BIAS Transformer T203, and Associated Circuitry - Revision history

Gordonp at 20:39, 11 November 2020

2020-11-11T20:39:49Z

@@ Line 71: / Line 71: @@
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 [[Repair|Back to Repair]]

Gordonp at 17:47, 4 June 2020

2020-06-04T17:47:14Z

← Older revision		Revision as of 17:47, 4 June 2020
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	<p>		<p>
	<span>		<span>
	[[File:C209_c210.jpg\|500px\|thumb\|~~left~~]]		[[File:C209_c210.jpg\|500px\|thumb\|right]]
	C209 and C210 upgraded, mechanically secured, and labelled		C209 and C210 upgraded, mechanically secured, and labelled
	A pair of new capacitors - same 50uF, but uprated from 150VDC to 250VDC, working temperature range -20C to +85C. The capacitors are labelled, as is the T203 Bias-Transformer centre-tap connection (I may be the next person helped by this clear labelling!). An additional layer of clear heat-shrink was added to ensure HV sturdiness, and the nylon mounting clamps are spaced a further 8mm off the chassis.		A pair of new capacitors - same 50uF, but uprated from 150VDC to 250VDC, working temperature range -20C to +85C. The capacitors are labelled, as is the T203 Bias-Transformer centre-tap connection (I may be the next person helped by this clear labelling!). An additional layer of clear heat-shrink was added to ensure HV sturdiness, and the nylon mounting clamps are spaced a further 8mm off the chassis.
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	<span>		<span>
	[[File:Whoops_terminal_strip.jpg\|500px\|thumb\|~~right~~]]		[[File:Whoops_terminal_strip.jpg\|500px\|thumb\|left]]
	<p>I broke this brittle terminal-strip.</p>		<p>I broke this brittle terminal-strip.</p>
	<p>While working underneath the Relay Shelf, I broke a terminal-strip. Unable to find an exact replacement, I opted for two smaller terminal-strips, turned 90-degrees to the original. And, this allowed me to neatly separate the two functions on the original: the Step-Start circuit, and the BIAS connections.</p>		<p>While working underneath the Relay Shelf, I broke a terminal-strip. Unable to find an exact replacement, I opted for two smaller terminal-strips, turned 90-degrees to the original. And, this allowed me to neatly separate the two functions on the original: the Step-Start circuit, and the BIAS connections.</p>
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	<span>		<span>
	[[File:C203_step_start.jpg\|500px\|thumb\|~~left~~]]		[[File:C203_step_start.jpg\|500px\|thumb\|right]]
	Replacement C203 step-start capacitor, securely mounted.		Replacement C203 step-start capacitor, securely mounted.

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	[[File:Underside_relayshelf_tidy.jpg\|500px\|thumb\|~~right~~]]		[[File:Underside_relayshelf_tidy.jpg\|500px\|thumb\|left]]
	Underside of Relay Shelf, now tidied.		Underside of Relay Shelf, now tidied.

Gordonp at 17:46, 4 June 2020

2020-06-04T17:46:33Z

@@ Line 20: / Line 20: @@
 When I look at the previous T203, especially the type of insulation and the under-chassis un-laced wiring, it makes me wonder if my burned T203 was already a replacement...? Hmmm... I will thoroughly check each and every circuit associated with this transformer, because it seems possible that this BIAS transformer, in this amp, has been an on-going issue. I intend to firmly quash all the problems now!
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 </p>

Gordonp at 17:32, 4 June 2020

2020-06-04T17:32:38Z

← Older revision		Revision as of 17:32, 4 June 2020
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			[[Repair\|Back to Repair]]

			[[Screen Supply Overhaul\|On to Screen Supply Overhaul]]

Gordonp at 17:29, 4 June 2020

2020-06-04T17:29:43Z

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 I replaced C203, making sure it's well-secured, and well-insulated. There should never be a problem of fat-fingers causing future short-circuits! The new C203 is rated at 200VDC, which improves on the original 150VDC rating, especially comforting considering how the incoming AC line-voltage has increased over the decades: designed with 115VAC/230VAC in mind, my current voltage is ~6% higher at 122/244 (just measured it).
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Gordonp at 17:27, 4 June 2020

2020-06-04T17:27:43Z

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 <p>While working underneath the Relay Shelf, I broke a terminal-strip. Unable to find an exact replacement, I opted for two smaller terminal-strips, turned 90-degrees to the original. And, this allowed me to neatly separate the two functions on the original: the Step-Start circuit, and the BIAS connections.</p>
 </span>
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Gordonp at 17:24, 4 June 2020

2020-06-04T17:24:04Z

← Older revision		Revision as of 17:24, 4 June 2020
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	<p>
	<span>		<span>
	[[File:Whoops_terminal_strip.jpg\|500px\|thumb\|right]]		[[File:Whoops_terminal_strip.jpg\|500px\|thumb\|right]]
	I broke this brittle terminal-strip		<p>I broke this brittle terminal-strip.</p>
	While working underneath the Relay Shelf, I broke a terminal-strip. Unable to find an exact replacement, I opted for two smaller terminal-strips, turned 90-degrees to the original. And, this allowed me to neatly separate the two functions on the original: the Step-Start circuit, and the BIAS connections.		<p>While working underneath the Relay Shelf, I broke a terminal-strip. Unable to find an exact replacement, I opted for two smaller terminal-strips, turned 90-degrees to the original. And, this allowed me to neatly separate the two functions on the original: the Step-Start circuit, and the BIAS connections.</p>
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Gordonp at 17:23, 4 June 2020

2020-06-04T17:23:06Z

← Older revision		Revision as of 17:23, 4 June 2020
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	C209 and C210 upgraded, mechanically secured, and labelled		C209 and C210 upgraded, mechanically secured, and labelled
	A pair of new capacitors - same 50uF, but uprated from 150VDC to 250VDC, working temperature range -20C to +85C. The capacitors are labelled, as is the T203 Bias-Transformer centre-tap connection (I may be the next person helped by this clear labelling!). An additional layer of clear heat-shrink was added to ensure HV sturdiness, and the nylon mounting clamps are spaced a further 8mm off the chassis.		A pair of new capacitors - same 50uF, but uprated from 150VDC to 250VDC, working temperature range -20C to +85C. The capacitors are labelled, as is the T203 Bias-Transformer centre-tap connection (I may be the next person helped by this clear labelling!). An additional layer of clear heat-shrink was added to ensure HV sturdiness, and the nylon mounting clamps are spaced a further 8mm off the chassis.
			</span>
			</p>
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			<p>
			<span>
			[[File:Whoops_terminal_strip.jpg\|500px\|thumb\|right]]
			I broke this brittle terminal-strip
			While working underneath the Relay Shelf, I broke a terminal-strip. Unable to find an exact replacement, I opted for two smaller terminal-strips, turned 90-degrees to the original. And, this allowed me to neatly separate the two functions on the original: the Step-Start circuit, and the BIAS connections.
	</span>		</span>
	</p>		</p>

Gordonp at 17:20, 4 June 2020

2020-06-04T17:20:57Z

← Older revision		Revision as of 17:20, 4 June 2020
Line 20:		Line 20:

	When I look at the previous T203, especially the type of insulation and the under-chassis un-laced wiring, it makes me wonder if my burned T203 was already a replacement...? Hmmm... I will thoroughly check each and every circuit associated with this transformer, because it seems possible that this BIAS transformer, in this amp, has been an on-going issue. I intend to firmly quash all the problems now!		When I look at the previous T203, especially the type of insulation and the under-chassis un-laced wiring, it makes me wonder if my burned T203 was already a replacement...? Hmmm... I will thoroughly check each and every circuit associated with this transformer, because it seems possible that this BIAS transformer, in this amp, has been an on-going issue. I intend to firmly quash all the problems now!
			</span>
			</p>
			<br clear=all>

			<p>
			<span>
			[[File:C209_c210.jpg\|500px\|thumb\|left]]
			C209 and C210 upgraded, mechanically secured, and labelled
			A pair of new capacitors - same 50uF, but uprated from 150VDC to 250VDC, working temperature range -20C to +85C. The capacitors are labelled, as is the T203 Bias-Transformer centre-tap connection (I may be the next person helped by this clear labelling!). An additional layer of clear heat-shrink was added to ensure HV sturdiness, and the nylon mounting clamps are spaced a further 8mm off the chassis.
	</span>		</span>
	</p>		</p>

Gordonp at 17:14, 4 June 2020

2020-06-04T17:14:52Z

← Older revision		Revision as of 17:14, 4 June 2020
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			<p>
⚫	[[File:30s-1_replacement_bias_transfomer.jpg\|500px\|thumb\|left~~\|new Hammond PWDP-13042 bias-supply replacement transformer~~]]
			<span>
		⚫	[[File:30s-1_replacement_bias_transfomer.jpg\|500px\|thumb\|left]]

	The replacement Peter Dahl transfomer! It took 2-1/2 months from initiating the order, until delivery. I made the actual purchase through Digi-Key, who provided the customer-facing fulfilment for Hammond.		The replacement Peter Dahl transfomer! It took 2-1/2 months from initiating the order, until delivery. I made the actual purchase through Digi-Key, who provided the customer-facing fulfilment for Hammond.
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	<li>rectified and filtered DC runs through the HV-interlock circuit</li>		<li>rectified and filtered DC runs through the HV-interlock circuit</li>
	<li>rectified and filtered DC is used to operate the Antenna Relays (when an external short-to-ground occurs - often an Amp T/R relay inside the exciter)</li>		<li>rectified and filtered DC is used to operate the Antenna Relays (when an external short-to-ground occurs - often an Amp T/R relay inside the exciter)</li>
			</span>
			</p>
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			<p>
⚫	[[File:30s1_t203_laced_installed.jpg\|500px\|thumb\|~~left~~]]
			<span>
		⚫	[[File:30s1_t203_laced_installed.jpg\|500px\|thumb\|right]]
	T203 installed, laced and soldered into it's new home!		T203 installed, laced and soldered into it's new home!

	When I look at the previous T203, especially the type of insulation and the under-chassis un-laced wiring, it makes me wonder if my burned T203 was already a replacement...? Hmmm... I will thoroughly check each and every circuit associated with this transformer, because it seems possible that this BIAS transformer, in this amp, has been an on-going issue. I intend to firmly quash all the problems now!		When I look at the previous T203, especially the type of insulation and the under-chassis un-laced wiring, it makes me wonder if my burned T203 was already a replacement...? Hmmm... I will thoroughly check each and every circuit associated with this transformer, because it seems possible that this BIAS transformer, in this amp, has been an on-going issue. I intend to firmly quash all the problems now!
			</span>
			</p>
	<br clear=all>		<br clear=all>