DIY Audio Projects Forum

I have a vintage Heathkit PS-3 power supply that I have done the following to:

Replaces all electrolytic caps
Replaced the .1mf cap
Replaced both 1619 tubes with NOS tubes
Replaced the 6SJ7 tube with a NOS tube
Cleaned the pots with Deoxit cleaner

The power supply now ranges in output from -20v - 500. I am pretty sure that it isn't supposed to go negative. Can anyone tell me if they have had this issue before and what they did to correct it? I do not have the assembly manual (was picked up at a swap meet) but I do have the schematics.

Well I guess you took the right step.

Maybe there are some dodgy contacts along the chassis?

I would check grounds...


Keep posting!


Miguel

Went ahead and ordered the manual off of ebay. Will see what the bias adjustment needs to be for the sj7 tube. I may actually go through and replace all of the resistors with metal film so that they will be accurate values. Betting those carbon resistors are WAY off by now. After that it would basically be a brand new supply.

lexx21,
There is an adjustment VR. This VR should set the voltage. Since this VR is in the 0A2 bias regulator circuit, it sets the bias for the 6SJ7, which provides the voltage reference for the 1619 pair. The 0A2 tubes are gas zeners rated for 150VDC. They should have a nice blue or pinkish glow when they are operating. They are, believe it or not, light sensitive. Do not make your adjustment under bright light. You can check these tubes are working properly by simply measuring with one meter lead connected to the "B-" jack and the other lead at pin 4 (or 2 or 7) of tube "G". You should measure about 300VDC (288V to 324V by 0A2 specs). (Your positive meter test lead goes to the "B-" jack.) If you measure well above the 324V mark, then you have one or both 0A2 that are bad - replace both. If it is remarkably lower the 288V, then one of the 2 (or both) of the current limiting resistors whose values has drifted higher or the 6X5 is weak.

It wouldn't be a bad idea to check those old carbon resistors for drift. They were probably 10 or 20% tolerance types, which would have been fine. But I have observed that these old carbons do drift with age, so it is possible they have gone out of the generous tolerance originally given. Be careful of the metal films to be sure they are rated for the voltages present in this circuit. If this little cherry is anything like my IP-17, you have a pretty robust little power supply.

_________________
The key to a successful build is to keep the smoke IN the circuit.
-Les

Science without religion is lame, religion without science is blind. - Albert Einstien
_________________________________
LM380 Bridged Guitar Amp, Oatley K301 Phono Pre-amp, Oatley K272 Headphone Amp, Tube proto-board
Current project: 6V6 "pseudo Champ" prototype
Still to come (On hold): 6CG7/12AX7 Guitar amp (modified FireFly)

i made the measurements as you suggested and found that the voltage on pin2 of the 0a2 was about 600v. Adjusting the pot made no difference at all, but during the test the 6sj7 also died (was tested good prior).

I tested on my Eico 666 the 0a2 tubes and one showed good (125), the other showed replace (40). The 6sj7 just showed dead. When I was doing the measurement, I heard a faint pop from the 6sj7. I didn't short anything, so I probably need to check the socket and heater voltage going to that tube.

Ordering 0a2 tubes now. Any other suggestions on why the 6sj7 popped like that? I did have the unit on it's side to work on it. I don't see that it would make a difference though. I'm pretty sure the heater wouldn't short against the plate (well, sort of sure).

If one of the OA2 were bad, then that whole regulator circuit was non-functional. The 1619s are filamentary cathodes - that means their filament serves double duty as heater and cathode. These tube must stay in the vertical plane. Otherwise, the heater/cathode would contact the control grid. When you placed them in the horizontal that happened. The 6SJ7 was overloaded.
If there are no top side test points, turn the unit fully upside down and confirm the 1619s are fully vertical. Never power the unit on its ends.

Please don't take this wrong..
When you're doing a restoration, whether be solid state or vacuum tube, it's a good idea to research the active parts so you understand the operating parameters. For tubes, this is one of the best resources: Frank's electron tube database.

_________________
The key to a successful build is to keep the smoke IN the circuit.
-Les

Science without religion is lame, religion without science is blind. - Albert Einstien
_________________________________
LM380 Bridged Guitar Amp, Oatley K301 Phono Pre-amp, Oatley K272 Headphone Amp, Tube proto-board
Current project: 6V6 "pseudo Champ" prototype
Still to come (On hold): 6CG7/12AX7 Guitar amp (modified FireFly)

No offense taken at all. It's good information to know. I have plenty of spare 6sj7's so I just need to test the 1619 tubes in the morning to see if they are toast or still ok. After that, wait for delivery of the 0a2 set that I ordered today.

Testing the 1619s would be prudent.

_________________
The key to a successful build is to keep the smoke IN the circuit.
-Les

Science without religion is lame, religion without science is blind. - Albert Einstien
_________________________________
LM380 Bridged Guitar Amp, Oatley K301 Phono Pre-amp, Oatley K272 Headphone Amp, Tube proto-board
Current project: 6V6 "pseudo Champ" prototype
Still to come (On hold): 6CG7/12AX7 Guitar amp (modified FireFly)

It would seem that my Eico has no setting to test the 1619 and I can't find it on any of the charts that I have found online, including the 1978 chart.

It's in the 667 chart. I just posted to your other thread regarding the settings.

_________________
The key to a successful build is to keep the smoke IN the circuit.
-Les

Science without religion is lame, religion without science is blind. - Albert Einstien
_________________________________
LM380 Bridged Guitar Amp, Oatley K301 Phono Pre-amp, Oatley K272 Headphone Amp, Tube proto-board
Current project: 6V6 "pseudo Champ" prototype
Still to come (On hold): 6CG7/12AX7 Guitar amp (modified FireFly)