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Old 24th Apr 2017, 6:33 pm   #1
indigo.girl
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Default Ultra 6322 Radiogram restoration

I recently picked up a Ultra Model 6322 Radiogram for £20. It was completely non-functioning - just a pop when the previous owner turned it on apparently. Sounded like a good challenge to me This is what I have done to get it working again:

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1) Fault finding in the amplifier sections:
I removed the radio receiver / amplifier unit from the cabinet and connected a couple of 10 ohm resisters across the speaker connection points and tested all the voltage specs as per the service manual (obtained from the Service data CD ROM). Everything was within spec. I reconnected the speakers and added an audio signal at the gram pick up and now I had some sound coming through - so I presume during my spec checks some of the caps had had a chance to reform. Great - I now I something to work with . I had two obvious faults. I was getting most of the audio through the RHS speaker and there was a lots of hissing noise. I tackled these one at a time starting this the apparent LHS channel amplifier fault.

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2) Restoring the LH channel:
The audio from the LH speaker was weak compared to RH speaker. Reversing the speakers did not change this so I could rule out a speaker fault. I used signal injection to locate the component at fault, starting at the gram pick up and moving through the pre-amp section and into the amplifier. The fault was located around transistor VT14. Fault seen prior to VT14 but no fault when signal injected at test point 19 (VT14 collector). C72 located at the VT14 collector was then replaced (2uF electrolytic) solving the problem. For consistency I also replaced its counterpart C61 in the RH channel. I then decided to exchange all the electrolytics in both LH and RH amplifier sections (C68/79, C66/77, C65/76, C69, C70) and the three electrolytics in the radio sections (C50, C48, C54). I also replaced the big smoothing cap (2000uF, C57).

3) Resolving the background hissing noise on LH channel:
This hissing noise sounded similar to the noise made in between radio stations so I guessed at this being some kind of earthing problem. I noticed it only occurred when the 'gram' button was depressed. I had no static or indeed audio on any of the radio settings. Interestingly when I signal injected at the tape input the audio was clear without any hiss. The tape input is upstream of the pre-amp so I focused there first. Suspecting an earthing problem I used a wire grounded to the chassis and touched various points in the circuit. Grounding either the base input of the transistor (VT8) or the position after R42 (connected to the emitter) removed the static (but also stopped any audio signal getting through). I replace components one by one. C59 and R35 (on the base input line) were replaced - no effect. The two high value resistors R40 and R37 (both 4.7M) were removed from the circuit and resistance checked. R37 had gone very high (~30M) so I thought I had found the culprit. However, replacing both with new did not remove the hiss! I then swapped round the transistors from LH and RH pre-amp - no effect! R42 (100K) was in spec so the only suspect left was the variable resistor that could be adjusted to balance the channels. The service sheet stated 100K for this variable resistor but it read 300K. I removed it and replaced it with two fixed resistors (1M each as this was all I had to hand). This removed the hiss - so I suspect this pot was not earthing properly. So now I had a clear signal from both speakers

4) Renovating the turntable (Garrard 3000):
The platter could spin by hand but the pick-up arm could not be moved across to the playing position - suggesting an issue with a seized autochanger mechanism. The platter was easily removed after the c-clip was taken off. Applied heat with a hair dryer to enable the short spindle to be removed and the large cam gear etc. All cleaned and reassembled. The pick up dropping position was way out and needed major adjustment via the horizontal screw under the pick up arm. All looking good so I added power and played a record. After a few false starts the autochanger mechanism reset itself and all working nicely However, the audio was only from the LH speaker. Touching the audio wires at the back of the cart showed that the wires to the amplifier were OK - both giving a similarly loud thud.

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5) Checking the cartridge (Sonotone 9TA HC) and stylus.
I removed the stylus to take a look at the tip. I have recently bought a 1000X USB digital microscope /camera for less than a tenner from china on eBay. Its fantastic for the money. As you can see from the photo the tip was destroyed. So I replaced with a new stylus. However, I still had the issue of very low audio at the RH speaker. Luckily I had a spare Sonotone cartridge so I replaced it and this solved my problem. I did another test run with a record to then discover another issue. The audio was phenomenally loud! Comfortable only at virtually the lowest volume and even very loud when the volume was turned all the way down. At first I thought that perhaps the Sonotone cartridge was not the original supplied with this Garrard 3000 but some on-line research confirmed that it was. I swapped over with a cheap red and black generic cartridge and this too produced an extremely high volume suggesting that this wasn't a cart issue but an amplifier issue.

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6) Resolving the high volume problem:
I first suspected the volume potentiometer was the problem. I snipped out of circuit and measured its resistance and it matched the 20K quoted in the specs. The volume could be increased with the volume dial so I ruled this out as the source of the problem. The high volume was evident on both channels so the problem must be a component common to both channels - narrowing it down a lot. First I suspected the balancing variable resister that I had replaced with two 1M resistors (originally 150K each). I reduced the resistance at these positions but adding resistance in parallel but this made no difference. The only other components that were shared by both channels were electrolytics C69 and C70 and resistors R65 and R66 (on the main HT lines) but the caps had already been replaced and the resistors were within spec tolerances. So, I still don't know why the volume is so extraordinarily high. However, I have solved the problem by reducing the signal voltage that reaches the amplifier by 1/3 by using two resistors (22K and 47K) in series across each input and ground connector and connecting each pre-amp channel (at R34 & R35) between the two resistors. This reduces the volume down to an acceptable level and the volume can be usefully varied across the whole of the range now.

So, now I have a working turntable and amplifier. Future tasks will be to refurbish the wooden cabinet itself and to get the radio receiver up and running. I'll update this thread if and when I get there

Last edited by indigo.girl; 24th Apr 2017 at 6:41 pm.
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Old 24th Apr 2017, 9:04 pm   #2
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Default Re: Ultra 6322 Radiogram restoration

Nice job. A lot of people don't bother with 70s radiograms so nice to see that you're bringing this one back to life. Good luck with the cabinet & tuner.
Mark.
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Old 25th Apr 2017, 9:03 am   #3
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Default Re: Ultra 6322 Radiogram restoration

Well done very nice write up. I remember these I think the cabinet finish was like you get with Danish oil. Mick.
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Old 25th Apr 2017, 1:20 pm   #4
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Default Volume too loud from Ultra 6322 radiogram

Hi everyone,
This is an interesting and unusual problem. The volume I'm getting from my Ultra 6322 radiogram is too loud. I only have the gram working at the moment and I've solved the problem by reducing the input signal voltage using a couple of resisters as a potential divider. I'm just curious though was to why it was so loud.

Its a Garrard 3000 deck with a sonotone 9TA HC cartridge (as originally supplied) but even a bog standard red/black generic cart delivers way more signal that the amplifier can handle. Its so loud that even with the volume dial down to its absolute lowest I'm still getting enough sound to listen to it play through the speakers. The high volume is evident on both channels, the volume variable pot is within spec and its had a full re-capping. I've recently done a write up of the restoration here covering a few more details.

http://www.vintage-radio.net/forum/s...d.php?t=135983

Anyone encountered this before? Normally we get problems with too little signal rather than too much!
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Old 25th Apr 2017, 1:45 pm   #5
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Default Re: Volume too loud from Ultra 6322 radiogram

An unusual problem, as you say it's usually the othe way round. Is it the same on Radio or an externally connected Tape Deck? Make sure that potential divider has not altered the frequency curve of the 9TA.
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Old 25th Apr 2017, 2:13 pm   #6
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Default Re: Volume too loud from Ultra 6322 radiogram

In the other thread you mentioned changing the balance pot with some resistors, for a mid point balance the resistors should be 47k or 56k each and the junction of the two resistors should be connected to the supply +ve rail, which, looking at the schematic, appears to be chassis.

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Old 25th Apr 2017, 10:39 pm   #7
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Default Re: Ultra 6322 Radiogram restoration

Well done! Just one small query, if I may? Have you replaced the turntable on the 3000? Surely it should be bigger than that? Definitely not a criticism, just curious.

Barry
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Old 26th Apr 2017, 10:49 pm   #8
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Default Re: Ultra 6322 Radiogram restoration

I was wondering the same thing, browsing on google images it shows the record deck on these to be the same size as the base his record deck is sat on.
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Old 29th Apr 2017, 10:59 pm   #9
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Default Re: Ultra 6322 Radiogram restoration

Is the 3000 turntable one of Garrard's two-part platters? If so, it's missing the upper/outer part.
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Old 30th Apr 2017, 12:02 pm   #10
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Default Re: Ultra 6322 Radiogram restoration

The 3000 did have a two-part turntable, but it would be very difficult to remove the top section. It looks like the whole thing has been replaced with one from a different Garrard deck, i.e an Autoslim, or a 1000, but neither of those had a mat like this one.
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Old 30th Apr 2017, 9:03 pm   #11
indigo.girl
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Default Receiver problem with Ultra 6322 radiogram

Hi everyone,
I have been working on a restoration of the above radiogram. Lots done so far and I now have the gram, pre-amp and amp sections working well. I have now turned my attention to the VHF radio function - so far only silence.

1) I have started with checking out the voltage specs listed on the service manual. The main HT across the amplifier sections is 26V (as quoted in manual) however when I switch to VHF radio (S2B on) the HT line feeding VT5 and VT6 is only 9V (rather than 13.5V). R32 runs along this HT line but the resistance is 1K (tested, as quoted) so is not the reason for the lower than expected voltage.

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2) I have checked all the spec voltages for VT4, VT5 and VT6. Everything is much lower than quoted but I noticed 0V at the collector of VT5. I removed VT5 (AF116) and confirmed it was non-functional (short between collector and emitter). I have replaced with a used spare OC44 (suggested by radiomuseum as a replacement). I now get close to spec values at VT5. However, this change alone has only partially corrected the HT (now up 2V to 11V but still below 13.5V quoted). The collector voltage at VT4 has also reduced and is quite far from spec.

The current Vt measurements are as follows (quoted in brackets)

VT4 b= 0.45 (0.6V); c=5 (9.5V) ; e=0.15 (0.6V)
VT5 b= 0.45 (0.6V); c=11 (12.3V) ; e=0 (0.5V)
VT6 b= 1.5 (1.6V); c=9.5 (11.2V) ; e=0.12 (0.4V)

3) I noticed during voltage testing that when I touched VT5 collector or VT6 base with the voltmeter I picked up a radio broadcast - even better if I touch using a 30cm wire. The station is unknown (does not sound like a normal FM station) and is not affected by tuning via the dial. However, despite this reception I get nothing at all without the wire via the FM aerial alone. I have checked the integrity of the coils on the antennae and they are intact.

I'm at a bit of a loss now what to try next. Is there anyway to inject a radio signal at various points to see where the fault lies? I do not have any special equipment so hoping for a homemade solution

Any thoughts much appreciated
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Old 30th Apr 2017, 9:10 pm   #12
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Default Re: Ultra 6322 Radiogram restoration

Yes, I forgot to mention the platter. This is how I found it and it doesn't match the original photos of the Garrard 3000 . Here are some close ups. It's a Garrard platter though...
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Old 30th Apr 2017, 9:24 pm   #13
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Default Re: Receiver problem with Ultra 6322 radiogram

Given that VT4 is an AF115, could it be the 'tin whisker' problem? Personally I regard all AE11x devices as 'replace on sight', these days using Russian Germanium transistors, which are often to be found on eBay for around £1 each. Admittedly it's odd that on AM the voltages are normal, yet VT4's collector voltage is very low on FM, but I'd still at least check the transistor first.
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Old 30th Apr 2017, 9:27 pm   #14
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Default Re: Receiver problem with Ultra 6322 radiogram

Unfortunately an OC44 is not a good substitute for an AF116 when used as an FM IF amplifier. It is quite likely that most of the AF116s and whatever the tuner transistors are will be shorted. It is a common fix to snip the screen wires of suspected AF11*s and see if that restores operation.

Repair of the AF11*s is possible by a pulse of energy from a capacitor or by heating the base of the can up with a soldering iron, but my preferred solution is to replace them with AF12*s although other subs are possible.

There are threads about repairing AF11* transistors if you want to go that way.

Ron
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Old 1st May 2017, 12:08 am   #15
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Default Re: Receiver problem with Ultra 6322 radiogram

I've read through quite a few of the old tin whisker threads - fascinating stuff. It looks like my AF116 has shorts between Emitter and screen and also collector and screen (hence my original result of em-coll shorts). I've tried to zap the screen shorts with a 12V battery and been successful - no more shorts between screen or between em & coll. Unfortunately the transistor still doesn't work when put back into the circuit
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Old 1st May 2017, 1:13 am   #16
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Default Re: Receiver problem with Ultra 6322 radiogram

I've put the spare OC44 back into position VT5 and tested each of the SW, MW and LW. I actually get really good reception from LW - but nothing on SW, MW (or FM). So at least now I know that the shared IF stages must be working ok (or at least OK enough - since the voltages are still out of spec).
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Old 1st May 2017, 3:03 am   #17
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Default Re: Receiver problem with Ultra 6322 radiogram

VT4 has a low collector so I decided to snip the screen leg just in case this is a tin whisker problem - and yes it was

Now VT4-6 are all in spec with voltages and the correct HT voltages feed into the FM OSC and the AM OSC. With this I'm now getting reception on all AM stations and also FM.

I think I'll replace VT3-VT6 with AF12x to be sure - but I have now located the problem so I know its worth doing now

Really pleased
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Old 1st May 2017, 10:15 am   #18
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Default Re: Volume too loud from Ultra 6322 radiogram

Quote:
Originally Posted by Edward Huggins View Post
An unusual problem, as you say it's usually the othe way round. Is it the same on Radio or an externally connected Tape Deck? Make sure that potential divider has not altered the frequency curve of the 9TA.
Hi Edward - it's pretty loud on radio as well but it seems to be more extreme with the gram input. Knocking the signal down by 1/3 with a 47k:100k resistor pair has helped a lot.

Could you explain a little more about what you mean by the altering the frequency curve of the cart please? Thanks
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Old 1st May 2017, 10:17 am   #19
indigo.girl
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Default Re: Volume too loud from Ultra 6322 radiogram

Quote:
Originally Posted by ms660 View Post
In the other thread you mentioned changing the balance pot with some resistors, for a mid point balance the resistors should be 47k or 56k each and the junction of the two resistors should be connected to the supply +ve rail, which, looking at the schematic, appears to be chassis.
Hi Lawrence,
I've inserted the correct resistors now in place of the variable pot - both 47k. Makes no noticeable difference compared to when I have a pair of 1Ms in there.
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Old 1st May 2017, 10:21 am   #20
indigo.girl
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Default Re: Ultra 6322 Radiogram restoration

Thinking instead I will order a batch of BF450 Si transistors to replace the AF115 & 16s. Seems this can be a low cost alternative to the AF12xs
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