Project: Citation 16A

[Super Noob]

Well back to my Citation 16A.

The offset was high in one channel... so I started by pulling and rebuilding the left channel. This AMP is twin powered with twin transformers. It has ten (10) outputs per channel.

The project was in neutral and was pushed to the side as I could not get it working correctly. Turns out that when I replaced the compensating transistor on this channel, I incorrectly install it (above) on terminal block. Only took me about a year to find the mistake. Once corrected, this channel offset still was off (-40 ma). At this point, I elected to replace the Q1 (op transistors). For the 'A' it was double transistor packaged in one unit. Per the direction of EchoWars from a 2007 post, I elected to HFE match two ZTX694B transistors to less than 1% and heat-shrink them together.

Once installed was able to dial offset to less than 1mV. So this weekend, I tackled the other amp board and other channel. More post to follow.

 

[Super Noob]

Here is the other channel rebuild:

Before:

After:

All the emitter .5 ohm sand block resistors were changed along with diodes, caps, compensation transistor.

Outputs re-pasted.

 

[Super Noob]

Here is the relay board:

Before:

After:

 

[Super Noob]

Here are the amp boards.

All caps were replaced including ceramics, all diodes including zeners, four resistors, and all trimmers.

 

[Super Noob]

LED board caps changed as well three incorrect LED.

Here is the after pic:

Large filter caps were replaced along with 2.2uF stacked film bypass caps and some high value bleed resistors. The unit caps would hold charge = so this was a necessary upgrade to bleed off the stored energy.

 

[Super Noob]

Bridge Rectifiers Rebuilt (2x)

 

[Super Noob]

Completed:

She was born July 1976 and rebuilt 42 years later.

Offset measures less than 1mV, and the bias was set to 50mV after about 30 minutes.

The idle of the amp is 60 degrees Celsius or 140 degrees Fahrenheit = she is not only a looker but a cooker as well.

Did some listening last evening, and this amp is very impressive. Anyways, time to move on to my G7500.

Thanks for viewing and any comments.

 

[totem]

Always had a thing for the 16A I can remember the first time I saw one, I was at a school dance where
Brian Adams was playing with Sweeney Todd funny thing is I don't recall much about the band
but do remember the amp go figure.

 

[Roadrash]

Just out of curiosity, how did you arrive at 50mv for the idle current setting? The sevice manual for the Citation 16 calls for 10mv cold, and to recheck after 15 minutes. Is it different for the 16a? If not, that may be why you're seeing 140 degrees at idle. I just had my 16 recapped and serviced, and it barely gets warm after being pushed fairly hard for awhile.

 

[Super Noob]

Just out of curiosity, how did you arrive at 50mv for the idle current setting? The sevice manual for the Citation 16 calls for 10mv cold, and to recheck after 15 minutes. Is it different for the 16a? If not, that may be why you're seeing 140 degrees at idle. I just had my 16 recapped and serviced, and it barely gets warm after being pushed fairly hard for awhile.

https://www.hifiengine.com/manual_library/harman-kardon/citation-16a.shtml

See page 21 of document or page 19 labeled in the manual. +/- 10 mV for offset and 50mV for the bias. For reference this is a 16A not a 16.

This is a cooker = FYI. 60 C is the quiescent temperature.

The IC based 16 has an OP amp controlled by a chip which is very hard to replace.

 

[Roadrash]

https://www.hifiengine.com/manual_library/harman-kardon/citation-16a.shtml

See page 21 of document or page 19 labeled in the manual. +/- 10 mV for offset and 50mV for the bias. For reference this is a 16A not a 16.

This is a cooker = FYI. 60 C is the quiescent temperature.

The IC based 16 has an OP amp controlled by a chip which is very hard to replace.

So the settings are different for the 16a vs the 16. I was just curious because after I changed the big caps in my 16 the bias was around 65 mv and it got very warm at idle. Once I set the bias according to the service manual it ran cool again. It seems that I remember reading that the 16a tends to run appreciably warmer than the 16 now that I think about it. Thanks for posting up your repairs and pics!