I guess the other thing to try is put everything back in again, power it up and measure some voltages
Or another to buy a full set of caps and transistors for that channel and replace the lot
Anyway, the next step will have to wait a week, i'm back home next Friday
Sugden A21 series 1
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- Old Hand
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#31 Re: Sugden A21 series 1
Thoughts are just little stories that our brains tell us !
- Mike H
- Amstrad Tower of Power
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#32 Re: Sugden A21 series 1
Offhand no idea ~ 100k? 47k? 10k? Try several...richardcooper2k wrote:yep 2 meg resistance range
so connect a resistor from base to collector ?
What sort of value ?
You're looking for whether it conducts when the bias is applied.And what am i looking for (send me a link if it's easier - i tried google but didn't find anything yet)
There don't seem to be any problems with the diode tests so it should.
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
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- Old Hand
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#33 Re: Sugden A21 series 1
I seemed to be stalling with the fault investigation and simply replacing all the transistors on the faulty power amp channel has become the more attractive option. So i have ordered them along with replacement electrolytics including the power supply/output coupling ones (ordered 3300uF rather than 2500uF).
I also stumbled across another sugden circuit which seems to have an extra input stage but has the additional components the one i have has, that aren't on the series 2 circuit diagram. i.e. the parallel diode, the extra resistor near the trim pot and the RC network near the output:
http://sound-au.com/tcaas/sugden10w.pdf
I also stumbled across another sugden circuit which seems to have an extra input stage but has the additional components the one i have has, that aren't on the series 2 circuit diagram. i.e. the parallel diode, the extra resistor near the trim pot and the RC network near the output:
http://sound-au.com/tcaas/sugden10w.pdf
Thoughts are just little stories that our brains tell us !
- Mike H
- Amstrad Tower of Power
- Posts: 20189
- Joined: Sat Oct 04, 2008 5:38 pm
- Location: The Fens
- Contact:
#34 Re: Sugden A21 series 1
Very interesting!
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."