PL400 Build help

[BrickbyBrick]

Do a quick check with your DVM on diode scale. Check all junctions forwards and backwards including C-E checks in both directions.

What do you have for electronic test equipment?

I have a Fluke 114 which unfortunately doesn't have that capability.

I took out all the but the bottom row of transistors and the max DV voltage on the bias is +60ma. So it seems that there are some bum transistors in the bunch. Must've been that one leg that was shorted to ground?

 

[MusicSteve]

What Bias Transistor are you Using?

 

[BrickbyBrick]

What Bias Transistor are you Using?

the 5088 that was supplied with the kit

 

[Gepetto]

I have a Fluke 114 which unfortunately doesn't have that capability.

I took out all the but the bottom row of transistors and the max DV voltage on the bias is +60ma. So it seems that there are some bum transistors in the bunch. Must've been that one leg that was shorted to ground?

Well that is a bummer. That DVM capability is pretty key for work like this. It will be a crap shoot trying to figure out which is damaged without that capability. Do you have a friend with a Fluke that has that capability?

 

[BrickbyBrick]

Well that is a bummer. That DVM capability is pretty key for work like this. It will be a crap shoot trying to figure out which is damaged without that capability. Do you have a friend with a Fluke that has that capability?

I'll be doing more work like this, so it might be time to upgrade. Been working mostly on tube gear and never needed that test.

 

[gene french]

they recommended a fluke 77IV to me...just bought one on ebay...my chinese dvm missed an obvious problem...

 

[MusicSteve]

I'll be doing more work like this, so it might be time to upgrade. Been working mostly on tube gear and never needed that test.

I think it has a diode tester. it under the Ohm (sound icon)
Yes
Test/Measurement Functions
Resistance, Frequency (Hz), AC Current, DC Voltage, Capacitance, Continuity Test, DC Current, AC Voltage, Diode Test
Features
Auto Power Off, Auto-Ranging, Over Range Protection, Manual-Ranging, Backlight, Data Hold, Bar Graph Display, True RMS, Battery Door Access, Average Value Mode, Min-Max Value Mode

 

[Gepetto]

For a few dollars more than the 77 IV, I would recommend something like the Fluke 179 that gets you true RMS capability as well.

 

[BrickbyBrick]

With all the TO-3 transistors out I'm still only getting a reading of 50mV on the bias test point.

Does that seem like another component has failed? Bias transistors?

All other voltages check out fine. B+, B- , 15V + and -

 

[MusicSteve]

so The RT board blow the fuse? which one? (+ or -) and what output transistor shorted out to ground? explain inside view, could you mark it w a pic (were on the Rt back board)
Did any other fuse blow? 8a?

 

[BrickbyBrick]

so The RT board blow the fuse? which one? (+ or -) and what output transistor shorted out to ground? explain inside view, could you mark it w a pic (were on the Rt back board)

No it was the 5AGX fuse that blew.

Top
1 2 3 4
5 6 7 8
9 10 11 12 Power Transformer side
13 14 15 16
Bottom

It was #6 that shorted. If that diagram makes sense.

I'm double checking the manual but I think that only the 115 and 117 has the diode check. I have the 114.

 

[MusicSteve]

With all the TO-3 transistors out I'm still only getting a reading of 50mV on the bias test point.

Does that seem like another component has failed? Bias transistors?

All other voltages check out fine. B+, B- , 15V + and -

No it was the 5AGX fuse that blew.

Top
1 2 3 4
5 6 7 8
9 10 11 12 Power Transformer side
13 14 15 16
Bottom

It was #6 that shorted. If that diagram makes sense.

I'm double checking the manual but I think that only the 115 and 117 has the diode check. I have the 114.

Do you have this look at arrow?

 

[MusicSteve]

With all the TO-3 transistors out I'm still only getting a reading of 50mV on the bias test point.

Does that seem like another component has failed? Bias transistors?

All other voltages check out fine. B+, B- , 15V + and -

You need at least the Bottom row installed, did mark the #6

 

[BrickbyBrick]

Do you have this look at arrow?

Yes that is on my DMM

 

[MusicSteve]

No it was the 5AGX fuse that blew.

Top
1 2 3 4
5 6 7 8
9 10 11 12 Power Transformer side
13 14 15 16
Bottom

It was #6 that shorted. If that diagram makes sense.

I'm double checking the manual but I think that only the 115 and 117 has the diode check. I have the 114.

back view? or inside?

 

[MusicSteve]

Yes that is on my DMM

ok set it to that and touch both meter leads together it should make a buzzing noises and show 00

 

[BrickbyBrick]

back view? or inside?

Back view

 

[BrickbyBrick]

ok set it to that and touch both meter leads together it should make a buzzing noises and show 00

So I’m checking for continuity?

 

[MusicSteve]

So I’m checking for continuity?

Yes

 

[MusicSteve]

Do a quick check with your DVM on diode scale. Check all junctions forwards and backwards including C-E checks in both directions.

What do you have for electronic test equipment?

You can now do what joe said 000 is a short (Bad)

and put 4-bottom ones in (update NO)