Vipersan
Emmett Browns Ghost
- Joined
- Jun 29, 2009
- Messages
- 10,918
- Reaction score
- 6,663
- Points
- 113
- Age
- 66
- My Satellite Setup
-
IP9000HD +
TD110 Dish and TD88 Dish in Tandem
66°East to 60°West.
AZbox PrmHD + OpnbxS9HD + Skybox + DrHD F15
2x VboxII AZ-EL
2 m+ Alcoa PF + BSC421 C-Band lnbf...
+SS2/TwHnS2-3200 pci/TBS6925 pci
1.5 Fortec Star -Gbox - HtoH Ku/Ka/C
- My Location
- UK
...but a long way back in my shop..
Back to the early nineteen seventies in fact ..
Nelson brought me a Ferrograph Amp for repair ...
In truth I have worked on this amp before and this is it's second visit ..
This time I decided not to search for the crackling noise on one of the channels ..as this would take a long time ..and prove less economical than to rebuild the channel ..
So ..I finally managed to get the schematic and board layout ..so the next step was to source the components ..
roughly 100 ..
A mix of carbon resistors ..transistors and capacitors ..
Well ..few if any original philips caps still existed so originals where possible and modern equivalents if not..
These I gathered from various UK suppliers..
Next the half watt carbon resistors ..
The most economical way to approach this was to buy a 'kit' containing about 10 of each need value ..plus many I didn't need ..
Sourced from China ...as greedy UK suppliers wanted about 4 times the price for the same components.
Finally Transistors..
Luckilly the output transistors could be reused as these would be almost impossible to source ...
which is not to say the others were easy ..
Finally found someone with 'old' new stock in Holland who was prepared to ship me what I needed ..
Having got everything together ...and armed with the schematic I set about rebuilding the amp channel driver board ..
Completed it yesterday ...and on powering up was rewarded with ...errr ..
Nothing .
Turned out the test speaker I had connected to this channel was open circuit ...so borrowed the speaker off the working channel ..
To say that the sound quality is anything other than superb would not be doing it justice..
They certainly knew how to build an amp back then.
Anyone familiar with the Ferrograph name knows it was ascociated with quality ...and the BBC ..
Not reassembled yet ..but another success in the making..
rgds
Evan
Back to the early nineteen seventies in fact ..
Nelson brought me a Ferrograph Amp for repair ...
In truth I have worked on this amp before and this is it's second visit ..
This time I decided not to search for the crackling noise on one of the channels ..as this would take a long time ..and prove less economical than to rebuild the channel ..
So ..I finally managed to get the schematic and board layout ..so the next step was to source the components ..
roughly 100 ..
A mix of carbon resistors ..transistors and capacitors ..
Well ..few if any original philips caps still existed so originals where possible and modern equivalents if not..
These I gathered from various UK suppliers..
Next the half watt carbon resistors ..
The most economical way to approach this was to buy a 'kit' containing about 10 of each need value ..plus many I didn't need ..
Sourced from China ...as greedy UK suppliers wanted about 4 times the price for the same components.
Finally Transistors..
Luckilly the output transistors could be reused as these would be almost impossible to source ...
which is not to say the others were easy ..
Finally found someone with 'old' new stock in Holland who was prepared to ship me what I needed ..
Having got everything together ...and armed with the schematic I set about rebuilding the amp channel driver board ..
Completed it yesterday ...and on powering up was rewarded with ...errr ..
Nothing .
Turned out the test speaker I had connected to this channel was open circuit ...so borrowed the speaker off the working channel ..
To say that the sound quality is anything other than superb would not be doing it justice..
They certainly knew how to build an amp back then.
Anyone familiar with the Ferrograph name knows it was ascociated with quality ...and the BBC ..
Not reassembled yet ..but another success in the making..
rgds
Evan
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