A gem!
Pirate:
You got a geat deal at 10 bucks!! Just the cost of the Iron is worth several times that!
She is quite the prize and yes it is definately worth the time, trouble and the cash you will want to lay out.
These amps have been researched to death looking for a better, newer, safer way to operate. Take full advantage of the lessons learned over the decades when dealing/ modifying/ repairing these amps. Once done-up these amps will run better than new, and will last another fourty years.
_______________________________________Rick...........
Pirate:
You got a geat deal at 10 bucks!! Just the cost of the Iron is worth several times that!
She is quite the prize and yes it is definately worth the time, trouble and the cash you will want to lay out.
These amps have been researched to death looking for a better, newer, safer way to operate. Take full advantage of the lessons learned over the decades when dealing/ modifying/ repairing these amps. Once done-up these amps will run better than new, and will last another fourty years.
_______________________________________Rick...........
The tuner is a matching 350B, I'll snap and post a pic this weekend, they are both in extraordinary shape actually and there isn't a scratch on the rosewood colored wood cases or the faces.
The two came with these speakers that match in color:
http://sheridan.kruitz.com/
The have small "feet" on the bottom. The rear speaker connection is a 1/4" jack and does have the black brightness knob. I don't have high expectations for them, but perhaps with poly caps and a tweeter upgrade, they may surprise.
I do have 2 sets of small advents, a large advent (walnut), and a set of dynaco A-35 that might be good matches. All my other speakers are '80s vintage.
I'm afraid this set would have ended up on the curb if I hadn't snatched them, the owner didn't seem to give them much value.
The two came with these speakers that match in color:
http://sheridan.kruitz.com/
The have small "feet" on the bottom. The rear speaker connection is a 1/4" jack and does have the black brightness knob. I don't have high expectations for them, but perhaps with poly caps and a tweeter upgrade, they may surprise.
I do have 2 sets of small advents, a large advent (walnut), and a set of dynaco A-35 that might be good matches. All my other speakers are '80s vintage.
I'm afraid this set would have ended up on the curb if I hadn't snatched them, the owner didn't seem to give them much value.
Thanks all for your help way back when on this amp. I've scheduled a diagnostic assessment with a local repairman the week of May19 and I want to take care of some things ahead of that to make the most of the visit. My plan is to get some guidance from him and take it myself from there.
1. I'm going to do the checks Akita recommended to check for continuity discussed in Post #3. I don't understand the second suggestion, though, regarding "heater pair". I've attached the link to the schematic for this unit, can someone clarify where the measurement points would be:
http://hhscott.com/pdf/fs/233_299C.JPG
Also, measuring the "HT" transformer, how is that done?
2. I will have a new 5RA4 and set of 6U8As on hand to sub in if these test bad (the tech does have a tube tester). Does the 6U8A need to be a matched pair? He said he had 7591s in case we needed those.
3. I have talked to this tech and he said to check the "condenser on the cathode of the rectifier" that it may be shorted and that it would be the first one if there were several. Does that mean that I should be checking C206 for a short?
4. This tech is not in favor of wholesale electrolytic replacement. He did say there were some that would definitely need to be changed. He's foreign and a bit hard to understand, I think he said "the ones at the tube". Anyway, which caps are a definite must, I'll go ahead and take care of those too. Please reference the cap designation, "bias or coupling caps" don't mean anything to me. Again, only the "must do" ones, please.
While on the subject, which are the "bias" and "coupling caps" on this schematic?
5. Post #12 recommended replacing the selenium rectifier. Can I get a mouser part number or better info to make a selection?
All a bit vague, I know. The unit has yet to be turned on and won't be until the tech gets ahold of it. By the way, the tech is Anthony Morcos of European Electronics in Washington, DC. Seems like a good guy so far...
1. I'm going to do the checks Akita recommended to check for continuity discussed in Post #3. I don't understand the second suggestion, though, regarding "heater pair". I've attached the link to the schematic for this unit, can someone clarify where the measurement points would be:
http://hhscott.com/pdf/fs/233_299C.JPG
Also, measuring the "HT" transformer, how is that done?
2. I will have a new 5RA4 and set of 6U8As on hand to sub in if these test bad (the tech does have a tube tester). Does the 6U8A need to be a matched pair? He said he had 7591s in case we needed those.
3. I have talked to this tech and he said to check the "condenser on the cathode of the rectifier" that it may be shorted and that it would be the first one if there were several. Does that mean that I should be checking C206 for a short?
4. This tech is not in favor of wholesale electrolytic replacement. He did say there were some that would definitely need to be changed. He's foreign and a bit hard to understand, I think he said "the ones at the tube". Anyway, which caps are a definite must, I'll go ahead and take care of those too. Please reference the cap designation, "bias or coupling caps" don't mean anything to me. Again, only the "must do" ones, please.
While on the subject, which are the "bias" and "coupling caps" on this schematic?
5. Post #12 recommended replacing the selenium rectifier. Can I get a mouser part number or better info to make a selection?
All a bit vague, I know. The unit has yet to be turned on and won't be until the tech gets ahold of it. By the way, the tech is Anthony Morcos of European Electronics in Washington, DC. Seems like a good guy so far...
Not someone I have heard of, not an issue for immediate concern, but I assume you have checked to see that he is familiar with Scott gear. Unfortunately there are lot of hacks out there.
Incidentally if you are having a tech look at this there really is little point in your doing anything. (sorry) He needs to do all of this anyway in order to understand what is wrong with the amplifier.
I have a 299A with all original electrolytics, and they are fine. I got it in the original box unused in the late 1980's (unfortunately I totally modded it - well I paid $45 for it and I was young..
) However at this juncture I would be concerned if the tech does not replace all of the cans or rebuild in the case where they are no longer available. 
The bias filter cap is frequently bad and note the reverse can polarity before replacement. (Can is POSITIVE.)
Make sure he does NOT use 7591XYZ from Sovtek if you need new output tubes! Repinned 6L6 and not very good ones at that..
The real Sovtek 7591 may not fit well, JJ are smaller, but not great on the reliability front.
Something else to be aware of is that the schematic you have linked to has a huge error -- the 5AR4 filament is not connected to ground as shown, that line should have been shown as connected to the HV winding center tap and the bias winding center tap.
Repairing Scott tuners properly is an art, I would be very careful about who you give this to for repair.
There are multiple revisions to the stereo decoder, and without these updates almost nothing but a new telefunken 6U8A will work. (sometimes not even then)
IIRC These use ratio detectors and usually require new diodes - germanium types like the originals work best. BTW They are great sounding tuners when they work properly, and have better than average rf performance for a tube tuner..
Tell him to be careful when removing the tuning knob/dial face (if necessary) - they are prone to cracking, and never over tighten the grub screw upon reinstallation. (Incidentally these use a concentric shaft set with ball bearing and race reduction drive. Treat with care.)
Incidentally if you are having a tech look at this there really is little point in your doing anything. (sorry) He needs to do all of this anyway in order to understand what is wrong with the amplifier.
I have a 299A with all original electrolytics, and they are fine. I got it in the original box unused in the late 1980's (unfortunately I totally modded it - well I paid $45 for it and I was young..
) However at this juncture I would be concerned if the tech does not replace all of the cans or rebuild in the case where they are no longer available. The bias filter cap is frequently bad and note the reverse can polarity before replacement. (Can is POSITIVE.) Make sure he does NOT use 7591XYZ from Sovtek if you need new output tubes! Repinned 6L6 and not very good ones at that..
The real Sovtek 7591 may not fit well, JJ are smaller, but not great on the reliability front.
Something else to be aware of is that the schematic you have linked to has a huge error -- the 5AR4 filament is not connected to ground as shown, that line should have been shown as connected to the HV winding center tap and the bias winding center tap. Repairing Scott tuners properly is an art, I would be very careful about who you give this to for repair.
There are multiple revisions to the stereo decoder, and without these updates almost nothing but a new telefunken 6U8A will work. (sometimes not even then)
IIRC These use ratio detectors and usually require new diodes - germanium types like the originals work best. BTW They are great sounding tuners when they work properly, and have better than average rf performance for a tube tuner..
Tell him to be careful when removing the tuning knob/dial face (if necessary) - they are prone to cracking, and never over tighten the grub screw upon reinstallation. (Incidentally these use a concentric shaft set with ball bearing and race reduction drive. Treat with care.)
Is it recommended to replace the selenium rectifier with an 1N4004? I understand that the bias needs to be adjusted when going to these, I can leave that for the tech to check out.
Again, just trying to take care of some of these items that most likely will need replacement anyway so that I can get the most out of my service visit, don't want to have to lug this thing back to him because of some small issue.
Again, just trying to take care of some of these items that most likely will need replacement anyway so that I can get the most out of my service visit, don't want to have to lug this thing back to him because of some small issue.
soft delay
check out this board, it is a two wire PCB that delays the HV on amplifiers like the scott's
http://www.nervenet.info/HT_delay
regards
check out this board, it is a two wire PCB that delays the HV on amplifiers like the scott's
http://www.nervenet.info/HT_delay
regards
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