Parabee resistance check

OK that's good. What's the resistance reading from the ground buss to 1T on the power transformer?
 
OK, now try measuring resistance from 1S on the transformer to that same point on the ground buss, and then from 1F on the transformer to the ground buss. Use either autorange or manually set the meter to the 20K ohms range.
 
That sounds like the ground that the transformer gets might be wrong.  I don't have a schematic so I have no idea where the transformer/power supply ties back to the ground bus.  Try heating up the grounding connections and the ones that should give you the resistance (to ground??) Doc called for.  I tried looking but couldn't find the number for 1S and 1F.
 
No, 1T is the ground tap, and that's OK. The rectifier's are OK, the high voltage secondary is putting out about the right voltage, it's just these resistance readings that are weird and there doesn't seem to be any good reason for them to be that way other than the meter being fooled by something in the circuit. Without actually having eyes on the amp I can't really come up with anything else to test that would be very relevant.  At this point if it was in my lab I'd probably fire it up and see what kind of voltages I get, particularly if all resistance measurements are now the same on the good amp and this one (and honestly I'm a little lost on that point since the thread has grown...)
 
To recap:

The original issue was that resistance checks on both amps were spot on except for T1 and T2 on both.  This led me to believe I made the same bonehead mistake on both amps. 

I installed the tubes, put a shorting plug on the rca jack, and did a voltage check on the right amp:

Terminal                Spec                    Actual
1                        365VAC                33VAC
2                        365VAC                5.5VAC
15                        465VDC                5mVDC
A1                        75VDC                  0VDC
A2                        450VDC                11mVDC
A4                        75VDC                  0VDC
B6                        187VDC                1.4VDC
B8                        3VDC                    11mVDC


Doc, I will be happy to provide pictures if that would help.  Thank you.

 
OK, a few pages ago you had readings on the unloaded high voltage secondary (1S, 1F) that looked pretty reasonable. Now with the amp circuit reattached to the power transformer the voltages look like there is a short somewhere that is pulling things way down. Try pulling the tubes and checking the voltage at terminal 15 again. The voltage may rise higher than 465V without the tubes loading it.
 
I decided to do a voltage check comparison with the left amp, with the shorting plug, but without tubes.

I switched off the amp as soon as I turned it on.  There is a buzz and a bright arcing at the connection of 1T and the hair-fine wire going into the transformer
 
That sounds like the transformer wire isn't continuous to the transformer lug.  The high voltage would arc across the break point.

I'm just stabbing around in the dark as I know nothing about a Parabee.  I suppose it is an older 300B design.
 
MarimbaMan said:
I decided to do a voltage check comparison with the left amp, with the shorting plug, but without tubes.

I switched off the amp as soon as I turned it on.  There is a buzz and a bright arcing at the connection of 1T and the hair-fine wire going into the transformer
Click to expand...

Look at that connection closely, preferably with a magnifier to see if the wire is disconnected or otherwise damaged.
 
I used a 10X jeweler's loupe and a Maglite, and it's still pretty hard to make out what's going on.  The left amp seems to have two hair wires coming out of the transformer, and the right amp seems to only have one.  Could the arcing be between the two wires?  There also seems to be more varnish around the two wires on the left amp.  I am very hesitant to mess with them too much, I don't want to break them or melt them.
 
Ah hah, that would certainly account for the infinite resistance readings, assuming it was like that before the spark (which I suspect is likely as discussed back a few pages). With some care one can usually tack solder them back on. If you are successful be sure to check the T1/T2 resistance again to see if it reads correctly, before giving it power.

Once again I am sorry, I'm having a little trouble keeping track of the events. Has the other amp been given the voltage test yet?
 
To clarify, the low voltage readings above were for the right amp.  I wanted to do a voltage reading on the left amp for comparison, and that's when I found the arcing problem on the left amp.  I'll attempt a repair on this now
 
Sorry, you did indeed say the left amp. Definitely focus on that amp first.
 
Good news!

Left amp:  I tack soldered the hair wire, and did resistance readings from 1T to T4, 0 ohms.
resistance on T1 = 157 ohms
resistance on T2 =  167 ohms

all resistance on the left amp is now within spec.

Bad news!

I've blown two 2A fuses when powering on to do the voltage check
 
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