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Both of those caps seem to be connected to the bias circuitry, and have their + end connected to ground. I don't see any connection between the cap and the ground switch. Death caps are always a film type (not electrolytic) and have a 600v+ rating.

Actually, those switches look like ground lift switches -- much more dangerous than the death cap ones.

--mark

they are ground lift switches.

the caps other end is at the 1k and diode turret.

hmm....

Extra filtering for the bias, perhaps to reduce hum. This forms a pi filter (cap, 1k, cap) between the diode and the 100ks.

--mark

cool!
Thanks Professor!

Ok so extra filtering.. what's the value of these caps? I guess 100uF 63V for the regular one, and how much for the extra?

Would it be beneficial to add this extra cap to my amp?

Anyway, I added an extra 100uF cap just like on that '69 amp. Not sure if it sounds any different or has less noise (probably not), but it did bring the bias down about 1mA. So it might help those with hot running tubes and no adjustable bias

cool!
next time I am in that amp, I will check the value and the bias.

Soon you will be up all hours of the night and will have PLENTY of opportunity! hehe

three weeks from today!

Sorry to kick this one back up, but does anyone have some details on how the "blown fuse indicators" are wired?

Unfortunately, those are mains voltage dependent. Just connect a 240 volt neon across the mains fuse, and it will light up when the mains fuse opens -- assuming you're using 220..240 volt mains.

The HT light was a 240 volt neon with a 100k resistor in series, again across the fuse.

--mark

Mark,
You're in luck. I did some searching and found what is close to the real neon bulb indicators used on some DR103's.
The company who makes the blown fuse indicator bulbs is Arcolectric (a UK-based company). They are the right size based on other images of fuse indicators I found online. These NEON indicators are good for 250V AC (which is why neon is used and is linked off the mains connector). The hole size is about 6mm and this has a small chrome bezel (which based by the photo below looks like it has one as well).

Here's an example of one on a DR103



Now they have different lens colors, but i'm sure us die-hard hiwatters want the closest one possible so here's the part numbers to both Red and Amber;



Red Lens; L104100NAA



Amber Lens; L104100NAB

These indicators are relatively cheap (about $2.00 each!). Pop two in for each fuse holder and you're ready to go! I hope this helps a few of those looking for these! As for connectivity, AFAIK it runs off the tip terminal on the fuse holder and straight into the brown wire from the mains connector, but don't take my word for it, I haven't done my amp yet but this should help

Hamtone wrote:I saw this picture at PC and it looks like most of his amps have had a slave/direct out added, at least thats what it looks like in one of the pictures. Does anyone know for sure?

http://www.petecornish.co.uk/dghiwatthistory.html

The input jack is a Pre-amp Bypass Input used back in 1994 during the P.U.L.S.E. tour when he decided to use an Alembic F-2B Pre-Amp through 3 Hiwatts which split off into the other 3 Slave Hiwatts to run his Doppola's and Heil Talk Talk.

I'm a Gilmour Fan

P.S.
He reverted back into using the original DR103 preamps, which were never disconnected in the first place.