Nikko HB-18005 (inside a STA-1101)

flambart · 18th March 2012, 09:18 PM

Hi, yesterday I've got a nice Nikko STA-1101 receiver. Really a strange, massive 40 years old boy, very very well built (wiring apart...), in excellent conditions.
Unfortunately, the right pre-amp channel does not work. I've discovered a faulty IC, labeled "Nikko HB-18005", that is mounted inside the first stage ("Flat amplifier" card, immediately after the volume potentiometer). This component is a 8 pin custom IC, and it's no more available , of course.

I think it's not so complicate to replace it with something equivalent, but neither schematics nor datasheet seem to be available

Anyone has any idea or documentation about ? I've also realized that the power amp transistors have been replaced , and now the right channel mounts two 2SC1030 and the left two 2SD551. Which are the proper ones ?

Thanks so much to everyone

Ciao, Paolo

sakis · 19th March 2012, 09:19 AM

as about the buffer IC you may ID the pins 4 is - V 8 is +V or so, inputs and outputs install a base for the IC you then you can try anything you want starting from 4558 or 5532 ...I would say not to go to anything extreme of the OPA series unless you have instruments and knowledge to verify present oscillation.

For outputs you need obviously to replace only if blown also there you may put anything you like ...example will be MJ150003-4 .... non though will be drop in replacements you need to run bias set up procedure from scratch

All changes need to be symmetric you have to replace both N and P transistors working or not .... both channels also for symmetry reasons

then you need to recap the all amplifier

some info here vintage amplifier repair/upgrade manual

flambart · 20th March 2012, 10:09 PM

Thank you so much Sakis, your interventions are always wise and gentle

In the meantime, I've found in Internet (Analog Alley) the official "IC replacement bulletin" from Nikko, about the subsitution of my HB-18005

It's based on 2 normal npns, and few other components. I'm preparing the PCB

I'll let you know

Thanks a lot again, Paolo

18th March 2012, 09:18 PM	#1
flambart diyAudio Member Join Date: Sep 2009	Nikko HB-18005 (inside a STA-1101) Hi, yesterday I've got a nice Nikko STA-1101 receiver. Really a strange, massive 40 years old boy, very very well built (wiring apart...), in excellent conditions. Unfortunately, the right pre-amp channel does not work. I've discovered a faulty IC, labeled "Nikko HB-18005", that is mounted inside the first stage ("Flat amplifier" card, immediately after the volume potentiometer). This component is a 8 pin custom IC, and it's no more available , of course. I think it's not so complicate to replace it with something equivalent, but neither schematics nor datasheet seem to be available Anyone has any idea or documentation about ? I've also realized that the power amp transistors have been replaced , and now the right channel mounts two 2SC1030 and the left two 2SD551. Which are the proper ones ? Thanks so much to everyone Ciao, Paolo

19th March 2012, 09:19 AM	#2
sakis diyAudio Member Join Date: Jan 2006 Location: nea makri athens greece	as about the buffer IC you may ID the pins 4 is - V 8 is +V or so, inputs and outputs install a base for the IC you then you can try anything you want starting from 4558 or 5532 ...I would say not to go to anything extreme of the OPA series unless you have instruments and knowledge to verify present oscillation. For outputs you need obviously to replace only if blown also there you may put anything you like ...example will be MJ150003-4 .... non though will be drop in replacements you need to run bias set up procedure from scratch All changes need to be symmetric you have to replace both N and P transistors working or not .... both channels also for symmetry reasons then you need to recap the all amplifier some info here vintage amplifier repair/upgrade manual __________________ SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Where to place amp: Inside a common cab or inside speakers?	goldyrathore	Chip Amps	3	3rd September 2010 12:39 PM
Realistic STA-7 receiver	rpapps	Solid State	8	17th May 2005 01:49 AM
FS: RCA HB-3 Tube Handbooks	Jimmy D.	Swap Meet	1	7th March 2005 02:04 PM
PANASONIC capacitors TS-HA or TS-HB! Other caps?	ulysse21	Parts	2	25th March 2004 07:10 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

20th March 2012, 10:09 PM	#3
flambart diyAudio Member Join Date: Sep 2009	Thank you so much Sakis, your interventions are always wise and gentle In the meantime, I've found in Internet (Analog Alley) the official "IC replacement bulletin" from Nikko, about the subsitution of my HB-18005 It's based on 2 normal npns, and few other components. I'm preparing the PCB I'll let you know Thanks a lot again, Paolo