Greetings,
My friend and I determined that the inputs are
all functioning properly and that the power supply is fine.
We then traced the input signal to the large rectangular transistor on the top of the board Q30/Q31 [all seems fine up to there] just before the large amplifying transistors Q36-Q45 [5/side]. Is there any precedent for the big ones going bad, being blown? Is there any one or group to try replacing first or just replace all of them. Can you recommend a source for them?
Any suggestions would be a great help!
Thank you for your time.
Sincerely,
Tim Mical
My friend and I determined that the inputs are
all functioning properly and that the power supply is fine.
We then traced the input signal to the large rectangular transistor on the top of the board Q30/Q31 [all seems fine up to there] just before the large amplifying transistors Q36-Q45 [5/side]. Is there any precedent for the big ones going bad, being blown? Is there any one or group to try replacing first or just replace all of them. Can you recommend a source for them?
Any suggestions would be a great help!
Thank you for your time.
Sincerely,
Tim Mical
Citation 7.1
We have never used "2SD" parts
2SC2389 are 120v high gain low noise 100mA NPN
2SA1038 are 120v high gain low noise 100mA PNP
There are many substitutes for these
We did not use a 2SD1292
Why do you want to replace the output devices?
Which transistors are run to the edge?
We see NO stability issues.
Who is "you and I" and what amplifier was built in 1993?
The opamps are for protection and the DC servo
Please do not comment about an amplifier without knowing what is actaully inside it
We have never used "2SD" parts
2SC2389 are 120v high gain low noise 100mA NPN
2SA1038 are 120v high gain low noise 100mA PNP
There are many substitutes for these
We did not use a 2SD1292
Why do you want to replace the output devices?
Which transistors are run to the edge?
We see NO stability issues.
Who is "you and I" and what amplifier was built in 1993?
The opamps are for protection and the DC servo
Please do not comment about an amplifier without knowing what is actaully inside it
Quote:
We have never used "2SD" parts
I guess I have to say bs to that.... every single Citation that was sold by the shop I work for had 2SD1292's in it.
Either someone doesn't know what was put in the amps or there was a parts substitution. I had pictures showing the transistor line up but these were lost in a recent hard drive melt down.
Every and I mean every Citation amplifier we sold blew up. There were some issues with this amplifier that we experienced as well. Its a very nice looking amplifier but unfortunately we didn't have good luck with any of the batch we had. Maybe it was just the luck of the draw and we managed to get the ones that slipped threw quality control.
Quote:
Please do not comment about an amplifier without knowing what is actaully inside it
Unfortunately I have had the experience of knowing what is inside these amps.
We have never used "2SD" parts
I guess I have to say bs to that.... every single Citation that was sold by the shop I work for had 2SD1292's in it.
Either someone doesn't know what was put in the amps or there was a parts substitution. I had pictures showing the transistor line up but these were lost in a recent hard drive melt down.
Every and I mean every Citation amplifier we sold blew up. There were some issues with this amplifier that we experienced as well. Its a very nice looking amplifier but unfortunately we didn't have good luck with any of the batch we had. Maybe it was just the luck of the draw and we managed to get the ones that slipped threw quality control.
Quote:
Please do not comment about an amplifier without knowing what is actaully inside it
Unfortunately I have had the experience of knowing what is inside these amps.
Citation 7.1
I guess I have to say bs to that.... every single Citation that was sold by the shop I work for had 2SD1292's in it.
"Burnedfingers" I went to our records of what was purchased for these amplifiers and am looking at the schematics and I see NO 2SD1292. Sorry to burst your bubble but we never used this Rohm part. We carry a full inventory of all semiconductors for these amplifiers and I certainly do not keep this part.
In addition your rudeness is by what you write, and you know what I mean, is not appreciated.
No parts substitution as our purchasing computer has no such part in the library.
Please explain the amplifier and housejkeeping schematics to me as you claim that you know what is inside. I would be interested to hear your answer.
Early versions of these amplifiers had issues with the Toshiba devices which we used in the first stage of the emitter follower O/P section. These were very high Ft and low capacitance parts which HK insisted we use to get the dumb bnadwidth they wanted. The original spec called for a 600KHz response -3dB.
These were 2SC3423 and 2SA1360 which were substituted with Rohm devices 2SD1763A and 2SB1186A
I guess I have to say bs to that.... every single Citation that was sold by the shop I work for had 2SD1292's in it.
"Burnedfingers" I went to our records of what was purchased for these amplifiers and am looking at the schematics and I see NO 2SD1292. Sorry to burst your bubble but we never used this Rohm part. We carry a full inventory of all semiconductors for these amplifiers and I certainly do not keep this part.
In addition your rudeness is by what you write, and you know what I mean, is not appreciated.
No parts substitution as our purchasing computer has no such part in the library.
Please explain the amplifier and housejkeeping schematics to me as you claim that you know what is inside. I would be interested to hear your answer.
Early versions of these amplifiers had issues with the Toshiba devices which we used in the first stage of the emitter follower O/P section. These were very high Ft and low capacitance parts which HK insisted we use to get the dumb bnadwidth they wanted. The original spec called for a 600KHz response -3dB.
These were 2SC3423 and 2SA1360 which were substituted with Rohm devices 2SD1763A and 2SB1186A
If I had the pictures I took of the amplifiers I serviced I would gladly post them. I listed what I found and I'm sorry if your records don't show the parts I found. This is not uncommon with other amplifier manufacturers to uncover something not on the official BOM.
With respect to oscillation ...I have a Tech services Information sheet dated March 17,1999 listing measures to eliminate amplifier shut down as a result of using 4 conductor speaker wire. This is just the tip of the iceberg for this amplifier and not the only oscillation issue I uncovered.
With respect to my attitude or opinion on this amplifier..... since I have been inside this marvel of an amplifier I am allowed to express my opinion and I personally don't care if you respect my opinion or not.
I am very happy to say that I serviced my last Citation amplifier over two years ago. I will draw the conclusion that either the owners have traded the amplifier in on something else or I got the bugs out and they continue to run.
With respect to this post and any continued communication with you... I'm done talking about this joke of an amplifier.
With respect to oscillation ...I have a Tech services Information sheet dated March 17,1999 listing measures to eliminate amplifier shut down as a result of using 4 conductor speaker wire. This is just the tip of the iceberg for this amplifier and not the only oscillation issue I uncovered.
With respect to my attitude or opinion on this amplifier..... since I have been inside this marvel of an amplifier I am allowed to express my opinion and I personally don't care if you respect my opinion or not.
I am very happy to say that I serviced my last Citation amplifier over two years ago. I will draw the conclusion that either the owners have traded the amplifier in on something else or I got the bugs out and they continue to run.
With respect to this post and any continued communication with you... I'm done talking about this joke of an amplifier.
Hi guys,
It's my first post, so be easy on me!
I have the opportunity to own a Citation 7.1, in which I'm very keen on doing so, however I'm slightly worried by what I've read on this forum as, regards to reliability..
I'm not into all the technical speak, so please bare with me...I will get there eventually!
@ MOER or anyone if you can help;
You say the Toshiba part was forced implantation by HK, but later to be replaced by a presumed more reliable Rohm part...
Would you say the Toshiba part has a particularly high failure rate anyway, regardless of age and use?
Secondly, What batch numbers are effected?
And finally...
What are the batch numbers of the units which include the Rohm parts?
Thanks in advance.
It's my first post, so be easy on me!
I have the opportunity to own a Citation 7.1, in which I'm very keen on doing so, however I'm slightly worried by what I've read on this forum as, regards to reliability..
I'm not into all the technical speak, so please bare with me...I will get there eventually!
@ MOER or anyone if you can help;
You say the Toshiba part was forced implantation by HK, but later to be replaced by a presumed more reliable Rohm part...
Would you say the Toshiba part has a particularly high failure rate anyway, regardless of age and use?
Secondly, What batch numbers are effected?
And finally...
What are the batch numbers of the units which include the Rohm parts?
Thanks in advance.
HK 7.1
I do not have the record of the serial #s vs when we changed the Toshiba to Rohm parts. However it is very easy to identify by removing the top cover.
When you have the amplifier, please email me at zedaudio@aol.com and I can walk you through this process. It takes about 1 minute.
Stephen Mantz
Zed Audio Corporation
I do not have the record of the serial #s vs when we changed the Toshiba to Rohm parts. However it is very easy to identify by removing the top cover.
When you have the amplifier, please email me at zedaudio@aol.com and I can walk you through this process. It takes about 1 minute.
Stephen Mantz
Zed Audio Corporation
I know I'm reviving an old thread. But free schematics are available for free -- see link. Also, I'm having some problems with one channel of my 7.1, it probably got blown when the amp protection circuits tripped. Are the input transistors the most likely to be blown?
HARMAN-KARDON CITATION-7.1 SM Service Manual free download, schematics, eeprom, repair info for electronics
HARMAN-KARDON CITATION-7.1 SM Service Manual free download, schematics, eeprom, repair info for electronics
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