HR2510 Bias adjustment? No go...

[baconater4749]

When going to set the bias, the adjustments VR112, and VR113 won't adjust at all. I have 1.40mah, and zero on the second adjustment we'd nt. Any one have this issue? I am stumped, thank you for any ideas or fix, Mark. KB9GTB

 

[nomadradio]

First thing comes to mind is the aftermath of a previous breakdown. Unless both the final and driver are the factory originals, one or the other or both has failed and been replaced some time or another in the last 25 years.

When a final or driver fails, it can cause collateral damage, mostly to other components on the input side of the transistor. This can affect the DC-bias current feeding the base of either transistor and disrupt the meter reading.

Leads me to ask what prompted you to check this? Might save time if you mentioned the nature of a fault that got your attention to begin with.

73

 

[Mark A Bradley]

Howdy, the radio stopped receive and transmit, so I went to go give it a alignment, I did a total recap job, and 30+ years old, never had it done. When I went to calibrate the bias, this is what I found, and I did pull the final and driver and they checked out with a analog meter. This is when I stopped, I pulled the Pll board, had a bad blown diode, went ahead and changed the Voltage Regulators, and recapped the Pll board, and capped the display board. After all of that, the radio still will not receive or transmit.

What I did is went to check the SMD parts on t he back of the PLL board, and found a few bad Capacitor, and had to order them from Amazon, so I went ahead and ordered a $39.00 booklet of these little things. I want to replace those bad parts, and see if the pots for adjusting the Frequency will move the Frequency. I hear a lot of people bitching that adjusting the Frequency on the PLL board, the pots will not adjust, they do nothing, unless you start screwing in other pots that are not on the alignment list.

So this is why I brought up that question, I cannot adjust the Bios, and one of the adjustment is a 0Mah, so I need to figure that out, and see why the radio does not do anything. I have 2 more of these 2510 and they are doing the same thing, and one need a Pll board, Talk soon,any ideas on fixing the whole radio,,LOL,Mark 73's KB9GTB

 

[Rogerbird1]

Howdy, the radio stopped receive and transmit, so I went to go give it a alignment, I did a total recap job, and 30+ years old, never had it done. When I went to calibrate the bias, this is what I found, and I did pull the final and driver and they checked out with a analog meter. This is when I stopped, I pulled the Pll board, had a bad blown diode, went ahead and changed the Voltage Regulators, and recapped the Pll board, and capped the display board. After all of that, the radio still will not receive or transmit.

What I did is went to check the SMD parts on t he back of the PLL board, and found a few bad Capacitor, and had to order them from Amazon, so I went ahead and ordered a $39.00 booklet of these little things. I want to replace those bad parts, and see if the pots for adjusting the Frequency will move the Frequency. I hear a lot of people bitching that adjusting the Frequency on the PLL board, the pots will not adjust, they do nothing, unless you start screwing in other pots that are not on the alignment list.

So this is why I brought up that question, I cannot adjust the Bios, and one of the adjustment is a 0Mah, so I need to figure that out, and see why the radio does not do anything. I have 2 more of these 2510 and they are doing the same thing, and one need a Pll board, Talk soon,any ideas on fixing the whole radio,,LOL,Mark 73's KB9GTB

Hello,
First question, are you measuring the Bias in USB mode?

Ok, that may have been a dumb question.. Sorry..

No bias adjustment, as was stated above could be damage caused by a failing component. Have you checked the Bias Diodes?
I would lift one side out of the circuit and Ohm them out .
Simple test and result, reads like a diode, probably OK, shorted or open.. need to replace.
Next I would check the glue status on the torroids. If it is Brown or Black, or corroded anywhere, the torroids will need to be removed and cleaned and checked for continuity.

Make sure the soldering is clean and has no shorts.

Let me know if I can help,

Roger
'Rogerbird'
(rogerbird1 @ aim . com)

 

[Mark A Bradley]

Hello,
First question, are you measuring the Bias in USB mode?

Ok, that may have been a dumb question.. Sorry..

No bias adjustment, as was stated above could be damage caused by a failing component. Have you checked the Bias Diodes?
I would lift one side out of the circuit and Ohm them out .
Simple test and result, reads like a diode, probably OK, shorted or open.. need to replace.
Next I would check the glue status on the torroids. If it is Brown or Black, or corroded anywhere, the torroids will need to be removed and cleaned and checked for continuity.

Make sure the soldering is clean and has no shorts.

Let me know if I can help,

Roger
'Rogerbird'
(rogerbird1 @ aim . com)

Sorry for the late reply. No,where are the Diodes, or shall I say which ones are the Bias Diodes, never really messed with a 2510. I fixed the display board, a Recap, and a new Display Pll Chip, now it does not shut off any more. Can you help give me a few hints on this Bias section, I have been looking at the Schematics, I have been busy, had no time to investigate, will have time Wed, and Thurs, all day. For now, need to know which are the Bios adjustment Diodes, thank you, will keep updates,,THANKS

 

[Dmans]

Please disregard the “state” of this unit as these 2 diodes may be the only good parts left in it!


73
David

 

[Rogerbird1]

Please disregard the “state” of this unit as these 2 diodes may be the only good parts left in it!
View attachment 43939

73
David

also a great example of the torroid coil glue.