HeathKit Amplifier AA-1800

Not yet, but I think both of those will get a recap irregardless of operational status. In my working life I was a paperwork nut besides fixing HVAC. If you guys wait a little bit I will create a spreadsheet + photo layout of all the caps values, voltages for both the AP-1800 and the AA-1800. Something like this one I made for my TEAC + OTARI MX-50505 four channel reel-to-reel system. I also replaced the caps in the OTARI. And I totally redrew all the schematics for the OTARI. Example below. Much more data than I can fit on poor old AudioKarma's servers . Anyone interested?
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HVAC - how much difference do you think the caps will improve the unit? Also, would we have to do the power sections also? It doesn't make sense to do the pre-amp without doing the amp does it? I have used Nichicon and Elna with good success. I have also completed a lot of 80's speaker crossovers, and just about every cap I pulled was over uf by at least 10%, and most 20%. I have yet to find a cap the was under value. Wonder if these board caps suffer the same consequences?
 
Hello BJJB Jr.;
I am presently in the middle of a teardown of my forty year old Heathkit pro gear setup. So far the only item that shows signs of distress (low, distorted output - one channel) is the AJ-1600 FM Tuner.
Many would argue that all capacitors, being "wet chemistry" should be pulled and replaced in equipment of this era. I am a member of that school. And being retired and needing something to do makes it fun. The cost is minimal. Axial type caps are rapidly disappearing from the suppliers. Even "audio grade" lead-type capacitors seem to be harder to get. Everything is going SMD. Bad for us old guys!
Heathkit makes it very easy to perform a recap. All the PCB's are easy to get to, have tough foil construction, and the documentation is exceptional.

So, I think the answer to your questions would be yes, a recap will certainly improve the sound. And definitely improve reliability. Especially the power supply. And you are correct; if you are doing one, do them all.

If a 250 watt amplifier with 100 volt DC power supplies virtually directly connected to your speakers goes flakey bad things can happen very quickly. So why risk trusting 40 year old devices that there is universal agreement they have a expiration date? There's a fellow on the Internet who recently obtained a unbuilt AP-1800 preamplifier. He went thru testing many of the capacitors that had been bagged up forty years ago. They all tested fine. But he stated he was going to buy and install new caps. Makes sense to me.

I am working on scans that will help others with recapping these guys. Let me polish them up and I will submit to this post. Standby.
Chris
 
I had a AP-1800 pre for a few years. it was my work set up so it didn't get pushed but I thought it sounded fine. I didn't recap it and doubt it was recapped before I got it.

I'd get the power amp working. I'd only use the pre and power bits to see how it sounds. add the other stuff once you know these are working (or leave out).

if these are your first separates, don't forget to turn on the pre first, volume down, turn on power amp (if you are using the speaker switch on the pre amp, set to off), wait until protection relay clicks in, select speaker. reverse when you turn off the gear.

I'd keep it simple and not use the speaker switch on the preamp. pre out to power amp. use a CD player or similar source on the aux 1 or aux 2.
 
Add some locks on the speaker outputs! And add an extra set of outputs on the back. Run them thru key controlled relays.
And those level controls are the Allen Bradley Type J's I was talking about earlier. They even have lock nuts on the shafts.

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Retired HVAC said:
Hello BJJB Jr.;
I am presently in the middle of a teardown of my forty year old Heathkit pro gear setup. So far the only item that shows signs of distress (low, distorted output - one channel) is the AJ-1600 FM Tuner.
Many would argue that all capacitors, being "wet chemistry" should be pulled and replaced in equipment of this era. I am a member of that school.
.....
Click to expand...
The tuner probably has quite a few ceramic capacitors. Those are very unlikely to need replacement.
 
Hello fred soop. Thanks for writing. I made a list of all the caps that have a polarity. I agree that the ceramics, Mylars, and the Tantalums can remain. I'm a "shotgun" recapper. I figure if the boards out; why not? The ones in blue were ordered and arrive today. I'm probably going to regret this recap. I think it will be a miracle if it picks up any stations after all these guys are pulled and replaced. Wish me luck!
Chris
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I also replace all electrolytics and many film caps. I recently worked on an amplifier that came with many pages of paperwork and the original owner was apparently replacing single capacitors as they went bad over the years. There was channel unbalance and a lot of still, sort of working, but bulging dried out electrolytics. No reason to not clear the boards and start over. This also allows replacement of carbon composition resistors with metal film, or at least carbon film and bumping up values of coupling capacitors.
 
Hello all. Will sign off of this AA-1800 posting. Great advise and nice talking with you all.
May start another post concerning the AJ-1600 FM Tuner which I kinda' snuck into this one. The recap went fine. The list above is accurate in both value and count.
But of course the recap did not fix the low, distorted output. Poking around (why did I give away my analog scope?) I found that, believe it or not, the 19kHZ & 38kHZ CoilCraft P/N 52-183 was dragging down the signal. A company with this name exists and I just wrote them about availability. Hmmmm...
Probably just end up jumping it out. Heathkit warns this could be bad: "The output ..... is coupled to low-pass filter F205. This filter additionally attenuates any remaining 19 kHz signal and greatly attenuates the 38kHz subcarrier frequency.These frequencies must be eliminated, as nearly as possible, to prevent tape recording problems". No biggie for me.
Chris
BTW; look at all those pretty capacitors! (I'll get the grey boy showing on the upper right changed out today)
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Chris:
I was looking at the capacitor list for the Heathkit equipment that you have and the FIRST cap listed is for the AM tuner board C131. Your list says the value is .47mfd and the sch. says the value is .33mfd. Which is correct?
I have two AJ1600 tuners and the audio output from the AM section is low and checking the sch and your list shows the difference. In my experience repairing commercial equip. , the value range really does not make that much difference. I will use a .47 mfd mylar cap to replace this electrolytic.
Thank You VERY much for the work that you did for this list and more. I will be ordering the caps from this list for my equip soon.
Ed
 
Good morning edlipman.
Good catch on the value mismatch. When recapping I start with Heathkits part listing value in the manual. Then I double-check what they list in the step-by-step instructions. Then, since Heathkit does not list voltages in either of those locations, I pull the PCB's and obtain the voltage values from the parts on board. At that point I also check to see they jive with the µF values. I never thought of the schematic as a final check.
To sum up: The manual (©1978 p/n 595-2147-02) / parts listing / actual on-board part for my tuner was 0.47µF. And a quick check after replacement showed the tuner did pick up a AM station or two. Not a lot of AM stations in Dover, DE I guess. I'm a FM listener.
BTW; I started a "Heathkit AM/FM Stereo Digital Tuner AJ-1600" posting on this site that has some stuff that may help you on your recap project.
Chris
 
Update:
Found another cap value mismatch.
C292 shown on schematic as 250µF but listed on parts list (and actual part value installed on PCB) ends up being a 220µF.
Chris
 
Replacing power supply capacitors in AA-1800? My amp is working fine, but after reading through this thread, I think I want to replace the capacitors in the power supply. The 40-year original one were rated at 13,000 uF @ 100 v. Since the voltage I measure at the output is actually slightly higher than 100 v, is using 100v rated capacitors risky?

I haven't done much of a search for replacement capacitors, but it seems that I would need to buy 100v rated capacitors or 200v rated ones - which ranges from risky to overkill. Also, 13,000 uF isn't that common of a rated value - would going to 15,000 uF be too much? Do you have a recommendation for a good source to purchase these?

Ben
 
Ben - I know it's late for this but coincidentally I recently recapped my AA-1800 and I replaced the two 13,000 uF filter capacitors with 15,000 uF. I believe the manufacturer is NIPPON Chem-Con. The casing color is like a Ford Mustang "Grabber Blue." The caps along with a number of other electrolytics, transistors and a few other components were included in a pre-packaged kit for refurbishing the AA-1800. My amp is working great.
 
BJJB Jr. - For what it's worth at this late date I can tell you that I recently recapped my AA-1800 using one of those refurbishing "kits" that a seller on eBay pre-packages for a variety of vintage amps and preamps. I was able to install all of the various components on the amplifier PCBs without separating them from the power transistors and heat sinks. Most of the affected components are located around the edges of the boards and are relatively easy to remove and replace. Those few components that are tucked a little further within the gap between the boards & heatsinks can be installed with the deft use of needle-nose pliers and a little creativity (i.e., shorten the leads and bend them slightly as necessary to facilitate angling the part into the holes in the boards.) Maybe use a short stiff piece of wire in your other hand to help guide the stubborn leads into their holes. Working like this in the midst of other components close by you can't be like a bull in a china shop but at age 69 with somewhat limited close-up vision I was able to do it without much difficulty.
 
Weeb said:
BJJB Jr. - For what it's worth at this late date I can tell you that I recently recapped my AA-1800 using one of those refurbishing "kits" that a seller on eBay pre-packages for a variety of vintage amps and preamps. I was able to install all of the various components on the amplifier PCBs without separating them from the power transistors and heat sinks. Most of the affected components are located around the edges of the boards and are relatively easy to remove and replace. Those few components that are tucked a little further within the gap between the boards & heatsinks can be installed with the deft use of needle-nose pliers and a little creativity (i.e., shorten the leads and bend them slightly as necessary to facilitate angling the part into the holes in the boards.) Maybe use a short stiff piece of wire in your other hand to help guide the stubborn leads into their holes. Working like this in the midst of other components close by you can't be like a bull in a china shop but at age 69 with somewhat limited close-up vision I was able to do it without much difficulty.
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Thanks Weeb, I just completed my AA-1800 rebuild with a kit I bought online for $185. I think the kit was worth it overall, as the seller sells just the 2 large caps for the same price. The new caps were the same as yours 15kuf Nippon. Overall nice kit. I would however recommend, these other upgrades I did. Replaced all the large carbo resistors (all out of spec), AND they are the main source of the stable 50 volt rail. Replaced both of the input pots (100k), as they were shot. Replaced the short input audio cables. Replaced the input rca connectors, as the original would spin. Replaced the speaker terminals with banana jacks. Set bias at 35va and offset to 0. Sings along wonderful, and soooo nice to have those accurate pots. bj
 
BJJB Jr. said:
Thanks Weeb, I just completed my AA-1800 rebuild with a kit I bought online for $185. I think the kit was worth it overall, as the seller sells just the 2 large caps for the same price. The new caps were the same as yours 15kuf Nippon. Overall nice kit. I would however recommend, these other upgrades I did. Replaced all the large carbo resistors (all out of spec), AND they are the main source of the stable 50 volt rail. Replaced both of the input pots (100k), as they were shot. Replaced the short input audio cables. Replaced the input rca connectors, as the original would spin. Replaced the speaker terminals with banana jacks. Set bias at 35va and offset to 0. Sings along wonderful, and soooo nice to have those accurate pots. bj
Click to expand...
Nice to hear from you my friend. Sounds like you done good with that AA-1800. Thanks for elaborating on the changes you made - it's good info for me. I had considered changing the input pots on my amp and had the parts on my wish list but decided against biting off more than I could chew since it was working fine except for a very slight hiss in the right channel. I bought the amp in roughly 2005 from a guy who had built it back in the day and personally recapped it circa 2002-2004. He was more of a tech than I am and even gave me all the old parts he replaced. I didn't notice the hiss until a few years later, and it is the reason I finally did the recap, which cured it. However after I got my system up and running I was perplexed to find a problem with my AP-1800 preamp. The right channel had reduced volume and slight distortion in the phono 1 circuit off and on. So I bought another recap kit from the same eBay source, recapped the unit and carefully cleaned every switch and pot with Deox. Everything sounds like new again and I'm very happy, so much so that I'm attaching a picture to show off a bit! I think you'll recognize the Heathkit components. The rack is Heathkit as well. Resting (unmounted) on top of the preamp is a 1990ish Yamaha "Natural Sound" CD player. The turntable is a Bang & Olufsen TX 2, also 1990ish. Peeking in on the right is my vintage Nakamichi LX-3 cassette deck circa mid-70s. Everything runs through a pair of JBL L112 speakers that my wife gave me as a wedding present back in '83 (she loves me for some reason).
 

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