Dean Rantala
HiFI Droogie
Purchased this old gem some 15 years ago.
Over the years, it has needed a couple transistors and a half-hearted re-cap of the 4 amp boards.
A couple years back, one of the channels of the phono inputs went out, the noise in the amp section has become horrid and finally.... one channel has completely went out.
I got lucky and found a spare 900+ for parts on eBay really cheap (missing one amp board, cover, few knobs and couple jacks). I did this because... I am going to bite the bullet and do a full restoration on the original one I have had for years now.
For those not familiar... this was not only one of HK's most powerful receiver of the 70's, but had BUILT-IN SQ and CD-4 decoding.
Now, I never purchased it for quad use - and own no quad discs. Honestly, have no desire to get into that as a 2-channel guy. But this brings me to my first questions...
The entire phono pre-amp is integrated with the CD-4 board. It is my understanding that - due to CD-4 limitations - the phono signal is always cut above 15k or so, even in stereo mode. Is this true?
If so, it makes me wonder if it is even worth messing with preserving the CD-4 board or just roll a nice custom phono pre-amp board (non cd-4) from the designs at Elliot Sound Products? I see little use in preserving a feature that has (from what I understand) little-to-no software support.
The only album that would remotely interest me in quad would have been Pink Floyd DSOTM, and even that never seems to have made it to a CD-4 format.
The SQ matrix however... it seems this is just a matrix decoder and can do some neat tricks even with normal stereo tracks?
I will have extra LD3130's for the phono pre-amp IF I decide to repair the CD-4 circuit (from the spare unit).
My next round of questions involves the FM section. Honestly, this receiver has always sucked big time in the FM reception department. I recently purchased a nice Rigol DS1202Z-E Oscilloscope as well as a Rigol DG1022 function generator. I have never done an FM alignment before, but figured I cannot make it any worse than it is. Along with these 2 new pieces of lab equipment -I got several multimeters, 2 regulated linear power supplies (one is +/- dual rail), frequency counters, etc... Should I have all the equipment needed to perform this procedure?
I plan to recap the entire FM section as well as replace all the 2SC458's. So an alignment is most likely going to be necessary.
Over the years, it has needed a couple transistors and a half-hearted re-cap of the 4 amp boards.
A couple years back, one of the channels of the phono inputs went out, the noise in the amp section has become horrid and finally.... one channel has completely went out.
I got lucky and found a spare 900+ for parts on eBay really cheap (missing one amp board, cover, few knobs and couple jacks). I did this because... I am going to bite the bullet and do a full restoration on the original one I have had for years now.
For those not familiar... this was not only one of HK's most powerful receiver of the 70's, but had BUILT-IN SQ and CD-4 decoding.
Now, I never purchased it for quad use - and own no quad discs. Honestly, have no desire to get into that as a 2-channel guy. But this brings me to my first questions...
The entire phono pre-amp is integrated with the CD-4 board. It is my understanding that - due to CD-4 limitations - the phono signal is always cut above 15k or so, even in stereo mode. Is this true?
If so, it makes me wonder if it is even worth messing with preserving the CD-4 board or just roll a nice custom phono pre-amp board (non cd-4) from the designs at Elliot Sound Products? I see little use in preserving a feature that has (from what I understand) little-to-no software support.
The only album that would remotely interest me in quad would have been Pink Floyd DSOTM, and even that never seems to have made it to a CD-4 format.
The SQ matrix however... it seems this is just a matrix decoder and can do some neat tricks even with normal stereo tracks?
I will have extra LD3130's for the phono pre-amp IF I decide to repair the CD-4 circuit (from the spare unit).
My next round of questions involves the FM section. Honestly, this receiver has always sucked big time in the FM reception department. I recently purchased a nice Rigol DS1202Z-E Oscilloscope as well as a Rigol DG1022 function generator. I have never done an FM alignment before, but figured I cannot make it any worse than it is. Along with these 2 new pieces of lab equipment -I got several multimeters, 2 regulated linear power supplies (one is +/- dual rail), frequency counters, etc... Should I have all the equipment needed to perform this procedure?
I plan to recap the entire FM section as well as replace all the 2SC458's. So an alignment is most likely going to be necessary.
