this in a few days...
Ge0
Re: Zapco DC Reference 500.1
Re: Zapco DC Reference 500.1
Quote:
Originally Posted by
geolemon
:runfire:
:snap:
:pout:
Yep. Spent the entire day today on the operating table. 4 hours to swap out output transistors and to re-bias the Class A/B stage. The amp section works but the input section is brain dead. I think the DSP is damanged. Stuck in a re-flashing loop.
I'm pulling the plug. Working on a deal for a Helix monoblock that will match the V Eight I'm getting on Tuesday.
Ge0
