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I have one in stock, DM your address and I'll send it out FoC.
EDIT: Is it axial, or radial?
Rift Amplification
Brackley, Northamptonshire
www.riftamps.co.uk
If it is a 4.7uF and a non-electrolytic cap can be found in the right value and physical size with the same or better voltage rating then it will be fine to use.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
I think typo as well IC. Where is it in the circuit. MIGHT be a downstream decoupler in the pre amp circuit but if so pretty mean designer! Always used to be 8mfd but 10 is the minimum these days.
Dave.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
The reason I screamed 'Noooooo' is that I've had two Prosonics across my bench in the past year, both with burnt out chokes and a shorted 4.7uf Poly in that position. Interestingly, both were recapped by the same tech. I now stock that value EC for this exact reason.
Can't explain it, but a 4.7uf 500v elec is cheaper than a choke replacement
Rift Amplification
Brackley, Northamptonshire
www.riftamps.co.uk
I've only ever worked on a couple of Prosonics and unfortunately my memory is going a bit as to what was in them.
That is also why all amps should have an HT fuse!
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
anyhoo, on to the pictures ...
Rift Amplification
Brackley, Northamptonshire
www.riftamps.co.uk
If none I think it can be assumed to be a production error caused by a typo. If it does change the sound, then it's a deliberate choice.
There shouldn't be much AC on it in that position after the choke though.
I don't know what the ripple voltage will be, but I would guess less than the signal voltage in something like a phase inverter coupling cap position.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Ref the two radial caps in series (?) I suspect they are 10mfd at well under 500V and therefore should have had equalizing resistors across them. I agree ALL amps should have HT fuses and HT bleed resistors are very, very desirable.
Re foil V electrolytic? One place where you DON'T want to replace electros' with foil is a speaker crossover network. Even if the value is spot one the frequency response goes to ***T!
Dave.
I've got a 22uF@500V that is going in, my cloth ears won't notice the difference.
A recent sticker inside the amp suggests if you live in essex amp repair standards can be variable. I would be mighty ticked off if somebody did a hack job like this on my amp !
I think I have some 4.7uf F&T caps around, you can certainly get them easy enough to avoid going the poly route.
@Almach If that was my amp I would pull the board and do the job properly
Alternatively they could be fake caps!
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
First thing I did was checked the bias. Switch to SS rectification , 474V on the CT and err ... 474V on both anodes. OT primaries measure around 55 Ohms each. Bias pot is roughly central and there's -51V on the grid.
Looking closer someone has added two 1.5K resistors in series with the grids of the output valves, Those 220Ks are fed from the bias pot via the brown wire.
Does the amp sound any different with the 22uF cap?
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein