Search results

The transistor(s) with the flying leads/small PCB attached. I don't have the circuit diagram available therefore, I'm unable to supply the transistor designation(s) - there's a Vbe multiplier transistor on each heatsink. EDIT: TR125 & TR126 (from the picture in post 90).

In the supplied picture, the Vbe multiplier transistor type is NOT visible (it may be a limitation of the camera). ALL the other heatsink mounted transistor types are clearly visible. It suggests that you've mounted the transistor incorrectly. The metal tab (under the thin plastic coating)...

There may be (are) errors in the service manual. The 22000uF capacitors are rated @ 69V max working voltage. 1000008635.jpg From memory, the normal voltages on the 22000uF caps are approximately + & - 63V. The voltages will be lower when using the bulb limiter (mandatory). Good Luck! You'll...

I heard this on the radio today. 2 great voices/singers.

It's a Philips DC motor with a servo attached - straight outta Eindhoven! The same/similar motor is used in the FONS CQ30 & FONS International, and various Philips models: e.g. 222, 312 & 406. Regardless of what you may read on social media platforms or hear from sewing circle members, the...

Indeed! It may be the lighting, but your supplied picture suggests that >50% of the replaced components have dry joints. That's undesirable and needs to be corrected. And the 5k6 resistors supply the LEDs. That's highly undesirable - there should only be DC on these white wires and if...

I see you're back in... The above is an extremely worrying statement for the following reasons; 1) It defies ALL known 'physics' & OHMS LAW! 2) No other reasons are necessary. Regardless of how good the storytellers tale is, resistors NEVER i.e: NOT EVER decrease in value (unless they...

Whilst I was a 'fanboi', I never actually saw him perform live (but I have seen the left-most backing singer perform live - twice!). In 1974, Diamond Dogs was my first Bowie album purchase, then I bought his back catalogue. For me, 1976 (it was a great year for music) Station to Station is his...

If you want the +/- 22V supplies at the power amp to be closer to spec whilst on the 58W bulb, lift R667 & R668. If you need more volts, also lift R683 & R684. Again, please check the voltages at ALL terminals of TR101, TR103, TR105, TR107 & TR109 - things may have changed! Good Luck...

Many thanks for the info... Maybe... Maybe not... Please confirm the voltages @ the BASES, EMITTERS & COLLECTORS of TR111 & TR113. Also, please check the voltages at ALL terminals of TR101, TR103, TR105, TR107 & TR109 - things may have changed since you isolated various sections of the...

I've reviewed this thread starting @ post #1 instead of post #114. Notes/findings... Post #12 By OPT, I hope/assume (dangerous) that you were referring to TR157 & TR159. Please don't use acronyms - they cause confusion (and don't exist outside the Hipster world). Always use the circuit...

Please check it and ensure that it's functional. In post #205, you inadvertently proved that the Class B stage transistors were doing what they should be doing on a positive half-cycle. If you were to reconnect R157 to the junction of R167 & R169 and disconnect the other end of R157 from...

Nice work... The Long Shot has been eliminated. Go for the 'less brutal' option (above) and note the changes... If there's nothing significant, BRUTE FORCE will be required. You'll discover the issue. Good Luck! ADDENDUM: Lift R157 - it appears to be connected to the junction of R167 & R169...

Nice info... The BASE voltages should be close to 0V! There is no obvious source of +33V. Look for errant solder blobs or other unwanted conductive detritus. You can (BRUTE) force 0V on the BASES by connecting both of them to the 0V busbar. However, you may see smoke being released (that'll help...

As the previous fault-finding exercises have yielded nothing, it's time to 'up your game'! Whilst on the bulb limiter, try the following; 1) Lift one end of R171, R173 & R159. 2) Measure the B, E & C voltages @ TR127, TD129, TR139, TR141, TR157 & TR159. 3) Measure the voltage @ L101. Please...

The BASE voltages @ TR115 & TR117 suggest that both transistors should be conducting, but the EMITTER voltages say there's 0mA flowing through R153 & R155. Bizarre! Long shot... check TR133 and associated components in the ZDR network. N.B. R229 is not in the ZDR network, but I believe that...

Thanks for the info... In a previous request/picture, you clipped the voltages present @ TR113. Please post the B,C & E voltages plus the voltage across R151. As you've noted, TR115 has the same voltage @ B & E. It's either a piece of wire or it's off. You've also posted that TR117 has -18V2 @...

I didn't notice that until now (even though you clearly stated the -18.2V ' TR117 C & E). That does appear to be a problem. Thinks... EDIT: Please measure and post the voltages @ TR118 B,C & E.

If the modifications made no change to the current fault, there's no need to modify the other (functional) channel. Just measure as is - fully-functional. And reverse the modifications to the duff channel. Good Luck!

You're isolating the power amp section from previous stage(s) influence and removing the DC offset correction servo. You're removing variables - you can't solve problems when there are too many variables at play. Nice reasoning... And the reason is currently unknown. I believe that you've...

Deleted! (partial post)

Many thanks for the measurements (the above voltages are different from your previous update), although I still disagree with your assertion regarding TR111's orientation - there'd be no way you'd get your previous set of voltage readings. In order to progress, you'll need to expand the...

However, your supplied voltage readings of +40V2 @ BASE and +40V8 @ EMITTER, suggest that TR111 is correctly orientated - it's a PNP transistor! What does appear to be abnormal is -25V7 @ BASE & EMITTER of TR115. BUTT (and it's a big one), if your measurements are correct, there's 'gun-smoke'...

Whilst on the bulb limiter, please measure the voltages at each side of R319, R133, R135 & R163. Please measure the Base, Collector and Emitter voltages of TR105, TR107, TR109, TR111 & TR115. N.B. The voltages shown on the circuit diagram may be incorrect... Please post the results. Good Luck!

STOP!! (Avionic has already caught this...) Set the quiescent current to its absolute minimum (Class B operation) - it's SAFE to do so! Then proceed... N.B. A beer is OK during troubleshooting... Once the issue(s) have been resolved, several beers should be consumed whilst listening to the...