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Scott amp 299-D motorboating

If it doesn't hum, try it. Just be warned that if you connect other sources to it that have grounded cords, you may end up with hum. If you want to keep the 2 prong cord, use one line cap from the neutral side to chassis. That should make you measure near zero volts from chassis to ground. You'd need a polarized cord, otherwise you've got a 50/50 shot of getting it right.It also relies on the outlets in your wall being wired correctly, which is not a sure bet.

That said, I have a pair of mono amps that came with 2 prong cords, both have 3 prong cords now, and they behave themselves just fine without going to any silly measures. I have also tied them to my computer as a source, and it didn't go stupid there either.
 
Ok I've done it with a polarized cord and the neutral line cap to the chassis. I compared with the outlet ground clipped to the chassis and the noise was lower with the two prong and cap (volume at max speaker-off with headphones). I now measure about 3Vac between the chassis and house ground. I'll tell my client to make sure his outlet is wired correctly with this thing. Now I'm tempted to disable the accessory outlet on the back panel.
 
Just coming back from vacation. While doing the last tweeking on this amp I noticed the power xfrmer gets pretty hot to touch but I know it's normal. I don't like the JJ multicap can capacitor being so close to it. It gets hot too after an hour. I'm wondering if it could help to install a small aluminum sheet between them. Cannot really put more time into this repair though...
 

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Heat shield not a bad idea, but unless there is enough air space between the parts I suspect it may actually make the situation worse. Looks like any metal in there would be nearly touching both the transformer and the cap, at which point you'd be dumping heat more directly in there.
 
It is not normal for the power tranny on this model to get hot. I have been running a 299D for about one year. All original power supply caps and a quad of NOS GE output tubes. The power tranny as well as the large caps run cool, I kid you not. I had it's cousin, the LK-72-B, and that cooked.
 
Hmm are you sure? Interesting. I'm wondering what could draw all that current. New rectifier tube, all power tubes and PI new. All filter caps replaced, termistor on AC line and just on idle it gets pretty hot to touch after an hour. It's also very warm in the shop, no air conditioning.

Each power tube dissipate 13W so about 50w total on idle...
 
I am certain. My power tranny can be grabbed w/o burning your hand. Can't be more than 140 - 150 degrees. Only the tubes get hot hot.
 
On 2nd thought, my estimate on the tranny temp is high. More like 130 degrees. It is not uncomfortable to grab onto and continue holding it. I will need to find my I.R. temperature thingie to confirm.
 
I found my infrared thermometer [marketed by General Tools].
Here are the results taken on my 299D that has been running for hours. Volume is set pretty high. Hilton Ruiz on piano. Given are the readings from the hottest area of each component, as temps vary from side-to-side, top-to-bottom. Readings are in Farenheit.

Power tranny 123
Audio tranniies 95 & 100
Bruce Jenner 99 [seemed funny at the time]
Upright cans 115 to 128, only because of proximity to heat sources.
7591 180 to 330 on each tube, depending on where the laser is pointed.
Except for the tubes [and wire-wound resistors], all components run cool, as you see.
 
My HH Scott is a girl amplifier. She never had a male appendage, and [all] her sockets are squeaky-clean and properly-lubricated.

The perfect woman.
 
Well do to rules & regulations, I'll say you have a different way of putting words to things. 299D is one of the finest integrateds & deserves praise. I have an LK-72 & know them well. I could easily live with this as my only amp.. Not looking to knock you, you have different style of describing, and all is well.... Cheers......
 
This is my second HH Scott. My first, an LK-72B was stupidly sold about 15 years ago.
When I sold the first Scott, it was because my uncle had given me a Fisher X-202-B. The Scott is way superior, and simpler to repair, if needed.
 
Similar thing ! I lent mine to a friend that begged it off me. All though I got a good buck, it took all that money to get another. There's something about these amps that kick-ass.... and I agree, Fishers are very nice, but lack that mojo of these amps. I end up installing the bias/balance controls of the 299D. Like most amps of that time period they run hot ! I try to get the Hammond organ 7591s, Anyway, don't lend yours out !!
 
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