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Heathkit AP-1800 Preamp -

jeffs79

jeffs79

AK Subscriber
Subscriber
Picked up a Heathkit AP-1800 preamp a few weeks ago.

Love the looks and functionality but it has a few issues -

Does anyone out there have a copy of the service manual/schematic for it - or, anyone have one and experienced similar issues?

The two issues with mine are:

1-Moving coil input hums with or without a MC Cartridge attached - important as I swap cartridges a lot and while I have a separate MM/MC pre, it would be nice to use the one in the Heathkit.

2-High frequency bleed through pre out selector switch - when I am playing amp "A" and switch to "B", high frequencies still are passing through to amp "A" at a lower level.

Getting ready to address both issues but would like a copy of the schematic before I jump in.
 
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Hey

Hi Jeff,

I have a few of the AP-1800's and none of them have either of the issues you describe. It is my favorite preamp of all time as you might have guessed.

I do have an original assembly manual with schematics but I'm currently on a ship until the end of November. If nobody comes through for you and you can wait till then, shoot me a PM and I'll be happy to scan the whole manual for you.

I hope you're able to straighten out the issues you're having. I've found the AP-1800 to be a very flexible and sonically neutral preamp.
 
Thanks for the offer!

Despite the issues noted with mine, I am very happy with it in terms of performance and features. While I'm fairly certain I can troubleshoot it without the assembly manual/schematics, having them is always helpful.

If no one else chimes in, I'm sure I'll be in touch.
 
Hey Jeff; I'm going to take a shot in the dark here and guess that the A/B amp switch probably grounds the deselected output. Fixing that problem may be as simple as shooting some Deoxit into that switch. Maybe. :scratch2:
 
Thanks for the reply, Artie.
I've tried the deoxit approach a few times with no change. The switch was my first though but it seems that there is more to it.
 
Still looking for the service manual. If someone happens to have it it would be greatly appreciated.

Happy New Year!
 
Springtime bump. I have my 1800 apart and caps on order but still could really use the assembly / service manual.
 
Schematic for AP-800

Jeffs79, I just found the schematic for my Heathkit AP-1800 and scanned it into pdf format so I won't lose it again. I also have the PCB artwork showing the component placement. The files are too big to attach here. If you are still looking for them, PM me with your e-mail address and I'll send them to you.
 
I know this is an old link, but if someone still has a copy of the AP1800 manual available, I would very much appreciate a copy.... my unit has a problem and a manual would make it much easier to troubleshoot.... Thanks!
 
bpasok said:
I know this is an old link, but if someone still has a copy of the AP1800 manual available, I would very much appreciate a copy.... my unit has a problem and a manual would make it much easier to troubleshoot.... Thanks!
Click to expand...

PM sent! Good luck with the troubleshooting!
 
jeffs79 said:
Springtime bump. I have my 1800 apart and caps on order but still could really use the assembly / service manual.
Click to expand...
Would you mind sharing the cap BOM you've put together? I'm thinking about restoring mine at some point. May not happen until I retire, but I always like to plan ahead.

Rick
 
Hey Rick.

Unfortunately I don't have a BOM for this. Should be pretty easy to make a list after you get into it from what I recall.

My AP-1800 is long gone. A very nice pre though and worth the recap.
 
jeffs79 said:
Hey Rick.

Unfortunately I don't have a BOM for this. Should be pretty easy to make a list after you get into it from what I recall.

My AP-1800 is long gone. A very nice pre though and worth the recap.
Click to expand...
Okay. Thanks.
 
toobleu said:
Schematic for AP-800

Jeffs79, I just found the schematic for my Heathkit AP-1800 and scanned it into pdf format so I won't lose it again. I also have the PCB artwork showing the component placement. The files are too big to attach here. If you are still looking for them, PM me with your e-mail address and I'll send them to you.
Click to expand...

Can you please send me the AP-1800 schematics to my personal email ? thanks.
 
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