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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Thu Jun 22, 2017 6:31 am
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BMW2002Ti wrote:
Ryan41018 wrote:

Pin 1 284.6
Pin 2 46.96
Pin 3 61.44
Pin 6 284.1
Pin 7 48.69
Pin 8 61.45




So the red numbers are not correct? Latest values are good?


The set of numbers of pins 1,2, 3,6,7,8 were readings that i measured after i had lifted the 330k, 22k and 680ohm legs to test them and then had resoldered them back in (meaning the readings were taken after I had reflowed the solder.

Last night when I measured the caps you listed, i didn't read all pins just 2 and 7 as you note.


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Thu Jun 22, 2017 11:09 am
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I reflowed all solder joints for the resistors and caps that are going onto the Phase Inverter and heres my new readings

Pin1 282.00
Pin2 46.70
Pin 3 60.65
Pin 6 282.4
Pin 7 48.02
Pin 8 60.62

???????????


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Thu Jun 22, 2017 12:54 pm
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Ryan41018 wrote:


The set of numbers of pins 1,2, 3,6,7,8 were readings that i measured after i had lifted the 330k, 22k and 680ohm legs to test them




Why ? This is not usefull.


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Thu Jun 22, 2017 1:04 pm
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stratele52 wrote:
Ryan41018 wrote:


The set of numbers of pins 1,2, 3,6,7,8 were readings that i measured after i had lifted the 330k, 22k and 680ohm legs to test them




Why ? This is not usefull.


The BMW Guy suggested.

The OT is not expensive, I will purchase new one? What do you think?


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Thu Jun 22, 2017 1:14 pm
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Ryan41018 wrote:
[


Why ? This is not usefull.




BMW can't suggest that

The OT is not expensive, I will purchase new one? What do you think?[/quote]

BMW Guy suggested reading voltage with resistor remove. Reading ohms yes, not voltage.

I never replace any part if I'm not sure ( with test ) it is bad.


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Thu Jun 22, 2017 1:24 pm
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stratele52 wrote:
Ryan41018 wrote:
[


Why ? This is not usefull.




BMW can't suggest that

The OT is not expensive, I will purchase new one? What do you think?


BMW Guy suggested reading voltage with resistor remove. Reading ohms yes, not voltage.

Maybe I Misunderstood? Heres his text from post below.....

The caps that have red arrows next to them. Measure VDC at green arrows.

You will need to pull one leg of each 330k-ohm resistor (orange-orange-yellow) tail of the PI (my photo has 1 meg-ohm resistors ---- (brown-black-green), as I reverted the circuit back to AB763). They are below the pink asterisks.


I never replace any part if I'm not sure ( with test ) it is bad.[/quote]


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Thu Jun 22, 2017 6:12 pm
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Ryan, the reason you are reading VDC at pins 2 and 7, is to see if the coupling caps (brown blob and blue cylinders) are leaking DC voltage. Leaking DC caps will cause the distortion you described.

There is still something wrong. You're measurement at pins 2 and 7 should be the same (or nearly the same) as the readings at the green arrows. Less than 2-3 VDC. Yet, when you re-read them --- you are getting 40+ VDC (46.7 and 48.2 VDC).

I will bow out, here and let you and Stratele fix this amp, as it seems I am just confusing you.

Good luck!


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Fri Jun 23, 2017 9:41 pm
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BMW2002Ti wrote:
Ryan, the reason you are reading VDC at pins 2 and 7, is to see if the coupling caps (brown blob and blue cylinders) are leaking DC voltage. Leaking DC caps will cause the distortion you described.

There is still something wrong. You're measurement at pins 2 and 7 should be the same (or nearly the same) as the readings at the green arrows. Less than 2-3 VDC. Yet, when you re-read them --- you are getting 40+ VDC (46.7 and 48.2 VDC).

I will bow out, here and let you and Stratele fix this amp, as it seems I am just confusing you.

Good luck!
Just watching the thread, but I have to agree w/ BMW, there should be little to no VDC on the grids of the PI(indicative of leaking caps in the previous stage). There shouldn't be a signal on the grid until you pluck a string. Not familiar w/ the schematic, haven't looked but if there is a GNFL make sure its resistors aren't blown also since it may be routed to the PI. just my 2 cents. Of course this isn't to say the O/T is good/bad at this point, the circuit doesn't appear to function as it should.


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Sat Jun 24, 2017 8:55 pm
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There will be dc voltage on the pi grids. Its coming through the cathode circuit. Your voltage is probably correct.
Lets back up a bit. Was the hi b+ voltage measured from an empty tube socket pin 3 or at the backside of the socket while it was off standby? There will be a big difference in the two methods. Regardless, I don't think that is the issue.

You can compare the 2 sides of the ot by installing just one power tube at a time and comparing the sound. It will sound funny, but the key is they should sound the same. Its unlikely to be the ot. Those failures are usually accompanied with smoke, bad smells, blown fuses and an eerie silence.
It can be useful to break the daisy chain of circuits to determine if the problem is in the preamp or power amp sections. The best place to do this is to drive a signal into the reverb return RCA jack. An adaptor to your guitar should work. It may need a boost pedal to drive it hard enough. If the problem remains, it's in the pi, power stage or speaker. If its gone, it's back up in the preamp.

If it's not tubes or speakers, I would start tapping with a sharpie marker on the coupling caps to see if one has gone microphonic. The 250pf treble caps will be sensitive, but the rest should be quiet. It's a common issue with the disc caps coupling to the phase inverter.
Good luck.


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Sun Jun 25, 2017 7:07 pm
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Tim, thanks for redeeming me. I will do this test and see what comes up.

Thanks a bunch!


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Wed Jun 28, 2017 1:40 pm
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TimsAudio wrote:
There will be dc voltage on the pi grids. Its coming through the cathode circuit. Your voltage is probably correct.
Lets back up a bit. Was the hi b+ voltage measured from an empty tube socket pin 3 or at the backside of the socket while it was off standby? There will be a big difference in the two methods. Regardless, I don't think that is the issue.

You can compare the 2 sides of the ot by installing just one power tube at a time and comparing the sound. It will sound funny, but the key is they should sound the same. Its unlikely to be the ot. Those failures are usually accompanied with smoke, bad smells, blown fuses and an eerie silence.
It can be useful to break the daisy chain of circuits to determine if the problem is in the preamp or power amp sections. The best place to do this is to drive a signal into the reverb return RCA jack. An adaptor to your guitar should work. It may need a boost pedal to drive it hard enough. If the problem remains, it's in the pi, power stage or speaker. If its gone, it's back up in the preamp.

If it's not tubes or speakers, I would start tapping with a sharpie marker on the coupling caps to see if one has gone microphonic. The 250pf treble caps will be sensitive, but the rest should be quiet. It's a common issue with the disc caps coupling to the phase inverter.
Good luck.



Tim the amp sounds normal until I get to 4 on volume, heres what I have done as prescribed in your post:

1) Pulled one 6V6 at time and volume drops a bit and fuzziness kicks in just a bit but same overall output per se.

2) Tapped coupling caps (blue bulgy) and no mircrophonic noise

3) Inserted my guitar (with rca coupler /adapter) into the input with no result, but i do get signal inserting it into the Reverb Output RCA jack?

4) Tesing V6 on standby I get the following:

Pin 1---- (0.048_
Pin 2----(-0.0640)
Pin 3----(0.016)
Pin 6----(-0.590)
Pin 7----(-0.552)
Pin 8----(0.008)

with standby switched up (all power on)

Pin 1----(289.4)
Pin 2----(48.05)
Pin 3----(62.40)
Pin 6----(290.3)
Pin 7----(49.49)
Pin 8----(62.30)

Thanks, Tim


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Wed Jun 28, 2017 2:21 pm
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Seems your new stby/on V6 readings are good.
Your output section tubes,caps and resistors all checked out fine.
You installed new 16uf electrolytic, what brand and power rating?
To go back further, what wattage Celestion speaker did you install and was it new or used?
You probably need to go through the entire signal path to eliminate any other problems all caps, resistors, potentiometers, switches etc. if your not ready to replace the O/T as stratele suggested.
Doing the work is time consuming but will be beneficial if other issues remain.


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Wed Jun 28, 2017 3:07 pm
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sfceric64 wrote:
Seems your new stby/on V6 readings are good.
Your output section tubes,caps and resistors all checked out fine.
You installed new 16uf electrolytic, what brand and power rating?
To go back further, what wattage Celestion speaker did you install and was it new or used?
You probably need to go through the entire signal path to eliminate any other problems all caps, resistors, potentiometers, switches etc. if your not ready to replace the O/T as stratele suggested.
Doing the work is time consuming but will be beneficial if other issues remain.



Caps - Sprague Atom 16uf - 500V
Celestion - 50W (but even a Fender out of my other Fender amp sux) and it was brand new.

When the bass tone control is down it sounds just "oK" but turning it up sounds crappy as sampled in the Video.


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Wed Jun 28, 2017 6:23 pm
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In your demo you were in normal channel, have you tried other tubes in V1? You should probably look at all the preamp caps/resistors.
When you installed the PS Caps did you replace all the coupling electrolytic caps on the board also?


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Wed Jun 28, 2017 9:31 pm
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sfceric64 wrote:
In your demo you were in normal channel, have you tried other tubes in V1? You should probably look at all the preamp caps/resistors.
When you installed the PS Caps did you replace all the coupling electrolytic caps on the board also?


I did not replace any coupling electrolytic caps but was just reading the values on them to order online.

Does anyone know of a good source? And can I use axial type capacitors with the same values?


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