All,

Anyone experianced with the old Bogen HTA-250A,
everything turn-on, But I have no 70v output.. uh no output at all.
I've shematics, manual etc. But I never work at repairing a Bogen
before..

any idea, on where to start?

Follow-up

I got 8ohms and 4 ohms.. but they sound low..
I am using my PC as a signal generator. using the rca hz input jack...

still no 70v.

wrote:
All,

Anyone experianced with the old Bogen HTA-250A,
everything turn-on, But I have no 70v output.. uh no output at all.
I've shematics, manual etc. But I never work at repairing a Bogen
before..

any idea, on where to start?

Well, if you had ANY experience at all on audio amps you would not be
asking the question......

That said, always start with the power supply. read the voltage values
on the big caps (amp on/DVM). You should have high rail voltages from 25
to 60 volts typically. If you got no rail voltages, check for AC input
and output from the power transformer. If you got that check the
rectifier diodes or bridge rectifier packs.

If the PS checks out, put a audio signal in the input and use your scope
to follow its path. If you have signal at the amps direct output,
check to see if you have signal flow through the output transformer.
Output transformers do fail. I have even seen one fail ONLY on the 70
volt winding. And some old amps have a jumper on the back to route
the 70 volt. check carefully.

Basically, tackle stage at a time and go through it in a staged and
logical manner.

Just for reference, bad outputs and power supply problems would be at
the top of your list.......

Bob

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Bob Urz wrote:
wrote:
All,

Anyone experianced with the old Bogen HTA-250A,
everything turn-on, But I have no 70v output.. uh no output at all.
I've shematics, manual etc. But I never work at repairing a Bogen
before..

any idea, on where to start?

Well, if you had ANY experience at all on audio amps you would not be

asking the question......

you are correct.


That said, always start with the power supply. read the voltage
values
on the big caps (amp on/DVM). You should have high rail voltages from
25
to 60 volts typically. If you got no rail voltages, check for AC
input
and output from the power transformer. If you got that check the
rectifier diodes or bridge rectifier packs.

If the PS checks out, put a audio signal in the input and use your
scope
to follow its path. If you have signal at the amps direct output,
check to see if you have signal flow through the output transformer.
Output transformers do fail. I have even seen one fail ONLY on the 70

volt winding. And some old amps have a jumper on the back to route
the 70 volt. check carefully.

Basically, tackle stage at a time and go through it in a staged and
logical manner.

Just for reference, bad outputs and power supply problems would be at
the top of your list.......

Bob


thanks... I follwed that route, and basiclly I discovered I have a very
low signal output. I am going to have to dismantle the supply and then
extend the wiring so I can reach.. and trace the signal better.