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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
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3rd Dec 2022, 2:48 pm | #1 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,587
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Truvox PD-99 R2R Checkout
Brought this quite some time ago from a Forum member, its operational status was unknown, this is the first time I have found time to have a look.
Appears to be in quite good condition for its age, identical size as my PD-95. Early 1960's vintage, 4 track, 3 speed (3 motors), max 7" spools, Stereo, 3 heads, recorder with no internal speaker or power amp. This is another model from the Series 90. Unlike the PD-95 it does not have a hardwired mains cable but a 3 pin mini Bulgin mains socket on the rear panel (or top panel if machine used vertically), maybe a previous user modification, no mains cable came with the machine. Powered up slowly all OK and various light indicators light up. Tape counter belt intact and tape counter works. None of the tape transport piano keys will latch down so have to hold them down for Play, Rewind and Fast Forward operation. With 7" tape loaded, Fast wind in both directions works but when the respective fast wind key is released, the spool brakes appear to be slow to action and sometimes loose tape spools off before the spools come to stop. Also very noisy when stopping from fast winding, particularly Fast Forward wind, I think it is the capstan motor that is noisy. Play really struggles, tape is being driven by the good condition pinch roller but the take up spool often does not rotate to take up the tape. Went to plug in headphones to see if any playback sound but discovered there is no headphone/output socket (there are phono outputs). Not yet checked HT voltages. The preamplifier board assembly is metal encased, this will make it impossible to measure valve voltages etc without removing the complete chassis from the case. There is an L shaped cover that can be removed from the preamp but only would give limited acces to some components and impractical then to try and identify what components they are. There is a 5 pin DIN plug cable wired into the preamp connector, this I assume is a previous user modification, I will probably remove this. The heads cover is from another Truvox machine, it has the cut-outs for 2 slide switches (Erase cut & Track selection on PD-95) these switches are not on the heads cover on the PD-99. The cover is too shallow to fit so someone has fitted homemade spacers under the cover securing screws. David Last edited by DMcMahon; 3rd Dec 2022 at 2:58 pm. |
4th Dec 2022, 7:09 pm | #2 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,587
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Re: Truvox PD-99 R2R Checkout
Removed complete chassis from the wooden case to investigate the tape transport keys not latching down.
Unlike my PD-95 the PD-99 can stand vertically without support due to the pre-amp module acting like a base panel. However, the heavy weight of the chassis makes the chassis lean backward (as per photo 1) putting a lot of stress on the 2 brackets that secure the preamp module to the rest of the chassis, while working on it I put a block of wood in to help take the strain as per photo 2. Fixed the non-latching keys by cleaning and lubricating the small latching lever. In photo 3 the lever is not latched and photo 4 it is latched, It was a bit odd, the lever was not seized or even stiff but was not moving across when buttons pressed down. Photo 5 shows the whole key mechanism that was surprisingly lacking virtually any grease, just a couple of smal dried up bits of grease (the PD-95 by comparison had loads of grease). I later greased it well Also found that the Take Up spool brake was not reliably braking due to being too stiff, slackened off lock nut and oiled shaft, now OK. Checking Play operation again find that it sometimes works and quite often does not work, have not proved it yet but think it is due to erratic operation of the Play switch not switching mains power through to the Capstan motor. On top 7 1/2 ips tape speed there is some low level rumbling during play, think it is the capstan motor at fault. On Fast Forward wind there is loud rumbling when spool is braked when stop is pressed. At one stage thought it was the flywheel rumbling but after putting ear to screwdriver on both, it definitely appears to be the capstan motor. Rewind is relatively quiet (capstan motor and flywheel not rotating during Rewind). So to investigate the capstan motor rumbling would need to remove the complete motor drive assembly which looks quite difficult. First will check out if Playback and record work. David |
4th Dec 2022, 9:31 pm | #3 |
Dekatron
Join Date: Jun 2013
Location: East Sussex, UK.
Posts: 3,315
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Re: Truvox PD-99 R2R Checkout
I don’t think any Truvox of that era was meant to stand or be used upright. Almost all were used flat and many didn’t have any means of holding tape spools in place other than gravity.
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4th Dec 2022, 10:49 pm | #4 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,587
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Re: Truvox PD-99 R2R Checkout
I also think of this range of machines being used horizontally.
However see 7.1 in the photo attachment (taken from Truvox Series 90 Instruction Manual) this seems to indicate that they were capable of being used vertically. The Hublock spool retainers do hold the spools securely when operated vertically. The tape operations done in Post 1 were with recorder being run horizontally. The tape operations in Post 2 were done with unit vertical. Because the internal mains cable to the Bulgin mains socket is quite short, it is difficult operate this unit horizontally when out of its case. A good point made, so I will recheck any of the operational tape transport fault symptoms (like rumbling capstan) with unit back in its case for horizontal operation before considering removing the motor (s) drive assembly. David Last edited by DMcMahon; 4th Dec 2022 at 11:06 pm. Reason: Typo correction |
5th Dec 2022, 10:14 am | #5 | |
Octode
Join Date: Aug 2006
Location: Rye, East Sussex, UK.
Posts: 1,647
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Re: Truvox PD-99 R2R Checkout
Quote:
Upright or flat operation certainly had an impact on motor bearings and most 7"/10-1/2" semi-pro machines advised best practice accordingly. |
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8th Dec 2022, 6:06 pm | #6 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,587
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Re: Truvox PD-99 R2R Checkout
Retested tape transport operation with the chassis sitting horizontal, the rumbling during Play and Fast Forward wind when chassis vertical, does not occur with horizontal running.
Annoyingly the keys not latching issue has intermittently returned, the same problem as before, in that the latching lever does not always move. Checked out the main HT voltages all OK, was only able to check a small number of the valve electrode voltages, because so difficult to access the valve bases and locate/identify the associated components. Checked playback of tape with recordings on, by connecting the phono output sockets to external amplifier, no sound at all was obtained. Checked recording by connecting line signals from external amplifier into the Rad/PU phono sockets, got good record signal on the right channel VU meter but nothing on the left channel. Playback of the recording gave no sound at all. David |