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Ok! Thanks for helping explain your readings...

[ATTACH=full]42824[/ATTACH]

Sigh, ok, to help, doesn't look like anything is truly wrong on the D8's Audio Transformer side. - You are ok, that 833 ohms - if you look on the Graphic I sent back with your details - there are two resistors that act as a Divider to help set MIDPOINT for the Mod Limiter Circuit that uses VR 4 - once modulation gets into the line that D8 feeds the Driver and Final with - the DETECTED power across C73 - starts to DROP - the Limiter circuit senses this and begins to act. It's why I asked - to help you find this problem - you may need to remove C73, R73 and R72 - this will clear up that 833 ohm reading - it should go up HIGHER in ohmic value - keep them out of the circuit until we get D8 to quit blowing up on us. - Right now, if we left them in, it can goof up the readings we want to see.

Ok, for the other confusion, to put in 0 ohms, means you have a short, dead short, if that is typed in error - you're ok, just a typo, I use 1.000 as above to show the Ohmmeter is waiting for input - the leads show infinite. IF that is what you get - you're good, let's proceed.

then...
[ATTACH=full]42825[/ATTACH]

AND

[ATTACH=full]42826[/ATTACH]
So don't forget to UNSOLDER the Driver legs too...

Once the Cage is out of the box, you can then work on realigning the transistors so they don't cause any shorts to the side of the cage.

The Cage not only dissipates the heat, it also forms a RF shield and ground using rivets and tabs soldered to the main PCB and parts that isolate DC, but keep RF flowing into and out of Ground at that cage.

You can then properly seat and check for shorts to the Cage - for if there are any, be sure to use alcohol and a wipe to remove any chips, shavings, dirt and debris from the backsides of the transistors and use FRESH white heat sink paste (no not the grey it is also CONDUCTIVE to DC too) Again clean the Hardware of goo and burrs dirt and shavings - reassemble the hardware in proper order as shown earlier and recheck for shorts.
To reduce errors in reassembly - Use your photos and mine together to help put this back properly without having further damages or bad soldering in reassembly from interfering with your work as you put this back together.
Doing this in steps will make it simpler
Clean, remove excess solder from tabs
prefit cage and check it's alignment holes for it's mounting screws
same for transistor legs so they fit thru the slots so they can be resoldered
locate any parts on the components side and make sure they get soldered to their proper places on the Cage.
Note the cage to SIDE PANEL bolt, it's Nylon and uses an insulating washer - this prevents the cage from shorting to CHASSIS in error.
Begin reassembly by;
Align tabs and transistor legs and place the cage towards it in-seated position and carefully align tabs flanges, slots and legs to their locations they feed thru on the main PCB.
Press cage gently into the main PCB and align IT'S main Lug near centerline of the board ahead of rear panel.
Align and install side-panel spacing insulator washer and Nylon bolt finger tight...
using a side to side and twisting motion - align mounting flanges to bolt holes in main PCB
install the installing Mounting bolts thru their tooth washers into main PCB - do not tighten them at this time.
review tension and alignment and reflow solder on the main Ground Mounting Tab as needed to help seat the board
- at this time tighten the main PCB to Cage Flanges bolts observing the alignment of the transistor legs fed thru their slots
verify the Cage shorts only to Main PCB Ground not to side panel or chassis ground points for main PCB Board mounting.
Reflow solder to transistors - check for shorts and they are not touching CAGE - verify all component LEGS that they are standoff from and not pinched by or otherwise shorting to cage.
Once the Cage is positively clear of shorting to tab or other issues - realign the tabs to fit the holes, legs to fit the slots and start putting this back together. See above...

Remember!

Reinstall MOD Limiter parts C73, R72 and R73 once you've verified that D8 is not shorting out to the CAGE or any parts it is NOT supposed to be connected to.

Solder in D8 - again check for shorts - finding none, do up a test keyup to make sure she shows wattage - else you may have issues with the MOSFET conversion and you'll have to go back to Bipolar 2078 to make this stable and work again - once that is complete, then look into what went wrong in the MOSFET conversion the first time and let's see if we can make it work this time.

<blockquote data-quote="Handy Andy" data-source="post: 754365" data-attributes="member: 52309">Ok! Thanks for helping explain your readings...[ATTACH=full]42824[/ATTACH]Sigh, ok, to help, doesn&#039;t look like anything is truly wrong on the D8&#039;s Audio Transformer side. - You are ok, that 833 ohms - if you look on the Graphic I sent back with your details - there are two resistors that act as a Divider to help set MIDPOINT for the Mod Limiter Circuit that uses VR 4 - once modulation gets into the line that D8 feeds the Driver and Final with - the DETECTED power across C73 - starts to DROP - the Limiter circuit senses this and begins to act. It&#039;s why I asked - to help you find this problem - you may need to remove C73, R73 and R72 - this will clear up that 833 ohm reading - it should go up HIGHER in ohmic value - keep them out of the circuit until we get D8 to quit blowing up on us. - Right now, if we left them in, it can goof up the readings we want to see.Ok, for the other confusion, to put in 0 ohms, means you have a short, dead short, if that is typed in error - you&#039;re ok, just a typo, I use 1.000 as above to show the Ohmmeter is waiting for input - the leads show infinite. IF that is what you get - you&#039;re good, let&#039;s proceed.then...[ATTACH=full]42825[/ATTACH]AND[ATTACH=full]42826[/ATTACH]
So don&#039;t forget to UNSOLDER the Driver legs too...Once the Cage is out of the box, you can then work on realigning the transistors so they don&#039;t cause any shorts to the side of the cage.The Cage not only dissipates the heat, it also forms a RF shield and ground using rivets and tabs soldered to the main PCB and parts that isolate DC, but keep RF flowing into and out of Ground at that cage.You can then properly seat and check for shorts to the Cage - for if there are any, be sure to use alcohol and a wipe to remove any chips, shavings, dirt and debris from the backsides of the transistors and use FRESH white heat sink paste (no not the grey it is also CONDUCTIVE to DC too) Again clean the Hardware of goo and burrs dirt and shavings - reassemble the hardware in proper order as shown earlier and recheck for shorts.<ul>
<li data-xf-list-type="ul">To reduce errors in reassembly - Use your photos and mine together to help put this back properly without having further damages or bad soldering in reassembly from interfering with your work as you put this back together.</li>
<li data-xf-list-type="ul">Doing this in steps will make it simpler<ul>
<li data-xf-list-type="ul">Clean, remove excess solder from tabs</li>
<li data-xf-list-type="ul">prefit cage and check it&#039;s alignment holes for it&#039;s mounting screws</li>
<li data-xf-list-type="ul">same for transistor legs so they fit thru the slots so they can be resoldered</li>
<li data-xf-list-type="ul">locate any parts on the components side and make sure they get soldered to their proper places on the Cage.</li>
<li data-xf-list-type="ul">Note the cage to SIDE PANEL bolt, it&#039;s Nylon and uses an insulating washer - this prevents the cage from shorting to CHASSIS in error.</li>
<li data-xf-list-type="ul">Begin reassembly by;<ul>
<li data-xf-list-type="ul">Align tabs and transistor legs and place the cage towards it in-seated position and carefully align tabs flanges, slots and legs to their locations they feed thru on the main PCB.</li>
<li data-xf-list-type="ul">Press&nbsp; cage gently into the main PCB and align IT&#039;S main Lug near centerline of the board ahead of rear panel.</li>
<li data-xf-list-type="ul">Align and install side-panel spacing insulator washer and Nylon bolt finger tight...</li>
<li data-xf-list-type="ul">using a side to side and twisting motion - align mounting flanges to bolt holes in main PCB </li>
<li data-xf-list-type="ul">install the installing Mounting bolts thru their tooth washers into main PCB - do not tighten them at this time.</li>
<li data-xf-list-type="ul">review tension and alignment and reflow solder on the main Ground Mounting Tab as needed to help seat the board </li>
<li data-xf-list-type="ul">- at this time tighten the main PCB to Cage Flanges bolts observing the alignment of the transistor legs fed thru their slots</li>
<li data-xf-list-type="ul">verify the Cage shorts only to Main PCB Ground not to side panel or chassis ground points for main PCB Board mounting.</li>
<li data-xf-list-type="ul">Reflow solder to transistors - check for shorts and they are not touching CAGE - verify all component LEGS that they are standoff from and not pinched by or otherwise shorting to cage.</li>
</ul></li>
</ul></li>
</ul>Once the Cage is positively clear of shorting to tab or other issues - realign the tabs to fit the holes, legs to fit the slots and start putting this back together. See above...<ul>
<li data-xf-list-type="ul">Remember!</li>
</ul>
Reinstall MOD Limiter parts C73, R72 and R73 once you&#039;ve verified that D8 is not shorting out to the CAGE or any parts it is NOT supposed to be connected to.
Solder in D8 - again check for shorts - finding none, do up a test keyup to make sure she shows wattage - else you may have issues with the MOSFET conversion and you&#039;ll have to go back to Bipolar 2078 to make this stable and work again - once that is complete, then look into what went wrong in the MOSFET conversion the first time and let&#039;s see if we can make it work this time.</blockquote>

[QUOTE="Handy Andy, post: 754365, member: 52309"] Ok! Thanks for helping explain your readings... [ATTACH=full]42824[/ATTACH] Sigh, ok, to help, doesn't look like anything is truly wrong on the D8's Audio Transformer side. - You are ok, that 833 ohms - if you look on the Graphic I sent back with your details - there are two resistors that act as a Divider to help set MIDPOINT for the Mod Limiter Circuit that uses VR 4 - once modulation gets into the line that D8 feeds the Driver and Final with - the DETECTED power across C73 - starts to DROP - the Limiter circuit senses this and begins to act. It's why I asked - to help you find this problem - you may need to remove C73, R73 and R72 - this will clear up that 833 ohm reading - it should go up HIGHER in ohmic value - keep them out of the circuit until we get D8 to quit blowing up on us. - Right now, if we left them in, it can goof up the readings we want to see. Ok, for the other confusion, to put in 0 ohms, means you have a short, dead short, if that is typed in error - you're ok, just a typo, I use 1.000 as above to show the Ohmmeter is waiting for input - the leads show infinite. IF that is what you get - you're good, let's proceed. then... [ATTACH=full]42825[/ATTACH] AND [CENTER][ATTACH=full]42826[/ATTACH] So don't forget to UNSOLDER the Driver legs too...[/CENTER] Once the Cage is out of the box, you can then work on realigning the transistors so they don't cause any shorts to the side of the cage. The Cage not only dissipates the heat, it also forms a RF shield and ground using rivets and tabs soldered to the main PCB and parts that isolate DC, but keep RF flowing into and out of Ground at that cage. You can then properly seat and check for shorts to the Cage - for if there are any, be sure to use alcohol and a wipe to remove any chips, shavings, dirt and debris from the backsides of the transistors and use FRESH white heat sink paste (no not the grey it is also CONDUCTIVE to DC too) Again clean the Hardware of goo and burrs dirt and shavings - reassemble the hardware in proper order as shown earlier and recheck for shorts. [LIST] [*][COLOR=#b30000]To reduce errors in reassembly - [I][B]Use your photos and mine together to help put this back properly without having further damages or bad soldering in reassembly from interfering with your work as you put this back together.[/B][/I][/COLOR] [*][COLOR=#b30000][I][B]Doing this in steps will make it simpler[/B][/I][/COLOR] [LIST] [*][COLOR=#b30000][I][B]Clean, remove excess solder from tabs[/B][/I][/COLOR] [*][COLOR=#b30000][I][B]prefit cage and check it's alignment holes for it's mounting screws[/B][/I][/COLOR] [*][COLOR=#b30000][I][B]same for transistor legs so they fit thru the slots so they can be resoldered[/B][/I][/COLOR] [*][COLOR=#b30000][I][B]locate any parts on the components side and make sure they get soldered to their proper places on the Cage.[/B][/I][/COLOR] [*][COLOR=#b30000][I][B]Note the cage to SIDE PANEL bolt, it's Nylon and uses an insulating washer - this prevents the cage from shorting to CHASSIS in error.[/B][/I][/COLOR] [*][COLOR=#b30000][I][B]Begin reassembly by;[/B][/I][/COLOR] [LIST] [*][COLOR=#b30000][I][B]Align tabs and transistor legs and place the cage towards it in-seated position and carefully align tabs flanges, slots and legs to their locations they feed thru on the main PCB.[/B][/I][/COLOR] [*][B][COLOR=rgb(179, 0, 0)][I]Press cage gently into the main PCB and align IT'S main Lug near centerline of the board ahead of rear panel.[/I][/COLOR][/B] [*][COLOR=#b30000][B][I]Align and install side-panel spacing insulator washer and Nylon bolt finger tight...[/I][/B][/COLOR] [*][COLOR=#b30000][B][I]using a side to side and twisting motion - align mounting flanges to bolt holes in main PCB [/I][/B][/COLOR] [*][I][B][B][COLOR=#b30000]install the installing Mounting bolts thru their tooth washers into main PCB - [/COLOR][COLOR=#ff8000]do not tighten them at this time.[/COLOR][/B][/B][/I] [*][COLOR=#b30000][I][B]review tension and alignment and reflow solder on the main Ground Mounting Tab as needed to help seat the board [/B][/I][/COLOR] [*][COLOR=#b30000][I][B]- at this time tighten the main PCB to Cage Flanges bolts observing the alignment of the transistor legs fed thru their slots[/B][/I][/COLOR] [*][COLOR=#b30000][I][B]verify the Cage shorts only to Main PCB Ground not to side panel or chassis ground points for main PCB Board mounting.[/B][/I][/COLOR] [*][COLOR=#b30000][I][B]Reflow solder to transistors - check for shorts and they are not touching CAGE - verify all component LEGS that they are standoff from and not pinched by or otherwise shorting to cage.[/B][/I][/COLOR] [/LIST] [/LIST] [/LIST] Once the Cage is positively clear of shorting to tab or other issues - realign the tabs to fit the holes, legs to fit the slots and start putting this back together. [I]See above... [/I] [LIST] [*][I][COLOR=#00b300][B]Remember![/B][/COLOR][/I] [/LIST] [INDENT][INDENT][B][I][COLOR=#0000b3]Reinstall MOD Limiter parts C73, R72 and R73 once you've verified that D8 is not shorting out to the CAGE or any parts it is NOT supposed to be connected to.[/COLOR][/I][/B][/INDENT][/INDENT] Solder in D8 - again check for shorts - finding none, do up a test keyup to make sure she shows wattage - else you may have issues with the MOSFET conversion and you'll have to go back to Bipolar 2078 to make this stable and work again - once that is complete, then look into what went wrong in the MOSFET conversion the first time and let's see if we can make it work this time. [/QUOTE]

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