Re: [drakelist] AC-4R upgrades

"Ken Winterling" <[EMAIL PROTECTED]> made an utterance to the drakelist gang -- According to Tom this supply also had an open 10K HV bleeder/load resistor. Whatever caused it to fail may have caused the 220K resistor to fail. I

Re: [drakelist] AC-4R upgrades

"Ken Winterling" <[EMAIL PROTECTED]> made an utterance to the drakelist gang -- Tom, There is a 220K bleeder/load resistor, R8, across the medium B+, 250V, supply to ground. If it is open the medium B+ will be pulled up toward

Re: [drakelist] AC-4R upgrades

An open 220k bleeder resistor makes sense. I guess you could check that by disconnecting it and checking the resistance. Makes me wonder what would cause it to fail. Assuming 250 volts it would need to dissipate 0.28 watt. If it's a 1/2 watt carbon composition resistor, it might have increased i

Re: [drakelist] AC-4R upgrades

I lifted the 220k bleeder from ground and it measured about 230k, probably not enough of a change to account for such a high voltage. I soldered the bleeder back to ground and untied the connection between the 10k 25w load resistor between the HV and 250v supply. The 250v supply now reads a reason

Re: [drakelist] AC-4R upgrades

ar as I'm concerned I would avoid the original > AC-3 > in daily use. You wisely chose to use it on the test bench instead. > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] ] On Behalf Of Donnie Garrett > Sent: Tuesday, December 12, 2006

Re: [drakelist] AC-4R upgrades

expensive. As far as I'm concerned I would avoid the original AC-3 in daily use. You wisely chose to use it on the test bench instead. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Donnie Garrett Sent: Tuesday, December 12, 2006 5:27 AM To: To

Re: [drakelist] AC-4R upgrades

AIL PROTECTED] On Behalf Of Donnie Garrett Sent: Tuesday, December 12, 2006 5:27 AM To: Tom Taylor Cc: drakelist@www.zerobeat.net Subject: Re: [drakelist] AC-4R upgrades "Donnie Garrett" <[EMAIL PROTECTED]> made an utterance to the drakelist gang -

Re: [drakelist] AC-4R upgrades

"Donnie Garrett" <[EMAIL PROTECTED]> made an utterance to the drakelist gang -- Tom: I have one of the early AC3 supplies that used a HV choke. Garey K4OAH and I had a lot of discussions about its design some time back after I d

RE: [drakelist] AC-4R upgrades

IL PROTECTED] On Behalf Of Donnie Garrett Sent: Tuesday, December 12, 2006 5:27 AM To: Tom Taylor Cc: drakelist@www.zerobeat.net Subject: Re: [drakelist] AC-4R upgrades "Donnie Garrett" <[EMAIL PROTECTED]> made an utterance to the drakelist gang

Re: [drakelist] AC-4R upgrades

ge- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Donnie Garrett Sent: Tuesday, December 12, 2006 5:27 AM To: Tom Taylor Cc: drakelist@www.zerobeat.net Subject: Re: [drakelist] AC-4R upgrades "Donnie Garrett" <[EMAIL PROTECTED]> made an utterance to the drakel

Re: [drakelist] AC-4R upgrades

Hey, thanks for the tip! I just checked the vertical ceramic load resistor and it is open, just like yours. Last night I decided to just replace all the electrolytic capacitors under the chassis (and the diodes as well). Before clipping out the old parts, I took voltage measurements so I'd have a

Re: [drakelist] AC-4R upgrades

ROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Donnie Garrett Sent: Tuesday, December 12, 2006 5:27 AM To: Tom Taylor Cc: drakelist@www.zerobeat.net Subject: Re: [drakelist] AC-4R upgrades "Donnie Garrett" <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---

[drakelist] AC-4R upgrades

I have a number of Drake A, B, and C twin combos. I decided to upgrade all the power supplies with AC-4R boards. Since most of the caps are now 30 to 40 years old, I don't want to risk a bias supply going out and ruining the finals or some short ruining the transformers. I order a bunch of blank b

Re: [drakelist] AC-4R upgrades

Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang -- Tom - I don't think so. I'm one of the worst for keeping things "original", but I don't think these units are THAT rare. I guess you could keep the

Re: [drakelist] AC-4R upgrades

Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang -- Tom - Yeah, that's typical. You're taking the right approach, since a failure in the Bias supply can take out more than just the finals, even if the

Re: [drakelist] AC-4R upgrades

Would I be destroying something of historical worth by converting that early, and perhaps rare AC-3, to a modern supply? That would mean removing the choke and essentially all the parts underneath the chassis? The AC-4R (as I'm sure you're aware) replaces everything but the transformer, the cables