9444A

[GFORCEMS12]

I bought an Altec Lansing 9444A and wanted to find out what everything was on the back panel, how to hook it up and use it. Does anybody have or know where I can a get complete manual for it. I read the pages this site has on the 9444b but it doesn't give the info I seek. Any help is appreciated.

[GM]

Greets!

Maybe here? http://www.servicemanuals.net/

GM

[bfish]

I scanned my hardcopy to PDF, and will email you a copy. Watch for an incoming 4.5MB attachment.

[Todd W. White]

Send me one too, and I will try to get it on the website when I do the upgrade - I'm working on getting a whole lot of new literature scans posted as soon pretty soon.

[bfish]

Will do. The scanned version is 11MB, and I made a reduced size copy for emailing. Will try the big one first.

[bfish]

My $39/mo. Cox account choked on the file size, but the $19/yr. Hotmail took it OK.....go figure!

[amh]

bfish;

Does your manual include the service portion with schematics and bias/offset adjustment procedures? I also have a few 9444As, but only manuals for the 9444Bs. No luck so far finding info for the As.

Thanks

[bfish]

Yes, it's complete. Send me your email addy, (mine's in my profile), and I'll send a copy. Todd should have the file now, so it should be available as soon as he gets the chance, but I'll post the offset and bias procedure anyway. The components designations referred to are marked on the board, it's a very simple procedure;

9444A(SA) only
Control settings--Dual Mode, both attenuators at 0.
All I/Os disconnected.
Allow 2-3 minutes warmup for values to stabilize.

DC offset adjustment;
Adjust trimpot R15 for 0VDC, +/- 10mvDC at Channel 1 output terminals.
Adjust trimpot R115 for 0VDC, +/- 10mvDC at Channel 2 output terminals.

Bias adjustment;
Adjust trimpot R27 for 1.2 volts across R40 (100 ohm x 1W)
Adjust trimpot R127 for 1.2 volts across R140 (100 ohm x 1W)

[cclark65]

Any chance you have the settings for a 9446 amp?
I have one that overheats on one channel, need to find what that is and get it adjusted properly again. I have some info about the 9446 that was sent to me a while back, but not a lot.

Thanks!

[bfish]

Hi, Charles!

No, I haven't come up with any more 9446 info than what I sent you earlier, but I have been looking, and asking around. If you can determine the right trimpots to tweak, I'm sure the DC offset could be set as close as possible to 0VDC at the channel outputs, just like the 9444. The remaining pair of trimpots would be bias, and there is likely a 1W or larger 100 ohm resistor near each of those for a measurement point. If you can find the operating data for your particular output transistor(s), look for the suggested idle bias current, which will be in milliamps, which you can convert to the correct voltage drop to look for across the 100 ohm resistor (OPT topology and quantity is a factor to consider in the calculation).

With all I/O unhooked, it won't hurt anything to do a little tweaking the trimpots to determine which is which. I'd start with the meter on DCmv on Channel 1 output terminals, and give each pot a quarter-turn both ways, looking for the one that has the most dramatic + and - effect, which will be the offset pot. The pot with a corresponding number (i.e. R51-Ch1 and R151-Ch2), will be offset for the other channel, and the remaining ones will be bias, and similarly numbered.

If there is more wrong with the amp than being out of adlustment, you'll likely only get the predicted results on one channel, or maybe neither, in which case all this is for naught until you get the real problem fixed. If your protection circuitry is functional, and the amp performs but gets too hot, it shouldn't be too serious though. Verify the fan cycles from low to high during warmup. If you can't hear the change, use the voltmeter on the fan leads to tell, line V. is high speed.

If you get into it and have problems, give me a call, and I'll try to help. Won't be near the phone Fri.-Sun.

To clarify a possible misinterpretation of my above posted procedure for the 9444A, the input attenuators should be turned all the way down (fully CCW).