studiomaster powerhouse Horizon schematics

[GEOFFOS.]

I have a POWERHOUSE HORIZON 1208. and channel 1 has a lot of 'white
noise,'worse when advancing the 'gain control. I have tried replacing the
op-amp BA4560 the one nearest the Mic input channel 1. My problem is I cannot
identify the 2 transistors at the Mic gain control, think they are PNP low
noise devices BF A126B? but not found anywhere when searching from Google. The
other transistors are easily available: type BC549C. Is there anyone who
would know what type of Transistors these are or an equivalent?

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[Phil Allison]

"GEOFFOS."

I have a POWERHOUSE HORIZON 1208. and channel 1 has a lot of 'white
noise,'worse when advancing the 'gain control. I have tried replacing the
op-amp BA4560 the one nearest the Mic input channel 1. My problem is I
cannot
identify the 2 transistors at the Mic gain control, think they are PNP low
noise devices BF A126B? but not found anywhere when searching from Google.
The
other transistors are easily available: type BC549C. Is there anyone who
would know what type of Transistors these are or an equivalent?

** Studiomaster commonly used 2N4403s at the mic input.



..... Phil

 

[N_Cook]

On 12/10/2013 19:18, GEOFFOS. wrote:

I have a POWERHOUSE HORIZON 1208. and channel 1 has a lot of 'white
noise,'worse when advancing the 'gain control. I have tried replacing the
op-amp BA4560 the one nearest the Mic input channel 1. My problem is I
cannot
identify the 2 transistors at the Mic gain control, think they are PNP low
noise devices BF A126B? but not found anywhere when searching from
Google. The
other transistors are easily available: type BC549C. Is there anyone who
would know what type of Transistors these are or an equivalent?

Try 2SA126B

 

[Arfa Daily]

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:tcI6u.60928$3z5.60051@fx13.am4...

"GEOFFOS." <f6ceedb9c75b52f7fcc0a55cf0cfbf5d_951@example.com> wrote in
message news:13966$5259925a$43de0cc0$23215@news.flashnewsgroups.com...
I have a POWERHOUSE HORIZON 1208. and channel 1 has a lot of 'white
noise,'worse when advancing the 'gain control. I have tried replacing the
op-amp BA4560 the one nearest the Mic input channel 1. My problem is I
cannot
identify the 2 transistors at the Mic gain control, think they are PNP
low
noise devices BF A126B? but not found anywhere when searching from
Google. The
other transistors are easily available: type BC549C. Is there anyone
who
would know what type of Transistors these are or an equivalent?


The service manual appears to be available on eserviceinfo

http://www.eserviceinfo.com/index.php?what=search2&searchstring=studiomaster+powerhouse+horizoand
good old
elektrotanyahttp://elektrotanya.com/studiomaster_powerhouse_horizon_150_1516_sch.pdf/download.htmlbut
make sure that you know how to use elektrotanya, without getting
suckedinto taking download 'helper' software

Arfa
>

In fact, I just went and downloaded the elektrotanya one, and it is a very
good copy. The mic input diff amp appears to be based around TR1 and TR2,
both of which are shown to be 2SA970 PNP types. These then feed into IC1a,
one half of a 4560

Arfa

 

[Arfa Daily]

"GEOFFOS." <f6ceedb9c75b52f7fcc0a55cf0cfbf5d_951@example.com> wrote in
message news:13966$5259925a$43de0cc0$23215@news.flashnewsgroups.com...

I have a POWERHOUSE HORIZON 1208. and channel 1 has a lot of 'white
noise,'worse when advancing the 'gain control. I have tried replacing the
op-amp BA4560 the one nearest the Mic input channel 1. My problem is I
cannot
identify the 2 transistors at the Mic gain control, think they are PNP low
noise devices BF A126B? but not found anywhere when searching from Google.
The
other transistors are easily available: type BC549C. Is there anyone who
would know what type of Transistors these are or an equivalent?

The service manual appears to be available on eserviceinfo

http://www.eserviceinfo.com/index.php?what=search2&searchstring=studiomaster+powerhouse+horizoand good old elektrotanyahttp://elektrotanya.com/studiomaster_powerhouse_horizon_150_1516_sch.pdf/download.htmlbut make sure that you know how to use elektrotanya, without getting suckedinto taking download 'helper' softwareArfa