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H.H. Scott 299 restoration

G

Geno1317

New Member
I just picked up a very dusty H.H. Scott 299 (A). I have no idea if it works as I have not turned it on. It was sitting on top of an in use Sansui 5000A which was sitting on top of a two very pretty Bozak B-500 speakers. In the same purchase I also got a Teac A-1040S R2R and at least 50 recorded tapes. I got it all for a price that will make you sick! That cheap! I'm very new to tube amps and honestly very new to any and all vintage audio but for the last few months it's been my new passion. I'd really like to clean and restore this myself but I honestly don't know where to start. Am I biting off more than I can chew? Completely blind to what it entails but I tend to catch on quickly, ha. What would you do? How much can I expect pay for restoration? Everything is there, looks like all original Scott tubes and everything. I even got all the original manuals for all the items mentioned. I'm stoked to say the least. My final question is, does anyone know where I can find an instructional step by step process to follow? For Dummies? Ha. Thanks.
 
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Well, call me an idiot but I did it... I plugged it in for 10 seconds tops, even though I know I'm not supposed to. I've been reading aimlessly for hours and I just couldn't take it anymore. My curiosity got the best of me. All the tubes started to glow. I take this as a good sign. Now, what to do?
 
Geno1317 said:
Well, call me an idiot but I did it... I plugged it in for 10 seconds tops, even though I know I'm not supposed to. I've been reading aimlessly for hours and I just couldn't take it anymore. My curiosity got the best of me. All the tubes started to glow. I take this as a good sign. Now, what to do?
Click to expand...
Hook it up to some speakers you don't care if it blows?
 
I would be a little more careful with it. You don't want to damage an output transformer or take out the output tubes. Just can't be certain with an old unit for which you have no recent history.

Nice looking amp. At least try to do a slow, controlled ramp up of the line voltage with a variac to do a bit of reforming on the power supply capacitors or read up on "dim bulb tester".

Have fun,
John
 
BTW, what you have is the second generation HH Scott 299 amplifier. Just a different layout of the tubes.
 
Geno1317 said:
Is the tube layout the only difference? What was the reason for the change?
Click to expand...

I can't answer your question with authority. But... it may have been to get the heat toward the rear of the chassis and therefore run cooler. HH Scott also moved the output tubes of the later 299 series (which moved up to the 7591 octal tube) to the very rear of the chassis instead of in front of the output transformers. Heat is your enemy in electronics, especially with electrolytic capacitors.

If you don't already have this link, check out the HH Scott website:

http://hhscott.com/photo.htm

Their forum was great many years ago. But it no longer works, very unfortunate.
 
kvflyer said:
I can't answer your question with authority. But... it may have been to get the heat toward the rear of the chassis and therefore run cooler. HH Scott also moved the output tubes of the later 299 series (which moved up to the 7591 octal tube) to the very rear of the chassis instead of in front of the output transformers. Heat is your enemy in electronics, especially with electrolytic capacitors.

If you don't already have this link, check out the HH Scott website:

http://hhscott.com/photo.htm

Their forum was great many years ago. But it no longer works, very unfortunate.
Click to expand...

So just to be clear, my tubes are set up like the 299B but the face plate is of "A". I'm such a newbie an I'm assuming mine is still an A but a second edition of the A. Is that correct? Because the B's face specifically states B.
 
Geno1317 said:
So just to be clear, my tubes are set up like the 299B but the face plate is of "A". I'm such a newbie an I'm assuming mine is still an A but a second edition of the A. Is that correct? Because the B's face specifically states B.
Click to expand...

If it has the 299 face plate, it is a second edition 299. And yes, the 299B did have the same basic layout. I have all three versions but they are packed away right now so I can't just go look for differences.

Again, the 299 did come in two versions. All good stuff.
 
Great find! Always check the fuse. And install a slightly smaller amperage as not stress the power xmer & play it safe . 10 seconds will not bring the amp up to full power. It will lite up the heaters/filiments. If the correct rectifier tube is installed (5ar4/GZ34) it will take 40 seconds to bring up the amp to working voltage (if all is OK). Watch the can filter cap for heat or spitting it's gut out.... Nice amp!
 
crispycircuit said:
Great find! Always check the fuse. And install a slightly smaller amperage as not stress the power xmer & play it safe . 10 seconds will not bring the amp up to full power. It will lite up the heaters/filiments. If the correct rectifier tube is installed (5ar4/GZ34) it will take 40 seconds to bring up the amp to working voltage (if all is OK). Watch the can filter cap for heat or spitting it's gut out.... Nice amp!
Click to expand...
crispycircuit said:
Great find! Always check the fuse. And install a slightly smaller amperage as not stress the power xmer & play it safe . 10 seconds will not bring the amp up to full power. It will lite up the heaters/filiments. If the correct rectifier tube is installed (5ar4/GZ34) it will take 40 seconds to bring up the amp to working voltage (if all is OK). Watch the can filter cap for heat or spitting it's gut out.... Nice amp!
Click to expand...

Thank you! That's awesome!
 
Geno1317 said:
I just picked up a very dusty H.H. Scott 299 (A).
Click to expand...

I have one and have had many over the years. It's a great amp and well worth restoration. Speaker selection is key, the amp puts out ~12-14W per channel.

In general a complete overhaul is pretty straight forward, about an evening's work -

Review tube electronic safety practices.
Get correct schematic and/or assembly manual copies
Test tubes, replace any weak or out.
Replace all coupling caps between the tubes.
Replace all filter caps in the power supply.
Replace the selenium rectifier with diodes and trim to correct voltage.
Clean all the pots & switches with contact cleaner.
Take an old tube, put in each socket, and rock around. Tension any contacts that seem weak.
Center your bias & balance pots.
Turn on, bring up operating voltage on variac, bias amp.
Ideally you are all done but in reality all the above may reveal other issues such as assembly mistakes by the original builder.

Bottom line, everything is fixable.
 
soundmotor said:
I have one and have had many over the years. It's a great amp and well worth restoration. Speaker selection is key, the amp puts out ~12-14W per channel.

In general a complete overhaul is pretty straight forward, about an evening's work -

Review tube electronic safety practices.
Get correct schematic and/or assembly manual copies
Test tubes, replace any weak or out.
Replace all coupling caps between the tubes.
Replace all filter caps in the power supply.
Replace the selenium rectifier with diodes and trim to correct voltage.
Clean all the pots & switches with contact cleaner.
Take an old tube, put in each socket, and rock around. Tension any contacts that seem weak.
Center your bias & balance pots.
Turn on, bring up operating voltage on variac, bias amp.
Ideally you are all done but in reality all the above may reveal other issues such as assembly mistakes by the original builder.

Bottom line, everything is fixable.
Click to expand...

That brings me to another question. What speakers do you recommend? I'm such a newbie, thanks again.
 
Geno1317 said:
That brings me to another question. What speakers do you recommend? I'm such a newbie, thanks again.
Click to expand...

When mine was set up I had some JBL 18Ti on it. They were easy to drive and worked well with the 299. I'd look for similar 2-way speakers with efficiency the high 80s.

I had the 299 on other speakers too but struggling to remember what.
 
Dadbar, thanks for that link. VTV is a very cool magazine! Just about every page had me drooling. Is there a link to all of them?

BillWojo
 
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